Kinematic in-vitro comparison between the normal knee and two techniques for reconstruction of the anterior cruciate ligament.

The influence of anterior cruciate ligament sectioning and the results of its reconstruction on joint kinematics were studied using eight cadaver knees and a computerized system for analysis of three-dimensional motions. A Dacron(®) prosthesis was used in a transcondylar isometric drill-guide-determined route, and in an over-the-top route. After sectioning of the anterior cruciate ligament, the tibial motion increased in several passive laxity tests including anterior/posterior translation as well as varus/valgus and internal/external rotation. Increased valgus rotation was also seen during a simulated active extension manoeuvre. The effect of anterior cruciate ligament reconstruction was seen only on anterior/posterior translation, where the drill-guide technique restored, and the over-the-top technique partially restored, normal sagittal play at 90° of knee flexion. At 30° of knee flexion both methods reduced, but did not normalize, anterior/posterior translation. An adverse effect of both techniques, more prominent with the drill-guide technique which involved an extensive notchplasty, was abnormal external tibia[ rotation in 90° of knee flexion with the tibia in a gravity-determined position. Both techniques resulted in less than normal external rotation in the screw-home mechanism.