The Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient-Acceptable Symptomatic State after Medial Patellofemoral Ligament Reconstruction

PURPOSE: To define the minimal clinically important difference (MCID), substantial clinical benefit (SCB) and patient-acceptable symptomatic state (PASS) for patient-reported outcome measures (PROMs) after medial patellofemoral ligament reconstruction (MPFLR) and to investigate the role of preoperative, demographic, and intraoperative variables for predicting achievement of these thresholds. METHODS: This retrospective cohort study used a prospectively maintained database of patients undergoing primary MPFLR between August 2015 and December 2019. PROMs included the International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS joint replacement (JR), and Kujala. Anchor-based and distribution-based methods were used to calculate the MCID, SCB, and PASS. Regression analyses were performed to identify prognosticators for achievement of clinically significant thresholds. RESULTS: 139 patients met inclusion criteria (mean age: 21.7± 8.2 years). At 6 months, the MCID values were 8.3 (KOOS-Pain) and 8.5/13.5 (Kujala); SCB values were 1.4 (KOOS-Pain) and 43.7 (KOOS-QOL); and PASS values were 64.9 (IKDC), 83.3 (KOOS-Symptom), 76.8 (KOOS-Pain), 91.2 (KOOS-ADL), 47.5 (KOOS-Sport), 40.6 (KOOS-QOL), and 78.1 (KOOS-JR). At 1 year, the MCID values were 4.2 (KOOS-Pain), 7.2 (KOOS-ADL), 12.4 (KOOS-QOL) and 25.2 (KOOS-JR); SCB were 23.6 (IKDC), 4.2 (KOOS-Symptom), 19.7 (KOOS-Pain), 6.5 (KOOS-ADL), 55.0 (KOOS-Sport), 6.3 (KOOS-QOL), and 19.6/25.2 (KOOS-JR); and PASS were 65.5 (IKDC), 80.4 (KOOS-Symptom), 84.7 (KOOS-Pain), 99.3 (KOOS-ADL), 57.5 (KOOS-Sport), 53.1 (KOOS-QOL), and 76.3 (KOOS-JR). In regression analysis, greater age, body mass index, and preoperative PROMs were negative prognosticators for achieving clinically significant thresholds. Conversely, male gender increased the likelihood of achieving PASS for Kujala at 6 months and KOOS-ADL at 1 year. CONCLUSIONS: This study established thresholds for the MCID, SCB, and PASS at 6 months and 1 year after MPFLR, providing physicians an evidence-based method to advise patients and assess outcomes with this surgery. Older patients and those with higher preoperative outcome scores are less likely to report improvement and satisfaction with MPFLR, while male patients are more likely to report some satisfaction. LEVEL OF EVIDENCE: Level III, retrospective cohort study (diagnosis).