Surgical technique: Muscle transfer restores extensor function after failed patella-patellar tendon allograft.

Abstract

Extensor mechanism allograft provides an effective remedy for severe quadriceps deficiency caused by loss of the patella, patellar tendon, and quadriceps tendon in TKA. Late failure is common, however, and major quadriceps deficiency occurs after removal of the allograft material. Six human cadaver specimens were dissected to evaluate the feasibility of transferring the vastus medialis, vastus lateralis, and medial head of the gastrocnemius muscle to fill the defect caused by loss of the patella and extensor tendon mechanism after failure and removal of allograft material. Transfer of the medial and lateral vastus muscles with their distal attachments into the tibia achieved closure of the defect but did not provide robust tendon material to fill the defect in the anterior knee. The medial gastrocnemius muscle reached easily to the muscular portion of the vastus medialis and lateralis flaps and provided secure closure of the anterior knee and strong attachment of viable muscle and tendon. Five knees (five patients) with failed patella-patellar tendon allograft between August 2008 and April 2010 were repaired using this technique. Mean extensor lag was 47° (range, 35°-62°) before surgery and improved to 12° (range, 5°-15°) 1 year after surgery. These preliminary results suggest that the described muscle transfer technique may provide an approach to salvage the failed extensor mechanism allograft after TKA.