Comparative Analysis of Clinically Meaningful Recovery Trajectories Following Unicompartmental Arthroplasty and Patello-Femoral Arthroplasty.

Abstract

Medial unicompartmental knee arthroplasty (UKA), lateral UKA, and patello-femoral arthroplasty (PFA) are established treatments for isolated compartmental knee osteoarthritis. Despite its growing popularity, the comparative speed of functional recovery between procedures remains poorly defined. We therefore assessed the time to the minimal clinically important difference (MCID) between procedures for various patient-reported outcome measures (PROMs). A retrospective review of 2,487 patients from a multi-institutional arthroplasty registry was conducted (1,938 medial UKA, 283 lateral UKA, and 256 PFA). The Knee Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS), Patient-Reported Outcomes Measurement Information System (PROMIS) Global Physical Health, and PROMIS Physical Function Short Form-10a (PF-10a) were used. Rates of MCID achievement and time to MCID were compared across cohorts using both non-interval-censored and interval-censored survival analyses. The secondary outcomes included conversion to total knee arthroplasty (TKA), non-conversion reoperation, and predictors of PROM improvement. The rates of MCID achievement did not differ significantly between procedures for any of the three PROMs. The median times to MCID for all three PROMs were similar across cohorts for both the non-interval-censored data and the interval-censored data (KOOS-PS: 1.0 versus 0.8 versus 1.3 months; P = 0.29; PROMIS Global Physical Health: 0.7 versus 0.8 versus 1.4 months; P = 0.69; PROMIS PF-10a: 1.4 versus 1.4 versus 1.8 months; P = 0.93). The two-year conversion to TKA rates were comparable, while PFA demonstrated higher two-year non-conversion reoperation rates (9.0 versus 1.7 versus 3.8%; P < 0.001). On multivariable analysis, PFA was associated with lower odds of improvement in PROMIS PF-10a scores compared with medial UKA (odds ratio (OR) 0.56; P = 0.022). Medial UKA, lateral UKA, and PFA demonstrated similar rates of MCID achievement and times to MCID. These findings support similar early recovery trajectories across partial knee arthroplasty procedures and provide valuable data for patient counseling and expectation management.