Proprioceptive Deficits Are Comparable before Unicondylar and Total Knee Arthroplasties, But Greater in the More Symptomatic Knee of the Patient

The clinical importance of the known proprioceptive deficit in patients with osteoarthritis of the knee is unclear. Attention to the factors that influence proprioception is needed to better understand the role that proprioception plays in the disease process and to assess how these deficits influence clinical outcomes of various treatment options for osteoarthritis. We hypothesized that preoperative proprioception would be poorer in knees with greater symptoms and that knees considered candidates for unicompartmental arthroplasty would have superior proprioception to those in which a total knee arthroplasty was indicated because of the less extensive disease process in the former group. Proprioceptive thresholds were measured in 119 patients with osteoarthritis and no prior knee arthroplasties who were scheduled for unicondylar or total knee arthroplasty. Proprioception examinations consisted of passively flexing and extending each of the bilateral knees in patients independently, from 45° flexion until the blinded patient identified motion. Proprioceptive thresholds for flexion and extension were computed from the angular delays that elapsed before the patient recognized the stimulus. Multiple regression analysis was done to assess the association that these proprioceptive thresholds had with patient factors (age, gender, body mass index, activity level, functional capacity) and knee factors (surgical history, osteoarthritis severity, angular deformity, instability, range of motion). Patient age was the strongest predictor of proprioceptive thresholds, with older patients tending to respond slower to stimulus. Comparison of the right and left knees of each patient showed that proprioception was significantly poorer in the more symptomatic of the two knees. Preoperative thresholds did not differ between knees that received a total knee arthroplasty and those that received a unicondylar arthroplasty.