Parosteal osteosarcoma of the posterior aspect of the distal part of the femur - Oncological and functional results following a new resection technique

Background: Parosteal osteosarcoma is a low-grade malignant bone tumor that arises from the surface of the metaphysis of long bones. Parosteal osteosa rcoma is usually well differentiated and displays a low propensity to metas tasize. Wide resection of a parosteal osteosarcoma has been shown to provid e a relatively risk-free method of preventing local recurrence. We propose a new method of resection of parosteal osteosarcomas located in the poplite al paraosseous space of the distal part of the femur. This method involves resection of the mass through separate medial and lateral incisions, which allows for wide margins yet limits the amount of dissection of the soft tis sues and the neurovascular bundle. Methods: Six patients with parosteal osteosarcoma located in the posterior aspect of the distal part of the femur underwent resection of the lesion an d reconstruction with a posterior hemicortical allograft through dual media l and lateral incisions. The patients were evaluated with regard to pain, p ostoperative function, union of the allograft (osteosynthesis), and the pre valence of local recurrence. Results: The average time until the last follow-up assessment was 4.3 years . No metastases developed, and there were no local recurrences. All patient s were free of disease at the last follow-up evaluation. Postoperatively, t he average range of motion of the knee was 0 to 122 degrees. Five of the si x patients were free of pain at the time of the latest follow-up. Five of t he six patients returned to their preoperative active functional status. Conclusions: We recommend resection of a parosteal osteosarcoma located on the posterior surface of the femur through separate medial and lateral inci sions. This approach provides minimal dissection of the neurovascular bundl e but ample exposure for reconstruction with a hemicortical allograft.