Extensor mechanism allograft reconstruction in TKA at a mean of 56 months

Extensor mechanism disruption in total knee arthroplasty (TKA) occurs infrequently but often requires surgical intervention. We compared two cohorts undergoing extensor mechanism allograft reconstruction and presumed both types of extensor mechanism allograft reconstruction will be successful but for different indications and forms of extensor failure. Nineteen consecutive patients with extensor mechanism disruption after TKA were treated. Two different types of extensor mechanism allografts were used: quadriceps tendon-patella-patella tendon-tibial tubercle, and Achilles tendon allograft. Demographic factors, diagnosis at extensor failure, Knee Society clinical rating scores, radiographs, and patient satisfaction were recorded. The average time from extensor mechanism disruption to surgery was 6.6 months (range, 1-24 months). At a mean followup of 56 months (range, 24-96 months), all patients were community ambulators. The mean Knee Society score improved from 27 points preoperatively to 76 points postoperatively. There was no loss of knee flexion postoperatively. The mean postoperative lag was 14 degrees. Fifteen patients had an extensor lag of less than 10 degrees. All patients thought their functional status had improved, and 89% were satisfied with the results of the allograft reconstruction. The total extensor mechanism allograft and Achilles tendon allograft both were successful in the treatment of the failed extensor mechanism.