Surgical technique: extraarticular knee resection with prosthesis-proximal tibia-extensor apparatus allograft for tumors invading the knee.

BACKGROUND: Intraarticular extension of a tumor requires a conventional extraarticular resection with en bloc removal of the entire knee, including extensor apparatus. Knee arthrodesis usually has been performed as a reconstruction. To avoid the functional loss derived from the resection of the extensor apparatus, a modified technique, saving the continuity of the extensor apparatus, has been proposed, but at the expense of achieving wide margins. In tumors involving the joint cavity, the entire joint complex including the distal femur, proximal tibia, the full extensor apparatus, and the whole inviolated joint capsule must be excised. We propose a novel reconstructive technique to restore knee function after a true extrarticular resection.

DESCRIPTION OF TECHNIQUE: The approach involves a true en bloc extraarticular resection of the whole knee, including the entire extensor apparatus. We performed the reconstruction with a femoral megaprosthesis combined with a tibial allograft-prosthetic composite with its whole extensor apparatus (quadriceps tendon, patella, patellar tendon, and proximal tibia below the anterior tuberosity).

PATIENTS AND METHODS: We retrospectively reviewed 14 patients (seven with bone and seven with soft tissue tumors) who underwent this procedure from 1996 to 2009. Clinical and radiographic evaluations were performed using the MSTS-ISOLS functional evaluation system. The minimum followup was 1 year (average, 4.5 years; range, 1-12 years).

RESULTS: We achieved wide margins in 13 patients (two contaminated), and marginal in one. There were three local recurrences, all in the patients with marginal or contaminated resections. Active knee extension was obtained in all patients, with an extensor lag of 0° to 15° in primary procedures. MSTS-ISOLS scores ranged from 67% to 90%. No patients had neurovascular complications; two patients had deep infections.

CONCLUSIONS: Combining a true knee extraarticular resection with an allograft-prosthetic composite including the whole extensor apparatus generally allows wide resection margins while providing a mobile knee with good extension in patients traditionally needing a knee arthrodesis.

LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.