This study aimed to develop a self-questionnaire index relevant to lower limb functional assessment reflecting clinical symptoms and activity restrictions associated with activities of daily living (ADL) for patients with knee osteoarthritis. This cross-sectional study enrolled patients with knee osteoarthritis (Kellgren/Lawrence grade ≥ 1). Participants evaluated clinical symptoms and activity restrictions using self-reported questionnaires. Radiographic evaluation, knee joint range of motion (ROM), and lower limb muscle strength were assessed. Associations between clinical symptoms, activity restrictions, and knee and hip joint function were evaluated using multiple and logistic regression analysis. Overall, 142 participants were included in the final analysis. Patients with knee pain while rising from a chair had lower knee and hip extension strength (knee extension β = - 0.28; 95% confidence interval (CI), - 0.41 to - 0.14; P < 0.0001; hip extension β = - 0.26; 95% CI, - 0.42 to - 0.08; P = 0.0034), and restricted knee extension ROM (odds ratio [OR] = 2.17; 95% CI, 1.02-4.63; P = 0.041). Patients with knee pain during stair climbing, turning or who were unable to stand on one leg without external support had reduced hip abduction muscle strength (β = - 0.17; 95% CI, - 0.27 to - 0.07; P = 0.0008). Patients with knee pain while rising from a chair or stepping showed more severe knee joint degeneration on radiographic evaluation (OR = 3.26; 95% CI, 1.11-10.91; P = 0.03). The self-questionnaire index reflected clinical symptoms and activity restrictions associated with ADL and was significantly associated with lower limb function in individuals with knee osteoarthritis.
Keywords: Activities of daily living; Knee osteoarthritis; Muscle; Pain; Questionnaire; Range of motion.