Magnetic resonance imaging study of alteration of tibiofemoral joint articulation after posterior cruciate ligament injury.

Cadaveric studies have shown that the posterior cruciate ligament (PCL) is an important constraint to posterior translation of the tibia. Arthroscopic studies have shown that chronic PCL injuries predispose to articular cartilage lesions in the medial compartment and the patellofemoral joint. The aim of the present study was to investigate sagittal plane articulation of the tibiofemoral joint of subjects with an isolated PCL injury. Magnetic resonance was used to generate sagittal images of 10 healthy knees and 10 knees with isolated PCL injuries. The subjects performed a supine leg press against a 150N load. Images were generated at 15° intervals as the knee flexed from 0 to 90°. The tibiofemoral contact and the flexion facet centre (FFC) were measured from the posterior tibial cortex. The contact pattern and FFC was significantly more anterior in the injured knee from 45 to 90° of knee flexion in the medial compartment compared to the healthy knee. The greatest difference between the mean TFC points of both groups occurred at 75 and 90°, the difference being 4mm and 5mm respectively. The greatest difference between the mean FFC of both groups occurred at 75° of flexion, which was 3mm. There was no significant difference in the contact pattern and FFC between the injured and healthy knees in the lateral compartment. Our findings show that there is a significant difference in the medial compartment sagittal plane articulation of the tibiofemoral joint in subjects with an isolated PCL injury.