Thank you so much, I appreciate the opportunity to give our research here to the committee and I'd like to thank my co-authors from the Steadman Clinic in Vail and also University of Pittsburgh. Our disclosures are in the program. So as we just heard from that great talk previously that we found that posterior instability is really a different animal than anterior instability with cumulative microtrauma being the common pathologic mechanism. As Dr. Provencio showed us in his Houston award winning paper, that vague pain without a specific injury mechanism is typically the most common way this occurs and we all know the military population and those like American football players in that flexed internally rotated position are the ones that are at biggest risk. Really the thought leaders of this category are in the room right now. We know that Brett Owen's excellent article about the increased retroversion being a risk factor for developing posterior instability in a paper from our group talking about bone width of the glenoid being decreased and leading to surgical failure rates in a great paper by Dr. Tokish talking about the 13.5% bone loss and decreased return to full duty as mentioned in the last talk. A paper that we had come out a few years ago, we found a revision rate of 6.4% with the risk factors shown here below for surgical failure rate including decreased glenoid bone width. A great study that was shown in the last paper as well that Dr. Provencio really showed us that posterior bony morphology is really different and distinct from anterior instability. You can see in this picture here in the slide that it's off axis in this loss of bony concavity in this decreased, I'm sorry, increased slope from superior to inferior rather than as you see in this bottom right corner, the anterior instability which is that abrupt along the axis. Posterior instability is 30 degrees off axis as you can see in the top picture here. Another great study showed from Dr. Provencio and Dr. Romeo that a lot of these scans can be off axis. I'm sure everyone that's measuring these on FOSS views is sometimes not super accurate so correcting of those images I think are important. We know anterior bone loss has really known failure rates but what about posterior? So the purpose of our study was to evaluate advanced MRI measures that Dr. Provencio showed over those last few studies on manually reformatted MRIs in patients who underwent posterior shoulder capsular labor repair and we hypothesized that those that failed surgical repair would have decreased glenoid bone width and greater percent bone loss. So we included patients that were over 18 that had unidirectional posterior instability that underwent arthroscopic capsular labor repair with minimum two-year follow-up and we excluded MDI patients. So we had 75 MRIs and did the more standard MRI evaluations of glenoid and labral version and glenoid bone width and labral width and percent loss as seen here in the perfect circle method and then we reformatted the MRIs as shown here in this study. This is CT obviously but reformatted it to make sure we had an on FOSS view. And then we repeated those same measures and then we did the more advanced measures of slope and angle of the bone loss as seen in the pictures here and then labral height and percent subluxation. So we defined failure based on revision surgery, a subjective stability score of less than five and an ASES score less than 60. So we basically found all the failures we could and then we matched them with non-failures and we found that there was indeed again a narrow glenoid bone width of 25.5 versus 28.8 between the failures and non-failures and again not surprisingly a higher percentage of glenoid bone loss in the failures as well. I think this is the most interesting part of our study with linear regression analysis. We found that with 11% bone loss as you can see there we had a 10 times higher failure rate and when we got to 15% bone loss we had a 25 times higher failure rate with arthroscopic posterior capsule labor repair. So when we compared the corrected and uncorrected MRI measures we found that the percent glenoid bone loss was actually overestimated before you correct them. The glenoid bone width didn't quite meet significance with the correction and uncorrection. So certainly with more patients and more normal patients to evaluate we would have better power in this study. Again we all know ASES score isn't the best study or the best scoring system for these active patients so having a higher cutoff may be more accurate and representative of those that fail. So we think this is an important study for again the percent bone loss really giving us an idea of the risk of failure with 15% being 25 times higher failure rate and it really underscores the importance of posterior glenoid bone loss and how different it is than anterior instability. And again I think it's important that overestimation or inaccuracy of some of these MRIs that aren't on FOSS is something we should consider and that width and bone loss again percent are risk factors for failure but we have to remember that really overall arthroscopic posterior capsule labor repair usually have really great outcomes. So thank you for your attention and time.

posterior shoulder instability

cumulative microtrauma

retroversion

glenoid bone width

MRI assessments