Stress computed tomography for evaluating posterolateral knee laxity.

A new method is presented to quantify the extent of posterolateral knee laxity. Stress computed tomography (CT) is performed to determine external rotation of the tibia on both knees. Manual maximum external torque is applied to the tibia from both feet by an examiner while both femurs are stabilized by a tape at approximately 30 degree of knee flexion. CT images are acquired at this position and side-to-side differences of external rotation are determined from the images by standard computer software. The technique is simple and helps to quantify posterolateral knee laxity before and after surgical procedures of posterolateral knee reconstruction.