LAKE BUENA VISTA, FLA. – Academic surgeons earn an average of 10% or $1.3 million less in gross income across their lifetime than surgeons in private practice, an analysis shows.

Some surgical specialties fare better than others, with academic neurosurgeons having the largest reduction in gross income at $4.2 million (–24.2%), while academic pediatric surgeons earn $238,376 more (1.53%) than their private practice counterparts. They were the only ones to do so.

Several academic surgical specialties did not make the 10% average, including trauma surgeons whose lifetime earnings were down 12% or $2.4 million, vascular surgeons at 13.8% or $1.7 million, and surgical oncologists at 12.2% or $1.3 million.

Patrice Wendling/Frontline Medical Group

“The concern that we have is that the academic surgeons are where the education of the future lies,” lead study author Dr. Joseph Martin Lopez said at the annual scientific assembly of the Eastern Association for the Surgery of Trauma (EAST).

Every year a new class of surgeons is faced with the question of academic practice or private practice, but they are also struggling with increasing student loan debt and longer training as more surgical residents elect to enter fellowship rather than general practice.

This growing financial liability coupled with declining physician reimbursement could rapidly shift physician practices and thus threaten the fiscal viability of certain surgical fields or academic surgical careers.

“The more financially irresponsible you make it to become an academic surgeon, the more we put at risk our current mode of training,” Dr. Lopez of Wake Forest University in Winston-Salem, N.C., said.

To account for additional factors outside gross income, the investigators ran the numbers using a second analysis, a net present value calculation, however, and came up with roughly the same salary gap to contend with.

Net present value (NPV) calculations are commonly used in business to calculate the profitability of an investment and also have been used in the medical field to gauge return on investment for various careers. The NPV calculation accounts for positive and negative cash flows over the entire length of a career, using in this case, a 5% discount rate and adjusting for inflation, Dr. Lopez explained.

Both the lifetime gross income and 5% NPV calculation used data from the Medical Group Management Association’s 2012 physician salary report, the 2012 Association of American Medical Colleges physician salary report, and the AAMC database for residency and fellow salary.

The NPV assumed a career length of 37-39 years, based on a retirement age of 65 years for all specialties. Positive cash flows included annual salary less federal income tax. Negative cash flows included the average principal for student loans, according to the AAMC, and interest at 5%, the average for the three largest student loan lenders in 2014, he said. Student loan repayment was calculated for a fixed-rate loan to be paid over 25 years beginning after residency or any required fellowship.

The average reduction in 5% NPV across surgical specialties for an academic surgeon versus a privately employed surgeon was 12.8% or $246,499, Dr. Lopez said.

Once again, academic neurosurgeons had the largest reduction in 5% NPV at 25.5% or a loss of $619,681, followed closely by trauma surgeons (23% or $381,179) and surgical oncologists (16.3% or $256,373). Academic pediatric surgeons had the smallest reduction in 5% NPV at 4.2% or $88,827.

During a discussion of the provocative poster, attendees questioned whether it was fair to say that private surgeons make more money without acknowledging the risk they face, compared with surgeons employed in an academic setting.

Dr. Lopez countered that, increasingly, even private surgeons are no longer truly private surgeons.

“More and more surgical groups are being bought up by hospitals, and even the private surgical groups are being bought up by hospitals, which does stabilize your income to some extent,” he said.

“We all still have [relative value unit] goals to meet and RVU incentives that make it so you can get paid a little more, but it’s something that’s a consideration. It is a risk-reward to be a private surgeon. Depending on how your contract is structured or how your group decides to pay the partners, it may be that if you don’t take very much call or take that many cases, you’ll end up on the short end of the stick.”

Dr. Ben L. Zarzaur, a general surgeon at Indiana University in Indianapolis who comoderated the poster discussion, pointed out that market pressures unaccounted for in the model can dramatically influence a surgeon’s salary over a lifetime.

Dr. Lopez agreed, citing how the increasing number of stent placements by cardiologists, for example, has impacted the bottom line of cardiothoracic surgeons. The NPV calculation was specifically used, however, because it gets at market forces such as inflation and return on investment, not addressed by gross income figures alone.

Finally, Dr. Zarzaur turned and asked the relatively young crowd what they would do if offered $600,000 a year, but had to work 110 hours a week or could get $250,000 and work only 40 hours a week.

Most responded that they’d choose the former to repay their student loans and then switch to the lower-paying position.

Responders made much of job satisfaction, work-life balance, and the ability of surgeons in academic practice to take time away from clinical work to conduct research, their ready access to continuing medical education, and their ability to educate the next generation of surgeons.

“Any time we see this academic-private disparity, you have to think about these secondary gains,” Dr. Zarzaur said.

“This is really interesting work. It gets into why we choose what we do, why we’d take $600,000, work 110 hours a week, and get our rear ends kicked. The flip side is, if I saw this, why would you ever go into academics? But people still choose to do it. I’m in academics so there’s a bias, but we choose to do it anyway up to a point. I don’t know where that point is, but up to a point we do.”

[email protected]

LAKE BUENA VISTA, FLA. – Academic surgeons earn an average of 10% or $1.3 million less in gross income across their lifetime than surgeons in private practice, an analysis shows.

Some surgical specialties fare better than others, with academic neurosurgeons having the largest reduction in gross income at $4.2 million (–24.2%), while academic pediatric surgeons earn $238,376 more (1.53%) than their private practice counterparts. They were the only ones to do so.

Several academic surgical specialties did not make the 10% average, including trauma surgeons whose lifetime earnings were down 12% or $2.4 million, vascular surgeons at 13.8% or $1.7 million, and surgical oncologists at 12.2% or $1.3 million.

Patrice Wendling/Frontline Medical Group

“The concern that we have is that the academic surgeons are where the education of the future lies,” lead study author Dr. Joseph Martin Lopez said at the annual scientific assembly of the Eastern Association for the Surgery of Trauma (EAST).

Every year a new class of surgeons is faced with the question of academic practice or private practice, but they are also struggling with increasing student loan debt and longer training as more surgical residents elect to enter fellowship rather than general practice.

This growing financial liability coupled with declining physician reimbursement could rapidly shift physician practices and thus threaten the fiscal viability of certain surgical fields or academic surgical careers.

“The more financially irresponsible you make it to become an academic surgeon, the more we put at risk our current mode of training,” Dr. Lopez of Wake Forest University in Winston-Salem, N.C., said.

To account for additional factors outside gross income, the investigators ran the numbers using a second analysis, a net present value calculation, however, and came up with roughly the same salary gap to contend with.

Net present value (NPV) calculations are commonly used in business to calculate the profitability of an investment and also have been used in the medical field to gauge return on investment for various careers. The NPV calculation accounts for positive and negative cash flows over the entire length of a career, using in this case, a 5% discount rate and adjusting for inflation, Dr. Lopez explained.

Both the lifetime gross income and 5% NPV calculation used data from the Medical Group Management Association’s 2012 physician salary report, the 2012 Association of American Medical Colleges physician salary report, and the AAMC database for residency and fellow salary.

The NPV assumed a career length of 37-39 years, based on a retirement age of 65 years for all specialties. Positive cash flows included annual salary less federal income tax. Negative cash flows included the average principal for student loans, according to the AAMC, and interest at 5%, the average for the three largest student loan lenders in 2014, he said. Student loan repayment was calculated for a fixed-rate loan to be paid over 25 years beginning after residency or any required fellowship.

The average reduction in 5% NPV across surgical specialties for an academic surgeon versus a privately employed surgeon was 12.8% or $246,499, Dr. Lopez said.

Once again, academic neurosurgeons had the largest reduction in 5% NPV at 25.5% or a loss of $619,681, followed closely by trauma surgeons (23% or $381,179) and surgical oncologists (16.3% or $256,373). Academic pediatric surgeons had the smallest reduction in 5% NPV at 4.2% or $88,827.

During a discussion of the provocative poster, attendees questioned whether it was fair to say that private surgeons make more money without acknowledging the risk they face, compared with surgeons employed in an academic setting.

Dr. Lopez countered that, increasingly, even private surgeons are no longer truly private surgeons.

“More and more surgical groups are being bought up by hospitals, and even the private surgical groups are being bought up by hospitals, which does stabilize your income to some extent,” he said.

“We all still have [relative value unit] goals to meet and RVU incentives that make it so you can get paid a little more, but it’s something that’s a consideration. It is a risk-reward to be a private surgeon. Depending on how your contract is structured or how your group decides to pay the partners, it may be that if you don’t take very much call or take that many cases, you’ll end up on the short end of the stick.”

Dr. Ben L. Zarzaur, a general surgeon at Indiana University in Indianapolis who comoderated the poster discussion, pointed out that market pressures unaccounted for in the model can dramatically influence a surgeon’s salary over a lifetime.

Dr. Lopez agreed, citing how the increasing number of stent placements by cardiologists, for example, has impacted the bottom line of cardiothoracic surgeons. The NPV calculation was specifically used, however, because it gets at market forces such as inflation and return on investment, not addressed by gross income figures alone.

Finally, Dr. Zarzaur turned and asked the relatively young crowd what they would do if offered $600,000 a year, but had to work 110 hours a week or could get $250,000 and work only 40 hours a week.

Most responded that they’d choose the former to repay their student loans and then switch to the lower-paying position.

Responders made much of job satisfaction, work-life balance, and the ability of surgeons in academic practice to take time away from clinical work to conduct research, their ready access to continuing medical education, and their ability to educate the next generation of surgeons.

“Any time we see this academic-private disparity, you have to think about these secondary gains,” Dr. Zarzaur said.

“This is really interesting work. It gets into why we choose what we do, why we’d take $600,000, work 110 hours a week, and get our rear ends kicked. The flip side is, if I saw this, why would you ever go into academics? But people still choose to do it. I’m in academics so there’s a bias, but we choose to do it anyway up to a point. I don’t know where that point is, but up to a point we do.”

[email protected]

LAKE BUENA VISTA, FLA. – Academic surgeons earn an average of 10% or $1.3 million less in gross income across their lifetime than surgeons in private practice, an analysis shows.

Some surgical specialties fare better than others, with academic neurosurgeons having the largest reduction in gross income at $4.2 million (–24.2%), while academic pediatric surgeons earn $238,376 more (1.53%) than their private practice counterparts. They were the only ones to do so.

Several academic surgical specialties did not make the 10% average, including trauma surgeons whose lifetime earnings were down 12% or $2.4 million, vascular surgeons at 13.8% or $1.7 million, and surgical oncologists at 12.2% or $1.3 million.

Patrice Wendling/Frontline Medical Group

“The concern that we have is that the academic surgeons are where the education of the future lies,” lead study author Dr. Joseph Martin Lopez said at the annual scientific assembly of the Eastern Association for the Surgery of Trauma (EAST).

Every year a new class of surgeons is faced with the question of academic practice or private practice, but they are also struggling with increasing student loan debt and longer training as more surgical residents elect to enter fellowship rather than general practice.

This growing financial liability coupled with declining physician reimbursement could rapidly shift physician practices and thus threaten the fiscal viability of certain surgical fields or academic surgical careers.

“The more financially irresponsible you make it to become an academic surgeon, the more we put at risk our current mode of training,” Dr. Lopez of Wake Forest University in Winston-Salem, N.C., said.

To account for additional factors outside gross income, the investigators ran the numbers using a second analysis, a net present value calculation, however, and came up with roughly the same salary gap to contend with.

Net present value (NPV) calculations are commonly used in business to calculate the profitability of an investment and also have been used in the medical field to gauge return on investment for various careers. The NPV calculation accounts for positive and negative cash flows over the entire length of a career, using in this case, a 5% discount rate and adjusting for inflation, Dr. Lopez explained.

Both the lifetime gross income and 5% NPV calculation used data from the Medical Group Management Association’s 2012 physician salary report, the 2012 Association of American Medical Colleges physician salary report, and the AAMC database for residency and fellow salary.

The NPV assumed a career length of 37-39 years, based on a retirement age of 65 years for all specialties. Positive cash flows included annual salary less federal income tax. Negative cash flows included the average principal for student loans, according to the AAMC, and interest at 5%, the average for the three largest student loan lenders in 2014, he said. Student loan repayment was calculated for a fixed-rate loan to be paid over 25 years beginning after residency or any required fellowship.

The average reduction in 5% NPV across surgical specialties for an academic surgeon versus a privately employed surgeon was 12.8% or $246,499, Dr. Lopez said.

Once again, academic neurosurgeons had the largest reduction in 5% NPV at 25.5% or a loss of $619,681, followed closely by trauma surgeons (23% or $381,179) and surgical oncologists (16.3% or $256,373). Academic pediatric surgeons had the smallest reduction in 5% NPV at 4.2% or $88,827.

During a discussion of the provocative poster, attendees questioned whether it was fair to say that private surgeons make more money without acknowledging the risk they face, compared with surgeons employed in an academic setting.

Dr. Lopez countered that, increasingly, even private surgeons are no longer truly private surgeons.

“More and more surgical groups are being bought up by hospitals, and even the private surgical groups are being bought up by hospitals, which does stabilize your income to some extent,” he said.

“We all still have [relative value unit] goals to meet and RVU incentives that make it so you can get paid a little more, but it’s something that’s a consideration. It is a risk-reward to be a private surgeon. Depending on how your contract is structured or how your group decides to pay the partners, it may be that if you don’t take very much call or take that many cases, you’ll end up on the short end of the stick.”

Dr. Ben L. Zarzaur, a general surgeon at Indiana University in Indianapolis who comoderated the poster discussion, pointed out that market pressures unaccounted for in the model can dramatically influence a surgeon’s salary over a lifetime.

Dr. Lopez agreed, citing how the increasing number of stent placements by cardiologists, for example, has impacted the bottom line of cardiothoracic surgeons. The NPV calculation was specifically used, however, because it gets at market forces such as inflation and return on investment, not addressed by gross income figures alone.

Finally, Dr. Zarzaur turned and asked the relatively young crowd what they would do if offered $600,000 a year, but had to work 110 hours a week or could get $250,000 and work only 40 hours a week.

Most responded that they’d choose the former to repay their student loans and then switch to the lower-paying position.

Responders made much of job satisfaction, work-life balance, and the ability of surgeons in academic practice to take time away from clinical work to conduct research, their ready access to continuing medical education, and their ability to educate the next generation of surgeons.

“Any time we see this academic-private disparity, you have to think about these secondary gains,” Dr. Zarzaur said.

“This is really interesting work. It gets into why we choose what we do, why we’d take $600,000, work 110 hours a week, and get our rear ends kicked. The flip side is, if I saw this, why would you ever go into academics? But people still choose to do it. I’m in academics so there’s a bias, but we choose to do it anyway up to a point. I don’t know where that point is, but up to a point we do.”

[email protected]

Open-surgery knot tying is easily learned and performed, but knot tying during arthroscopic procedures can be both challenging and frustrating. According to Burkhart and colleagues,^1,2 knot security is defined as the effectiveness of the knot in resisting slippage when load is applied, whereas loop security is the effectiveness in maintaining a tight suture loop while a knot is being tied. Arthroscopic knots commonly begin with an initial slipknot locked in place with a series of half-hitches. During arthroscopic surgery, the surgeon usually must tie an arthroscopic knot to obtain secure tissue fixation, an essential component of soft-tissue repair. A secure knot provides optimal tissue apposition for healing, which will ultimately improve functional outcome. For a knot to be effective, it must have both knot security and loop security. Knot security depends on knot configuration, the coefficient of friction, ductility, handling properties, solubility and diameter of suture material, internal interference, slack between throws, and surgeon experience. Tissue fluid and tissue reaction to suture material may affect knot and loop security.

The ideal knot would be easy to tie and reproducible and would not slip or stretch before tissue is healed. The ideal suture material should provide adequate strength to hold soft tissue in an anatomically correct position until healing can occur. It should also be easily and efficiently manipulated by arthroscopic means when tissues are being secured with knots and secure suture loops. Studies have been conducted to evaluate the security of knots tied with arthroscopic techniques, knot configurations, and suture materials, and these investigations have often evaluated knot performance under single load-to-failure (LTF) test scenarios and cyclic loading in vitro (dry environment) in a room-temperature environment.^2-10 To our knowledge, few if any attempts have been made to simulate in situ conditions at body temperature when testing knot security. The fluid environment and the temperature could potentially affect the effectiveness of knots, as knot security depends on friction, internal interference, and slack between throws.¹

We conducted a study to evaluate biomechanical performance (knot security, loop security) during destructive testing of several different suture materials with various arthroscopic knot configurations. The study was performed under in vitro (dry environment) and in situ (wet environment) conditions by surgeons with different levels of experience.

Materials and Methods

This investigation was conducted at the Orthopaedic Research Institute at Via Christi Health in Wichita, Kansas. The study compared 4 different suture materials tied with 3 different commonly used arthroscopic knots by 3 surgeons with different levels of experience. The 4 types of braided polyblend polyethylene sutures were Fiberwire (Arthrex, Naples, Florida), ForceFiber (Stryker, San Jose, California), Orthocord (DePuy-Mitek, Warsaw, Indiana), and Ultrabraid (Smith & Nephew, Memphis, Tennessee). Each suture material was tied with 3 arthroscopic knots—static surgeon’s knot, Weston knot,¹¹ Tennessee slider¹²—and a series of 3 reversing half-hitches on alternating posts (RHAPs) (Figure 1). These knots were chosen based on studies showing they have a higher maximum force to failure when combined with 3 RHAPs.^{1,2,5,9,13-17}

We evaluated performer variability with the help of 3 investigator-surgeons who differed in their level of experience tying arthroscopic knots. This experience was defined on the basis of total number of arthroscopies performed—one of the most important factors predicting basic arthroscopic skills. Our surgeon A was a sports medicine fellowship–trained surgeon with 10 years of experience and a significant number of arthroscopies performed annually (350); surgeon B was a sports medicine fellowship–trained surgeon with 3 years of experience and an annual arthroscopy volume of more than 250 procedures; and surgeon C was a third-year orthopedic resident with about 100 arthroscopies performed.

All knots were tied on a standardized post 30 mm in circumference, which provided a consistent starting circumference for each knot and replicated the suture loop created during arthroscopic rotator cuff repair. All knots were tied using standard arthroscopic techniques, with a standard knot pusher and a modified arthroscopic cannula, in a dry environment (Figure 2). Servohydraulic materials testing system instruments (model 810; MTS Systems, Eden Prairie, Minnesota) were used to test the knot security and loop security of each combination of knots and suture types. Two round hooks (diameter, 3.9 mm) were attached to the actuator and the load cell (Figure 3). Loops were preloaded to 6 N to avoid potential errors caused by slack in the loops or by stretching of suture materials and to provide a well-defined starting point for data recording.

LTF testing was performed for both in vitro and in situ conditions using 10 samples of each suture–knot configuration for each mechanical testing. Each type of testing was conducted for a total of 240 suture–knot combinations per investigator. For the in vitro condition, each suture loop was initiated with 5 preconditioning loading cycles, from 6 N to 30 N at 1 Hz. The load was then applied continuously at a crosshead speed of 1 mm/s until “clinical failure” (3 mm crosshead displacement). We used this criterion for clinical failure, as studies have indicated that 3 mm is the point at which tissue apposition is lost.^15,18-21 After the crosshead reached the 3-mm displacement, the loads (under load control) were held for 5 minutes at maximum load, and then load was applied continuously at a crosshead speed of 1 mm/s until complete structure failure. Load and displacement data were collected at a frequency of 20 Hz.

For the in situ condition, the same test parameters were used, except that each combination of the suture loop was preloaded to 6 N and soaked in physiologic solution bath (human blood plasma) at 37°C (body temperature) for 24 hours before testing in an effort to simulate the aqueous medium in vivo after surgery. The in situ tests were performed under physiologic solution maintained at 37°C to approximate postoperative physical conditions.

Statistical Analysis

Means and standard deviations of the knot security and loop security achieved by the surgeons (different experience levels) were calculated for each test configuration and each test condition. These values were used to determine the statistical relevance of the difference in arthroscopic loop security and knot security in each configuration. One-way analysis of variance (ANOVA) performed with SPSS Version 19.0 software (SPSS, Chicago, Illinois) with the least significant difference (LSD) multiple comparisons post hoc analysis was used to determine if any observed differences between the types of braided polyblend sutures, the types of sliding knots, the test conditions (in vitro, in situ), and the levels of surgeon experience were significant for each knot configuration. The level of significance of differences was set at P < .001.

Results

Figure 4 shows the mean maximum clinical failure load (3 mm of displacement) of different arthroscopic knot configurations for different braided polyblend sutures by surgeons of different levels of experience. In the comparison of biomechanical performance (knot and loop security) under in vitro and in situ conditions, no significant difference was detected when Ultrabraid suture material was used, regardless of surgeon experience, for all knot configurations. For surgeon B, there was no significant difference between in vitro and in situ conditions for any knot configurations or suture materials. When Orthocord suture material was used, Weston knots tied by surgeon A, and static surgeon’s knots by surgeons A and C, resulted in a significant difference between the in vitro and in situ conditions. When ForceFiber suture material was used, only Weston knots and Tennessee slider knots by surgeon A had a significant difference between in vitro and in situ conditions. Weston knots by surgeon A exhibited a significant difference between in vitro and in situ conditions, except when Ultrabraid suture material was used.

Surgeon C’s Tennessee slider knots with all polyblend sutures showed significantly lower loads at clinical failure compared with all the other knot configurations and with knots tied by the other 2 surgeons under both in vitro and in situ conditions. Overall, knots tied by surgeon B had higher clinical failure load than knots tied by the other 2 surgeons.

Figure 5 shows the mean ultimate failure load (complete structural failure) of different arthroscopic knot configurations for different braided polyblend sutures by surgeons of different levels of experience. Knots tied with Orthocord suture material had the overall lower ultimate failure load compared with other suture materials, whereas knots tied with Ultrabraid suture material had the overall highest ultimate failure load. However, the ultimate failure loads for all the knots tied using any suture material, regardless of surgeon experience, were more than 61 N, which is the estimated minimum required ultimate load per suture during a maximum muscle contraction.¹

Figure 6 shows the percentage of knot slipping at constant clinical failure load. Orthocord and Fiberwire suture materials had the lowest incidence of knot slippage. Surgeon C had complete knot slippage at constant clinical failure load using ForceFiber with the Weston knot and Ultrabraid with the Tennessee slider knot. When using Ultrabraid or ForceFiber, surgeons A and C had at least 2 knots slip for all knot configurations.

Discussion

Optimization of knot security for any given knot configuration, suture material, and surgeon experience level during arthroscopic knot tying is crucial.^1-10 Our study results showed that, under single LTF test scenarios, there was a significant difference between in vitro and in situ conditions with respect to both knot configuration and surgeon experience level, except when Ultrabraid suture material was used. Arthroscopic sliding knots are lockable or nonlockable.^7,12 With lockable sliding knots, slippage may be prevented by tensioning the wrapping limb, which distorts the post in the distal part of the knot, resulting in a kink in the post, thereby increasing the internal interference that increases the resistance of the knot from backing off. With nonlockable sliding knots, slippage may be prevented by the tight grip of the wrappings around the initial post.⁷ The static surgeon’s knot and the Tennessee slider knot are nonlockable, whereas the Weston knot is a distal lockable sliding knot. Compared with nonlockable sliding knots, lockable sliding knots cause less suture loop enlargement. In 1976, Tera and Aberg²² studied the strength of knotted thread for 12 different types of suture knots combined with 11 types of suture material. They conducted their study 1 week after suture material was inserted into the subcutaneous tissue of rabbits. Their results show a greater propensity for certain suture materials to slip when tested in an aqueous environment. In 1998, Babetty and colleagues²³ used Wistar rats to compare the in vivo strength, knot efficiency, and knot security of 4 types of sliding knots and to assess tissue reaction as a result of knot configuration, knot volume, and suture size. They found that 4/0 knots lost more strength than 2/0 knots did, and they concluded that the tissue response to all the knots, except 2/0 nylon, was similar. They indicated that the inflammatory sheath volume varied with knot volume, suture size, and knot configuration. Our results agree with observations that exposure to an aqueous environment alters the force to clinical failure of comparable suture and knot configurations.

In addition, our findings indicate that surgeon familiarity with certain knots has a major effect on knot security. The difference in our 3 surgeons’ levels of familiarity with certain knots was somewhat minimized by the knot tying they practiced before submitting knots for testing. The findings contrast with those of Milia and colleagues,²⁴ who conducted a biomechanical study to determine the effect of experience level on knot security. They compared an experienced arthroscopic shoulder surgeon with a junior-level orthopedic resident surgeon and concluded that experience did not affect knot security. However, the knots in their study were tied by hand, not through an arthroscopic cannula with instruments. Our findings suggest that both experienced and less experienced orthopedic residents should be encouraged to practice arthroscopic knot tying in a nonsurgical environment in order to become comfortable tying arthroscopic knots.

Braided nonabsorbable polyester suture traditionally has been found to be stronger than monofilament absorbable polydioxanone (PDS) and to have less slippage potential.^8,9,25 Several studies have determined that the braided polyblend sutures now commonly used for arthroscopic knots have better strength profiles over more traditional materials.^12,26,27 Orthocord has a dyed absorbable core (PDS, 68%), an undyed nonabsorbable ultrahigh-molecular-weight polyethylene (UHMWPE, 32%) sleeve, and a polyglactin coating.^9,10 Both Ultrabraid and ForceFiber are made with braided UHMWPE and have just a few variations in weave patterns. Fiberwire has a multifiber UHMWPE core covered with braided polyester suture material. Several biomechanical studies^25,26,28 have evaluated different arthroscopic sliding knot configurations with different suture materials, and all concluded that a surgeon who is choosing an arthroscopic repair technique should know the differences in suture materials and the knot strengths afforded by different knot configurations, as suture material is an important aspect of loop security. Our findings agree with their findings, that suture materials have a major effect on knot security, even with a series of 3 RHAPs, as in theory the RHAPs should minimize suture friction, internal interference, and slack between knot loops—emphasizing the effect of material selection. Furthermore, our findings also indicated that suture materials with a core in their design (Fiberwire, Orthocord) tend to have the lowest incidence of knot slippage. We had suspected that suture surface characteristics and suture construction could be important factors in knot slippage.

Our experimental design had its limitations. First, although we simulated factors such as temperature, plasma environment, and surgeon experience, tying a knot on a standardized post (30 mm in circumference) differed from what is typically done clinically. Second, the metal hooks used in this study were not compressible and did not interpose in the substance of the knot as soft tissue does in the clinical setting. Third, knots were tied with no tension against the sutures, whereas clinically knots are tied under tension as tissues are pulled together in reconstructions. Fourth, it was assumed that soaking in a physiologic solution bath (human blood plasma) at 37°C (body temperature) for 24 hours before testing was sufficient to simulate the aqueous medium in vivo after surgery, but these parameters may not represent conditions in a patient who has just undergone an arthroscopic shoulder repair and adheres to a passive motion protocol. Fifth, there was no blinding of knot type, and there was no randomization of tying order or testing order. Sixth, only a single LTF test was performed, and incremental cyclic loading can be more useful, as it has long been recognized as a leading source of failure in orthopedic repairs.

Conclusion

These study results advance our overall understanding of the biomechanics of the different knot configurations and loop security levels of the different braided polyblend sutures used in arthroscopic procedures through LTF in both in vitro and in situ conditions. Overall, no suture material was superior to any other in a fluid environment, as the combination of aqueous environment and surgeon level of experience with arthroscopic knot tying has a major effect on knot security under single LTF test scenarios. However, our data showed that Ultrabraid suture material had no effect on knot effectiveness over the fluid environment and the temperature. Furthermore, the study showed that the Tennessee slider knot had the steepest learning curve. This study may provide an alternative arthroscopic knots option for soft-tissue repair in which use of certain suture materials is limited.

Open-surgery knot tying is easily learned and performed, but knot tying during arthroscopic procedures can be both challenging and frustrating. According to Burkhart and colleagues,^1,2 knot security is defined as the effectiveness of the knot in resisting slippage when load is applied, whereas loop security is the effectiveness in maintaining a tight suture loop while a knot is being tied. Arthroscopic knots commonly begin with an initial slipknot locked in place with a series of half-hitches. During arthroscopic surgery, the surgeon usually must tie an arthroscopic knot to obtain secure tissue fixation, an essential component of soft-tissue repair. A secure knot provides optimal tissue apposition for healing, which will ultimately improve functional outcome. For a knot to be effective, it must have both knot security and loop security. Knot security depends on knot configuration, the coefficient of friction, ductility, handling properties, solubility and diameter of suture material, internal interference, slack between throws, and surgeon experience. Tissue fluid and tissue reaction to suture material may affect knot and loop security.

The ideal knot would be easy to tie and reproducible and would not slip or stretch before tissue is healed. The ideal suture material should provide adequate strength to hold soft tissue in an anatomically correct position until healing can occur. It should also be easily and efficiently manipulated by arthroscopic means when tissues are being secured with knots and secure suture loops. Studies have been conducted to evaluate the security of knots tied with arthroscopic techniques, knot configurations, and suture materials, and these investigations have often evaluated knot performance under single load-to-failure (LTF) test scenarios and cyclic loading in vitro (dry environment) in a room-temperature environment.^2-10 To our knowledge, few if any attempts have been made to simulate in situ conditions at body temperature when testing knot security. The fluid environment and the temperature could potentially affect the effectiveness of knots, as knot security depends on friction, internal interference, and slack between throws.¹

We conducted a study to evaluate biomechanical performance (knot security, loop security) during destructive testing of several different suture materials with various arthroscopic knot configurations. The study was performed under in vitro (dry environment) and in situ (wet environment) conditions by surgeons with different levels of experience.

Materials and Methods

This investigation was conducted at the Orthopaedic Research Institute at Via Christi Health in Wichita, Kansas. The study compared 4 different suture materials tied with 3 different commonly used arthroscopic knots by 3 surgeons with different levels of experience. The 4 types of braided polyblend polyethylene sutures were Fiberwire (Arthrex, Naples, Florida), ForceFiber (Stryker, San Jose, California), Orthocord (DePuy-Mitek, Warsaw, Indiana), and Ultrabraid (Smith & Nephew, Memphis, Tennessee). Each suture material was tied with 3 arthroscopic knots—static surgeon’s knot, Weston knot,¹¹ Tennessee slider¹²—and a series of 3 reversing half-hitches on alternating posts (RHAPs) (Figure 1). These knots were chosen based on studies showing they have a higher maximum force to failure when combined with 3 RHAPs.^{1,2,5,9,13-17}

We evaluated performer variability with the help of 3 investigator-surgeons who differed in their level of experience tying arthroscopic knots. This experience was defined on the basis of total number of arthroscopies performed—one of the most important factors predicting basic arthroscopic skills. Our surgeon A was a sports medicine fellowship–trained surgeon with 10 years of experience and a significant number of arthroscopies performed annually (350); surgeon B was a sports medicine fellowship–trained surgeon with 3 years of experience and an annual arthroscopy volume of more than 250 procedures; and surgeon C was a third-year orthopedic resident with about 100 arthroscopies performed.

All knots were tied on a standardized post 30 mm in circumference, which provided a consistent starting circumference for each knot and replicated the suture loop created during arthroscopic rotator cuff repair. All knots were tied using standard arthroscopic techniques, with a standard knot pusher and a modified arthroscopic cannula, in a dry environment (Figure 2). Servohydraulic materials testing system instruments (model 810; MTS Systems, Eden Prairie, Minnesota) were used to test the knot security and loop security of each combination of knots and suture types. Two round hooks (diameter, 3.9 mm) were attached to the actuator and the load cell (Figure 3). Loops were preloaded to 6 N to avoid potential errors caused by slack in the loops or by stretching of suture materials and to provide a well-defined starting point for data recording.

LTF testing was performed for both in vitro and in situ conditions using 10 samples of each suture–knot configuration for each mechanical testing. Each type of testing was conducted for a total of 240 suture–knot combinations per investigator. For the in vitro condition, each suture loop was initiated with 5 preconditioning loading cycles, from 6 N to 30 N at 1 Hz. The load was then applied continuously at a crosshead speed of 1 mm/s until “clinical failure” (3 mm crosshead displacement). We used this criterion for clinical failure, as studies have indicated that 3 mm is the point at which tissue apposition is lost.^15,18-21 After the crosshead reached the 3-mm displacement, the loads (under load control) were held for 5 minutes at maximum load, and then load was applied continuously at a crosshead speed of 1 mm/s until complete structure failure. Load and displacement data were collected at a frequency of 20 Hz.

For the in situ condition, the same test parameters were used, except that each combination of the suture loop was preloaded to 6 N and soaked in physiologic solution bath (human blood plasma) at 37°C (body temperature) for 24 hours before testing in an effort to simulate the aqueous medium in vivo after surgery. The in situ tests were performed under physiologic solution maintained at 37°C to approximate postoperative physical conditions.

Statistical Analysis

Means and standard deviations of the knot security and loop security achieved by the surgeons (different experience levels) were calculated for each test configuration and each test condition. These values were used to determine the statistical relevance of the difference in arthroscopic loop security and knot security in each configuration. One-way analysis of variance (ANOVA) performed with SPSS Version 19.0 software (SPSS, Chicago, Illinois) with the least significant difference (LSD) multiple comparisons post hoc analysis was used to determine if any observed differences between the types of braided polyblend sutures, the types of sliding knots, the test conditions (in vitro, in situ), and the levels of surgeon experience were significant for each knot configuration. The level of significance of differences was set at P < .001.

Results

Figure 4 shows the mean maximum clinical failure load (3 mm of displacement) of different arthroscopic knot configurations for different braided polyblend sutures by surgeons of different levels of experience. In the comparison of biomechanical performance (knot and loop security) under in vitro and in situ conditions, no significant difference was detected when Ultrabraid suture material was used, regardless of surgeon experience, for all knot configurations. For surgeon B, there was no significant difference between in vitro and in situ conditions for any knot configurations or suture materials. When Orthocord suture material was used, Weston knots tied by surgeon A, and static surgeon’s knots by surgeons A and C, resulted in a significant difference between the in vitro and in situ conditions. When ForceFiber suture material was used, only Weston knots and Tennessee slider knots by surgeon A had a significant difference between in vitro and in situ conditions. Weston knots by surgeon A exhibited a significant difference between in vitro and in situ conditions, except when Ultrabraid suture material was used.

Surgeon C’s Tennessee slider knots with all polyblend sutures showed significantly lower loads at clinical failure compared with all the other knot configurations and with knots tied by the other 2 surgeons under both in vitro and in situ conditions. Overall, knots tied by surgeon B had higher clinical failure load than knots tied by the other 2 surgeons.

Figure 5 shows the mean ultimate failure load (complete structural failure) of different arthroscopic knot configurations for different braided polyblend sutures by surgeons of different levels of experience. Knots tied with Orthocord suture material had the overall lower ultimate failure load compared with other suture materials, whereas knots tied with Ultrabraid suture material had the overall highest ultimate failure load. However, the ultimate failure loads for all the knots tied using any suture material, regardless of surgeon experience, were more than 61 N, which is the estimated minimum required ultimate load per suture during a maximum muscle contraction.¹

Figure 6 shows the percentage of knot slipping at constant clinical failure load. Orthocord and Fiberwire suture materials had the lowest incidence of knot slippage. Surgeon C had complete knot slippage at constant clinical failure load using ForceFiber with the Weston knot and Ultrabraid with the Tennessee slider knot. When using Ultrabraid or ForceFiber, surgeons A and C had at least 2 knots slip for all knot configurations.

Discussion

Optimization of knot security for any given knot configuration, suture material, and surgeon experience level during arthroscopic knot tying is crucial.^1-10 Our study results showed that, under single LTF test scenarios, there was a significant difference between in vitro and in situ conditions with respect to both knot configuration and surgeon experience level, except when Ultrabraid suture material was used. Arthroscopic sliding knots are lockable or nonlockable.^7,12 With lockable sliding knots, slippage may be prevented by tensioning the wrapping limb, which distorts the post in the distal part of the knot, resulting in a kink in the post, thereby increasing the internal interference that increases the resistance of the knot from backing off. With nonlockable sliding knots, slippage may be prevented by the tight grip of the wrappings around the initial post.⁷ The static surgeon’s knot and the Tennessee slider knot are nonlockable, whereas the Weston knot is a distal lockable sliding knot. Compared with nonlockable sliding knots, lockable sliding knots cause less suture loop enlargement. In 1976, Tera and Aberg²² studied the strength of knotted thread for 12 different types of suture knots combined with 11 types of suture material. They conducted their study 1 week after suture material was inserted into the subcutaneous tissue of rabbits. Their results show a greater propensity for certain suture materials to slip when tested in an aqueous environment. In 1998, Babetty and colleagues²³ used Wistar rats to compare the in vivo strength, knot efficiency, and knot security of 4 types of sliding knots and to assess tissue reaction as a result of knot configuration, knot volume, and suture size. They found that 4/0 knots lost more strength than 2/0 knots did, and they concluded that the tissue response to all the knots, except 2/0 nylon, was similar. They indicated that the inflammatory sheath volume varied with knot volume, suture size, and knot configuration. Our results agree with observations that exposure to an aqueous environment alters the force to clinical failure of comparable suture and knot configurations.

In addition, our findings indicate that surgeon familiarity with certain knots has a major effect on knot security. The difference in our 3 surgeons’ levels of familiarity with certain knots was somewhat minimized by the knot tying they practiced before submitting knots for testing. The findings contrast with those of Milia and colleagues,²⁴ who conducted a biomechanical study to determine the effect of experience level on knot security. They compared an experienced arthroscopic shoulder surgeon with a junior-level orthopedic resident surgeon and concluded that experience did not affect knot security. However, the knots in their study were tied by hand, not through an arthroscopic cannula with instruments. Our findings suggest that both experienced and less experienced orthopedic residents should be encouraged to practice arthroscopic knot tying in a nonsurgical environment in order to become comfortable tying arthroscopic knots.

Braided nonabsorbable polyester suture traditionally has been found to be stronger than monofilament absorbable polydioxanone (PDS) and to have less slippage potential.^8,9,25 Several studies have determined that the braided polyblend sutures now commonly used for arthroscopic knots have better strength profiles over more traditional materials.^12,26,27 Orthocord has a dyed absorbable core (PDS, 68%), an undyed nonabsorbable ultrahigh-molecular-weight polyethylene (UHMWPE, 32%) sleeve, and a polyglactin coating.^9,10 Both Ultrabraid and ForceFiber are made with braided UHMWPE and have just a few variations in weave patterns. Fiberwire has a multifiber UHMWPE core covered with braided polyester suture material. Several biomechanical studies^25,26,28 have evaluated different arthroscopic sliding knot configurations with different suture materials, and all concluded that a surgeon who is choosing an arthroscopic repair technique should know the differences in suture materials and the knot strengths afforded by different knot configurations, as suture material is an important aspect of loop security. Our findings agree with their findings, that suture materials have a major effect on knot security, even with a series of 3 RHAPs, as in theory the RHAPs should minimize suture friction, internal interference, and slack between knot loops—emphasizing the effect of material selection. Furthermore, our findings also indicated that suture materials with a core in their design (Fiberwire, Orthocord) tend to have the lowest incidence of knot slippage. We had suspected that suture surface characteristics and suture construction could be important factors in knot slippage.

Our experimental design had its limitations. First, although we simulated factors such as temperature, plasma environment, and surgeon experience, tying a knot on a standardized post (30 mm in circumference) differed from what is typically done clinically. Second, the metal hooks used in this study were not compressible and did not interpose in the substance of the knot as soft tissue does in the clinical setting. Third, knots were tied with no tension against the sutures, whereas clinically knots are tied under tension as tissues are pulled together in reconstructions. Fourth, it was assumed that soaking in a physiologic solution bath (human blood plasma) at 37°C (body temperature) for 24 hours before testing was sufficient to simulate the aqueous medium in vivo after surgery, but these parameters may not represent conditions in a patient who has just undergone an arthroscopic shoulder repair and adheres to a passive motion protocol. Fifth, there was no blinding of knot type, and there was no randomization of tying order or testing order. Sixth, only a single LTF test was performed, and incremental cyclic loading can be more useful, as it has long been recognized as a leading source of failure in orthopedic repairs.

Conclusion

These study results advance our overall understanding of the biomechanics of the different knot configurations and loop security levels of the different braided polyblend sutures used in arthroscopic procedures through LTF in both in vitro and in situ conditions. Overall, no suture material was superior to any other in a fluid environment, as the combination of aqueous environment and surgeon level of experience with arthroscopic knot tying has a major effect on knot security under single LTF test scenarios. However, our data showed that Ultrabraid suture material had no effect on knot effectiveness over the fluid environment and the temperature. Furthermore, the study showed that the Tennessee slider knot had the steepest learning curve. This study may provide an alternative arthroscopic knots option for soft-tissue repair in which use of certain suture materials is limited.

Open-surgery knot tying is easily learned and performed, but knot tying during arthroscopic procedures can be both challenging and frustrating. According to Burkhart and colleagues,^1,2 knot security is defined as the effectiveness of the knot in resisting slippage when load is applied, whereas loop security is the effectiveness in maintaining a tight suture loop while a knot is being tied. Arthroscopic knots commonly begin with an initial slipknot locked in place with a series of half-hitches. During arthroscopic surgery, the surgeon usually must tie an arthroscopic knot to obtain secure tissue fixation, an essential component of soft-tissue repair. A secure knot provides optimal tissue apposition for healing, which will ultimately improve functional outcome. For a knot to be effective, it must have both knot security and loop security. Knot security depends on knot configuration, the coefficient of friction, ductility, handling properties, solubility and diameter of suture material, internal interference, slack between throws, and surgeon experience. Tissue fluid and tissue reaction to suture material may affect knot and loop security.

The ideal knot would be easy to tie and reproducible and would not slip or stretch before tissue is healed. The ideal suture material should provide adequate strength to hold soft tissue in an anatomically correct position until healing can occur. It should also be easily and efficiently manipulated by arthroscopic means when tissues are being secured with knots and secure suture loops. Studies have been conducted to evaluate the security of knots tied with arthroscopic techniques, knot configurations, and suture materials, and these investigations have often evaluated knot performance under single load-to-failure (LTF) test scenarios and cyclic loading in vitro (dry environment) in a room-temperature environment.^2-10 To our knowledge, few if any attempts have been made to simulate in situ conditions at body temperature when testing knot security. The fluid environment and the temperature could potentially affect the effectiveness of knots, as knot security depends on friction, internal interference, and slack between throws.¹

We conducted a study to evaluate biomechanical performance (knot security, loop security) during destructive testing of several different suture materials with various arthroscopic knot configurations. The study was performed under in vitro (dry environment) and in situ (wet environment) conditions by surgeons with different levels of experience.

Materials and Methods

This investigation was conducted at the Orthopaedic Research Institute at Via Christi Health in Wichita, Kansas. The study compared 4 different suture materials tied with 3 different commonly used arthroscopic knots by 3 surgeons with different levels of experience. The 4 types of braided polyblend polyethylene sutures were Fiberwire (Arthrex, Naples, Florida), ForceFiber (Stryker, San Jose, California), Orthocord (DePuy-Mitek, Warsaw, Indiana), and Ultrabraid (Smith & Nephew, Memphis, Tennessee). Each suture material was tied with 3 arthroscopic knots—static surgeon’s knot, Weston knot,¹¹ Tennessee slider¹²—and a series of 3 reversing half-hitches on alternating posts (RHAPs) (Figure 1). These knots were chosen based on studies showing they have a higher maximum force to failure when combined with 3 RHAPs.^{1,2,5,9,13-17}

We evaluated performer variability with the help of 3 investigator-surgeons who differed in their level of experience tying arthroscopic knots. This experience was defined on the basis of total number of arthroscopies performed—one of the most important factors predicting basic arthroscopic skills. Our surgeon A was a sports medicine fellowship–trained surgeon with 10 years of experience and a significant number of arthroscopies performed annually (350); surgeon B was a sports medicine fellowship–trained surgeon with 3 years of experience and an annual arthroscopy volume of more than 250 procedures; and surgeon C was a third-year orthopedic resident with about 100 arthroscopies performed.

All knots were tied on a standardized post 30 mm in circumference, which provided a consistent starting circumference for each knot and replicated the suture loop created during arthroscopic rotator cuff repair. All knots were tied using standard arthroscopic techniques, with a standard knot pusher and a modified arthroscopic cannula, in a dry environment (Figure 2). Servohydraulic materials testing system instruments (model 810; MTS Systems, Eden Prairie, Minnesota) were used to test the knot security and loop security of each combination of knots and suture types. Two round hooks (diameter, 3.9 mm) were attached to the actuator and the load cell (Figure 3). Loops were preloaded to 6 N to avoid potential errors caused by slack in the loops or by stretching of suture materials and to provide a well-defined starting point for data recording.

LTF testing was performed for both in vitro and in situ conditions using 10 samples of each suture–knot configuration for each mechanical testing. Each type of testing was conducted for a total of 240 suture–knot combinations per investigator. For the in vitro condition, each suture loop was initiated with 5 preconditioning loading cycles, from 6 N to 30 N at 1 Hz. The load was then applied continuously at a crosshead speed of 1 mm/s until “clinical failure” (3 mm crosshead displacement). We used this criterion for clinical failure, as studies have indicated that 3 mm is the point at which tissue apposition is lost.^15,18-21 After the crosshead reached the 3-mm displacement, the loads (under load control) were held for 5 minutes at maximum load, and then load was applied continuously at a crosshead speed of 1 mm/s until complete structure failure. Load and displacement data were collected at a frequency of 20 Hz.

For the in situ condition, the same test parameters were used, except that each combination of the suture loop was preloaded to 6 N and soaked in physiologic solution bath (human blood plasma) at 37°C (body temperature) for 24 hours before testing in an effort to simulate the aqueous medium in vivo after surgery. The in situ tests were performed under physiologic solution maintained at 37°C to approximate postoperative physical conditions.

Statistical Analysis

Means and standard deviations of the knot security and loop security achieved by the surgeons (different experience levels) were calculated for each test configuration and each test condition. These values were used to determine the statistical relevance of the difference in arthroscopic loop security and knot security in each configuration. One-way analysis of variance (ANOVA) performed with SPSS Version 19.0 software (SPSS, Chicago, Illinois) with the least significant difference (LSD) multiple comparisons post hoc analysis was used to determine if any observed differences between the types of braided polyblend sutures, the types of sliding knots, the test conditions (in vitro, in situ), and the levels of surgeon experience were significant for each knot configuration. The level of significance of differences was set at P < .001.

Results

Figure 4 shows the mean maximum clinical failure load (3 mm of displacement) of different arthroscopic knot configurations for different braided polyblend sutures by surgeons of different levels of experience. In the comparison of biomechanical performance (knot and loop security) under in vitro and in situ conditions, no significant difference was detected when Ultrabraid suture material was used, regardless of surgeon experience, for all knot configurations. For surgeon B, there was no significant difference between in vitro and in situ conditions for any knot configurations or suture materials. When Orthocord suture material was used, Weston knots tied by surgeon A, and static surgeon’s knots by surgeons A and C, resulted in a significant difference between the in vitro and in situ conditions. When ForceFiber suture material was used, only Weston knots and Tennessee slider knots by surgeon A had a significant difference between in vitro and in situ conditions. Weston knots by surgeon A exhibited a significant difference between in vitro and in situ conditions, except when Ultrabraid suture material was used.

Surgeon C’s Tennessee slider knots with all polyblend sutures showed significantly lower loads at clinical failure compared with all the other knot configurations and with knots tied by the other 2 surgeons under both in vitro and in situ conditions. Overall, knots tied by surgeon B had higher clinical failure load than knots tied by the other 2 surgeons.

Figure 5 shows the mean ultimate failure load (complete structural failure) of different arthroscopic knot configurations for different braided polyblend sutures by surgeons of different levels of experience. Knots tied with Orthocord suture material had the overall lower ultimate failure load compared with other suture materials, whereas knots tied with Ultrabraid suture material had the overall highest ultimate failure load. However, the ultimate failure loads for all the knots tied using any suture material, regardless of surgeon experience, were more than 61 N, which is the estimated minimum required ultimate load per suture during a maximum muscle contraction.¹

Figure 6 shows the percentage of knot slipping at constant clinical failure load. Orthocord and Fiberwire suture materials had the lowest incidence of knot slippage. Surgeon C had complete knot slippage at constant clinical failure load using ForceFiber with the Weston knot and Ultrabraid with the Tennessee slider knot. When using Ultrabraid or ForceFiber, surgeons A and C had at least 2 knots slip for all knot configurations.

Discussion

Optimization of knot security for any given knot configuration, suture material, and surgeon experience level during arthroscopic knot tying is crucial.^1-10 Our study results showed that, under single LTF test scenarios, there was a significant difference between in vitro and in situ conditions with respect to both knot configuration and surgeon experience level, except when Ultrabraid suture material was used. Arthroscopic sliding knots are lockable or nonlockable.^7,12 With lockable sliding knots, slippage may be prevented by tensioning the wrapping limb, which distorts the post in the distal part of the knot, resulting in a kink in the post, thereby increasing the internal interference that increases the resistance of the knot from backing off. With nonlockable sliding knots, slippage may be prevented by the tight grip of the wrappings around the initial post.⁷ The static surgeon’s knot and the Tennessee slider knot are nonlockable, whereas the Weston knot is a distal lockable sliding knot. Compared with nonlockable sliding knots, lockable sliding knots cause less suture loop enlargement. In 1976, Tera and Aberg²² studied the strength of knotted thread for 12 different types of suture knots combined with 11 types of suture material. They conducted their study 1 week after suture material was inserted into the subcutaneous tissue of rabbits. Their results show a greater propensity for certain suture materials to slip when tested in an aqueous environment. In 1998, Babetty and colleagues²³ used Wistar rats to compare the in vivo strength, knot efficiency, and knot security of 4 types of sliding knots and to assess tissue reaction as a result of knot configuration, knot volume, and suture size. They found that 4/0 knots lost more strength than 2/0 knots did, and they concluded that the tissue response to all the knots, except 2/0 nylon, was similar. They indicated that the inflammatory sheath volume varied with knot volume, suture size, and knot configuration. Our results agree with observations that exposure to an aqueous environment alters the force to clinical failure of comparable suture and knot configurations.

In addition, our findings indicate that surgeon familiarity with certain knots has a major effect on knot security. The difference in our 3 surgeons’ levels of familiarity with certain knots was somewhat minimized by the knot tying they practiced before submitting knots for testing. The findings contrast with those of Milia and colleagues,²⁴ who conducted a biomechanical study to determine the effect of experience level on knot security. They compared an experienced arthroscopic shoulder surgeon with a junior-level orthopedic resident surgeon and concluded that experience did not affect knot security. However, the knots in their study were tied by hand, not through an arthroscopic cannula with instruments. Our findings suggest that both experienced and less experienced orthopedic residents should be encouraged to practice arthroscopic knot tying in a nonsurgical environment in order to become comfortable tying arthroscopic knots.

Braided nonabsorbable polyester suture traditionally has been found to be stronger than monofilament absorbable polydioxanone (PDS) and to have less slippage potential.^8,9,25 Several studies have determined that the braided polyblend sutures now commonly used for arthroscopic knots have better strength profiles over more traditional materials.^12,26,27 Orthocord has a dyed absorbable core (PDS, 68%), an undyed nonabsorbable ultrahigh-molecular-weight polyethylene (UHMWPE, 32%) sleeve, and a polyglactin coating.^9,10 Both Ultrabraid and ForceFiber are made with braided UHMWPE and have just a few variations in weave patterns. Fiberwire has a multifiber UHMWPE core covered with braided polyester suture material. Several biomechanical studies^25,26,28 have evaluated different arthroscopic sliding knot configurations with different suture materials, and all concluded that a surgeon who is choosing an arthroscopic repair technique should know the differences in suture materials and the knot strengths afforded by different knot configurations, as suture material is an important aspect of loop security. Our findings agree with their findings, that suture materials have a major effect on knot security, even with a series of 3 RHAPs, as in theory the RHAPs should minimize suture friction, internal interference, and slack between knot loops—emphasizing the effect of material selection. Furthermore, our findings also indicated that suture materials with a core in their design (Fiberwire, Orthocord) tend to have the lowest incidence of knot slippage. We had suspected that suture surface characteristics and suture construction could be important factors in knot slippage.

Our experimental design had its limitations. First, although we simulated factors such as temperature, plasma environment, and surgeon experience, tying a knot on a standardized post (30 mm in circumference) differed from what is typically done clinically. Second, the metal hooks used in this study were not compressible and did not interpose in the substance of the knot as soft tissue does in the clinical setting. Third, knots were tied with no tension against the sutures, whereas clinically knots are tied under tension as tissues are pulled together in reconstructions. Fourth, it was assumed that soaking in a physiologic solution bath (human blood plasma) at 37°C (body temperature) for 24 hours before testing was sufficient to simulate the aqueous medium in vivo after surgery, but these parameters may not represent conditions in a patient who has just undergone an arthroscopic shoulder repair and adheres to a passive motion protocol. Fifth, there was no blinding of knot type, and there was no randomization of tying order or testing order. Sixth, only a single LTF test was performed, and incremental cyclic loading can be more useful, as it has long been recognized as a leading source of failure in orthopedic repairs.

Conclusion

These study results advance our overall understanding of the biomechanics of the different knot configurations and loop security levels of the different braided polyblend sutures used in arthroscopic procedures through LTF in both in vitro and in situ conditions. Overall, no suture material was superior to any other in a fluid environment, as the combination of aqueous environment and surgeon level of experience with arthroscopic knot tying has a major effect on knot security under single LTF test scenarios. However, our data showed that Ultrabraid suture material had no effect on knot effectiveness over the fluid environment and the temperature. Furthermore, the study showed that the Tennessee slider knot had the steepest learning curve. This study may provide an alternative arthroscopic knots option for soft-tissue repair in which use of certain suture materials is limited.

Anterior cruciate ligament (ACL) injuries are common, and arthroscopic ACL reconstruction is a routine procedure. Successful ACL reconstruction requires correct placement of the graft within the anatomical insertion of the native ACL.^1-3 Errors in surgical technique—specifically, improper femoral tunnel placement—are the most common cause of graft failure in patients who present with recurrent instability after ACL reconstruction.⁴ There has been much emphasis on placing the tunnel more centrally in the ACL footprint as well as in a more horizontal position, which is thought to provide better rotational control and anterior-to-posterior translational stability.^5-7

Two common techniques for creating the femoral tunnel, transtibial and anteromedial drilling, have their unique limitations. Transtibial drilling can place the tunnel high in the notch, resulting in nonanatomical, vertical graft placement.^8,9 This technique can be modified to obtain a more anatomical tunnel, but the risk is the tunnel will be short and close to the joint line.¹⁰ To avoid these difficulties, surgeons began using an anteromedial portal.^11,12 Although anteromedial drilling places the tunnel in a more anatomical position, it too has drawbacks, including the need to hyperflex the knee, a short tunnel, damage to articular cartilage, proximity to neurovascular structures, and difficulty in visualization during drilling.^13-16

Femoral tunnel drilling techniques using flexible guide pins and reamers have been developed to address the limitations of rigid instruments. When we first started using flexible instruments through anteromedial portals, there were multiple incidents of reamer breakage during drilling. We therefore developed a technique that uses a flexible guide pin with a rigid reamer to place the femoral tunnel in an anatomical position. The patient described in this article provided written informed consent for print and electronic publication of this report.

Technique

We begin with our standard arthroscopic portals, including superolateral outflow, lateral parapatellar, and medial parapatellar portals. The medial parapatellar portal is placed under direct visualization with insertion of an 18-gauge spinal needle, ensuring the trajectory reaches the anatomical location of the native ACL on the lateral femoral condyle (LFC). The ACL stump is débrided with a shaver and a radiofrequency ablator, leaving a remnant of tissue to assist with tunnel placement. We do not routinely perform a notchplasty unless there is a concern about possible graft impingement, or the notch is abnormally small. The anatomical footprint is marked with a small awl (Figure 1), and the arthroscope is moved into the anteromedial portal to confirm anatomical placement of the awl mark (Figure 2).

With the knee flexed to 100° to 110°, a flexible 2.7-mm nitonol guide pin (Smith & Nephew, Memphis, Tennessee) is placed freehand through the anteromedial portal into the anatomical footprint of the ACL, marked by the awl, and is passed through the femur before exiting the lateral skin. In most cases, we prefer freehand placement of the awl and pin; however, a femoral drill guide may be used to place the pin into the anatomical footprint of the ACL (Figure 3). The flexible pin allows for knee hyperflexion, clearance of the medial femoral condyle, central placement of the pin between the footprints of the anteromedial and posterolateral bundles for anatomical single-bundle reconstruction, and drilling of a long tunnel (average, 35-40 mm). The pin has a black laser marking that should be placed at the edge of the articular surface of the LFC to ensure appropriate depth of insertion (Figure 4).

A small incision is then made around the guide wire on the lateral thigh, and an outside-in depth gauge is used to obtain an accurate length for the femoral tunnel. The gauge must abut the femoral cortex for accurate assessment of tunnel length. We use an Endobutton (Smith & Nephew) for fixation of the graft in the tunnel. The measured length of the tunnel is used to select an Endobutton of appropriate size and the proper reaming depth for suspension. We routinely use a 10- or 15-mm Endobutton, which provides an average 20 to 25 mm of graft inside the bony tunnel. The knee may then be relaxed to a normal resting flexion angle off the side of the bed, and the arthroscope is inserted into a medial portal or an accessory anteromedial portal to ensure anatomical placement of the pin. Using a flexible guide pin allows the knee to be relatively extended, providing good visualization of overall positioning in relation to the posterior wall of the LFC, whereas keeping the knee in a flexed position (as with a rigid guide pin) can often compromise this visualization.

Using a solid reamer corresponding to the size of the graft, we drill over the guide pin to the appropriate depth, again with the knee hyperflexed (Figure 5), making sure not to breach the lateral femoral cortex, which would compromise fixation with the Endobutton. After drilling with the rigid reamer is completed, placement of the tunnel in an anatomical position is again confirmed with the knee in the normal resting flexion angle (Figure 6). Once the tibial tunnel is drilled at the anatomical footprint, the graft is passed with the proper-length Endobutton and is fixed on the tibial side with a bioabsorbable interference screw 1 to 2 mm larger than the soft-tissue graft and tibial tunnel size. The knee is flexed to 30° while the tibial screw is placed. Graft tension and impingement are then checked (Figure 7). Postoperative anteroposterior and lateral radiographs of the knee may be obtained to confirm anatomical placement of the tunnels as well as proper positioning of the Endobutton (Figures 8A, 8B).

Discussion

Successful ACL reconstruction depends heavily on anatomical tunnel positioning. Failure to place the femoral tunnel in the anatomical footprint of the native ACL results in incomplete restoration of knee kinematics, rotational instability, and graft failure.^1-7 Two common techniques for creating this tunnel, transtibial and anteromedial drilling, can reliably place it in an anatomical position. Each technique, however, has limitations. Transtibial drilling can place the tunnel too vertical and high in the notch, or produce a short tibial tunnel close to the joint line.^8-10 Anteromedial drilling requires knee hyperflexion, risks damaging the articular cartilage and nearby neurovascular structures, and makes visualization difficult.^13-16

One option for addressing some of the difficulties and limitations with anteromedial drilling is to use flexible guide pins and reamers, as first introduced by Cain and Clancy.¹ In a cadaveric study, Silver and colleagues¹⁷ demonstrated that interosseous tunnels drilled with flexible guide pins were on average more than 6 mm longer than those drilled with rigid pins and consistently were 40 mm or longer. In addition, all tunnels drilled with flexible guide pins were on average 42.3 mm away from the peroneal nerve and 26.1 mm away from the femoral origin of the lateral collateral ligament—safe distances.

Steiner and Smart¹⁸ compared flexible and rigid instruments used to drill transtibial and anteromedial (without hyperflexion) anatomical femoral tunnels in ACL reconstruction in cadaveric knees. Although transtibial drilling with flexible pins produced anatomical tunnels, the tunnels were shorter, and the pins exited more posterior in comparison with anteromedial drilling with flexible pins. Transtibial tunnels drilled with rigid pins were nonanatomical and exited more superior and anterior on the femur, resulting in longer tunnels. Anteromedial tunnels drilled with rigid and flexible pins were placed anatomically, but flexible pins produced longer tunnels, did not require hyperflexion (120°), could easily be placed with the knee in 90° of flexion, and did not violate the posterior femoral cortex.

Five times in our early experience with flexible guide pins and reamers, the reamer broke when LFC reaming was initiated. In each case, the broken reamer was retrieved. However, these complications resulted in increased surgical time and cost. In addition, an unretrievable reamer could have caused further injury and suboptimal outcomes. We subsequently developed an anteromedial technique that uses a flexible guide pin with a rigid reamer to place the femoral tunnel in an anatomical position (Figure 9). The flexible pin provides consistent placement of anatomical tunnels averaging 35 to 40 mm in length. Use of the flexible pin does not require constant hyperflexion of the knee, and it allows for better visualization of the posterior wall of the LFC, ensures anatomical graft placement, and decreases the risk of damaging articular cartilage and causing neurovascular injury. Use of the rigid reamer negates the risks and additional costs associated with reamer breakage. It is unclear why 5 flexible reamers broke during our early use of flexible guide pins and reamers, but it is possible that, because of the patients’ anatomy, placement of the pin in the correct anatomical position in the ACL footprint put a significant amount of abnormal stress on the reamer during tunnel reaming, leading to breakage and failure.

A short femoral tunnel is a common complication of using an anteromedial portal for tunnel drilling.^13-16 With the technique we have been using, tunnel lengths average 35 to 40 mm. To address the occasional shorter tunnel, we use Endobutton Direct (Smith & Nephew), which allows for direct fixation of the graft on the button, maximizing the amount of graft in the femoral tunnel and minimizing graft–tunnel length mismatch. In the event there is a lateral wall breach during overdrilling with the reamer, the femoral graft may be secured with screw and post, with interference screw, or with the larger Xtendobuton (Smith & Nephew).

We have successfully used this technique with bone–patellar tendon–bone (BPTB) and hamstring autografts, as well as allografts. Complications, such as graft–tunnel length mismatch, have been uncommon, but, when using BPTB grafts, passing the bone block into the femoral tunnel can be difficult because of the sharp turn required.

Conclusion

Successful ACL reconstruction depends heavily on placement of the graft within the anatomical insertion of the native ACL. With the development of techniques that use flexible guide pins and reamers, it has become possible to place longer anatomical femoral tunnels without the need for hyperflexion. Use of a flexible guide pin with a rigid reamer allows placement of longer anatomical tunnels through an anteromedial portal, reduces time spent with the knee in hyperflexion, provides better viewing, poses less risk of damage to the articular cartilage and neurovascular structures, and at a lower cost with less risk of reamer breakage. In addition, this technique can be used with a variety of graft options, including BPTB grafts, hamstring autografts, and allografts.

Anterior cruciate ligament (ACL) injuries are common, and arthroscopic ACL reconstruction is a routine procedure. Successful ACL reconstruction requires correct placement of the graft within the anatomical insertion of the native ACL.^1-3 Errors in surgical technique—specifically, improper femoral tunnel placement—are the most common cause of graft failure in patients who present with recurrent instability after ACL reconstruction.⁴ There has been much emphasis on placing the tunnel more centrally in the ACL footprint as well as in a more horizontal position, which is thought to provide better rotational control and anterior-to-posterior translational stability.^5-7

Two common techniques for creating the femoral tunnel, transtibial and anteromedial drilling, have their unique limitations. Transtibial drilling can place the tunnel high in the notch, resulting in nonanatomical, vertical graft placement.^8,9 This technique can be modified to obtain a more anatomical tunnel, but the risk is the tunnel will be short and close to the joint line.¹⁰ To avoid these difficulties, surgeons began using an anteromedial portal.^11,12 Although anteromedial drilling places the tunnel in a more anatomical position, it too has drawbacks, including the need to hyperflex the knee, a short tunnel, damage to articular cartilage, proximity to neurovascular structures, and difficulty in visualization during drilling.^13-16

Femoral tunnel drilling techniques using flexible guide pins and reamers have been developed to address the limitations of rigid instruments. When we first started using flexible instruments through anteromedial portals, there were multiple incidents of reamer breakage during drilling. We therefore developed a technique that uses a flexible guide pin with a rigid reamer to place the femoral tunnel in an anatomical position. The patient described in this article provided written informed consent for print and electronic publication of this report.

Technique

We begin with our standard arthroscopic portals, including superolateral outflow, lateral parapatellar, and medial parapatellar portals. The medial parapatellar portal is placed under direct visualization with insertion of an 18-gauge spinal needle, ensuring the trajectory reaches the anatomical location of the native ACL on the lateral femoral condyle (LFC). The ACL stump is débrided with a shaver and a radiofrequency ablator, leaving a remnant of tissue to assist with tunnel placement. We do not routinely perform a notchplasty unless there is a concern about possible graft impingement, or the notch is abnormally small. The anatomical footprint is marked with a small awl (Figure 1), and the arthroscope is moved into the anteromedial portal to confirm anatomical placement of the awl mark (Figure 2).

With the knee flexed to 100° to 110°, a flexible 2.7-mm nitonol guide pin (Smith & Nephew, Memphis, Tennessee) is placed freehand through the anteromedial portal into the anatomical footprint of the ACL, marked by the awl, and is passed through the femur before exiting the lateral skin. In most cases, we prefer freehand placement of the awl and pin; however, a femoral drill guide may be used to place the pin into the anatomical footprint of the ACL (Figure 3). The flexible pin allows for knee hyperflexion, clearance of the medial femoral condyle, central placement of the pin between the footprints of the anteromedial and posterolateral bundles for anatomical single-bundle reconstruction, and drilling of a long tunnel (average, 35-40 mm). The pin has a black laser marking that should be placed at the edge of the articular surface of the LFC to ensure appropriate depth of insertion (Figure 4).

A small incision is then made around the guide wire on the lateral thigh, and an outside-in depth gauge is used to obtain an accurate length for the femoral tunnel. The gauge must abut the femoral cortex for accurate assessment of tunnel length. We use an Endobutton (Smith & Nephew) for fixation of the graft in the tunnel. The measured length of the tunnel is used to select an Endobutton of appropriate size and the proper reaming depth for suspension. We routinely use a 10- or 15-mm Endobutton, which provides an average 20 to 25 mm of graft inside the bony tunnel. The knee may then be relaxed to a normal resting flexion angle off the side of the bed, and the arthroscope is inserted into a medial portal or an accessory anteromedial portal to ensure anatomical placement of the pin. Using a flexible guide pin allows the knee to be relatively extended, providing good visualization of overall positioning in relation to the posterior wall of the LFC, whereas keeping the knee in a flexed position (as with a rigid guide pin) can often compromise this visualization.

Using a solid reamer corresponding to the size of the graft, we drill over the guide pin to the appropriate depth, again with the knee hyperflexed (Figure 5), making sure not to breach the lateral femoral cortex, which would compromise fixation with the Endobutton. After drilling with the rigid reamer is completed, placement of the tunnel in an anatomical position is again confirmed with the knee in the normal resting flexion angle (Figure 6). Once the tibial tunnel is drilled at the anatomical footprint, the graft is passed with the proper-length Endobutton and is fixed on the tibial side with a bioabsorbable interference screw 1 to 2 mm larger than the soft-tissue graft and tibial tunnel size. The knee is flexed to 30° while the tibial screw is placed. Graft tension and impingement are then checked (Figure 7). Postoperative anteroposterior and lateral radiographs of the knee may be obtained to confirm anatomical placement of the tunnels as well as proper positioning of the Endobutton (Figures 8A, 8B).

Discussion

Successful ACL reconstruction depends heavily on anatomical tunnel positioning. Failure to place the femoral tunnel in the anatomical footprint of the native ACL results in incomplete restoration of knee kinematics, rotational instability, and graft failure.^1-7 Two common techniques for creating this tunnel, transtibial and anteromedial drilling, can reliably place it in an anatomical position. Each technique, however, has limitations. Transtibial drilling can place the tunnel too vertical and high in the notch, or produce a short tibial tunnel close to the joint line.^8-10 Anteromedial drilling requires knee hyperflexion, risks damaging the articular cartilage and nearby neurovascular structures, and makes visualization difficult.^13-16

One option for addressing some of the difficulties and limitations with anteromedial drilling is to use flexible guide pins and reamers, as first introduced by Cain and Clancy.¹ In a cadaveric study, Silver and colleagues¹⁷ demonstrated that interosseous tunnels drilled with flexible guide pins were on average more than 6 mm longer than those drilled with rigid pins and consistently were 40 mm or longer. In addition, all tunnels drilled with flexible guide pins were on average 42.3 mm away from the peroneal nerve and 26.1 mm away from the femoral origin of the lateral collateral ligament—safe distances.

Steiner and Smart¹⁸ compared flexible and rigid instruments used to drill transtibial and anteromedial (without hyperflexion) anatomical femoral tunnels in ACL reconstruction in cadaveric knees. Although transtibial drilling with flexible pins produced anatomical tunnels, the tunnels were shorter, and the pins exited more posterior in comparison with anteromedial drilling with flexible pins. Transtibial tunnels drilled with rigid pins were nonanatomical and exited more superior and anterior on the femur, resulting in longer tunnels. Anteromedial tunnels drilled with rigid and flexible pins were placed anatomically, but flexible pins produced longer tunnels, did not require hyperflexion (120°), could easily be placed with the knee in 90° of flexion, and did not violate the posterior femoral cortex.

Five times in our early experience with flexible guide pins and reamers, the reamer broke when LFC reaming was initiated. In each case, the broken reamer was retrieved. However, these complications resulted in increased surgical time and cost. In addition, an unretrievable reamer could have caused further injury and suboptimal outcomes. We subsequently developed an anteromedial technique that uses a flexible guide pin with a rigid reamer to place the femoral tunnel in an anatomical position (Figure 9). The flexible pin provides consistent placement of anatomical tunnels averaging 35 to 40 mm in length. Use of the flexible pin does not require constant hyperflexion of the knee, and it allows for better visualization of the posterior wall of the LFC, ensures anatomical graft placement, and decreases the risk of damaging articular cartilage and causing neurovascular injury. Use of the rigid reamer negates the risks and additional costs associated with reamer breakage. It is unclear why 5 flexible reamers broke during our early use of flexible guide pins and reamers, but it is possible that, because of the patients’ anatomy, placement of the pin in the correct anatomical position in the ACL footprint put a significant amount of abnormal stress on the reamer during tunnel reaming, leading to breakage and failure.

A short femoral tunnel is a common complication of using an anteromedial portal for tunnel drilling.^13-16 With the technique we have been using, tunnel lengths average 35 to 40 mm. To address the occasional shorter tunnel, we use Endobutton Direct (Smith & Nephew), which allows for direct fixation of the graft on the button, maximizing the amount of graft in the femoral tunnel and minimizing graft–tunnel length mismatch. In the event there is a lateral wall breach during overdrilling with the reamer, the femoral graft may be secured with screw and post, with interference screw, or with the larger Xtendobuton (Smith & Nephew).

We have successfully used this technique with bone–patellar tendon–bone (BPTB) and hamstring autografts, as well as allografts. Complications, such as graft–tunnel length mismatch, have been uncommon, but, when using BPTB grafts, passing the bone block into the femoral tunnel can be difficult because of the sharp turn required.

Conclusion

Successful ACL reconstruction depends heavily on placement of the graft within the anatomical insertion of the native ACL. With the development of techniques that use flexible guide pins and reamers, it has become possible to place longer anatomical femoral tunnels without the need for hyperflexion. Use of a flexible guide pin with a rigid reamer allows placement of longer anatomical tunnels through an anteromedial portal, reduces time spent with the knee in hyperflexion, provides better viewing, poses less risk of damage to the articular cartilage and neurovascular structures, and at a lower cost with less risk of reamer breakage. In addition, this technique can be used with a variety of graft options, including BPTB grafts, hamstring autografts, and allografts.

Anterior cruciate ligament (ACL) injuries are common, and arthroscopic ACL reconstruction is a routine procedure. Successful ACL reconstruction requires correct placement of the graft within the anatomical insertion of the native ACL.^1-3 Errors in surgical technique—specifically, improper femoral tunnel placement—are the most common cause of graft failure in patients who present with recurrent instability after ACL reconstruction.⁴ There has been much emphasis on placing the tunnel more centrally in the ACL footprint as well as in a more horizontal position, which is thought to provide better rotational control and anterior-to-posterior translational stability.^5-7

Two common techniques for creating the femoral tunnel, transtibial and anteromedial drilling, have their unique limitations. Transtibial drilling can place the tunnel high in the notch, resulting in nonanatomical, vertical graft placement.^8,9 This technique can be modified to obtain a more anatomical tunnel, but the risk is the tunnel will be short and close to the joint line.¹⁰ To avoid these difficulties, surgeons began using an anteromedial portal.^11,12 Although anteromedial drilling places the tunnel in a more anatomical position, it too has drawbacks, including the need to hyperflex the knee, a short tunnel, damage to articular cartilage, proximity to neurovascular structures, and difficulty in visualization during drilling.^13-16

Femoral tunnel drilling techniques using flexible guide pins and reamers have been developed to address the limitations of rigid instruments. When we first started using flexible instruments through anteromedial portals, there were multiple incidents of reamer breakage during drilling. We therefore developed a technique that uses a flexible guide pin with a rigid reamer to place the femoral tunnel in an anatomical position. The patient described in this article provided written informed consent for print and electronic publication of this report.

Technique

We begin with our standard arthroscopic portals, including superolateral outflow, lateral parapatellar, and medial parapatellar portals. The medial parapatellar portal is placed under direct visualization with insertion of an 18-gauge spinal needle, ensuring the trajectory reaches the anatomical location of the native ACL on the lateral femoral condyle (LFC). The ACL stump is débrided with a shaver and a radiofrequency ablator, leaving a remnant of tissue to assist with tunnel placement. We do not routinely perform a notchplasty unless there is a concern about possible graft impingement, or the notch is abnormally small. The anatomical footprint is marked with a small awl (Figure 1), and the arthroscope is moved into the anteromedial portal to confirm anatomical placement of the awl mark (Figure 2).

With the knee flexed to 100° to 110°, a flexible 2.7-mm nitonol guide pin (Smith & Nephew, Memphis, Tennessee) is placed freehand through the anteromedial portal into the anatomical footprint of the ACL, marked by the awl, and is passed through the femur before exiting the lateral skin. In most cases, we prefer freehand placement of the awl and pin; however, a femoral drill guide may be used to place the pin into the anatomical footprint of the ACL (Figure 3). The flexible pin allows for knee hyperflexion, clearance of the medial femoral condyle, central placement of the pin between the footprints of the anteromedial and posterolateral bundles for anatomical single-bundle reconstruction, and drilling of a long tunnel (average, 35-40 mm). The pin has a black laser marking that should be placed at the edge of the articular surface of the LFC to ensure appropriate depth of insertion (Figure 4).

A small incision is then made around the guide wire on the lateral thigh, and an outside-in depth gauge is used to obtain an accurate length for the femoral tunnel. The gauge must abut the femoral cortex for accurate assessment of tunnel length. We use an Endobutton (Smith & Nephew) for fixation of the graft in the tunnel. The measured length of the tunnel is used to select an Endobutton of appropriate size and the proper reaming depth for suspension. We routinely use a 10- or 15-mm Endobutton, which provides an average 20 to 25 mm of graft inside the bony tunnel. The knee may then be relaxed to a normal resting flexion angle off the side of the bed, and the arthroscope is inserted into a medial portal or an accessory anteromedial portal to ensure anatomical placement of the pin. Using a flexible guide pin allows the knee to be relatively extended, providing good visualization of overall positioning in relation to the posterior wall of the LFC, whereas keeping the knee in a flexed position (as with a rigid guide pin) can often compromise this visualization.

Using a solid reamer corresponding to the size of the graft, we drill over the guide pin to the appropriate depth, again with the knee hyperflexed (Figure 5), making sure not to breach the lateral femoral cortex, which would compromise fixation with the Endobutton. After drilling with the rigid reamer is completed, placement of the tunnel in an anatomical position is again confirmed with the knee in the normal resting flexion angle (Figure 6). Once the tibial tunnel is drilled at the anatomical footprint, the graft is passed with the proper-length Endobutton and is fixed on the tibial side with a bioabsorbable interference screw 1 to 2 mm larger than the soft-tissue graft and tibial tunnel size. The knee is flexed to 30° while the tibial screw is placed. Graft tension and impingement are then checked (Figure 7). Postoperative anteroposterior and lateral radiographs of the knee may be obtained to confirm anatomical placement of the tunnels as well as proper positioning of the Endobutton (Figures 8A, 8B).

Discussion

Successful ACL reconstruction depends heavily on anatomical tunnel positioning. Failure to place the femoral tunnel in the anatomical footprint of the native ACL results in incomplete restoration of knee kinematics, rotational instability, and graft failure.^1-7 Two common techniques for creating this tunnel, transtibial and anteromedial drilling, can reliably place it in an anatomical position. Each technique, however, has limitations. Transtibial drilling can place the tunnel too vertical and high in the notch, or produce a short tibial tunnel close to the joint line.^8-10 Anteromedial drilling requires knee hyperflexion, risks damaging the articular cartilage and nearby neurovascular structures, and makes visualization difficult.^13-16

One option for addressing some of the difficulties and limitations with anteromedial drilling is to use flexible guide pins and reamers, as first introduced by Cain and Clancy.¹ In a cadaveric study, Silver and colleagues¹⁷ demonstrated that interosseous tunnels drilled with flexible guide pins were on average more than 6 mm longer than those drilled with rigid pins and consistently were 40 mm or longer. In addition, all tunnels drilled with flexible guide pins were on average 42.3 mm away from the peroneal nerve and 26.1 mm away from the femoral origin of the lateral collateral ligament—safe distances.

Steiner and Smart¹⁸ compared flexible and rigid instruments used to drill transtibial and anteromedial (without hyperflexion) anatomical femoral tunnels in ACL reconstruction in cadaveric knees. Although transtibial drilling with flexible pins produced anatomical tunnels, the tunnels were shorter, and the pins exited more posterior in comparison with anteromedial drilling with flexible pins. Transtibial tunnels drilled with rigid pins were nonanatomical and exited more superior and anterior on the femur, resulting in longer tunnels. Anteromedial tunnels drilled with rigid and flexible pins were placed anatomically, but flexible pins produced longer tunnels, did not require hyperflexion (120°), could easily be placed with the knee in 90° of flexion, and did not violate the posterior femoral cortex.

Five times in our early experience with flexible guide pins and reamers, the reamer broke when LFC reaming was initiated. In each case, the broken reamer was retrieved. However, these complications resulted in increased surgical time and cost. In addition, an unretrievable reamer could have caused further injury and suboptimal outcomes. We subsequently developed an anteromedial technique that uses a flexible guide pin with a rigid reamer to place the femoral tunnel in an anatomical position (Figure 9). The flexible pin provides consistent placement of anatomical tunnels averaging 35 to 40 mm in length. Use of the flexible pin does not require constant hyperflexion of the knee, and it allows for better visualization of the posterior wall of the LFC, ensures anatomical graft placement, and decreases the risk of damaging articular cartilage and causing neurovascular injury. Use of the rigid reamer negates the risks and additional costs associated with reamer breakage. It is unclear why 5 flexible reamers broke during our early use of flexible guide pins and reamers, but it is possible that, because of the patients’ anatomy, placement of the pin in the correct anatomical position in the ACL footprint put a significant amount of abnormal stress on the reamer during tunnel reaming, leading to breakage and failure.

A short femoral tunnel is a common complication of using an anteromedial portal for tunnel drilling.^13-16 With the technique we have been using, tunnel lengths average 35 to 40 mm. To address the occasional shorter tunnel, we use Endobutton Direct (Smith & Nephew), which allows for direct fixation of the graft on the button, maximizing the amount of graft in the femoral tunnel and minimizing graft–tunnel length mismatch. In the event there is a lateral wall breach during overdrilling with the reamer, the femoral graft may be secured with screw and post, with interference screw, or with the larger Xtendobuton (Smith & Nephew).

We have successfully used this technique with bone–patellar tendon–bone (BPTB) and hamstring autografts, as well as allografts. Complications, such as graft–tunnel length mismatch, have been uncommon, but, when using BPTB grafts, passing the bone block into the femoral tunnel can be difficult because of the sharp turn required.

Conclusion

Successful ACL reconstruction depends heavily on placement of the graft within the anatomical insertion of the native ACL. With the development of techniques that use flexible guide pins and reamers, it has become possible to place longer anatomical femoral tunnels without the need for hyperflexion. Use of a flexible guide pin with a rigid reamer allows placement of longer anatomical tunnels through an anteromedial portal, reduces time spent with the knee in hyperflexion, provides better viewing, poses less risk of damage to the articular cartilage and neurovascular structures, and at a lower cost with less risk of reamer breakage. In addition, this technique can be used with a variety of graft options, including BPTB grafts, hamstring autografts, and allografts.

SAN DIEGO – Cardiologists should switch from transfemoral to transradial access in acute coronary syndrome patients undergoing percutaneous coronary intervention, given the reduced mortality rates associated with the transradial approach in the MATRIX study and other studies, Dr. Cindy L. Grines said at the annual meeting of the American College of Cardiology.

Because U.S. interventionalists are “under the clock” when treating patients with ST-elevation myocardial infarction, “many physicians have been unwilling to risk having a difficult transradial case that would take too much time,” explained Dr. Grines, an interventional cardiologist at the Detroit Medical Center.

For that and other reasons, American interventionalists have been “slow adopters” of the transradial approach, currently using it for about 20% of PCIs, compared with a worldwide rate of about 70%.

It may take instituting incentives to get U.S. cardiologists to change their practice, Dr. Grines suggested in an interview. That could involve increased reimbursement for PCIs done transradially, an increased allowance on acceptable door-to-balloon times for STEMI patients treated transradially, or imposition of new standards for quality assurance that mandate use of transradial in a certain percentage of PCI cases, she said.

The MATRIX study included a second, independent, prespecified analysis that compared outcomes in patients randomized to treatment with two different antithrombin drugs, either bivalirudin (Angiomax) or unfractionated heparin.

That part of the study showed that while treatment with either of the two drugs resulted in no statistically significant difference in the study’s two primary endpoints, treatment with bivalirudin led to statistically significant reductions in all-cause death and cardiovascular death, as well as in major bleeding events, compared with patients treated with unfractionated heparin (Lancet 2015 [doi:10.1016/S0140-6736(15)60292-6]).

Although bivalirudin has generally been the more commonly used antithrombin drug in this clinical setting by U.S. interventionalists in recent years, results reported last year from the HEAT-PCI trial (Lancet 2014;384:1849-58) that showed better outcomes with unfractionated heparin have led to reduced use of bivalirudin, Dr. Grines said.

The new results from MATRIX coupled with results from other trials that compared those drugs can make clinicians “more confident about the benefit of bivalirudin,” she said.

Dr. Grines has been a consultant to and received honoraria from the Medicines Company, which markets Angiomax, and from Abbott Vascular, Merck, and the Volcano Group.

[email protected]


On Twitter @mitchelzoler

SAN DIEGO – Cardiologists should switch from transfemoral to transradial access in acute coronary syndrome patients undergoing percutaneous coronary intervention, given the reduced mortality rates associated with the transradial approach in the MATRIX study and other studies, Dr. Cindy L. Grines said at the annual meeting of the American College of Cardiology.

Because U.S. interventionalists are “under the clock” when treating patients with ST-elevation myocardial infarction, “many physicians have been unwilling to risk having a difficult transradial case that would take too much time,” explained Dr. Grines, an interventional cardiologist at the Detroit Medical Center.

For that and other reasons, American interventionalists have been “slow adopters” of the transradial approach, currently using it for about 20% of PCIs, compared with a worldwide rate of about 70%.

It may take instituting incentives to get U.S. cardiologists to change their practice, Dr. Grines suggested in an interview. That could involve increased reimbursement for PCIs done transradially, an increased allowance on acceptable door-to-balloon times for STEMI patients treated transradially, or imposition of new standards for quality assurance that mandate use of transradial in a certain percentage of PCI cases, she said.

The MATRIX study included a second, independent, prespecified analysis that compared outcomes in patients randomized to treatment with two different antithrombin drugs, either bivalirudin (Angiomax) or unfractionated heparin.

That part of the study showed that while treatment with either of the two drugs resulted in no statistically significant difference in the study’s two primary endpoints, treatment with bivalirudin led to statistically significant reductions in all-cause death and cardiovascular death, as well as in major bleeding events, compared with patients treated with unfractionated heparin (Lancet 2015 [doi:10.1016/S0140-6736(15)60292-6]).

Although bivalirudin has generally been the more commonly used antithrombin drug in this clinical setting by U.S. interventionalists in recent years, results reported last year from the HEAT-PCI trial (Lancet 2014;384:1849-58) that showed better outcomes with unfractionated heparin have led to reduced use of bivalirudin, Dr. Grines said.

The new results from MATRIX coupled with results from other trials that compared those drugs can make clinicians “more confident about the benefit of bivalirudin,” she said.

Dr. Grines has been a consultant to and received honoraria from the Medicines Company, which markets Angiomax, and from Abbott Vascular, Merck, and the Volcano Group.

[email protected]


On Twitter @mitchelzoler

SAN DIEGO – Cardiologists should switch from transfemoral to transradial access in acute coronary syndrome patients undergoing percutaneous coronary intervention, given the reduced mortality rates associated with the transradial approach in the MATRIX study and other studies, Dr. Cindy L. Grines said at the annual meeting of the American College of Cardiology.

Because U.S. interventionalists are “under the clock” when treating patients with ST-elevation myocardial infarction, “many physicians have been unwilling to risk having a difficult transradial case that would take too much time,” explained Dr. Grines, an interventional cardiologist at the Detroit Medical Center.

For that and other reasons, American interventionalists have been “slow adopters” of the transradial approach, currently using it for about 20% of PCIs, compared with a worldwide rate of about 70%.

It may take instituting incentives to get U.S. cardiologists to change their practice, Dr. Grines suggested in an interview. That could involve increased reimbursement for PCIs done transradially, an increased allowance on acceptable door-to-balloon times for STEMI patients treated transradially, or imposition of new standards for quality assurance that mandate use of transradial in a certain percentage of PCI cases, she said.

The MATRIX study included a second, independent, prespecified analysis that compared outcomes in patients randomized to treatment with two different antithrombin drugs, either bivalirudin (Angiomax) or unfractionated heparin.

That part of the study showed that while treatment with either of the two drugs resulted in no statistically significant difference in the study’s two primary endpoints, treatment with bivalirudin led to statistically significant reductions in all-cause death and cardiovascular death, as well as in major bleeding events, compared with patients treated with unfractionated heparin (Lancet 2015 [doi:10.1016/S0140-6736(15)60292-6]).

Although bivalirudin has generally been the more commonly used antithrombin drug in this clinical setting by U.S. interventionalists in recent years, results reported last year from the HEAT-PCI trial (Lancet 2014;384:1849-58) that showed better outcomes with unfractionated heparin have led to reduced use of bivalirudin, Dr. Grines said.

The new results from MATRIX coupled with results from other trials that compared those drugs can make clinicians “more confident about the benefit of bivalirudin,” she said.

Dr. Grines has been a consultant to and received honoraria from the Medicines Company, which markets Angiomax, and from Abbott Vascular, Merck, and the Volcano Group.

[email protected]


On Twitter @mitchelzoler

Micrograph showing HSCs

in the bone marrow

Scientists say they’ve identified a molecular pathway that is critical to hematopoietic stem cell (HSC) aging and can be manipulated to rejuvenate blood.

The researchers found that HSCs’ ability to repair damage caused by inappropriate protein folding in the mitochondria is essential for the cells’ survival and regenerative capacity.

The discovery has implications for research on reversing the signs of aging, a process thought to be caused by increased cellular stress and damage.

“Ultimately, a cell dies when it can’t deal well with stress,” said study author Danica Chen, PhD, of the University of California, Berkeley.

“We found that by slowing down the activity of mitochondria in the blood stem cells of mice, we were able to enhance their capacity to handle stress and rejuvenate old blood. This confirms the significance of this pathway in the aging process.”

Mitochondria host a multitude of proteins that must be folded properly to function correctly. When the folding goes awry, the mitochondrial unfolded-protein response (UPRmt) kicks in to boost the production of specific proteins to fix or remove the misfolded protein.

There has been little research on the UPRmt pathway, but studies in roundworms suggest its activity increases when there is a burst of mitochondrial growth.

Dr Chen and her colleagues noted that adult stem cells are normally in a quiescent state with little mitochondrial activity. They are activated only when needed to replenish tissue.

At that time, the mitochondrial activity increases, and stem cells proliferate and differentiate. When protein-folding problems occur, this fast growth could lead to more harm.

Dr Chen’s lab stumbled upon the importance of UPRmt in HSC aging while studying sirtuins, a class of proteins recognized as stress-resistance regulators.

The researchers noticed that levels of one particular sirtuin, SIRT7, increase as a way to help cells cope with stress from misfolded proteins in the mitochondria. But SIRT7 levels decline with age.

“We isolated blood stem cells from aged mice and found that when we increased the levels of SIRT7, we were able to reduce mitochondrial protein-folding stress,” Dr Chen said. “We then transplanted the blood stem cells back into mice, and SIRT7 improved the blood stem cells’ regenerative capacity.”

The researchers also found that HSCs deficient in SIRT7 proliferate more. This faster growth is due to increased protein production and increased activity of the mitochondria, and slowing things down appears to be a critical step in giving cells time to recover from stress.

Dr Chen likened this to an auto accident or stalled car stopping traffic on a freeway.

“When there’s a mitochondrial protein-folding problem, there is a traffic jam in the mitochondria,” she said. “If you prevent more proteins from being created and added to the mitochondria, you are helping to reduce the jam.”

Until this study, it was unclear which stress signals regulate HSCs’ transition to and from the quiescent state and how that related to tissue regeneration during aging.

“Identifying the role of this mitochondrial pathway in blood stem cells gives us a new target for controlling the aging process,” Dr Chen said.

She and her colleagues described this work in Science.

Micrograph showing HSCs

in the bone marrow

Scientists say they’ve identified a molecular pathway that is critical to hematopoietic stem cell (HSC) aging and can be manipulated to rejuvenate blood.

The researchers found that HSCs’ ability to repair damage caused by inappropriate protein folding in the mitochondria is essential for the cells’ survival and regenerative capacity.

The discovery has implications for research on reversing the signs of aging, a process thought to be caused by increased cellular stress and damage.

“Ultimately, a cell dies when it can’t deal well with stress,” said study author Danica Chen, PhD, of the University of California, Berkeley.

“We found that by slowing down the activity of mitochondria in the blood stem cells of mice, we were able to enhance their capacity to handle stress and rejuvenate old blood. This confirms the significance of this pathway in the aging process.”

Mitochondria host a multitude of proteins that must be folded properly to function correctly. When the folding goes awry, the mitochondrial unfolded-protein response (UPRmt) kicks in to boost the production of specific proteins to fix or remove the misfolded protein.

There has been little research on the UPRmt pathway, but studies in roundworms suggest its activity increases when there is a burst of mitochondrial growth.

Dr Chen and her colleagues noted that adult stem cells are normally in a quiescent state with little mitochondrial activity. They are activated only when needed to replenish tissue.

At that time, the mitochondrial activity increases, and stem cells proliferate and differentiate. When protein-folding problems occur, this fast growth could lead to more harm.

Dr Chen’s lab stumbled upon the importance of UPRmt in HSC aging while studying sirtuins, a class of proteins recognized as stress-resistance regulators.

The researchers noticed that levels of one particular sirtuin, SIRT7, increase as a way to help cells cope with stress from misfolded proteins in the mitochondria. But SIRT7 levels decline with age.

“We isolated blood stem cells from aged mice and found that when we increased the levels of SIRT7, we were able to reduce mitochondrial protein-folding stress,” Dr Chen said. “We then transplanted the blood stem cells back into mice, and SIRT7 improved the blood stem cells’ regenerative capacity.”

The researchers also found that HSCs deficient in SIRT7 proliferate more. This faster growth is due to increased protein production and increased activity of the mitochondria, and slowing things down appears to be a critical step in giving cells time to recover from stress.

Dr Chen likened this to an auto accident or stalled car stopping traffic on a freeway.

“When there’s a mitochondrial protein-folding problem, there is a traffic jam in the mitochondria,” she said. “If you prevent more proteins from being created and added to the mitochondria, you are helping to reduce the jam.”

Until this study, it was unclear which stress signals regulate HSCs’ transition to and from the quiescent state and how that related to tissue regeneration during aging.

“Identifying the role of this mitochondrial pathway in blood stem cells gives us a new target for controlling the aging process,” Dr Chen said.

She and her colleagues described this work in Science.

Micrograph showing HSCs

in the bone marrow

Scientists say they’ve identified a molecular pathway that is critical to hematopoietic stem cell (HSC) aging and can be manipulated to rejuvenate blood.

The researchers found that HSCs’ ability to repair damage caused by inappropriate protein folding in the mitochondria is essential for the cells’ survival and regenerative capacity.

The discovery has implications for research on reversing the signs of aging, a process thought to be caused by increased cellular stress and damage.

“Ultimately, a cell dies when it can’t deal well with stress,” said study author Danica Chen, PhD, of the University of California, Berkeley.

“We found that by slowing down the activity of mitochondria in the blood stem cells of mice, we were able to enhance their capacity to handle stress and rejuvenate old blood. This confirms the significance of this pathway in the aging process.”

Mitochondria host a multitude of proteins that must be folded properly to function correctly. When the folding goes awry, the mitochondrial unfolded-protein response (UPRmt) kicks in to boost the production of specific proteins to fix or remove the misfolded protein.

There has been little research on the UPRmt pathway, but studies in roundworms suggest its activity increases when there is a burst of mitochondrial growth.

Dr Chen and her colleagues noted that adult stem cells are normally in a quiescent state with little mitochondrial activity. They are activated only when needed to replenish tissue.

At that time, the mitochondrial activity increases, and stem cells proliferate and differentiate. When protein-folding problems occur, this fast growth could lead to more harm.

Dr Chen’s lab stumbled upon the importance of UPRmt in HSC aging while studying sirtuins, a class of proteins recognized as stress-resistance regulators.

The researchers noticed that levels of one particular sirtuin, SIRT7, increase as a way to help cells cope with stress from misfolded proteins in the mitochondria. But SIRT7 levels decline with age.

“We isolated blood stem cells from aged mice and found that when we increased the levels of SIRT7, we were able to reduce mitochondrial protein-folding stress,” Dr Chen said. “We then transplanted the blood stem cells back into mice, and SIRT7 improved the blood stem cells’ regenerative capacity.”

The researchers also found that HSCs deficient in SIRT7 proliferate more. This faster growth is due to increased protein production and increased activity of the mitochondria, and slowing things down appears to be a critical step in giving cells time to recover from stress.

Dr Chen likened this to an auto accident or stalled car stopping traffic on a freeway.

“When there’s a mitochondrial protein-folding problem, there is a traffic jam in the mitochondria,” she said. “If you prevent more proteins from being created and added to the mitochondria, you are helping to reduce the jam.”

Until this study, it was unclear which stress signals regulate HSCs’ transition to and from the quiescent state and how that related to tissue regeneration during aging.

“Identifying the role of this mitochondrial pathway in blood stem cells gives us a new target for controlling the aging process,” Dr Chen said.

She and her colleagues described this work in Science.

Pregnant woman

Photo by Nina Matthews

Results of a new analysis may help physicians predict the likelihood of complications in pregnant women with sickle cell disease (SCD).

The research showed that pregnant women with SCD had an increased risk of stillbirth, pre-eclampsia, preterm delivery, having infants who were born small for their gestational age, and other adverse outcomes.

Women with severe SCD, but not those with milder SCD, had a substantially higher risk of mortality than their healthy peers.

Researchers reported these findings in Blood.

“While we know that women with sickle cell disease will have high-risk pregnancies, we have lacked the evidence that would allow us to confidently tell these patients how likely they are to experience one complication over another,” said study author Eugene Oteng-Ntim, MD, of the Guy’s and St. Thomas’ NHS Foundation Trust in London, England.

“This reality makes it difficult for us as care providers to properly counsel our sickle cell patients considering pregnancy.”

To better estimate pregnancy-related complications in women with SCD, Dr Oteng-Ntim and his colleagues examined 21 published observational studies.

The team analyzed data on 26,349 pregnant women with SCD and 26,151,746 pregnant women who shared attributes with the SCD population, such as ethnicity or location, but were otherwise healthy.

The researchers classified the SCD population based on genotype, including 1276 women with the classic form (HbSS genotype), 279 with a milder form (HbSC genotype), and 24,794 whose disease genotype was unreported (non-specified SCD).

Thirteen of the studies originated from high-income countries ($30,000 income per capita or greater), and the remaining were from low- to median-income countries.

Compared to women without SCD, patients with HbSS genotype had an increased risk of death, with a risk ratio (RR) of 5.98. Women with non-specified SCD had an increased risk of death as well, with an RR of 18.51. There was only 1 death among women who were known to have HbSC SCD.

There was an increased risk of stillbirth among women with SCD, compared to those without the disease. The RRs were 3.94 for HbSS disease, 1.78 for HbSC disease, and 3.49 for non-specified SCD.

The researchers found a significantly lower risk of maternal mortality (odds ratio [OR]=0.15) and stillbirth (OR=0.28) in SCD patients from countries with a gross national income of $30,000 or greater. But income had no significant impact on pre-eclampsia, preterm delivery, or infants being small for their gestational age.

Women with all types of SCD had an increase in the risk of pre-eclampsia, compared to healthy women. The RRs were 2.43 for HbSS disease, 2.03 for HbSC disease, and 2.06 for non-specified SCD.

Women with SCD also had an increased risk of preterm delivery. The RRs were 2.21 for HbSS disease, 1.45 for HbSC disease, and 1.59 for non-specified SCD.

And women with SCD were more likely to have infants who were born small for their gestational age. The RRs were 3.72 for HbSS disease, 1.98 for HbSC disease, and 2.23 for non-specified SCD.

Analyses revealed that genotype (HbSS vs HbSC) had a significant impact on stillbirth, preterm delivery, and small infants, but it did not appear to impact the risk of pre-eclampsia.

The researchers said this study provides useful estimates of the morbidity and mortality associated with SCD in pregnancy.

“By improving care providers’ ability to more accurately predict adverse outcomes, this analysis is a first step toward improving universal care for all who suffer from this disease,” Dr Oteng-Ntim concluded.

Pregnant woman

Photo by Nina Matthews

Results of a new analysis may help physicians predict the likelihood of complications in pregnant women with sickle cell disease (SCD).

The research showed that pregnant women with SCD had an increased risk of stillbirth, pre-eclampsia, preterm delivery, having infants who were born small for their gestational age, and other adverse outcomes.

Women with severe SCD, but not those with milder SCD, had a substantially higher risk of mortality than their healthy peers.

Researchers reported these findings in Blood.

“While we know that women with sickle cell disease will have high-risk pregnancies, we have lacked the evidence that would allow us to confidently tell these patients how likely they are to experience one complication over another,” said study author Eugene Oteng-Ntim, MD, of the Guy’s and St. Thomas’ NHS Foundation Trust in London, England.

“This reality makes it difficult for us as care providers to properly counsel our sickle cell patients considering pregnancy.”

To better estimate pregnancy-related complications in women with SCD, Dr Oteng-Ntim and his colleagues examined 21 published observational studies.

The team analyzed data on 26,349 pregnant women with SCD and 26,151,746 pregnant women who shared attributes with the SCD population, such as ethnicity or location, but were otherwise healthy.

The researchers classified the SCD population based on genotype, including 1276 women with the classic form (HbSS genotype), 279 with a milder form (HbSC genotype), and 24,794 whose disease genotype was unreported (non-specified SCD).

Thirteen of the studies originated from high-income countries ($30,000 income per capita or greater), and the remaining were from low- to median-income countries.

Compared to women without SCD, patients with HbSS genotype had an increased risk of death, with a risk ratio (RR) of 5.98. Women with non-specified SCD had an increased risk of death as well, with an RR of 18.51. There was only 1 death among women who were known to have HbSC SCD.

There was an increased risk of stillbirth among women with SCD, compared to those without the disease. The RRs were 3.94 for HbSS disease, 1.78 for HbSC disease, and 3.49 for non-specified SCD.

The researchers found a significantly lower risk of maternal mortality (odds ratio [OR]=0.15) and stillbirth (OR=0.28) in SCD patients from countries with a gross national income of $30,000 or greater. But income had no significant impact on pre-eclampsia, preterm delivery, or infants being small for their gestational age.

Women with all types of SCD had an increase in the risk of pre-eclampsia, compared to healthy women. The RRs were 2.43 for HbSS disease, 2.03 for HbSC disease, and 2.06 for non-specified SCD.

Women with SCD also had an increased risk of preterm delivery. The RRs were 2.21 for HbSS disease, 1.45 for HbSC disease, and 1.59 for non-specified SCD.

And women with SCD were more likely to have infants who were born small for their gestational age. The RRs were 3.72 for HbSS disease, 1.98 for HbSC disease, and 2.23 for non-specified SCD.

Analyses revealed that genotype (HbSS vs HbSC) had a significant impact on stillbirth, preterm delivery, and small infants, but it did not appear to impact the risk of pre-eclampsia.

The researchers said this study provides useful estimates of the morbidity and mortality associated with SCD in pregnancy.

“By improving care providers’ ability to more accurately predict adverse outcomes, this analysis is a first step toward improving universal care for all who suffer from this disease,” Dr Oteng-Ntim concluded.

Pregnant woman

Photo by Nina Matthews

Results of a new analysis may help physicians predict the likelihood of complications in pregnant women with sickle cell disease (SCD).

The research showed that pregnant women with SCD had an increased risk of stillbirth, pre-eclampsia, preterm delivery, having infants who were born small for their gestational age, and other adverse outcomes.

Women with severe SCD, but not those with milder SCD, had a substantially higher risk of mortality than their healthy peers.

Researchers reported these findings in Blood.

“While we know that women with sickle cell disease will have high-risk pregnancies, we have lacked the evidence that would allow us to confidently tell these patients how likely they are to experience one complication over another,” said study author Eugene Oteng-Ntim, MD, of the Guy’s and St. Thomas’ NHS Foundation Trust in London, England.

“This reality makes it difficult for us as care providers to properly counsel our sickle cell patients considering pregnancy.”

To better estimate pregnancy-related complications in women with SCD, Dr Oteng-Ntim and his colleagues examined 21 published observational studies.

The team analyzed data on 26,349 pregnant women with SCD and 26,151,746 pregnant women who shared attributes with the SCD population, such as ethnicity or location, but were otherwise healthy.

The researchers classified the SCD population based on genotype, including 1276 women with the classic form (HbSS genotype), 279 with a milder form (HbSC genotype), and 24,794 whose disease genotype was unreported (non-specified SCD).

Thirteen of the studies originated from high-income countries ($30,000 income per capita or greater), and the remaining were from low- to median-income countries.

Compared to women without SCD, patients with HbSS genotype had an increased risk of death, with a risk ratio (RR) of 5.98. Women with non-specified SCD had an increased risk of death as well, with an RR of 18.51. There was only 1 death among women who were known to have HbSC SCD.

There was an increased risk of stillbirth among women with SCD, compared to those without the disease. The RRs were 3.94 for HbSS disease, 1.78 for HbSC disease, and 3.49 for non-specified SCD.

The researchers found a significantly lower risk of maternal mortality (odds ratio [OR]=0.15) and stillbirth (OR=0.28) in SCD patients from countries with a gross national income of $30,000 or greater. But income had no significant impact on pre-eclampsia, preterm delivery, or infants being small for their gestational age.

Women with all types of SCD had an increase in the risk of pre-eclampsia, compared to healthy women. The RRs were 2.43 for HbSS disease, 2.03 for HbSC disease, and 2.06 for non-specified SCD.

Women with SCD also had an increased risk of preterm delivery. The RRs were 2.21 for HbSS disease, 1.45 for HbSC disease, and 1.59 for non-specified SCD.

And women with SCD were more likely to have infants who were born small for their gestational age. The RRs were 3.72 for HbSS disease, 1.98 for HbSC disease, and 2.23 for non-specified SCD.

Analyses revealed that genotype (HbSS vs HbSC) had a significant impact on stillbirth, preterm delivery, and small infants, but it did not appear to impact the risk of pre-eclampsia.

The researchers said this study provides useful estimates of the morbidity and mortality associated with SCD in pregnancy.

“By improving care providers’ ability to more accurately predict adverse outcomes, this analysis is a first step toward improving universal care for all who suffer from this disease,” Dr Oteng-Ntim concluded.

Vials of drug and a syringe

The European Commission has granted orphan drug designation for intravenous (IV) alpha-1 antitrypsin (AAT) to treat graft-versus-host disease (GVHD).

AAT is a protein derived from human plasma that has demonstrated immunomodulatory, anti-inflammatory, tissue-protective, antimicrobial, and anti-apoptotic properties.

AAT may attenuate inflammation by lowering levels of pro-inflammatory mediators such as cytokines, chemokines, and proteases associated with GVHD.

The European Commission granted IV AAT orphan designation based on preliminary clinical and preclinical research.

Orphan designation is granted to a medicine intended to treat a rare condition occurring in not more than 5 in 10,000 people in the European Union. The designation allows the drug’s maker to benefit from incentives such as a 10-year period of market exclusivity, reduced regulatory fees, and protocol assistance from the European Medicines Agency.

IV AAT also has orphan designation to treat GVHD in the US.

Studies of AAT

AAT is being investigated in a phase 1/2 study involving 24 patients with GVHD who had an inadequate response to steroid treatment. The patients are enrolled in 4 dose cohorts, in which they receive up to 8 doses of AAT.

Interim results from this study were presented at the 2014 ASH Annual Meeting (abstract 3927). Preliminary results indicated that continuous administration of AAT as therapy for steroid-resistant gut GVHD is feasible in the subject population.

Following AAT administration, the researchers observed a decrease in diarrhea, a decrease in intestinal AAT loss, and improvement in endoscopic evaluation. In addition, AAT administration suppressed serum levels of pro-inflammatory cytokines and interfered with GVHD biomarkers.

Investigators have also published research on AAT in Blood. This study suggested that AAT has a protective effect against GVHD and enhances graft-vs-leukemia effects.

Kamada Ltd., the company developing IV AAT, plans to begin a phase 3 trial of the treatment in 2016 and get the product to market in 2019 or later.

Vials of drug and a syringe

The European Commission has granted orphan drug designation for intravenous (IV) alpha-1 antitrypsin (AAT) to treat graft-versus-host disease (GVHD).

AAT is a protein derived from human plasma that has demonstrated immunomodulatory, anti-inflammatory, tissue-protective, antimicrobial, and anti-apoptotic properties.

AAT may attenuate inflammation by lowering levels of pro-inflammatory mediators such as cytokines, chemokines, and proteases associated with GVHD.

The European Commission granted IV AAT orphan designation based on preliminary clinical and preclinical research.

Orphan designation is granted to a medicine intended to treat a rare condition occurring in not more than 5 in 10,000 people in the European Union. The designation allows the drug’s maker to benefit from incentives such as a 10-year period of market exclusivity, reduced regulatory fees, and protocol assistance from the European Medicines Agency.

IV AAT also has orphan designation to treat GVHD in the US.

Studies of AAT

AAT is being investigated in a phase 1/2 study involving 24 patients with GVHD who had an inadequate response to steroid treatment. The patients are enrolled in 4 dose cohorts, in which they receive up to 8 doses of AAT.

Interim results from this study were presented at the 2014 ASH Annual Meeting (abstract 3927). Preliminary results indicated that continuous administration of AAT as therapy for steroid-resistant gut GVHD is feasible in the subject population.

Following AAT administration, the researchers observed a decrease in diarrhea, a decrease in intestinal AAT loss, and improvement in endoscopic evaluation. In addition, AAT administration suppressed serum levels of pro-inflammatory cytokines and interfered with GVHD biomarkers.

Investigators have also published research on AAT in Blood. This study suggested that AAT has a protective effect against GVHD and enhances graft-vs-leukemia effects.

Kamada Ltd., the company developing IV AAT, plans to begin a phase 3 trial of the treatment in 2016 and get the product to market in 2019 or later.

Vials of drug and a syringe

The European Commission has granted orphan drug designation for intravenous (IV) alpha-1 antitrypsin (AAT) to treat graft-versus-host disease (GVHD).

AAT is a protein derived from human plasma that has demonstrated immunomodulatory, anti-inflammatory, tissue-protective, antimicrobial, and anti-apoptotic properties.

AAT may attenuate inflammation by lowering levels of pro-inflammatory mediators such as cytokines, chemokines, and proteases associated with GVHD.

The European Commission granted IV AAT orphan designation based on preliminary clinical and preclinical research.

Orphan designation is granted to a medicine intended to treat a rare condition occurring in not more than 5 in 10,000 people in the European Union. The designation allows the drug’s maker to benefit from incentives such as a 10-year period of market exclusivity, reduced regulatory fees, and protocol assistance from the European Medicines Agency.

IV AAT also has orphan designation to treat GVHD in the US.

Studies of AAT

AAT is being investigated in a phase 1/2 study involving 24 patients with GVHD who had an inadequate response to steroid treatment. The patients are enrolled in 4 dose cohorts, in which they receive up to 8 doses of AAT.

Interim results from this study were presented at the 2014 ASH Annual Meeting (abstract 3927). Preliminary results indicated that continuous administration of AAT as therapy for steroid-resistant gut GVHD is feasible in the subject population.

Following AAT administration, the researchers observed a decrease in diarrhea, a decrease in intestinal AAT loss, and improvement in endoscopic evaluation. In addition, AAT administration suppressed serum levels of pro-inflammatory cytokines and interfered with GVHD biomarkers.

Investigators have also published research on AAT in Blood. This study suggested that AAT has a protective effect against GVHD and enhances graft-vs-leukemia effects.

Kamada Ltd., the company developing IV AAT, plans to begin a phase 3 trial of the treatment in 2016 and get the product to market in 2019 or later.

MRI scanner

Magnetic resonance imaging (MRI) should be the gold standard for measuring liver iron concentration (LIC) in patients receiving ongoing transfusion therapy, according to a group of researchers.

The team found evidence suggesting that liver MRI is more accurate than liver biopsy in determining total body iron balance in patients with sickle cell disease and other disorders requiring regular blood transfusions.

The findings have been published in Magnetic Resonance Imaging.

“Measuring total body iron using MRI is safer and less painful than biopsy,” said study author John Wood, MD, PhD, of Children’s Hospital Los Angeles in California.

“In this study, we’ve demonstrated that it is also more accurate. MRI should be recognized as the new gold standard for determining iron accumulation in the body.”

Dr Wood and his colleagues came to this conclusion after analyzing data from 49 patients who were undergoing treatment with deferitazole, an experimental chelating agent.

The team looked at the amount of iron the patients were receiving by transfusion and the amount of chelating agent they consumed, providing insights into the expected changes in iron levels at 12, 24, and 48 weeks after the start of deferitazole.

To compare MRI and liver biopsy, the researchers used serial estimates of iron chelation efficiency (ICE) calculated by R2 and R2* MRI LIC estimates as well as by simulated liver biopsy (over all physically reasonable sampling variability).

The estimates suggested that MRI liver iron measurements (R2 and R2*) are more accurate than a physically realizable liver biopsy (which has a sampling error of 10% or higher).

For R2, the standard deviation of ICE was 44.8% at 12 weeks, 14.8% at 24 weeks, and 7.4% at 48 weeks. For R2*, the standard deviation was 22.9% at 12 weeks, 9.3% at 24 weeks, and 5.7% at 48 weeks.

For a biopsy with a sampling error of 0%, the standard deviation of ICE was 25.9% at 12 weeks, 12.8% at 24 weeks, and 6.7% at 48 weeks. For a biopsy with a sampling error of 10%, it was 32.8%, 16.5%, and 8.7%, respectively.

For a biopsy with a sampling error of 20%, the standard deviation of ICE was 49.1% at 12 weeks, 24.9% at 24 weeks, and 13% at 48 weeks. For a biopsy with a sampling error of 30%, it was 68.1%, 34.5%, and 18%, respectively. And for a biopsy with a sampling error of 40%, it was 88.1%, 44.6%, and 23.2%, respectively.

In practice, the accuracy of MRI compared to liver biopsy is likely even greater than these estimates suggest, Dr Wood said.

MRI scanner

Magnetic resonance imaging (MRI) should be the gold standard for measuring liver iron concentration (LIC) in patients receiving ongoing transfusion therapy, according to a group of researchers.

The team found evidence suggesting that liver MRI is more accurate than liver biopsy in determining total body iron balance in patients with sickle cell disease and other disorders requiring regular blood transfusions.

The findings have been published in Magnetic Resonance Imaging.

“Measuring total body iron using MRI is safer and less painful than biopsy,” said study author John Wood, MD, PhD, of Children’s Hospital Los Angeles in California.

“In this study, we’ve demonstrated that it is also more accurate. MRI should be recognized as the new gold standard for determining iron accumulation in the body.”

Dr Wood and his colleagues came to this conclusion after analyzing data from 49 patients who were undergoing treatment with deferitazole, an experimental chelating agent.

The team looked at the amount of iron the patients were receiving by transfusion and the amount of chelating agent they consumed, providing insights into the expected changes in iron levels at 12, 24, and 48 weeks after the start of deferitazole.

To compare MRI and liver biopsy, the researchers used serial estimates of iron chelation efficiency (ICE) calculated by R2 and R2* MRI LIC estimates as well as by simulated liver biopsy (over all physically reasonable sampling variability).

The estimates suggested that MRI liver iron measurements (R2 and R2*) are more accurate than a physically realizable liver biopsy (which has a sampling error of 10% or higher).

For R2, the standard deviation of ICE was 44.8% at 12 weeks, 14.8% at 24 weeks, and 7.4% at 48 weeks. For R2*, the standard deviation was 22.9% at 12 weeks, 9.3% at 24 weeks, and 5.7% at 48 weeks.

For a biopsy with a sampling error of 0%, the standard deviation of ICE was 25.9% at 12 weeks, 12.8% at 24 weeks, and 6.7% at 48 weeks. For a biopsy with a sampling error of 10%, it was 32.8%, 16.5%, and 8.7%, respectively.

For a biopsy with a sampling error of 20%, the standard deviation of ICE was 49.1% at 12 weeks, 24.9% at 24 weeks, and 13% at 48 weeks. For a biopsy with a sampling error of 30%, it was 68.1%, 34.5%, and 18%, respectively. And for a biopsy with a sampling error of 40%, it was 88.1%, 44.6%, and 23.2%, respectively.

In practice, the accuracy of MRI compared to liver biopsy is likely even greater than these estimates suggest, Dr Wood said.

MRI scanner

Magnetic resonance imaging (MRI) should be the gold standard for measuring liver iron concentration (LIC) in patients receiving ongoing transfusion therapy, according to a group of researchers.

The team found evidence suggesting that liver MRI is more accurate than liver biopsy in determining total body iron balance in patients with sickle cell disease and other disorders requiring regular blood transfusions.

The findings have been published in Magnetic Resonance Imaging.

“Measuring total body iron using MRI is safer and less painful than biopsy,” said study author John Wood, MD, PhD, of Children’s Hospital Los Angeles in California.

“In this study, we’ve demonstrated that it is also more accurate. MRI should be recognized as the new gold standard for determining iron accumulation in the body.”

Dr Wood and his colleagues came to this conclusion after analyzing data from 49 patients who were undergoing treatment with deferitazole, an experimental chelating agent.

The team looked at the amount of iron the patients were receiving by transfusion and the amount of chelating agent they consumed, providing insights into the expected changes in iron levels at 12, 24, and 48 weeks after the start of deferitazole.

To compare MRI and liver biopsy, the researchers used serial estimates of iron chelation efficiency (ICE) calculated by R2 and R2* MRI LIC estimates as well as by simulated liver biopsy (over all physically reasonable sampling variability).

The estimates suggested that MRI liver iron measurements (R2 and R2*) are more accurate than a physically realizable liver biopsy (which has a sampling error of 10% or higher).

For R2, the standard deviation of ICE was 44.8% at 12 weeks, 14.8% at 24 weeks, and 7.4% at 48 weeks. For R2*, the standard deviation was 22.9% at 12 weeks, 9.3% at 24 weeks, and 5.7% at 48 weeks.

For a biopsy with a sampling error of 0%, the standard deviation of ICE was 25.9% at 12 weeks, 12.8% at 24 weeks, and 6.7% at 48 weeks. For a biopsy with a sampling error of 10%, it was 32.8%, 16.5%, and 8.7%, respectively.

For a biopsy with a sampling error of 20%, the standard deviation of ICE was 49.1% at 12 weeks, 24.9% at 24 weeks, and 13% at 48 weeks. For a biopsy with a sampling error of 30%, it was 68.1%, 34.5%, and 18%, respectively. And for a biopsy with a sampling error of 40%, it was 88.1%, 44.6%, and 23.2%, respectively.

In practice, the accuracy of MRI compared to liver biopsy is likely even greater than these estimates suggest, Dr Wood said.

SAN DIEGO – Catheter ablation proved superior to amiodarone for treatment of persistent atrial fibrillation in patients with systolic heart failure in the randomized AATAC-AF trial.

The rate of the primary study endpoint – freedom from recurrent AF through 26 months of prospective follow-up– was 70% in the catheter ablation group, twice the 34% rate with amiodarone, Dr. Luigi Di Biase reported at the annual meeting of the American College of Cardiology. After covariate adjustment, the investigators found that recurrence was 2.5 times more likely in the patients treated with amiodarone.

But he added a major caveat: pulmonary vein antrum isolation (PVI) alone was no better than the antiarrhythmic drug. The high overall treatment success rate seen with catheter ablation in the trial was achieved by operators who performed PVI plus some additional form of ablation of their own choosing, such as elimination of non–pulmonary vein triggers, ablation of complex fractionated electrograms, and/or additional linear ablation lesions, according to Dr. Di Biase, head of electrophysiology at the Albert Einstein College of Medicine, New York.

AATAC-AF (Ablation versus Amiodarone for Treatment of Atrial Fibrillation in Patients with Congestive Heart Failure and an Implanted ICD/CRTD) was a multicenter, prospective, randomized trial involving 203 patients with persistent AF and heart failure with reduced ejection fraction. Patients randomized to ablation had to receive PVI at a minimum; operators could perform additional ablation according to their preference. Twenty percent of patients randomized to ablation received PVI alone; 80% underwent additional posterior wall and non–pulmonary vein trigger ablation. The 26-month rate of freedom from recurrence of AF was 36% in patients who received PVI alone and 79% in those who underwent more extensive ablations. A particular strength of the AATAC study was that all participants had an implantable cardioverter-defibrillator and/or cardiac resynchronization therapy device, permitting detection of AF with a much higher degree of accuracy than possible in most AF ablation trials.

Any recurrent AF episodes during the first 3 months of follow-up were excluded from the analysis, regardless of whether patients were in the ablation or amiodarone arms, in accord with the 3-month blanking period that’s standard among electrophysiologists. Patients averaged 1.4 ablation sessions during the first 3 months of the trial.

Regardless of treatment, patients in whom AF did not recur showed significantly greater improvement in left ventricular ejection fraction, exercise capacity, and heart failure–related quality of life.

In addition, all-cause mortality during follow-up was significantly lower in the ablation group: 8%, compared with 18% in patients assigned to amiodarone. Moreover, the rate of hospitalization for arrhythmia or worsening heart failure was 31% in the ablation group versus 57% in patients on amiodarone. The economic implications of this sharp reduction in hospitalizations will be the subject of further study, according to Dr. Di Biase.

Also noteworthy was the finding that seven patients had to discontinue amiodarone due to serious side effects: four because of thyroid toxicity, two for pulmonary toxicity, and one owing to hepatic dysfunction, he continued.

Discussant Dr. Richard I. Fogel, current president of the Heart Rhythm Society, commented that “the 70% arrhythmia-free follow-up was a little surprising to me.”

“That seems a little bit high, particularly in a group with persistent atrial fibrillation,” observed Dr. Fogel, who is chief executive officer at St. Vincent Medical Group, Indianapolis.

Dr. Di Biase attributed the high success rate to two factors: One, only highly experienced operators participated in AATAC, and two, most of them weren’t content to stick to PVI alone.

“If you try to do a more extensive procedure addressing non–pulmonary vein triggers in other areas in the left atrium, the success rate is increased by far,” the electrophysiologist said.

As for a possible mechanism for the mortality benefit seen with ablation, “several studies have shown that in a population with heart failure with reduced ejection fraction, atrial fibrillation is an independent predictor of mortality,” Dr. Di Biase said. “So I believe that staying in sinus rhythm may have affected the long-term mortality. If you have a treatment that reduces the amount of time in atrial fibrillation, you may reduce mortality.”

While catheter ablation is an increasingly popular treatment strategy in patients with drug-refractory paroxysmal AF, it has been understudied in the setting of AF and comorbid heart failure. These two conditions are commonly coexistent, and they feed on each other in a destructive way: AF worsens heart failure, and heart failure tends to make AF worse.

AATAC was funded by the participating investigators and institutions without external financial support. Dr. Di Biase reported serving as a consultant to Biosense Webster and St. Jude Medical and serving as a paid speaker for Atricure, Biotronik, Medtronic, Boston Scientific, and Epi EP.

[email protected]

SAN DIEGO – Catheter ablation proved superior to amiodarone for treatment of persistent atrial fibrillation in patients with systolic heart failure in the randomized AATAC-AF trial.

The rate of the primary study endpoint – freedom from recurrent AF through 26 months of prospective follow-up– was 70% in the catheter ablation group, twice the 34% rate with amiodarone, Dr. Luigi Di Biase reported at the annual meeting of the American College of Cardiology. After covariate adjustment, the investigators found that recurrence was 2.5 times more likely in the patients treated with amiodarone.

But he added a major caveat: pulmonary vein antrum isolation (PVI) alone was no better than the antiarrhythmic drug. The high overall treatment success rate seen with catheter ablation in the trial was achieved by operators who performed PVI plus some additional form of ablation of their own choosing, such as elimination of non–pulmonary vein triggers, ablation of complex fractionated electrograms, and/or additional linear ablation lesions, according to Dr. Di Biase, head of electrophysiology at the Albert Einstein College of Medicine, New York.

AATAC-AF (Ablation versus Amiodarone for Treatment of Atrial Fibrillation in Patients with Congestive Heart Failure and an Implanted ICD/CRTD) was a multicenter, prospective, randomized trial involving 203 patients with persistent AF and heart failure with reduced ejection fraction. Patients randomized to ablation had to receive PVI at a minimum; operators could perform additional ablation according to their preference. Twenty percent of patients randomized to ablation received PVI alone; 80% underwent additional posterior wall and non–pulmonary vein trigger ablation. The 26-month rate of freedom from recurrence of AF was 36% in patients who received PVI alone and 79% in those who underwent more extensive ablations. A particular strength of the AATAC study was that all participants had an implantable cardioverter-defibrillator and/or cardiac resynchronization therapy device, permitting detection of AF with a much higher degree of accuracy than possible in most AF ablation trials.

Any recurrent AF episodes during the first 3 months of follow-up were excluded from the analysis, regardless of whether patients were in the ablation or amiodarone arms, in accord with the 3-month blanking period that’s standard among electrophysiologists. Patients averaged 1.4 ablation sessions during the first 3 months of the trial.

Regardless of treatment, patients in whom AF did not recur showed significantly greater improvement in left ventricular ejection fraction, exercise capacity, and heart failure–related quality of life.

In addition, all-cause mortality during follow-up was significantly lower in the ablation group: 8%, compared with 18% in patients assigned to amiodarone. Moreover, the rate of hospitalization for arrhythmia or worsening heart failure was 31% in the ablation group versus 57% in patients on amiodarone. The economic implications of this sharp reduction in hospitalizations will be the subject of further study, according to Dr. Di Biase.

Also noteworthy was the finding that seven patients had to discontinue amiodarone due to serious side effects: four because of thyroid toxicity, two for pulmonary toxicity, and one owing to hepatic dysfunction, he continued.

Discussant Dr. Richard I. Fogel, current president of the Heart Rhythm Society, commented that “the 70% arrhythmia-free follow-up was a little surprising to me.”

“That seems a little bit high, particularly in a group with persistent atrial fibrillation,” observed Dr. Fogel, who is chief executive officer at St. Vincent Medical Group, Indianapolis.

Dr. Di Biase attributed the high success rate to two factors: One, only highly experienced operators participated in AATAC, and two, most of them weren’t content to stick to PVI alone.

“If you try to do a more extensive procedure addressing non–pulmonary vein triggers in other areas in the left atrium, the success rate is increased by far,” the electrophysiologist said.

As for a possible mechanism for the mortality benefit seen with ablation, “several studies have shown that in a population with heart failure with reduced ejection fraction, atrial fibrillation is an independent predictor of mortality,” Dr. Di Biase said. “So I believe that staying in sinus rhythm may have affected the long-term mortality. If you have a treatment that reduces the amount of time in atrial fibrillation, you may reduce mortality.”

While catheter ablation is an increasingly popular treatment strategy in patients with drug-refractory paroxysmal AF, it has been understudied in the setting of AF and comorbid heart failure. These two conditions are commonly coexistent, and they feed on each other in a destructive way: AF worsens heart failure, and heart failure tends to make AF worse.

AATAC was funded by the participating investigators and institutions without external financial support. Dr. Di Biase reported serving as a consultant to Biosense Webster and St. Jude Medical and serving as a paid speaker for Atricure, Biotronik, Medtronic, Boston Scientific, and Epi EP.

[email protected]

SAN DIEGO – Catheter ablation proved superior to amiodarone for treatment of persistent atrial fibrillation in patients with systolic heart failure in the randomized AATAC-AF trial.

The rate of the primary study endpoint – freedom from recurrent AF through 26 months of prospective follow-up– was 70% in the catheter ablation group, twice the 34% rate with amiodarone, Dr. Luigi Di Biase reported at the annual meeting of the American College of Cardiology. After covariate adjustment, the investigators found that recurrence was 2.5 times more likely in the patients treated with amiodarone.

But he added a major caveat: pulmonary vein antrum isolation (PVI) alone was no better than the antiarrhythmic drug. The high overall treatment success rate seen with catheter ablation in the trial was achieved by operators who performed PVI plus some additional form of ablation of their own choosing, such as elimination of non–pulmonary vein triggers, ablation of complex fractionated electrograms, and/or additional linear ablation lesions, according to Dr. Di Biase, head of electrophysiology at the Albert Einstein College of Medicine, New York.

AATAC-AF (Ablation versus Amiodarone for Treatment of Atrial Fibrillation in Patients with Congestive Heart Failure and an Implanted ICD/CRTD) was a multicenter, prospective, randomized trial involving 203 patients with persistent AF and heart failure with reduced ejection fraction. Patients randomized to ablation had to receive PVI at a minimum; operators could perform additional ablation according to their preference. Twenty percent of patients randomized to ablation received PVI alone; 80% underwent additional posterior wall and non–pulmonary vein trigger ablation. The 26-month rate of freedom from recurrence of AF was 36% in patients who received PVI alone and 79% in those who underwent more extensive ablations. A particular strength of the AATAC study was that all participants had an implantable cardioverter-defibrillator and/or cardiac resynchronization therapy device, permitting detection of AF with a much higher degree of accuracy than possible in most AF ablation trials.

Any recurrent AF episodes during the first 3 months of follow-up were excluded from the analysis, regardless of whether patients were in the ablation or amiodarone arms, in accord with the 3-month blanking period that’s standard among electrophysiologists. Patients averaged 1.4 ablation sessions during the first 3 months of the trial.

Regardless of treatment, patients in whom AF did not recur showed significantly greater improvement in left ventricular ejection fraction, exercise capacity, and heart failure–related quality of life.

In addition, all-cause mortality during follow-up was significantly lower in the ablation group: 8%, compared with 18% in patients assigned to amiodarone. Moreover, the rate of hospitalization for arrhythmia or worsening heart failure was 31% in the ablation group versus 57% in patients on amiodarone. The economic implications of this sharp reduction in hospitalizations will be the subject of further study, according to Dr. Di Biase.

Also noteworthy was the finding that seven patients had to discontinue amiodarone due to serious side effects: four because of thyroid toxicity, two for pulmonary toxicity, and one owing to hepatic dysfunction, he continued.

Discussant Dr. Richard I. Fogel, current president of the Heart Rhythm Society, commented that “the 70% arrhythmia-free follow-up was a little surprising to me.”

“That seems a little bit high, particularly in a group with persistent atrial fibrillation,” observed Dr. Fogel, who is chief executive officer at St. Vincent Medical Group, Indianapolis.

Dr. Di Biase attributed the high success rate to two factors: One, only highly experienced operators participated in AATAC, and two, most of them weren’t content to stick to PVI alone.

“If you try to do a more extensive procedure addressing non–pulmonary vein triggers in other areas in the left atrium, the success rate is increased by far,” the electrophysiologist said.

As for a possible mechanism for the mortality benefit seen with ablation, “several studies have shown that in a population with heart failure with reduced ejection fraction, atrial fibrillation is an independent predictor of mortality,” Dr. Di Biase said. “So I believe that staying in sinus rhythm may have affected the long-term mortality. If you have a treatment that reduces the amount of time in atrial fibrillation, you may reduce mortality.”

While catheter ablation is an increasingly popular treatment strategy in patients with drug-refractory paroxysmal AF, it has been understudied in the setting of AF and comorbid heart failure. These two conditions are commonly coexistent, and they feed on each other in a destructive way: AF worsens heart failure, and heart failure tends to make AF worse.

AATAC was funded by the participating investigators and institutions without external financial support. Dr. Di Biase reported serving as a consultant to Biosense Webster and St. Jude Medical and serving as a paid speaker for Atricure, Biotronik, Medtronic, Boston Scientific, and Epi EP.

[email protected]

Uncompensated hospital care costs fell by an estimated $7 billion in 2014 because of marketplace coverage and state Medicaid expansions under the Affordable Care Act, according to a March 23 report by the Department of Health & Human Services. State Medicaid expansions accounted for an estimated $5 billion of the reduction, the HHS analysis found.

U.S. hospitals provided $50 billion in uncompensated care in 2013, the report found. Based on estimated coverage gains in 2014, the HHS Office of the Assistant Secretary for Planning and Evaluation (ASPE) estimates that uncompensated care costs were $7.4 billion lower in 2014 than they would have been had insurance coverage remained at 2013 levels. Hospitals spent an estimated $27 billion in uncompensated care in 2014, compared with an estimated $35 billion at 2013 coverage levels, a 21% reduction in uncompensated care spending. To arrive at the figures, ASPE analyzed uncompensated hospital care levels and cost reports from the Centers for Medicare & Medicaid Services, census data, estimates from Gallup-Healthways, and Medicaid enrollment data.

While $5 billion of the reduction came from the 28 states that have expanded Medicaid, $2 billion resulted from the 22 states that have not expanded Medicaid, according to ASPE. The government noted that if the nonexpansion states had increases proportionately as large in Medicaid coverage as did the expansion states, their uncompensated care costs would have declined by an additional $1.4 billion.

March 23 marked the fifth anniversary of President Obama’s signing the ACA into law. In a statement by the White House, the president praised the law’s success, and its impact on patients and the country.

[email protected]

On Twitter @legal_med

Uncompensated hospital care costs fell by an estimated $7 billion in 2014 because of marketplace coverage and state Medicaid expansions under the Affordable Care Act, according to a March 23 report by the Department of Health & Human Services. State Medicaid expansions accounted for an estimated $5 billion of the reduction, the HHS analysis found.

U.S. hospitals provided $50 billion in uncompensated care in 2013, the report found. Based on estimated coverage gains in 2014, the HHS Office of the Assistant Secretary for Planning and Evaluation (ASPE) estimates that uncompensated care costs were $7.4 billion lower in 2014 than they would have been had insurance coverage remained at 2013 levels. Hospitals spent an estimated $27 billion in uncompensated care in 2014, compared with an estimated $35 billion at 2013 coverage levels, a 21% reduction in uncompensated care spending. To arrive at the figures, ASPE analyzed uncompensated hospital care levels and cost reports from the Centers for Medicare & Medicaid Services, census data, estimates from Gallup-Healthways, and Medicaid enrollment data.

While $5 billion of the reduction came from the 28 states that have expanded Medicaid, $2 billion resulted from the 22 states that have not expanded Medicaid, according to ASPE. The government noted that if the nonexpansion states had increases proportionately as large in Medicaid coverage as did the expansion states, their uncompensated care costs would have declined by an additional $1.4 billion.

March 23 marked the fifth anniversary of President Obama’s signing the ACA into law. In a statement by the White House, the president praised the law’s success, and its impact on patients and the country.

[email protected]

On Twitter @legal_med

Uncompensated hospital care costs fell by an estimated $7 billion in 2014 because of marketplace coverage and state Medicaid expansions under the Affordable Care Act, according to a March 23 report by the Department of Health & Human Services. State Medicaid expansions accounted for an estimated $5 billion of the reduction, the HHS analysis found.

U.S. hospitals provided $50 billion in uncompensated care in 2013, the report found. Based on estimated coverage gains in 2014, the HHS Office of the Assistant Secretary for Planning and Evaluation (ASPE) estimates that uncompensated care costs were $7.4 billion lower in 2014 than they would have been had insurance coverage remained at 2013 levels. Hospitals spent an estimated $27 billion in uncompensated care in 2014, compared with an estimated $35 billion at 2013 coverage levels, a 21% reduction in uncompensated care spending. To arrive at the figures, ASPE analyzed uncompensated hospital care levels and cost reports from the Centers for Medicare & Medicaid Services, census data, estimates from Gallup-Healthways, and Medicaid enrollment data.

While $5 billion of the reduction came from the 28 states that have expanded Medicaid, $2 billion resulted from the 22 states that have not expanded Medicaid, according to ASPE. The government noted that if the nonexpansion states had increases proportionately as large in Medicaid coverage as did the expansion states, their uncompensated care costs would have declined by an additional $1.4 billion.

March 23 marked the fifth anniversary of President Obama’s signing the ACA into law. In a statement by the White House, the president praised the law’s success, and its impact on patients and the country.

[email protected]

On Twitter @legal_med