Achilles tendon allograft for augmentation of the Hanssen patellar bone grafting.

PURPOSE: Severe patellar bone loss precludes the insertion of another patellar implant in revision total knee arthroplasty (TKA) and weakens the attachment of the patella to the quadriceps tendon. Hanssen described securing a tissue flap to the patellar rim allows the delivery of cancellous bone graft into the patellar bone defect. The purpose of this study is to describe the surgical technique and early clinical results of a modified Hanssen patelloplasty with an Achilles tendon allograft. METHODS: The modified technique described in three patients undergoing revision TKA aims to augment the extensor mechanism by securing an Achilles tendon allograft to the proximal part of the patellar tendon and the distal quadriceps tendon using mattress sutures. This serves to reinforce the extensor mechanism and decrease the risk of a tear of its patellar attachment. The patellar bone defect is grafted using corticocancellous bone chips. RESULTS: Over a 12- to 48-month follow-up, all reconstructions healed with an increase in patellar bone thickness. No patient had any extensor lag, and all patients achieved 110°-125° of flexion. The Western Ontario and McMaster University knee scores improved from 53 (23-88) preoperatively to 88.5 (66-100) at last follow-up, with no reported complications. CONCLUSIONS: Augmentation of the extensor mechanism with an Achilles tendon allows for early mobilization and excellent postoperative range of motion in patients with large patella bone defects and imminent patella fracture. LEVEL OF EVIDENCE: IV.