Muscle strength is a key predictor of physical function in advanced knee osteoarthritis

Skeletal muscle strength of the lower limbs is negatively impacted in advanced knee osteoarthritis. However, its role in predicting physical function of these patients remains unclear. Therefore, we aimed to evaluate hierarchical linear regression associations between lower limbs' maximal muscle strength, rate of force development and physical function in 50 patients (age: 65 ± 8 years; 22 males and 28 females; and BMI: 31 ± 5 kg/m²) with advanced knee osteoarthritis. Results revealed that leg press maximal strength and leg extension maximum voluntary contraction were associated with sit-to-stand and stair climbing performance (all p < 0.001) and accounted for variances of 29 % and 38 % in 30-s sit-to-stand and 37 % and 24 % in stair climbing performance, respectively. Leg press maximal strength and leg extension maximum voluntary contraction were also associated with Knee Injury and Osteoarthritis Outcome Score - Physical Function Short Form (KOOS-PS) (both p = 0.041), each accounting for 7 % of the variance. Similarly, rate of force development was associated with 30-s sit-to-stand (p < 0.001) and stair climbing performance (p = 0.05), explaining 22 % and 6 % of additional variances, respectively. No association was observed between measures of muscle strength and 40 m fast-paced walking. The present study highlights maximal muscle strength, and in part rate of force development, as powerful predictors of physical function in patients with advanced knee osteoarthritis and may be used as simple, valuable measures when evaluating patients’ physical function.