Differences in health outcomes of orthopedic rehabilitation after hip or knee replacement: a prospective pilot study benchmarking 23 rehabilitation facilities using Patient-Reported Outcome Measures (PROMs)

Abstract Background Patient-reported outcome measures (PROMs) are increasingly used for benchmarking hip and knee arthroplasty, yet evidence on their feasibility for public reporting of short-term rehabilitation outcomes remains limited. International initiatives such as ICHOM recommend combining disease-specific and generic PROMs, but practical frameworks for risk-adjusted benchmarking in routine rehabilitation are scarce. Methods In this prospective pilot study, 23 German rehabilitation facilities contributed data on patients following total hip (THA) or knee arthroplasty (TKA). Patients completed the HOOS-PS or KOOS-PS and the VR-12 PCS/MCS at admission and discharge after a standardized three-week multimodal rehabilitation program. For primary analyses, 961 THA and 961 TKA cases with complete pre- and post-data on at least one PROM were available. Facility-level unadjusted change was quantified using Cohen’s d z . Risk adjustment used pooled multiple linear regression including baseline PROMs, age, sex, and additional covariates retained via backward elimination ( p < 0.10), yielding standardized residual effect sizes (d res ) per facility. A composite Patient-Reported Outcome Quality Index (ProQI) weighted disease-specific standardized residuals at 50% and VR-12 PCS/MCS at 25% each, rescaled to a 0–100 metric with a normative mean of 90 and SD 30. Results Pooled pre-post effect sizes indicated clinically relevant improvements (THA: d z = 0.76 HOOS-PS, 0.76 PCS, 0.45 MCS; TKA: 0.83 KOOS-PS, 0.71 PCS, 0.39 MCS), with between-facility variability exceeding discrimination thresholds. Risk-adjusted d res identified facilities performing above or below expectations. ProQI values showed substantial dispersion (THA range 75.4–100; TKA 76.9–100), enabling intuitive differentiation of providers. Overall, ProQI completeness was 69% (THA) and 72% (TKA). Non-completer analyses showed small baseline differences but no systematic ProQI bias. Conclusion PROM-based, risk-adjusted benchmarking of short-term rehabilitation outcomes after hip and knee arthroplasty is feasible and meaningfully discriminative. The ProQI composite offers an interpretable, biopsychosocially grounded index for public reporting and quality management. Future work should enhance data completeness, refine risk adjustment, and validate the approach across broader cohorts and settings.