The cruciate ligaments in total knee arthroplasty: a kinematic analysis of 2 total knee arthroplasties.

In vivo weight-bearing fluoroscopic kinematic analysis using an interactive model fitting technique with 3-dimensional computer-aided design solid models was done using 16 anterior and posterior (bicruciate)-sparing and 6 posterior cruciate-sparing total knee arthroplasties (TKAs). All patients had a satisfactory clinical result with a minimum of 12 months' follow-up. The femorotibial contact position of TKAs started posterior to the midline in extension. Bicruciate TKAs revealed gradual posterior femoral rollback and limited anterior-posterior translation but remained posterior to the sagittal plane midline in all positions. Posterior cruciate-sparing TKAs began significantly posterior in extension, demonstrated progressive anterior translation with flexion, and had exaggerated medial condyle translation on deep knee bend. The posterior cruciate-retaining TKAs of this study had the most abnormal kinematic performance.