Improvement of sarcopenia after total knee arthroplasty in patients with knee osteoarthritis

PurposeThis study aimed to investigate changes in sarcopenia status and physical function after total knee arthroplasty (TKA) in patients with knee osteoarthritis (KOA).MethodsThis prospective observational study was conducted at a single general hospital. Seventy-one patients with KOA undergoing first TKA were classified into sarcopenia (n = 12) and non-sarcopenia (n = 59) groups based on the 2019 Asian Working Group for Sarcopenia criteria. Outcomes including walking speed, grip strength, skeletal muscle mass index (SMI), Knee Injury and Osteoarthritis Outcome Score (KOOS), knee joint muscle strength, and performance-based tests were evaluated preoperatively and at 6 and 12 months postoperatively. Analysis of covariance (ANCOVA) with age and sex as covariates was used to examine differences in improvement at 6 and 12 months. Clinical equivalence was evaluated using 90% confidence intervals and minimum clinically important differences.ResultsOf the 12 patients with preoperative sarcopenia, 10 (83.3%) improved at 12 months postoperatively. ANCOVA showed significant adjusted mean difference (aMD) of 0.31 for SMI at 12 months. No significant differences were found in grip strength (aMD: 0.60), KOOS pain (aMD: 0.01), or 40-m fast-paced walk test (aMD: -0.03). Clinical equivalence was observed for SMI, grip strength, KOOS pain, and 40-m fast-paced walk test, but not other outcomes.ConclusionsIn patients with KOA and sarcopenia, TKA combined with postoperative rehabilitation was associated with improvements in sarcopenia-related measures. Improvements in gait ability, grip strength, and appendicular skeletal muscle mass were comparable to those observed in non-sarcopenic patients.