Extensor Mechanism Allograft after Revision Knee Arthroplasty

Introduction: Extensor mechanism disruption after total knee arthroplasty is an infrequent but catastrophic complication. Treatment options include non-operative treatment with a brace, cast immobilization, extensor mechanism reconstruction and knee arthrodesis. The multitude of reported surgical techniques implies the challenging nature of this complication. We report a successful extensor mechanism reconstruction with an allograft.

Case Report: An 80 year old female patient with chronic renal failure, atrial fibrillation , pulmonary embolism, hypertension, obesity and hypothyroidism underwent an uneventful total knee arthroplasty in 2015. During follow-up the patella was noted to sublux and dislocate. A full lateral release was performed, that did not solve the problem. A revision arthroplasty was then performed elsewhere with the use of a rotating hinge knee. The patellar tendon was disrupted and repaired primarily during that surgery. On further follow-up she was noted to have a full extensor deficiency and was referred for an allograft reconstruction.

A full frozen allograft of the extensor mechanism : quadriceps tendon, patella , patellar tendon and tibial tuberosity was used. The tibial block was secured with screws. The quadriceps tendon was attached with non-absorbable suture.

Patient was discharged with a locked brace. On follow-up, range of motion was gradually increased. At four months follow-up she has an active range of motion of 10-90 degrees. Xrays show the graft in place.

Summary: Extensor mechanism allograft transplant is an uncommon but viable option for patellar tendon rupture in arthroplasty. The procedure is demanding but post-operative results are promising. And it may be considered as a salvage procedure instead of knee arthrodesis when primary or augmented repair is not possible or unsuccessful.