Treating extensor mechanism disruption after total knee arthroplasty

A consecutive series of 14 patients with chronic extensor mechanism disruption after total knee arthroplasty (TKA) were treated with allograft reconstruction. Preoperatively all patients had full passive extension but a complete extensor lag. The average time from extensor mechanism disruption to surgery was 7 months (range, 3-24 months). Two methods of reconstruction were used depending on specific indications: an Achilles tendon with calcaneal bone block (eight patients) or a quadriceps tendon-patella-patellar tendon-tibial tubercle composite graft (six patients). At followup averaging 42 months (range, 24-60 months) all patients were community ambulators, five patients used a cane, two patients used a walker, and seven patients used no assistive devices. One patient had a partial re-rupture and a 45degrees extensor lag, one patient had a 30degrees extensor lag, two patients had a 15degrees extensor lag, and 10 patients had a lag of less than 10degrees. All patients thought that their functional status had been improved and were satisfied with the results of the allograft reconstruction.