Beyond bone mineral density: associations of muscle quantity, muscle quality, and physical performance with FRAX-derived fracture risk in postmenopausal women

Abstract Objective Fracture risk assessment in osteoporosis is largely based on bone mineral density and FRAX, yet these approaches do not capture the contribution of muscle-related factors. This study investigated the association between muscle quantity, muscle quality, and physical performance with FRAX-derived fracture probability in postmenopausal women. Methods This cross-sectional study included 70 postmenopausal women with osteoporosis. Participants were categorized into low- and high-risk groups according to FRAX thresholds (major osteoporotic fracture ≥ 20% and/or hip fracture ≥ 3%). Rectus femoris muscle thickness (MT), cross-sectional area (CSA), pennation angle (PA), and echogenicity (Heckmatt scale) were assessed using ultrasonography. Physical performance was evaluated with the Short Physical Performance Battery (SPPB). Group comparisons and correlation analyses were performed. Results Demographic characteristics were comparable between groups. The high-risk group demonstrated significantly lower MT and CSA and higher muscle echogenicity. Physical performance, particularly SPPB total score, was significantly reduced in this group. FRAX-derived probabilities showed moderate inverse correlations with MT, CSA, and SPPB scores, and positive correlations with the Heckmatt score, with the strongest association observed for SPPB total score. Conclusions FRAX-derived fracture probability in postmenopausal women is associated not only with bone-related parameters but also with muscle structure, muscle quality, and physical performance. These findings highlight the potential relevance of muscle-related parameters within the broader musculoskeletal profile reflected by FRAX and support the need for further prospective research in this area.