Presenting on research I did as a fellow at the Steadman Clinic looking at arthroscopic treatment of multidirectional instability. Disclosures for this talk are listed on the program and website. So MDI is classically defined as instability in greater than two directions, including inferior. There are certainly many different phenotypes of MDI, including atraumatic and traumatic, and many patients have associated underlying hyperlaxity. Historically, it's a challenging diagnosis to characterize and treat and study. Nonoperative management is the hallmark of treatment for these patients, although research has shown that even patients who avoid surgery, many continue to experience pain, instability, and low satisfaction with their outcome. The open capsular shift was developed in the 1980s to address this issue. Unfortunately, there are concerns with the morbidity of the surgical approach and the ability to treat both the anterior and posterior capsule with this technique. Technological improvements have led to the arthroscopic treatment of this condition, with stated benefits being lower morbidity of the approach, ability to address circumferential pathology, and studies have shown that it decreases capsular volume more efficiently than an open shift. Studies have been done on short-term results after arthroscopic treatment for MDI, and overall have found fairly good results, however, these studies are limited by short-term follow-up and inconsistent definition of surgical failure. So given that the majority of these patients are young and active, we really need to know what the long-term outcomes of this intervention are. There might be concern that the pathologic capsular tissue may stretch out over time. Will this lead to late instability, a decline in patient function, and might this be more likely in an atraumatic group who have generalized laxity? Understanding this, the purpose of this study was, one, to report patient-reported outcomes in recurrent instability with minimum of five-year follow-up, two, compare patient-reported outcomes at short-term and long-term follow-up to see the longevity of this procedure and durability, and three, to compare the difference between several different phenotypes of MDI. We performed a retrospective review of a prospectively collected database on patients treated between 2005 and 2015. All patients had minimum of five-year outcomes and met the near-MDI definition for instability. We excluded patients who had prior surgery and who did not have documented inferior instability on their notes. Primary outcome was survivorship, and secondary outcomes included patient-reported outcomes and several subgroup analyses were performed. The operative technique was performed in the lateral decubitus position. It was an anchor-based repair, and a minimum of three anchors were placed anteriorly and posteriorly. Forty-three percent of patients underwent a rotator interval closure. Ultimately, we looked through 190 shoulders and 49 inclusion criteria. Most patients were admitted because they had a prior surgery or because a sulcus sign was not documented. What we found was that 28 percent reported feelings of recurrent instability at average of nine years postoperatively, 16 percent reported a redislocation event that required a relocation, and 10 percent underwent re-operation at a mean of 1.5 years after surgery. Kaplan-Meier's survivorship curve demonstrated survivorship of 80 percent at five years, and 75 percent at eight years postoperatively, using the definition of feelings of recurrent instability as reported by the patient. With regards to patient-reported outcomes, we demonstrated that all PROs significantly improved from preoperative to final follow-up at a mean of nine years postoperatively. Trying to assess the longevity of our improvement over time, we looked at patients with short-term follow-up and then long-term follow-up and demonstrated in this slide ASCS, but for all of our outcome measures, we had persistent improvement in outcome scores over time that did not decrease between short-term and long-term follow-up. We then were interested in the shoulders that we saw that reported recurrent instability but decided not to undergo revision surgery. We found that there were actually quite a few patients who were doing relatively well in that cohort. We found that they did demonstrate improved postoperative outcomes, but these were slightly decreased as a whole compared to patients who reported stable shoulders. Understanding that we did have patients who had feelings of instability but who had an acceptable ASCS score and postoperative result, we sought to redefine what meant a surgical success or failure in this population. A surgical success was thus defined as a stable shoulder or a shoulder who felt instability but had an acceptable ASCS result over 65. For this new definition, Kaplan-Meier survivorship curve demonstrated survivorship of 87 percent at five years and 82 percent at eight years. Finally, we compared the atraumatic and traumatic phenotypes of multidirectional instability and found that there were no differences in postoperative outcomes or patient satisfaction. There are two studies relevant that I wanted to discuss. One is an open shift done by Hamada and Fukuda, and the other is a study by Mitchell in a short-term follow-up of the arthroscopic technique, and what they found was remarkably similar results to us. They demonstrated between a 26 and 28 percent rate of recurrent instability, and just like our study, they found that patients who tend to fail tend to do so in the first few years after the intervention, and that once you get beyond that point, patients actually do pretty well. The limitations of this study, the main limitation is that we did not quantify or stratify patients by ligamentous laxity, which certainly would have been valuable in this patient population. So to conclude, the arthroscopic treatment of MDI has a low rate of reoperation at nine-year follow-up. About a quarter of patients experienced feelings of instability, but a number of these can still be considered surgical successes. Concerns that pathologic soft tissues may stretch out or loosen over time are unfounded. We found that PROs were persistently improved after final follow-up, and no patients required revision surgery beyond four years. And finally, the atraumatic phenotype of MDI can expect similar long-term outcomes to the traumatic patients. Thank you.

arthroscopic treatment

multidirectional instability

MDI

capsular shift

patient-reported outcomes