Movement detection impaired in patients with knee osteoarthritis compared to healthy controls: a cross-sectional case-control study.

The purpose of this study was to clarify whether osteoarthritis (OA) patients have a localized or a generalized reduction in proprioception. Twenty one women with knee OA (mean age [SD]: 57.1 [12.0] years) and 29 healthy women (mean age [SD]: 55.3 [10.1] years) had their joint position sense (JPS) and threshold to detection of a passive movement (TDPM) measured in both knees and elbows. JPS was measured as the participant's ability to actively reproduce the position of the elbow and knee joints. TDPM was measured as the participant's ability to recognize a passive motion of the elbow and knee joints. The absolute error (AE) for JPS (i.e., absolute difference in degrees between target and estimated position) and for TDPM (i.e., the difference in degrees at movement start and response when recognizing the movement) was calculated. For TDPM a higher AE (mean [SE]) was found in the involved knees in patients than in the matched knees of healthy participants (AE: 2.41 degrees [0.20 degrees] versus 1.47 degrees [0.14], p=0.001). The same held true for the non-involved knees between OA and healthy subjects (AE: 2.20 degrees [0.20 degrees] versus 1.57 degrees [0.14 degrees], p=0.016). Furthermore TDPM was higher in OA patients' right elbows compared to healthy participants' right elbows (AE: 2.15 degrees [0.20 degrees] versus 1.45 degrees [0.15 degrees], p=0.011). No significant difference between healthy women and OA patients regarding the left elbow for TDPM, or JPS was observed. The present age-controlled, cross-sectional study suggests that there is an increase in threshold to detection of a passive motion in knees and elbows for patients with knee OA. This indicates that OA may be associated with a generalized defect in proprioception with possible implications for the pathogenesis of the joint degeneration.