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 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 degrees and 40 degrees of knee flexion) toward flexion and extension, active reproduction of a 30 degrees passive angle change, and visual reproduction of a 30 degrees 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 of 1.5 degrees vs median of 0.5 degree) and in the extension trial from 40 degrees (median of 1.0 degree vs median of 0.5 degree) 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.