Thank you. Thanks for having me, AOSSM, and thanks to my co-authors. So as a background, the bare ACL repair or restoration procedure involves placing sutures into the tibial stump of an ACL tear, bringing those sutures into a femoral tunnel to re-approximate the stump edges to the femur, and then placing the bare scaffold over top of the repair. The purpose of the bare scaffold is to block the synovial fluid from washing away the clotting factors in the scaffold that will help the ACL heal. The first inhuman bare trial was in 2015. This was a single surgeon study involving 10 patients who underwent bare repair compared to 10 patients who underwent ACL reconstruction. The age group for this trial was 18 to 35, and the surgeries were done within 30 days of injury. The success from this trial led to a more robust bare 2 trial, which was a double-blinded randomized controlled trial involving 3 surgeons and 100 patients. 65 patients underwent the bare ACL repair procedure, and 35 underwent ACL reconstruction. The age group for this trial was expanded to 14 to 35, and surgery was done within 42 days of injury. The trial opened in May 2016 and was completed in May 2017, and of the 100 patients who were enrolled, 99 had two-year follow-up. Again, success from the bare 2 trial led to a bare 3 trial, which has just finished enrollment. It was slowed down a little bit due to COVID. This is a multi-center trial that involved 50 patients per center. In our institution, we were able to enroll 49 patients that have now two-year follow-up. The age group for this trial dropped down to ages 12 and up. So when you look at all three trials, the purpose of this report is to look at our data in these three trials and identify patients who underwent ACL repair procedure, failed that and required a reconstruction within two years of the repair. It's a case control Level 3 trial. So inclusion needed to participate in one of the three trials, bare 1, 2, or 3, needed to undergo ACL repair, and required revision surgery to ACL reconstruction within two years. I went through the eligibility criteria which just shows that in the bare 2 and 3 trials, the age groups dropped from 18 to 35 to 14 to 35 to 12 to no limit in the upper age group. All surgeries were done within 50 days of injury in the bare 3 trial and that was the largest gap between injury and surgery. We looked at pretty much everything we could think of that might influence the outcome. Patient demographics, injury characteristics, patient reported outcomes, imaging results preoperatively, including the tibial stump length and notch size, the tibial slope, and any intraoperative findings, chondral injuries, knee hyperextension, meniscal problems, things like that. So of the three bare trials at Boston Children's, we wound up with 123 patients that underwent repair, and the population really fits our group. So the age range was 16 to 23, with a median age of 17. So sort of a younger group than you'll see in other trials, 54% female, which is consistent with what we see. So of those 123 patients, 18 required conversion to a reconstruction within two years. So 18 patients within two years, 15%, and that's who we're looking at in this trial. Consort diagram just shows that we enrolled 124 patients that underwent bare and only lost one to follow-up, so that's where the 123 number comes into play. So when we look at the bivariate analysis of risk factors for requiring conversion to ACL reconstruction, younger age, contact injury, and increased medial tibial slope were the major bivariate risk factors identified. When we did a multivariable logistic regression analysis, the two independent predictors of revision were younger age and increased medial tibial slope. The effective age is not insignificant. When we looked at patients that were over 22 years old at our institution, 31 patients underwent ACL repair and were over 22 years old at the time of surgery, and were 31 for 31 there. None have undergone revision at the two-year follow-up. That rate changes with every year younger from there. So the age group 18 to 22 failed at about a 12% rate. The age 16 to 17 failed at a 22% rate, and age under 16 failed at a 26% rate. So the odds of requiring a revision ACL reconstruction decreased by 30% for every year increase in age. There was also a major effect of medial tibial slope, increasing 28% for each degree increase in medial tibial slope. Nothing else that we looked at ended up mattering, including sex, baseline IKDC, mark scores, knee hyperextension, or meniscal status. So in conclusion, younger age and higher medial tibial slope were both independent predictors for requiring ACL reconstruction within two years of a bare ACL repair procedure. Thank you. »» Thank you.

bare ACL repair procedure

scaffold

ACL tear

ACL reconstruction

predictors