Although extensor mechanism failure remains a catastrophic complication of knee arthroplasty, there are a number of contemporary techniques with reasonable outcomes that restore function. Chronic failures require advanced reconstruction techniques. Similar complication rates have been reported for the use of autografts, allografts, or mesh reconstructions. Here, we describe our surgical technique in allograft extensor mechanism reconstruction for chronic failures in salvage revision knee arthroplasty using a complete extensor mechanism allograft with a modified proximal fixation and case demonstrations.