In vivo function of posterior cruciate ligament before and after posterior cruciate ligament-retaining total knee arthroplasty.

PURPOSE

The object of this study was to investigate the in vivo function of the posterior cruciate ligament (PCL) in patients before and after a PCL-retaining total knee arthroplasty (TKA).

METHODS

Eleven patients with advanced osteoarthritis (OA) of the knee were recruited. Magnetic resonance scans of each OA knee were obtained, and 3D computer models, including the femoral and tibial insertion areas of the anterolateral and posteromedial bundles of the PCL, were created. Before and after PCL-retaining TKA, dual fluoroscopic images of each knee were acquired during weight-bearing knee flexion. The images and computer models were used to reproduce the in vivo motion of the knee. The function of the PCL bundles was described in terms of elongation, elevation and deviation. Twenty-two healthy controls were also included as normal references.

RESULTS

PCL bundles of the OA knees were overstretched during late knee flexion and orientated more medially throughout flexion compared with normal knees. After PCL-retaining TKA, PCL bundles were further overstretched during late flexion and changed from medially directed in normal and OA knees to almost sagittally directed, which may compromise function in controlling knee rotation.

CONCLUSIONS

The current PCL-retaining TKA systems and surgical techniques may not adequately re-establish normal biomechanics of PCL bundles after PCL-retaining TKA.