Anatomical reconstruction of the knee extensor apparatus for prepatellar myxofibrosarcoma

Allograft Reconstruction of the Extensor Mechanism after Resection of Soft Tissue Sarcoma

INTRODUCTION

Soft tissue tumors around the knee joint still pose problems for the excision and subsequent reconstruction.

METHODS

In the 6 included patients the soft tissue sarcoma has its base on the anterior surface of the extensor mechanism and expands towards the skin. The entire extensor apparatus (quadriceps tendon, patella, and patellar tendon) was resected and replaced by a fresh-frozen allograft.

RESULTS

The mean follow-up was 6.7 years (range: 2-12.4 years). In two patients a local recurrence occurred, resulting in a 5-year local recurrence-free rate of 66.7% (95% CI: 19.5%-90.4%). Distant metastases were found in 4 patients resulting in a 5-year metastasis-free rate of 33.3% (95% CI: 4.6%-67.5%). Two patients underwent at least one revision surgery, including one patient in whom the allograft had to be removed. According to the ISOLS function score 24.7 points (range: 19-28 points) were achieved at the last follow-up. The mean active flexion of the knee joint was 82.5° (range: 25-120°) and a mean extension lag of 10° (range: 0-30°) was observed.

CONCLUSIONS

The replacement of the extensor mechanism by an allograft is a reasonable option, allowing wide margins and restoration of active extension in most patients.

TRIAL REGISTRATION

The presented study is listed on the ISRCTN registry with trial number ISRCTN63060594.

Bone-patellar tendon-bone allograft reconstruction for peri-patellar tendon sarcomas: case series

INTRODUCTION

Reconstruction after wide resection for a sarcoma involving the knee extensor mechanism is challenging even if the tumor is small.

CASE DESCRIPTION

We report on four consecutive peri-patellar tendon sarcomas treated similarly at a single institution. Histological diagnoses were synovial sarcoma (two cases), clear cell sarcoma and extraskeletal Ewing's sarcoma (one case each). Follow-up periods after surgery were 18-67 months. All cases underwent pre-operative radiotherapy and subsequent surgery. After preoperative radiotherapy and wide resection including the patellar tendon, bone-patellar tendon-bone allograft was fixed to the residual patella and tibial tuberosity with screws and a cable wire. Soft tissue and skin defect over allograft was covered by free antero-lateral thigh flap. Post-operatively, the operated knee was splinted straight for at least 6 weeks, and then range-of-motion exercise was gradually introduced. Except for one case with a proximal tibial stress fracture 5 months post-operatively, no complication was observed. Both bone-bone junctions between allograft and residual bones were united within 1 year after surgery. At the latest clinical follow-up, all the patients had satisfactory functions with Musculoskeletal Tumor Society score of 28-30 out of 30 points and virtually full range of motion.

DISCUSSION AND EVALUATION

This case series is the first to report bone-patellar tendon-bone allograft for reconstruction after tumor resection with joint preservation and with satisfactory clinical outcomes.

CONCLUSIONS

Bone-patellar tendon-bone allograft reconstruction with vascularized flap reconstruction is a viable option for peri-patella tendon sarcomas.

[Extensor mechanism allograft and radiotherapy in the treatment of soft tissue sarcomas around the knee: Presentation of two clinical cases]

OBJECTIVE

Knee involvement of soft tissue sarcomas is rare and very difficult to treat. Reconstruction of the extensor mechanism of the knee is essential to restore the functionality. Functional outcome is compromised by poor soft tissue coverage, adjuvant local radiotherapy, and resection of the extensor apparatus. No results were found in the literature as regards treatment by resection and reconstruction of the extensor mechanism in combination with adjuvant radiotherapy. The effects of radiotherapy are also unknown in the allografts.

MATERIAL AND METHOD

. Two cases are presented of soft tissue sarcoma around de knee treated by resection, reconstruction of the extensor mechanism with cryopreserved cadaver allograft, and local radiotherapy.

RESULTS

After more than 3 years of follow up, both patients are free of disease and have a good joint balance.

DISCUSSION AND CONCLUSIONS

Resection of the tumor with adequate safety margins and reconstruction using cadaveric allograft preserves the extensor mechanism and function of the limb. The soft tissue coverage is an added problem that can be solved by propeller fasciocutaneous flap coverage. After surgery, the limb must be immobilized with a knee brace locked in extension. Local radiotherapy contributes to local control of the disease. The reconstruction of the extensor mechanism of the knee with allograft is a functional alternative to amputation, and it does not contraindicate adjuvant radiotherapy to improve local control of the disease.

Functional reconstruction of the knee extension mechanism following wide resection for a prepatellar soft-tissue sarcoma: A case report

Functional reconstruction following a wide resection for a malignant musculoskeletal tumor is often challenging, particularly for juxta-articular tumors. The current study describes a novel surgical procedure for the functional reconstruction of the knee extensor mechanism with a pedicle frozen auto-bone and -tendon graft, in a case of prepatellar clear cell sarcoma. The active range of motion of the knee was from 0-135°, and the extension muscular strength of the knee was evaluated as 5/5 by a manual muscle test at 14 months post-surgery (International Society of Limb Salvage score, 73%); this was improved compared with a similar procedure previously described by Muramatsu et al. This procedure must be considered following the wide resection of juxta-articular malignant musculoskeletal tumors.

Flap reconstruction of the knee: A review of current concepts and a proposed algorithm

A literature search focusing on flap knee reconstruction revealed much controversy regarding the optimal management of around the knee defects. Muscle flaps are the preferred option, mainly in infected wounds. Perforator flaps have recently been introduced in knee coverage with significant advantages due to low donor morbidity and long pedicles with wide arc of rotation. In the case of free flap the choice of recipient vessels is the key point to the reconstruction. Taking the published experience into account, a reconstructive algorithm is proposed according to the size and location of the wound, the presence of infection and/or 3-dimensional defect.

Recipient vessels in the free flap reconstruction around the knee

Microsurgical free tissue transfer is playing a critical role in reconstruction of the soft tissue around the knee to salvage the limb, especially when the defects exist with a wide zone of injury or with a poor soft tissue condition, where local flaps are unavailable. For a successful free flap transfer, proper selection of a recipient vessel is essential and challenging. The survival and other outcomes of the transferred flaps were closely related to which recipient vessel was used and the location of anastomosis. In this article, we review most of the clinical reports about using free flaps to reconstruct the soft tissue around the knee, excluding the cases of postamputation, and discuss about the recipient vessels that can be used.