PROPRIOCEPTION AFTER AN ACUTE KNEE LIGAMENT INJURY - A LONGITUDINAL-STUDY ON 16 CONSECUTIVE PATIENTS

A defect in proprioception has been found in selected patient groups t hat have an anterior cruciate ligament deficient knee at different tim es after the original injury. The time of development and the extent o f such defects were studied longitudinally on 16 consecutive patients. During the first year after a primary knee injury, which included a c omplete rupture of the anterior cruciate ligament, we repeatedly perfo rmed three tests of proprioception: (a) one to determine the threshold for detecting a passive motion from starting positions of 20 and 40 d egrees, (b) an active reproduction of a passive angular change, and (c ) a visual estimation of a passive angular change. The injured limb wa s compared with the uninjured limb and with the limbs of an age-matche d reference group of healthy subjects. The population did not have a n ormal distribution, and some patients had consistently extreme recordi ngs in the threshold tests at the various times of testing. Significan t differences were found between the groups at the starring position o f 20 degrees, when the injured knee was compared with the uninjured kn ee, after 1 month (p = 0.05), and after 2 months (p = 0.03). There was a trend toward a higher threshold for detecting a passive motion when the injured side was compared with the knees of the reference group a t 1 month (p = 0.06) but not later on. A similar pattern was found for the injured knee at the starting position of 40 degrees, but it was n ot significant. An impaired ability to detect a passive motion was reg istered for the nearly extended knee 1 and 2 month after. primary inju ry. In the active reproduction and visual estimation tests, no signifi cant defects were found at any time during the first year in these con secutively studied patients.