Proprioception in people with anterior cruciate ligament-deficient knees: Comparison of symptomatic and asymptomatic patients

Study Design: Nonrandomized prospective study. Objective: To evaluate proprioception in 2 groups of patients with anterior cruciate ligament (ACL) deficiency who had different severity of symptoms. Background: Defective proprioception has previously been found in patients with ACL-deficient knees. It has been suggested that sensory receptors of t he ACL and other knee joint ligaments contribute to proprioception and knee joint function and stability. Methods and Measures: A total of 17 patients with ACL deficiency (mean [SD] age, 28.8 +/- 5.6 years; range, 22-39 years) with few, if any, symptoms we re compared with 20 patients with ACL deficiency (mean [SD] age, 26.6 +/- 6 .1 years; range, 18-39 years) having instability and episodes of giving way . The groups were compared with each other and with an age-matched referenc e group of 19 nonimpaired subjects. Their mean (SD) age was 25.6 +/- 3.7 ye ars (range, 20-37 years). Three tests of proprioception were used: threshol d to detection of passive motion from 2 starting positions (20 degrees and 40 degrees of knee flexion) toward flexion and extension, active reproducti on of a 30 degrees passive angle change, and visual reproduction of a 30 de grees passive angle change. The Wilcoxon rank sum test was used for between -group comparisons. Results: Symptomatic patients had higher threshold to detection of passive motion in their injured side in the flexion trial from 20 degrees (median o f 1.5 degrees vs median of 0.5 degrees) and in the extension trial from 40 degrees (median of 1.0 degrees vs median of 0.5 degrees) than the asymptoma tic patients. No differences were found in the other threshold tests, activ e or visual reproduction tests. Conclusions: Patients with severe symptoms related to ACL deficiency were f ound to have inferior proprioceptive ability in some measurements compared with patients with a good knee function. The findings indicate that proprio ceptive deficits might influence the outcome of an ACL injury treated nonop eratively.