Post Mortem Comparisons

Well-functioning implants retrieved post-mortem.

Direct comparison of in-vivo kinematics and wear patterns on retrieved tibial inserts reveal very similar patterns of condylar contact and insert wear (i.e., fluoroscopy studies can predict location and distribution of wear) [8. 19, 20]. (See Figure 6)

Fig. 6. Post Mortem retrieved left tibial insert (upper left) showing wear characteristic of the ACL deficient pattern of motion. Wear is posterior in both compartments (lower left), with a much larger A/P extent on the medial side. In Vivo kinematics obtained during a stair-climbing activity (right) show an identical pattern. Tibio-femoral contact is near the A/P midline with the knee if flexed (green lines) and moves posteriorly as the knee extends (yellow lines). This paradoxical translation is much greater on the medial side. Despite the abnormal translations, the femur still externally rotates with flexion [5, 14].