Nonconstrained implants in revision total knee arthroplasty.

From March 1989 to March 1992, 39 knees were studied in 36 patients who had undergone revision total knee arthroplasty. A posterior stabilized modular prosthesis was used in 31 knees, and a standard condylar modular prosthesis was used in 8. Average followup was 20 months. The mean tibiofemoral angle was 2.1 degrees valgus (range, 22 degrees varus-23 degrees valgus) preoperatively, and 5.9 degrees valgus (range, 2 degrees varus-14 degrees valgus) postoperatively. Component placement in anteroposterior and lateral view was improved postoperatively. Postoperative patellar height was normal in 63.6% of the knees. Partial radiolucent lines were present in at least 1 prosthetic component in 72.7% of the knees, but no lines were complete. The Knee Society Pain Score improved from 50.5 points preoperatively to 82.7 points postoperatively. The Knee Society Function Score improved from 35.5 points to 56.1 points. Complications occurred in 20.5%. Since then, there has been 1 failure, an infection that subsequently led to knee fusion. Revision total knee arthroplasty presents difficult challenges, such as bone loss and ligamentous instability. A modular total knee replacement system allows the surgeon to do accurate preoperative planning and also to tackle unexpected problems intraoperatively. The authors' early results of revision total knee arthroplasty using a modular semiconstrained system are satisfactory.