A Low Anterior Thigh Muscle Thickness on the Nonaffected Side, but Not on the Affected Side, Predicts Lower Activities of Daily Living in Patients With Hip Fractures in Acute Care Settings

AIM: This study aims to examine the association between anterior thigh muscle thickness and the Barthel Index (BI) at discharge in older hip fracture patients. METHODS: This single-center prospective observational study was conducted at the Department of Orthopedic Surgery, Odawara Municipal Hospital (417 beds), Kanagawa, Japan. Patients aged ≥ 65 years who underwent rehabilitation after surgical treatment between August 2023 and July 2024 were included. Anterior thigh muscle thickness, the sum of the rectus femoris and vastus intermedius, was measured within 3 days post-operatively on both sides via ultrasound and categorized into sex-specific quartiles (Q1-Q4). Logistic regression analysis was used to examine associations between quartiles (Q1-Q3 vs. Q4) and the BI at discharge, adjusting for age, sex, body mass index, surgery waiting period, Hasegawa Dementia Scale-Revised score, grip strength, prefracture walking aid use, energy intake ratio, and medications. RESULTS: ) were analyzed. On the nonaffected side, the median (IQR) thickness was 9.7 mm (4.3-13.2) in Q1 and 16.4 mm (14.8-19.2) in Q3. Multivariable analysis revealed that, compared with Q4, Q1 (β = -21.141, 95% CI: -33.682 to -8.600, p < 0.001) and Q3 (β = -13.257, 95% CI: -25.211 to -1.303, p = 0.030) significantly predicted lower BI scores at discharge. No significant associations were found for the affected side. CONCLUSIONS: Lower nonaffected side muscle thickness is independently associated with functional status at discharge.