Association of the Sarcopenia Index and walking speed in patients undergoing knee arthroplasty

OBJECTIVE: To clarify the association between the Sarcopenia Index (SI) and walking speed in patients undergoing total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA). SUBJECTS: The subjects were 87 patients with knee osteoarthritis who underwent primary unilateral TKA or UKA from March 2024 to July 2025. METHODS: SI was calculated by dividing serum creatinine by serum cystatin C using preoperative blood test data. Walking speed was assessed using the 4 m walk test preoperatively and at 3 months postoperatively. For statistical analysis, multiple regression analysis was performed with postoperative walking speed as the dependent variable, SI as the explanatory variable, and age, sex, BMI, and preoperative walking speed as covariates. RESULTS: 50 TKA and UKA patients were included in the analysis. Multiple regression analysis showed that SI was a factor independently influencing postoperative walking speed (β = 0.24, 95% CI = 0.02 ― 0.45, p = 0.031). CONCLUSIONS: Preoperative SI was shown to be associated with postoperative walking speed. It was suggested that SI may be useful for predicting walking speed in TKA and UKA patients.