The use of metal augmentation for uncontained bone defects in revision total knee arthroplasty

Objective To explore the clinical results of the use of metal augmentation for uncon-tained bone defects in revision total knee arthroplasty. Methods A retrospective study was carried out on 62 patients with the use of metal augmentation and intramedullary stem for uncontained bone defects (AORI type Ⅱ) in 227 revision total knee arthroplasties from 1992 to 2001. There were 28 male and 34 female with a mean age of 67.8 years (range, 42 to 87 years). The diagnosis at the time of primary total knee arthroplasty was osteoarthritis in 51 (82.2%), rheumatoid arthritis in 8 (12.9%), lupus arthritis in 1 (1.6%) and posttrau-matic arthritis in 2 (3.2%). Revision was performed for aseptic loosening of femoral or tibial component in 30 (48.3%), reimplantation post- infection in 19 (30.6%), polyethylene wear with osteolysis in 3 (4.8%), malpo-sition or malalignment and instability in 10 (16.1%). Results Sixty-two patients were reviewed at a mean of 60.8 months (range, 13 to 132 months). Clinical evaluation revealed that the mean knee score of the knee society rating system had improved from 25 points preoperatively to 76 points postoperatively, the mean functional score from 40 points to 62 points at the latest follow-up and the mean range of motion ( had in-creased from a flexion arc of 78° to 87°. Radiolucent lines at the cement bone interface beneath the posteri-or femoral augmentation were present in 11 knees, beneath the medial tibial augmentation in 4 knees. None of radiolucent lines were progressive. All knees were asymptomatic. Two cases were failed due to recurrence of infection. One patient underwent for arthrodesis because of high risk for reinfection, another patient pre-ferred for resection arthroplasty and fused reimplantation. Post-operative manipulation under anesthesia for poor motion was carried out in 5 knees. Conclusion Metal augmentation for uncontained bone defects combined with intramedullary stem is feasible to accomplish, it provides immediate secure fixation to host bone, and improves success rate of revision knee arthroplasty, especially in elder patients.