Extensor Mechanism Allografts in Total Knee Arthroplasty

Forty knees in 40 patients who had a chronic extensor mechanism disruption after knee arthroplasty underwent extensor mechanism allograft placement to restore extensor function. Thirteen knees were infected previously and 11 knees did not respond to previous attempts at direct extensor repair or reconstruction. Two patients died and two patients underwent above the knee amputation because of recurrent infection. The final group of 36 patients was studied for a mean followup of 3.6 years (range, 2-10 years). Clinical evaluations were performed using a modified Knee Society scoring system. The average range of motion in the entire group of patients was 1.4 degrees extension to 98 degrees flexion. The average extensor lag was 13 degrees in 15 of 36 patients. There were eight extensor allograft ruptures, which were treated by repeat extensor allograft placement. The average knee scores for function improved from 37 points preoperatively to 68 points postoperatively. Despite these initial ruptures, 34 of 36 patients had a successful clinical result. These results support the use of this technique for complete extensor mechanism loss after knee arthroplasty when direct repair is unfavorable.