Extensor mechanism disruption, whether due to patella fracture or tendon rupture, generally occurs after low-energy trauma and frequently involves an indirect mechanism. When the fracture is comminuted and reconstruction is impossible, a partial or total patellectomy may be indicated. Although some authors advocate total patellectomy, partial patellectomy remains the standard treatment, especially for young and active patients. In the rare instance of a failed tendon repair after partial or total patellectomy, inadequate tissue is usually available for adequate restoration of the extensor mechanism. Extensor mechanism allograft, using the tibial tuberosity, patellar tendon, patella, and quadriceps tendon in continuity or the Achilles' tendon with calcaneal bone-block in continuity has been reported for extensor mechanism repair after total knee arthroplasty in patients who did not undergo patellectomy. We present a novel technique, using the bone patellar tendon bone allograft to reconstruct a posttraumatic defect of the extensor mechanism in a 28-year-old, active patient with a failed partial patellectomy following fracture of his patella. Union of the allograft was seen on x-ray after 4 months. After 6 months, the patient reached full range of motion and returned to his previous sporting activities.