Thanks Brian, good afternoon. So we're going to talk about bony bain cart repairs and the biomechanics of it. And there's going to be two talks in the row and I think the second one is a nice follow-up to the first one. So let's see how do I advance this. Okay I'd like to thank my co-authors. So single and double row technique has been described for bony bain cart lesions. It was described by Peter Millet. And it was biomechanically tested by Peter and also by George Othwell. And the forces that were applied in those biomechanics studies were tensile forces that are applicable when the shoulder is externally rotated. But nobody tested concavity compression, which is a very physiologic force that occurs in the glenohumeral joint. And it's important because of the fragment displacement and the step-off that may occur and potentially eventual arthritis. And also important for stability of the glenohumeral joint. So we wanted to test both techniques with concavity compression to see if the fragment is just as stable with double row compared to single row as it was shown in the previous studies. And that was our hypothesis that double row would lead to more stable fragment fixation. So we had 13 matched cadavers and we created 25% glenoid defects. Half fractures were repaired with double row technique and the contralateral glenoids were repaired with single row. And this is the pictures of the repair. So we applied 115 newtons of force across the glenohumeral joint and we tested that with 2,000 cycles with internal and external rotation at a frequency that would replicate post-operative rehabilitation. And the toggle was quantified with coordinate measuring machine. This is our setup with sensors in the glenoid and in the bony fragment. And what we showed is the double row technique resulted in significantly less displacement of the bony fragment compared to the single row. And this was done and calculated using MATLAB. The ultimate fracture displacement was also significantly less for the double row compared to the single row. So the conclusion of our study was that double row fixation was the most stable technique in this concavity compression model. That's the first presentation and I'll just keep going to the next one. What we also noted during this testing is that there was certainly some cartilage loss on the humeral head. So we wanted to, because right now there is no paper that I know of in literature that quantifies the cartilage loss on the humeral head when the suture is on the articular cartilage of the glenoid. So these are, again, same co-authors that I would like to thank. So these are the two techniques that are described right now in literature, which we tested in the previous study for biomechanical strength. And the results have been reported on both of these techniques. There are some other techniques that have been described, but there is no clinical outcome data on those. So these are basically the two basic techniques that we used to fix bony banchard lesions. So we hypothesized that the double row technique will actually increase the cartilage loss on the humeral head because of increased presence of suture on the glenoid. So testing was performed in 24 cadaveric glenoids, 12 right, 12 left. Again, same defects of 25% were created on the glenoid. Half fractures were fixed with double row and half with single row, and the samples were randomized. Again our setup, this time concavity compression was 750 newtons. So what we assumed is that by this point the fracture has healed, it's presumably an anatomic alignment, and now we applied the forces that are applicable to somebody where the fracture is healed and they return to moderate physical labor activity, which represents either 750 newtons or 90% of the cadaver body weight. And we cycled them through 20,000 cycles, so over a period of time. And cartilage defects were quantified through a custom MATLAB script. So we had 92 images, 51 for double row and 41 for single row. And the mean double row, the mean cartilage cutout for the double row technique was significantly greater compared to the single row. You can see in this picture, and the magnification for single row is a little bit greater here, but you can see in this picture that the depth of the lesion is significantly greater for the double row, it's also more broad. This is a graph representation of our results. So in conclusion, both single and double row fixation techniques that currently we use for bony bankart lesions create cartilage damage on the humeral head. The double row fixation technique, even though it's more biomechanically stable, actually leads to significantly higher cartilage damage on the humeral head. So despite superiority biomechanics-wise, we need to remember what happens on the humeral head. So this leaves room for innovation. We need to come up with new arthroscopic techniques that don't lay that suture on articular cartilage. And there's a paper in arthroscopy techniques by Steve Snyder where he described the technique where you drill the bony fragment. And I'll tell you, it's a fussy technique and actually not perfect, you have to peel some of the capsule that attaches to that fragment, but I'm not aware of any clinical outcomes on that technique. But there's definitely room for innovation to come up with a simpler technique that hopefully will avoid this cartilage damage in patients. Thank you.

bony bankart repairs

biomechanics

double row technique

cartilage loss

arthroscopic techniques