Thank you. My name is Harrison Schofield and I'm a fifth year orthopedic surgery resident at John Peter Smith Hospital in Fort Worth, Texas. I'll be presenting our research today on alternate knee loading following ACL repair versus reconstruction. I'd like to thank the AOSSM as well as my co-authors for allowing me to present this research. We have no relevant conflicts to disclose. Patient expectations are very high prior to ACL reconstruction with 91% expecting to turn to the same level of sport following surgery. However, the patient outcome data tells a different story with only 81% returning to any sport, 65% returning to pre-injury level of sport, and 55% returning to competitive level of sport. Also, 20% to 30% of patients saying graph re-rupture or contralateral ACL tear at long-term follow-up. Furthermore, up to 50% of patients say they'll have osteoarthritis of the knee following ACL reconstruction at 5 to 15 years after surgery. ACL repair was largely abandoned in clinical practice until a recent renewed interest. This can be mostly attributed to Fagan's study in 1976 that showed greater than 50% re-tear rate of ACL repairs with significant complications in mid-term follow-up. However, this study was performed on all ACL tear types, was performed through an arthrotomy. Rehab protocols were much different compared to today, and all techniques with absorbable sutures were used. Of note on re-analysis of the study's results, the proximal ACL tear had a much lower re-tear rate compared to mid-substance tears. Although current data has varied, some newer data on ACL repair shows a much lower re-tear rate at mid-term follow-up than the Fagan study, and appears to not be significantly higher compared to ACL reconstruction. There are many potential benefits to performing ACL repair for reconstruction, including preserving the native ACL innervation and blood supply, no associated graft site morbidity, improved early knee range of motion, possible improved knee biomechanics and proprioception, as well as possible decrease in long-term knee osteoarthritis. The purpose of this study was to analyze knee joint loading following ACL repair versus reconstruction. For our methods, we retrospectively reviewed 15 ACL repairs and 15 ACL reconstructions using BTB autograft. All patients underwent biomechanical testing at three months postoperatively. Patients performed a single leg squat test, and data was collected by a camera motion capture system, as well as force plate analysis. All ACL repairs were performed on Sherman type 1 or 2 tears. The repair method was similar to that published by Vanderlist et al., but was modified to include a single suture anchor in the femoral footprint. An internal brace was also placed along the anterior medial and posterior lateral aspect of the ACL. The patient demographics were all similar, except the patients in the ACL repair group are significantly older compared to the reconstruction group, which is a limitation of our study. The main findings of the study were that the ACL repair group had significantly greater peak knee extension moment, net knee joint power, and quadricep strength limb symmetry index compared to the ACL reconstruction group. Compared to ACL reconstruction, ACL repair patients demonstrated differing loading strategies, greater quadricep strength, and greater limb symmetry. These outcomes are despite the fact the repair group is older, which we expect to have a slower recovery of strength. These outcomes are unique to our knowledge and is the first study to compare kinetics between ACL repair and ACL reconstruction cohorts at the three-month time point. Prior research demonstrated quadricep strength at three months after surgery predicts strength at time of return to sport. Also quadricep strength deficits following ACL reconstruction using BTB autograft continued long after expected time of return to sport, with side-to-side differences of 23% and 14% at 6 and 12 months, respectively. Improved quadricep strength deficits are associated with poor self-reported outcomes, altered knee biomechanics, and increased risk of secondary injury. Some potential reasons for the improved quadricep strength of the repair is a less traumatic procedure, no associated graft site morbidity, and decreased arthrogenic muscle inhibition. Prior research has shown that greater peak knee joint loading is associated with decreased collagen turnover following ACL reconstruction. Furthermore, WellSan et al. demonstrated that decreased knee joint loading was associated with early knee osteoarthritis following ACL reconstruction. These studies support that decreased knee joint loading may be associated with osteoarthritis following ACL reconstruction. Prior literature demonstrates that ACL repair patients regain knee range of motion faster compared to ACL reconstruction with a trend towards decreased complication. This study adds to this previous literature in that ACL repair patients tend to regain quad strength and knee joint loading faster compared to ACL reconstruction. There are several limitations to this study, including that a short-term follow-up at three months and longer-term follow-up is needed. It's also a relatively small sample size with different ages between groups. This study does not include data on ACL healing and re-teriorates. Also due to the retrospective study design, we cannot determine a relationship between ACL repair and joint loading, and there is potential for selection bias. Thank you.

Harrison Schofield

orthopedic surgery resident

ACL repair

ACL reconstruction

patient expectations