Preoperative Gait Speed as a Predictor of Patient-Reported Outcomes After Total Hip Arthroplasty: Insights from Patient Acceptable Symptom State and K-Means Clustering Analyses.

Abstract

Total hip arthroplasty (THA) is a well-established procedure for hip osteoarthritis (OA); however, its clinical outcomes are variable, and the optimal timing for surgery remains unclear. Identifying the preoperative predictors that influence midterm patient-reported outcome measures (PROMs) could improve patient outcomes. This retrospective cohort study included 274 Asian patients who underwent primary THA for OA between 2012 and 2018, who completed preoperative physical assessments, and who responded to a postoperative mail survey. Preoperative variables included symptom duration, pain intensity, hip range of motion, lower-limb muscle strength, and 10-m free gait speed. PROMs were assessed using the Oxford Hip Score (OHS) and the Forgotten Joint Score-12 (FJS-12). Clinically meaningful outcomes were assessed using the Patient Acceptable Symptom State (PASS), defined as a score of ≥42 for the OHS and a score of ≥50 for the FJS-12. Additionally, K-means clustering was applied to categorize patients into an excellent outcome group and a control group on the basis of their PROMs. Multivariable regression analysis revealed that preoperative gait speed significantly predicted both the OHS and FJS-12 outcomes (p < 0.01). Furthermore, hip flexion range of motion and hip flexion strength were significantly associated with preoperative gait speed (p < 0.01). A receiver operating characteristic (ROC) curve analysis identified a gait speed cutoff value of 0.7 m/s for achieving the PASS for the OHS (area under the curve [AUC]: 0.69; p < 0.01) and a cutoff value of 1.0 m/s for achieving the PASS for the FJS-12 (AUC: 0.60; p = 0.01). K-means clustering identified preoperative gait speed as the sole significant predictor of classification into the excellent outcome group (odds ratio, 5.85; p < 0.01). The ROC curve analysis revealed a gait speed cutoff value of 1.0 m/s for classification into the excellent group (AUC: 0.64; p < 0.01). Preoperative gait speed, which reflects decreased mobility due to hip joint dysfunction, was a significant predictor of midterm PROMs after THA. Maintaining a preoperative gait speed of 1.0 m/s could serve as a critical threshold for achieving favorable postoperative outcomes, regardless of patient age. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.