Management of Bone Defects Using Bone Graft

A 56-year-old man with no significant medical history had a left medial unicondylar arthroplasty done at an outside institution for isolated medial knee osteoarthritis. He presented to our institution with several months of chronic knee pain and feelings of instability. He had no new trauma and no fevers or other constitutional symptoms suggestive of infection. On physical examination, he had a well-healed midline incision with a large effusion but no surrounding erythema. His active range of motion was 15 to 90 degrees with 10 mm varus and valgus laxity. The erythrocyte sedimentation rate (ESR) and C-reactive protein level (CRP) were within normal limits; aspiration of the knee revealed only 137 white blood cells with no bacteria. Standing radiographs ( Fig. 21.1 , A and B ) showed an unstable medial unicondylar arthroplasty with severe subsidence of the tibial tray and a large bony defect in the medial plateau. The overall alignment of the knee was valgus, which suggested a lateral plateau bony deficiency as well. Intraoperatively, the femoral and tibial components were both found to be grossly loose. On the tibial side, there was a large contained defect on the medial plateau and an uncontained defect on the lateral plateau. After all bony cuts were made and components were trialed, the defects were addressed. Because the medial defect was contained, morselized bone graft was packed into the defect. However, a wedge augment was used on the lateral side because the bony defect was uncontained there. A constrained condylar knee implant was used because of the lack of stability. The soft tissue envelope closed well, and the patient was made weight bearing as tolerated, with therapy focusing on increasing the range of motion. Postoperative radiographs are shown in Figure 21.1 , C and D .