and Anna for putting on a great meeting, and for the honor of presenting my research here today. So, to get started, these are disclosures. Our study is an Arthrex funded study to get us the cadavers, the implants, and the instruments used. So, as we all know, the ulnar collateral ligament is made up of three major components, the anterior, posterior, and oblique bundles. The anterior bundle is the main valgus restraint from 30 to 120 degrees of flexion. Pitching, or other overhand throws, does create a valgus force that can be near the ultimate tensile strength of the UCL, and this can result in microtrauma and chronic attritional tearing. Often, when pitchers or other overhand throwers sustain these types of injuries, they have to have surgery to return to play, and UCL repair, historically, for these types of injuries have resulted in poor outcomes. That is until Dr. Jobe came along and performed the first UCL reconstruction, which restored the valgus restraint in these throwers, allowed them to return to competition, and we all know about Tommy John, which is what the surgery is now named after. There have been evolving techniques since Dr. Jobe first performed the surgery, from exposure, ulnar nerve management, and then all types of fixation techniques on both the humerus and the ulna. Outcomes have been generally very good, with 78 to 94% of return to play at either the previous or higher level. However, the rehab for these injuries is extremely lengthy, and depending on who you read, it can be 13.8 to up to 20.5 months. Then, there's the concept of the internal brace, and what the internal brace is is it puts a high tensile strength suture in line with the orientation of ligament, and it creates a check ring, reducing the stress on the repair or reconstruction as it heals. This has already been applied to various ligaments throughout the body, and has been shown biomechanically to provide enhanced time zero stability. In the elbow, there has been the UCL repair, which Dr. Dugas has shown us to have equivalent load to failure, as well as greater resistance to gapping versus UCL reconstruction. Outcomes for UCL repair has been very good, with over 90% return to sport. Approximately six months, but this is only best for the acute or subacute UCL ruptures. The purpose of our study was to look at the elbow valgus stability of native, deficient, and three-strand docking UCL reconstructions with and without internal bracing. Then, we also compared the stiffness and load to failure of the UCL reconstruction with and without internal bracing. Our hypothesis was that the UCL reconstruction with internal bracing will demonstrate similar valgus stability compared to native and UCL reconstruction states without internal bracing at all flexion angles, and that there would be greater stiffness and load to failure compared to UCL reconstruction alone. So, we had 24 fresh frozen cadaveric elbows, and we created two matched cohorts, 13 males, 11 females, and equal in terms of laterality. There was no significant difference in age in our cohorts, with a mean age of 57.2 years. We've randomized these two groups into 12 groups, or 12 elbows in each group, with UCL reconstruction with internal bracing. And then, in terms of preparing the specimens, we thawed them overnight, and then we did an FCU muscle splitting approach. For our UCL reconstruction, this is the preferred technique of the senior author, where we did a three-strand docking technique, where we used the extra graft for the posterior limb. What has been shown biomechanically is that it's similar to two-strand docking technique with the added benefit of providing more collagen to the reconstructed ligament. For our internal bracing technique, we needed a way to figure out how we're gonna get fixation on both the ulna and the humerus. So, what we used, and based our ulnar fixation, was on this paper, actually out of our institution as well, showing that you can restore valgus stability up to 15 millimeters away from the ulna-humeral joint, along the medial ulnar ridge. So, what we did was we put a 2.6 millimeter soft anchor along the medial ulnar ridge, about 10 millimeters from the ulna-humeral joint, while our ulnar tunnels were drilled five millimeters from the ulna-humeral joint, and then we fixed it on the humerus through the humeral docking tunnel, and tied it over the humeral bone bridge. In order to potentially avoid any sort of stress shielding, we did put a freer elevator that was about two millimeters thick underneath the internal brace, and then we tensioned that after we tensioned the graft itself. For biomechanical testing, we tested the valgus angle through the range of motion with a torque of three newton meters. We cycled it five times per specimen and using motion tracking cameras, and we tested all four different states with 12 specimens in the UCL reconstruction and 12 with the internal brace. And then for our stiffness to load to failure, we did it at 70 degrees of flexion with a valgus load rate of 0.5 millimeters per second, comparing the UCL reconstruction with and without internal bracing. What we found for our results was that the intact was greater than deficient at all angles, which is not surprising. The UCL reconstruction was more stable than the deficient states from 50 to 120 degrees, while the UCL reconstruction with internal bracing was greater than deficient at all angles, but there was no significant difference between the UCL reconstruction with internal bracing and the UCL reconstruction alone. In terms of load to failure and stiffness, the UCL reconstruction with internal bracing was significantly stronger than the UCL reconstruction alone and in terms of stiffness, we found similar results with statistical significance. In terms of modes to failure, this is what we found in terms of graft rupture, fracture, and internal brace failure. What I wanted to point out here is that we did find statistical significance in that in our internal braced specimens, there were only three graft ruptures as opposed to UCL reconstruction alone, there were 10. So what we found in our study is that the elbow was not over-constrained through a range of motion. There were no significant differences between the native UCL reconstruction and UCL reconstruction with internal bracing at all flexion angles. The UCL reconstruction with internal bracing did provide a greater load to failure as well as stiffness, which is consistent with other biomechanical studies that have looked at this. Limitations is that we did not have true match pairs in our cohorts, unfortunately, but we did try to control for that by having similarities in age, gender, as well as laterality. The specimens were older with mean age of 57.2 and this is a time zero study, so we cannot simulate the in vivo UCL reconstruction. So what can we conclude from this is that the novel technique of UCL reconstruction with internal bracing has greater time zero stiffness and ultimate failure load. And the question is, can we extrapolate this to a clinical application? Is the internal brace protective of our UCL reconstruction graph? And can this possibly accelerate the rehabilitation in our throwing athletes? Thank you very much. Michael, if you could have a seat at the podium here.

UCL injuries

Tommy John surgery

internal brace

valgus stability

rehabilitation