Evolution of the rotating hinge for complex total knee arthroplasty.

Initial rotating hinge total knee designs were associated with a high failure rate. More recent designs have improved the patellofemoral articulation and the rotating hinge mechanism, added modular canal filling slotted fluted stems and metaphyseal sleeves, and improved the articulation between the mobile-bearing element and the tibial component. A series of patients with complex problems was studied. They underwent knee arthroplasty using a second generation rotating hinge component incorporating the design features listed above. Indications for surgery included medial collateral ligament disruption, revision of a previous hinged component with a massive bone loss, comminuted distal femur fracture or distal femoral nonunion in elderly patients, extensor mechanism disruption requiring reconstruction in an unstable knee, and ankylosis requiring femoral peel exposure with moderate residual flexion extension gap imbalance. A series of 23 knees in 22 patients was evaluated at the 2- to 9-year followup. The clinical results, range of motion, and satisfaction were comparable with that of a standard condylar revision knee arthroplasty despite the fact that the cases were more complex. These results warrant continued investigation of the role of rotating hinge in complex total knee arthroplasty.