Proprioception in the posterior cruciate ligament deficient knee

This study was undertaken to evaluate knee proprioception in patients with isolated unilateral posterior cruciate ligament (PCL) injuries. Eighteen su bjects with isolated PCL tears were studied 1-234 months after injury. The threshold to detect passive motion (TTDPM) was used to evaluate kinesthesia and the ability to passively reproduce passive positioning (RPP) to rest j oint position sense. Two starting positions were tested in all knees: 45 de grees (middle range) and 110 degrees (end range) to evaluate knee proprioce ption when the PCL is under different amounts of tension. TTDPM and RPP wer e tested as the knee moved into flexion and extension from both starting po sitions. A statistically significant reduction in TTDPM was identified in P CL-injured knees tested from the 45 degrees starting position, moving into flexion and extension. RPP was statistically better in the PCL-deficient kn ee as tested from 110 degrees moving into flexion and extension,No differen ce was identified in the TTDPM starting at 110 degrees or in RPP with the p resented angle at 45 degrees moving into flexion or extension. These subtle but statistically significant findings suggest that proprioceptive mechano receptors may play a clinical role in PCL-intact and PCL-deficient patients . Further, it appears that kinesthesia and joint position sense may functio n through different mechanisms.