PURPOSE: Limb salvage in bone sarcomas requires resection to clear margins and reconstruction of both bone and soft tissues. Wound healing problems can lead to hardware exposure, subsequent prosthesis infection with eventual amputation. In the pediatric sarcoma population, it is essential to not only have viable soft tissue coverage but one that minimizes donor site morbidity and maximizes function and growth over time. This is the largest series of pediatric knee sarcoma resection and reconstruction with endoprothesis and primary flap coverage.

METHODS: This is a prospective review of all sarcoma patients with primary gastrocnemius and soleus muscle flap coverage of knee endoprosthesis over the 10-year period 1997 to 2007. Ten patients (9 male, 1 female) underwent resection of proximal tibia with an average age of 14 years (range, 10 to 17). Pathology included osteosarcoma in 8 patients, Ewings (n=1) and spindle cell (n=1). After resection of the knee joint and proximal tibia to clear margins, the boney defect is reconstructed with an endoprosthesis. The soleus and gastrocnemius are independently rotated to cover the prothesis as well as the patellar tendon.

RESULTS: All patients had endoprosthetic coverage by gastrocnemius and soleus flaps; four patients had additional split-thickness skin graft over the gastrocnemius. All patients had resection of the skin at the tibial biopsy site, therefore, primary closure at this level would have been under tension or impossible in some patients. Any wound dehiscence would have resulted in exposure and potential infection of the endoprosthesis. The average length of tibial osteotomy from the knee joint was 17cm. The mean soft tissue mass resected with bone was 171cm². There was one flap failure that was reconstructed with a rectus abdominis free flap. Average follow-up was 31.2 months (range, 1 to 91 months). Two patient succumbed to metastatic disease. There were no cases of local recurrence. There was no limb loss, hardware exposure or infection. All wounds healed well. All patients achieved ambulation. Functionally, all patients attained excellent passive and active range of motion at the knee joint, and motor and sensory function was preserved in most. Leg length discrepancy was found in three patients who underwent opposite limb epiphysiodesis.

CONCLUSION: Results of this study support the use of gastrocnemius and soleus flaps as dependable coverage for knee endoprosthesis in the pediatric population. It not only provides well-vascularized soft tissue that reduces wound complications and hardware exposure but it achieves functional success through growth.