Impact of Sarcopenia and Functional Relationships Between Balance and Gait After Total Hip Arthroplasty

Background/Objectives: Total hip arthroplasty (THA) is an effective surgical intervention for restoring hip function and alleviating pain caused by osteoarthritis, femoral head avascular necrosis, or fractures. Despite its benefits, postoperative recovery is influenced by various factors, among which sarcopenia plays a critical role. This study aimed to analyze the characteristics of sarcopenia in THA patients admitted to a convalescent rehabilitation hospital and examine its relationship with functional variables such as balance and gait independence. Methods: This cross-sectional study included 84 THA patients, categorized into sarcopenia and non-sarcopenia groups using the Asian Working Group for Sarcopenia 2019 criteria. Data were collected on demographic characteristics (e.g., age, gender, height, weight, range of motion (ROM), manual muscle test (MMT)) and functional variables, including balance (Berg Balance Scale, BBS) and gait independence (Functional Ambulation Category, FAC). Results: The prevalence of sarcopenia among THA patients was 44.05%. Significant differences were observed between the sarcopenia and non-sarcopenia groups in sex, age, height, weight, ROM, MMT, BBS, and FAC (p < 0.05). Logistic regression analysis showed that advanced age increased the likelihood of sarcopenia (OR: 1.072, p < 0.05), whereas higher body weight reduced it (OR: 0.784, p < 0.05). However, sarcopenia was not significantly associated with balance (BBS: p = 0.710) or gait independence (FAC: p = 0.990). Instead, a significant positive correlation was found between FAC and BBS (OR: 0.413, p < 0.001), as well as BBS and FAC (OR: 0.467, p < 0.001), indicating that better balance was associated with greater gait independence and vice versa. Additionally, patients who underwent THA due to fractures had a lower FAC compared to those with osteoarthritis (OR: -0.276, p = 0.018). Conclusions: Sarcopenia is prevalent among THA patients, and functional variables such as balance and gait independence are closely associated. Additionally, age and body weight were identified as key factors related to sarcopenia. These findings emphasize the importance of early detection and management of sarcopenia in rehabilitation hospital settings and highlight the significance of functional variables in recovery.