Foot Posture as a Biomechanical Outcome Measure Following Total Knee Arthroplasty in Individuals with Severe Knee Osteoarthritis

Abstract Total knee arthroplasty (TKA) is commonly performed to relieve pain and improve knee function in individuals with severe knee osteoarthritis (OA). Abnormal foot mechanics can influence overall biomechanics and affect post-surgical outcomes. This study aimed to evaluate foot posture as a biomechanical outcome before and after TKA and to explore its relationship with pain and lower extremity function. Seventy-seven individuals with knee OA who underwent TKA, and 77 healthy controls were assessed. Foot posture was measured using the Foot Posture Index (FPI), pain using the Numerical Pain Rating Scale (NPRS), and function using the Lower Extremity Functional Scale (LEFS). Assessments were conducted preoperatively and at 6 weeks, 3 months, 6 months, and 12 months postoperatively. Preoperative FPI scores were significantly higher in the OA group than in controls (1.52 ± 2.5 vs. 0.70 ± 2.2; p = 0.03), indicating a more pronated foot posture. FPI scores did not significantly change throughout the follow-up period. At 6 months post-TKA, FPI remained higher than controls (p = 0.03), but the difference was not significant at 12 months (p = 0.12). A weak positive correlation was found between FPI and NPRS (r = 0.2; p < 0.05), but no correlation was observed with LEFS. Foot posture evaluation may support comprehensive rehabilitation planning after TKA.