How much improvement in patient reported outcomes after isolated medial patellofemoral ligament reconstruction is associated with surgeon-defined satisfactory outcomes? A JUPITER study

Introduction: The extent of change in Patient Reported Outcome Measures (PROMs) required to meet surgeon-defined satisfactory outcomes after isolated medial patellofemoral ligament reconstruction (MPFL-R) has not been reported. The primary aim of the study was to define the threshold value of maximal outcome improvement (MOI) in PROMs associated with surgeon-defined satisfactory postoperative outcomes. The secondary aim was to identify the most effective PROM in predicting these outcomes and to evaluate the factors associated with it. Methods: This is a retrospective review of prospectively collected data as part of the JUPITER multi-center study. Receiver operating characteristic curves were calculated to determine threshold values for MOI for 4 commonly used PROMs - Banff Patella Instability Instrument (BPII 2.0), Pediatric International Knee Documentation Committee (Pedi-IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS) and Kujala score - associated with surgeon-defined satisfactory outcomes. Multivariate analyses were performed to determine preoperative, intraoperative, and radiographic factors associated with satisfactory outcomes. Results: 284 patients were included in the analysis. 183 (66.9 ​%) patients achieved surgeon-defined satisfactory outcomes. For MOI, achieving an improvement in BPII 2.0 score greater than 65.86 ​% (Area under the curve (AUC): 0.75; CI: 068–0.80; p ​< ​0.0001) and in the Kujala score greater than 85.18 ​% (AUC: 0.69; CI: 0.62–0.75; p ​< ​0.0001) was associated with a satisfactory outcome. BPII 2.0 had the highest AUC while Kujala had the least AUC (p ​= ​0.04). Multiple logistic regression analysis showed that first-time dislocation or having 10 or more dislocations prior to surgery significantly decreased the odds of achieving satisfactory postoperative outcomes (OR 0.12, p ​= ​0.002). None of the radiographic parameters were associated with outcomes. Conclusion: MOI serves as an important measure to gauge clinical success after isolated MPFL-R. The study sets MOI thresholds for four commonly used PROMs, thus correlating patient- and surgeon-defined satisfactory outcomes after isolated MPFL-R. BPII 2.0 had good discriminative ability while Kujala had the least. The study identifies that isolated MPFL-R after first-time dislocation or after 10 or more dislocations are associated with decreased odds of satisfactory outcomes. Level of evidence: Level 4 retrospective review of prospectively collected data.