[TKA revision of semiconstraint components using the 3-step technique].

OBJECTIVE: The surgical goal is to achieve a pain free and stable knee joint after revision total knee arthroplasty in three steps. An important component of the technique is the reproducible restoration of the joint line. INDICATIONS: Revision total knee arthroplasty. CONTRAINDICATIONS: Complete bone loss at the knee joint (epicondyles and tibia plateau), persistent joint infection, loss of the extension apparatus, and neurological disease with progressive ligament instability. SURGICAL TECHNIQUE: Implantation of revision components is performed in three steps. The first step is the positioning of the tibia component at the correct height and rotation. As the position of the tibial articular surface is independent of the knee position, the tibia serves as a reference both in extension and in flexion. The second step consists of balancing the knee joint in flexion and, thereby, definition of the flexion gap and the rotation of the femoral component. In the third step, the reconstruction and balancing of the knee joint in extension is performed. POSTOPERATIVE MANAGEMENT: Mobilization with weight bearing and range of motion as tolerated depending on osseous and soft tissue condition at surgery. The surgical technique does not influence the further treatment.
RESULTS: In a prospective study, 168 consecutive knee revisions operated by the first author were examined clinically and radiologically preoperatively and at a mean follow-up of 38 months (range 22-61 months). There were 96 knees from women and 72 were from men with an average age of 74.6 years (range 51-92 years). Clinical results were based on the American Knee Society score. The score showed 47.6 (range 32-63) preoperatively and 81.5 (range 62-95) at follow-up. Radiologically, 92.7% of the knees showed a malposition <3°. The joint line was correctly reconstructed in 86.3% based on the preoperative plan; 89% of the patella showed correct tracking in the patella tangential view.