Bone graft for tibial defects in total knee arthroplasty.

Twenty-four knees with bone grafts for tibial defects at the time of either primary or revision total knee arthroplasty were followed for three to six years. With 22 of 24 bone grafts, union and revascularization were seen and no clinical collapse was present. In two, nonunion occurred, accompanied by collapse in one. Failure was attributed to varus alignment of the leg in one (a medial condylar graft) and to insufficient preparation of the bony bed in the second (bleeding bone was not exposed). Evidence for incorporation of the grafts was obtained by tomogram, bone scan, and bone biopsy. Incorporation was present by six months, but the time to complete remodeling was not determined. A bone graft is recommended for tibial defect involving 50% or more of the bony support of either tibial plateau. A bone graft is indicated whenever a cement column under the prosthesis would measure more than 5 mm in height.