On behalf of my co-authors, I'd like to present our research update on our prospectively collected cohort of patients who underwent isolated MPFL. These are our disclosures. It remains unclear which subset of patients with recurrent patellofemoral instability would benefit from a concomitant bony realignment procedure in addition to an MPFL reconstruction. We know that TTO is a powerful tool with safe and reliable outcomes, but to date there's no definitive measurements of trochlear dysplasia, patellar alta, or TTTG that necessitate the addition of a TTO. What we seek to understand with this study is when an isolated soft tissue procedure is sufficient to prevent postoperative recurrent instability. Our early outcomes were published in AJSM in 2019, and we showed that an isolated MPFL was an effective treatment for patellar instability with low recurrent instability rates, high return to sport rates, and significant improvement in patient-reported outcomes, irregardless of their bony anatomy within exclusion criteria. So the purpose of this current study was to provide midterm results on our previously reported recurrent instability events, return to sport, patient-reported outcome measures, and imaging measurements collected for patients who underwent isolated MPFL reconstruction as part of our ongoing prospective trial. This includes minimum 5-year outcomes data on a cohort of 50 patients, as well as 2-year outcomes data on an expanded cohort of 119 patients. The patients who did not meet exclusion criteria were enrolled in an institutional registry beginning in March 2014. And our exclusion criteria included a prior history of a patellar stabilization procedure, an offloadable inferior or lateral outer bridge grade 4 chondral defect, patients who reported anterior knee pain as greater than or equal to 50% of their chief complaint, and patients who had a jumping J sign, which means they required a dislocation to achieve full extension, which can be seen in this video here. This is a strobe diagram that details the patients who were excluded by specific criteria. So all patients who were not excluded underwent primary, unilateral, isolated MPFL reconstruction, regardless of their bony anatomy, for the treatment of recurrent patellar instability. We collected baseline demographics, recurrent instability events, return to sport rates, knee-specific patient-reported outcome measures, and the radiographic measurements listed here at baseline. There were 138 patients who underwent isolated MPFL reconstruction from March 2014 to December 2019. 72% of these patients were female, and their average age was 20 years. 219 patients reached the greater-than-two-year time point, of which we had 75% completed follow-up. And 50 patients reached the greater-than-five-year time point, of which 80% were completed follow-up. All patient-reported outcome measures statistically significantly improved, except for PD-FABS, which had no change over time. These are the patient-reported outcome measures individually shown here with their improvements over time, and these error bars indicate a 95% confidence interval. The average TTTG for all patients was 15.1. Katanda-Shamp's index was 1.1, Trochlear Depth Index 2.5. The PT-LTR, a measure of lateral patellar tracking, was 5.7, and the TT-LTR was 8.4, which is a measurement of extensor mechanism containment. 44% of patients had a TTTG less than 15. 43% had a TTTG between 15 and 19, and 13% of patients had a TTTG greater than 20. 32% of patients had a Katanda-Shamp's greater than 1.2, and 63% of patients had a Trochlear Depth Index of less than 3, which is, by definition, trochlear dysplasia. There were six patients who experienced recurrent instability during this five years plus follow-up time. The mean time to recurrent instability event was 2.97 years. The re-dislocation rate was 2%, and the re-subluxation rate was 4%, and the details for those six patients are seen here. The radiographic measurements for those six patients who experienced recurrent instability are listed here, and it's important to note that, aside from the first patient, all patients had a TTTG greater than 15, and the first patient, while they had a low TTTG, did have very significant patella alta with a Katanda-Shamp's of 1.45. There were 100 patients who participated in sports prior to surgery, and of those, 89% were able to return to sport, and 84% were able to return to their sport at the same or higher level. All patients returned to sport within two years, with a mean time of 9.1 months, and notably five patients did not participate in sports prior to surgery, but after surgery were able to participate in sports. So in conclusion, midterm outcomes for patients who underwent isolated MPFL reconstruction are shown to be favorable with low recurrent instability rates, high return to sport rates, and outcomes that are maintained at five years. Completion of the study enrollment with long-term follow-up will allow for a more robust assessment of long-term outcomes and incidence of recurrent instability events after isolated MPFL reconstruction. And ultimately, the goal of this work is the creation of a predictive score, like the ISIS score for the shoulder, that will utilize the bony and clinical characteristics of those patients who sustained return instability in order to better predict who might benefit from the addition of a bony realignment procedure at the time of their index operation. We have a few limitations for this study. It's a modest sample size of patients from a single surgeon at a single institution in a high volume of telephemeral practice, and while this does limit variability in surgical technique, it may not be generalizable to the community at large, and only six patients experienced recurrent instability, and therefore that limits our ability to deduce any trends in the cause of their failure. Future collaborative multicenter studies and well-designed prospective trials will seek to provide an answer to these questions and create a more algorithmic approach for the treatment of these patients. Thank you very much.

MPFL reconstruction

patellofemoral instability

bony realignment procedure

recurrent instability

patient-reported outcomes