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 the 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 were 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 reference group of 19 nonimpaired subjects. Their mean (SD) age was 25.6 ± 3.7 years (range, 20-37 years). Three tests of proprioception were used: threshold to detection of passive motion from 2 starting positions (20° and 40° of knee flexion) toward flexion and extension, active reproduction of a 30° passive angle change, and visual reproduction of a 30° 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° (median of 1.5° versus median of 0.5°) and in the extension trial from 40° (median of 1.0° versus median of 0.5°) than the asymptomatic patients. No differences were found in the other threshold tests, active or visual reproduction tests. Conclusions: Patients with severe symptoms related to ACL deficiency were found to have inferior proprioceptive ability in some measurements compared with patients with a good knee function. The findings indicate that proprioceptive deficits might influence the outcome of an ACL injury treated nonoperatively.
J Orthop Sports Phys Ther. 1999;29(10):587-594.
Key Words: anterior cruciate ligament, proprioception, threshold