Long-term followup of nonmodular total knee replacements.

The purpose of the current study was to evaluate and determine the mechanism and etiology of failure of components that failed in long-term followup of Anatomic Graduated Component total knee replacements. The authors previously reported the survivorship of 4583 Anatomic Graduated Component total knee arthroplasties done during a 17-year period. The current study was done to evaluate the etiology and cause of failure of the components that failed. There were six (0.18%) failures of the femoral component. There were 21 tibia components that failed (0.46%). Twelve tibial components failed because of an osteonecrotic lesion in the medial tibia plateau. The clinical survival rate with revision or loosening of one or more components was 98.9% at 15 years. No component was revised for polyethylene wear or osteolysis. This total knee replacement has proved to have minimal wear and excellent longevity with time with no revisions between 10 and 15 years despite having nearly flat-on-flat geometry and retaining the posterior cruciate ligament. The most common cause for revision (12 tibial components) was because of an osteonecrotic lesion in the medial tibia plateau, which developed after surgery and led to loosening.