Abstract
The effect of isolated posterior Cruciate ligament (PCL) reconstruction to eliminate combined posterior instability and posterolateral rotatory knee instability was investigated experimentally, using four anatomical knee specimens. The magnitudes of posterior tibial translation and of external tibial rotation were measured at flexion angles between 0°and 90°, under a 147 Newton (N) posteriorly directed force applied on the tibia. Measurements were made at four stages: firstly with all the ligaments preserved, secondly after complete sectioning of both the PCL and posterolateral structures (PLS), thirdly after reconstruction of the PCL, and finally after reconstruction of the PLS. Isolated PCL reconstruction significantly reduced both posterior translation and coupled external rotation at all flexion angles except 30°, but increases in posterior translation (7.0-9.5mm) and in external rotation (11.5-21.5°) remained. These increases then disappeared after PLS reconstruction. Therefore, it was concluded that both the PCL and PLS must be reconstructed to eliminate this combined instability.
