SENSORIMOTOR CHANGES AND FUNCTIONAL PERFORMANCE IN PATIENTS WITH KNEEOSTEOARTHRITIS

Objective-Muscles are essential components of our sensorimotor system that help maintain balance and perform a smooth gait, but it is unclea r whether arthritic damage adversely affects muscle sensorimotor funct ion. Quadriceps sensorimotor function in patients with knee osteoarthr itis (OA) was investigated, and whether these changes were associated with impairment of functional performance. Methods-Quadriceps strength , voluntary activation, and proprioceptive acuity (joint position sens e acuity) were assessed in 103 patients with knee OA and compared with 25 healthy control subjects. In addition, their postural stability, o bjective functional performance (the aggregate time for four activitie s of daily living), and disabilities (Lequesne index) were also invest igated. Results-Compared with the control subjects, the patients with knee OA had weaker quadriceps (differences between group mean 100N, CI 136, 63N), poorer voluntary activation (20% CI 13, 25%) that was asso ciated with quadriceps weakness, and impaired acuity of knee joint pos ition sense (1.28 degrees, CI 0.84, 1.73 degrees). As a group the pati ents were more unstable (p=0.0017), disabled (10, CI 7, 11), and had p oorer functional performance (19.6 seconds, CI 14.3, 24.9 seconds). Th e most important predictors of disability were objective functional pe rformance and quadriceps strength. Conclusions-In patients with knee O A, articular damage may reduce quadriceps motoneurone excitability, wh ich decreases voluntary quadriceps activation thus contributing to qua driceps weakness, and diminishes proprioceptive acuity. The arthrogeni c impairment in quadriceps sensorimotor function and decreased postura l stability was associated with reduced functional performance of the patients.