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

Abstract

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.

Fig. 1A–H

(A) The T-2 MR image of a 64-year-old man shows a synovial sarcoma of the left knee involving the intraarticular and extraarticular spaces. (B) A photograph shows the clinical status before surgery. (C) An intraoperative view after en bloc extraarticular knee resection is shown. (D) The resected specimen is composed of the knee complex en bloc, including the distal femur covered by the vastus intermedius with the unviolated suprapatellar pouch, the intact capsule, the entire extensor apparatus (quadriceps tendon, patella, patellar tendon, patellar retinaculum), the popliteus muscle and the insertions of the gastrocnemius muscles, the insertion of hamstrings and semimembranosus muscles, the collateral ligaments, the medial part of the fibular head, and the proximal tibia cut below the tibial tuberosity. (E) Knee reconstruction is accomplished by an allograft-prosthetic composite. The quadriceps tendon of the allograft is sutured to the host quadriceps, as shown in the intraoperative photograph. (F) As a result of the excision of a wide skin area together with the tumor, a free anterolateral thigh flap was used for coverage. (G) The allograft-prosthetic composite reconstruction is seen on the lateral postoperative radiograph. (H) Function at 27 months from surgery is shown. Complete active extension is restored.

Fig. 2A–B

(A) The surgical dissection line of a classic extraarticular resection is shown (continuous line) on the lateral MRI of the knee of a patient with a liposarcoma of the infrapatellar fat pad after inadequate surgery contaminating the joint. (B) The surgical dissection line according to the technique of patellar splitting and extensor mechanism preservation (dotted line) is shown. Surgical margins (B) are more likely to be inadequate.