Associated factors influencing pain and slower gait speed in older adults with knee osteoarthritis: a cross-sectional study.

Objective: Given the complex etiology and unclear pathogenesis of knee osteoarthritis (KOA), its prevention is important. This study aimed to investigate factors independently associated with pain severity and slower gait speed in older adults with KOA. Design: This cross-sectional study was performed at a Rehabilitation Training Center. In total, 120 patients at our hospital between 2024 and 2025 with a confirmed diagnosis of KOA and 119 healthy individuals were matched for demographic characteristics. Ultrasound-derived rectus femoris (RF) parameters-muscle thickness and cross-sectional area (CSA)-were measured at rest and during contraction. Pain was assessed using the Visual Analog Scale (VAS). Additional measures included knee flexion range of motion (ROM), knee joint position sense (proprioception), and the 10-meter walk test (10MWT) for gait speed. Results: Compared with healthy controls, KOA patients exhibited significantly lower walking speed, knee ROM, proprioceptive accuracy, RF muscle thickness and CSA, and tibial rotation angles. In KOA, faster gait speed (shorter 10MWT time) was positively correlated with knee ROM, RF thickness and CSA (both at rest and during contraction), and tibial rotation angles, while it was negatively correlated with VAS score and age. Multivariable regression analyses identified age, pain, RF thickness at rest, and total tibial rotation as independent correlates of slower gait speed. Additionally, higher body mass index, female sex, and slower gait speed were independently associated with greater knee pain. Conclusions: Older age, greater pain, reduced resting RF thickness, and diminished total tibial rotation were independently associated with slower gait speed; higher BMI, female sex, and slower gait speed were independently linked to more severe knee pain. These associations should be confirmed in future prospective interventional studies.