Relationship between body composition and clinical findings in women with knee osteoarthritis

This study aimed to investigate the relationship between DXA-derived body composition—particularly appendicular lean mass index (ALMI)—and pain, function, physical performance, psychological status, and quality of life in women aged over 50 years with knee osteoarthritis. Following ethics committee approval, 100 women aged ≥50 years with Kellgren–Lawrence grade ≥2 knee osteoarthritis diagnosed according to ACR clinical and radiological criteria, who provided written informed consent and presented between 27/01/2025 and 04/06/2025, were included. Demographic and anthropometric characteristics were recorded; muscle strength was assessed by handgrip strength, and physical performance by 4-m gait speed, chair stand tests, and the Timed Up and Go (TUG) test. Body composition was assessed using DXA, and participants were categorized into four groups according to ALMI (<5.5; 5.5–6.49; 6.5–7.49; ≥7.5 kg/m²). Pain was evaluated using VAS, function with WOMAC, psychological status with HADS, and quality of life with SF-36 (subscales and PCS/MCS). Due to non-normal distribution, Kruskal–Wallis tests with Bonferroni-adjusted post-hoc Mann–Whitney U tests and Spearman correlation analyses were performed. The mean age was 62.1±6.8 years, disease duration 7.6±5.7 years, and BMI 29.9±5.3 kg/m². Mean ALMI was 6.85±1.27 kg/m². WOMAC pain, function, and total scores differed significantly across ALMI groups, with decreasing symptom burden as muscle mass increased (all p<0.001), whereas WOMAC stiffness and VAS scores did not differ significantly. No significant differences were observed in handgrip strength, gait speed, chair stand tests, or TUG across ALMI groups (ρ=–0.151, p=0.133). HADS anxiety and depression scores were similar among groups. SF-36 physical functioning, role-physical, bodily pain, and PCS scores increased in parallel with ALMI (p<0.001, p=0.025, p=0.014, and p<0.001, respectively). Conversely, MCS scores were higher in the lowest ALMI group (p=0.008). A very strong negative correlation was observed between ALMI and WOMAC pain (ρ=–0.868, p=1.47×10⁻³¹). In women over 50 years with knee osteoarthritis, DXA-derived ALMI is closely associated with pain and functional impairment and parallels the physical components of quality of life. Higher MCS values in the low-ALMI group suggest that mental health may be influenced by factors independent of muscle mass. Incorporating ALMI into clinical assessment may help identify patients at risk for functional limitation and symptom burden.