Abstract
A clinical study was conducted to determine if measurements of anterior knee laxity taken prior to Cybex testing differ from measurements obtained after testing. Twenty-eight patients who each had one anterior cruciate ligament (ACL)-injured knee and one normal knee participated in the study. Physical therapists-certified athletic trainers performed tests of anterior laxity on all knees using the KT-1000 knee ligament arthrometer. Patients were then tested on the Cybex at 60 and 240 deg/sec. Laxity measurements were repeated after Cybex testing. Data were analyzed by paired t-tests. Nonreconstructed ACL-injured knees showed significant laxity increases after Cybex testing for passive anterior drawer with 15 lbs of force (t = 3.218, p < .01), with 20 lbs of force (t = 2.189, p < .05), and for quadriceps active displacement (t = 2.390, p < .05). Although not statistically significant, laxity decreases were observed for reconstructed ACL-injured knees for quadriceps active displacement. The laxity of normal knees did not change significantly for any tests.
The authors recommended that clinicians consistently perform KT-1000 measurements either before or after more vigorous clinical evaluations of patients with ACL injuries. The laxity increases observed among nonreconstructed ACL-injured knees may encourage therapists and athletic trainers to consider controlling anterior tibial displacement in ACL-injured patients.