Extensor mechanism allograft in total knee arthroplasty
Male patient, 85 years old, with previous total left patellectomy due to patellofemoral arthritis at age 60 who subsequently underwent left TKA at age 79 ( surgeries performed in a different hospital ). He developed pain and progressive limitation of active and passive knee extension causing restriction of activities of daily living. He became accompanied by the Knee group from IOT-HC/FMUSP in December 2008, at that time four years and nine months after arthroplasty. On physical examination the patient had restriction on knee extension with lag of 40 degrees in active extension and 20 degrees in passive extension. The patient only walked with the aid of a walker, with no load on the compromised member. He did not show any ligament instability. Radiographs showed loosening of the tibial component with significant tear of the polyethylene insert. The inflammatory markers (ESR and CRP) were normal and bone scan was not suggestive of an infectious process. In April 2009 the patient underwent revision arthroplasty and allograft extensor mechanism transplant. The graft consisted of quadriceps tendon - patella (full) - patellar tendon - anterior tibial tuberosity (ATT). The graft was obtained from the IOT-HC/FMUSP Tissue Bank, having been previously prepared and frozen, without viable cartilage. The graft placement was based on the lower pole of the patella, which was kept 2.5 cm above the joint line. A pin in the tibia was inserted in the topography of the anterior tuberosity, where the previously molded plug bone allograft (ATT) was fitted under pressure and fixed with a large fragments screw. The articular surface of the patella graft was not replaced for being insensitive; replacement could be an unnecessary source of complications (such as fracture). The quadriceps tendon graft was then sutured to the patient's quadriceps, tensing toward the graft proximal and distal quadriceps, through Kracow technique with high strength nonabsorbable multifilament wire, keeping the knee in full extension. The capsule and what remained of the remnant extensor apparatus were sutured over the graft with simple absorbable wire, covering it in an attempt to increase its vascularization. ( and ) Postoperatively the patient was maintained immobilized in extension for six weeks performing only isometric strengthening exercises and assisted passive range of motion gain. After the sixth week active exercises with progressive weight were allowed until the third month, when immobilization was discontinued.