I'd like to thank Anna for the opportunity to present here today. I have no conflicts of interest to disclose. So why is internal bracing the way of the future, maybe? To answer that question, I think we should go back to some stuff in the past. So for the sake of time, I used ACL repair as an example. So when we look at ACL repair, that was the standard of care, open primary repair technique, but abandoned in the 1990s. So why was it abandoned? It was largely because of the poor outcomes, which were due to the need for an open procedure, really mechanically poor fixation techniques that required prolonged periods of immobilization. So recently, there's been a new interest in ACL repair techniques, which I think is largely spiked by the improved results that are seen in some of the preclinical studies and some of the new options that we have for biological augmentation, as well as internal bracing. So a couple of years ago, when I was in a fellowship at Curlin-Joppa, I did a systematic review on the topic of ACL repair, and really what we found is that there was a large number of preclinical studies, like mostly the ones led by Dr. Murray, that show some of the promising results that she showed earlier, where ACL repair, even more so than ACL reconstruction, seem to be counter-protective to the need. But even when we look at the large number of clinical studies on ACL repair, they largely fall into two categories. We have the older studies on open ACL repairs that have long-term follow-up, but very poor outcomes, and then we have the newer studies with shorter-term follow-up, which show very promising results. So what can we learn from these studies? Well, what we learned is that there's a lot of different factors that influence whether repairs can be successful, and one of these things is the tear type and location. And actually, Dr. Sherman already discovered this after seeing some of the same poor mid- to long-term results that Dr. Feagin and Dr. Curl saw after the open ACL repair techniques. He was the first one that looked at a subgroup of his proximal repairs and saw that they fared a lot better, whereas the mid-substance tears had the worst outcomes. Then of course, biology comes into play, and lots of different authors have looked at various types of biological enhancement, ECM, SIS, PRP, and all of these have improved cross-sectional area compared to repair alone, but none of them have provided any kind of mechanical stability, and so there's no differences after these biological augmentations for incisive forces, stiffness, or any kind of mechanical properties. So when we look at age and skeletal maturity, I think studies like this first clinical case series of the three pediatric patients that underwent a primary repair with internal brace of a complete proximal or distal ACL avulsion, and then had this internal brace removed at three months post-op, and had a second look at arthroscopy performed, which showed that the ACL repair had completely healed and it had a stable knee, and didn't have any growth disturbance, I think these results all make us kind of excited, and I think that this is a small series, but certainly similar results have been shown in animal models where skeletally immature animals seem to have improved structural properties after ACL repair. And then lastly, the timing of surgery is very important. Several studies have shown that earlier surgery leads to better outcomes, so we look at the animal models when ACL repair was done at times zero versus two weeks versus six weeks, so the lay-in repair resulted in decreased yield loads, maximal loads, stiffness, and increased laxity. And these findings have already been shown in some of the older studies, for example, Dr. Lishholm's study published in 1982 on open ACL repairs, when he looked at all of his 175 patients, he actually also found the best results in those that had repair within four weeks after the injury. So then where does the internal bracing come into play? Well, I think that suture type and fixation technique is very important. Dr. Feig and Dr. Crowley used absorbable sutures that were tied to the IT band, which obviously is mechanically not a very sound construct, and Dr. Marshall already had better results using non-absorbable suture, but when we look at the more recent studies, Dr. Seitz and Dr. Murray, that used some type of internal brace as an augmentation, they found faster healing, higher yield loads, maximal loads, and stiffness. So the conclusion of our systematic review on ACL repair was that it is a feasible option for the right patient. The proximal tears, younger patients, ideally scheduling the immature, and those that have surgery early, soon after the injury, and if we can add some form of biology to it. But the caveat from all the previous literature was that some form of structural support, like a scaffold or an internal brace is needed for this biology to have any kind of effect. So I think the future of internal bracing is exciting. We have a couple of studies going on in my lab, where we're testing some internal bracing constructs on our six degrees of freedom robot. I hope to be able to present the results of our MCL study here in the near future. And the possibilities, of course, go beyond the knee, and can include some of the other joints and other ligaments. So lastly, I'd like to thank Anna again, I'd like to thank Dr. Kelly for inviting me, and then I'd like to thank the co-authors for my systematic review, who helped me put all this data together, Dr. Alit Raj and Dr. Olympus Vasti, two of the smartest guys I know. Thanks.

ACL repair

internal bracing

biological augmentation

tear type

skeletal maturity