Surgical technique: vastus medialis and vastus lateralis as flap transfer for knee extensor mechanism deficiency.

BACKGROUND: Loss of the quadriceps tendon, patella, and patellar tendon leaves a major anterior defect that is difficult to close and compromises knee extension strength. Gastrocnemius muscle transfer does not sufficiently cover such major defects. This paper describes a new surgical technique that addresses these defects and the results of eight cases of revision TKA managed with this new technique. DESCRIPTION OF TECHNIQUE: The new procedure transfers the vastus medialis or the vastus lateralis and their tibial attachments or both muscles and their distal expansions combined with gastrocnemius and soleus flaps to cover major deficiencies in the anterior knee. Nine cadaver knee specimens were dissected to determine the effect of the transfer on nerve and blood supply of the muscles.
METHODS: Eight patients underwent the new procedure between 2005 and 2009. Four knees had vastus medialis transfer, two vastus medialis and vastus lateralis transfer, two vastus medialis and medial gastrocnemius transfer, and two medial gastrocnemius and medial ½ of the soleus muscle transfer. Minimum followup was 15 months (mean, 43 months; range, 15-74 months). Patients were evaluated for anterior knee pain, quality of knee closure, ROM, extensor lag, walking ability, use of assistive devices, and ability to climb stairs with the operated extremity.
RESULTS: All patients achieved closure of the knee without synovial leaks by 10 days postoperatively. Mean flexion contracture at last followup was 3° (range, 0°-7°). Mean extension lag was 22° (range, 5°-65°). Extension lag was less in those knees that included gastrocnemius or soleus muscle transfer. None of the flaps developed necrosis.
CONCLUSIONS: The vastus medialis and vastus lateralis muscles provide adequate coverage for anterior soft tissue deficits of the knee.