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 osteosarcoma is usually well differentiated and displays a low propensity to metastasize. Wide resection of a parosteal osteosarcoma has been shown to provide a relatively risk-free method of preventing local recurrence. We propose a new method of resection of parosteal osteosarcomas located in the popliteal 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 tissues and the neurovascular bundle.
METHODS: Six patients with parosteal osteosarcoma located on the posterior aspect of the distal part of the femur underwent resection of the lesion and reconstruction with a posterior hemicortical allograft through dual medial and lateral incisions. The patients were evaluated with regard to pain, postoperative function, union of the allograft (osteosynthesis), and the prevalence 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 patients were free of disease at the last follow-up evaluation. Postoperatively, the average range of motion of the knee was 0 to 122 degrees. Five of the six patients were free of pain at the time of the latest follow-up. Five of the 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 incisions. This approach provides minimal dissection of the neurovascular bundle but ample exposure for reconstruction with a hemicortical allograft.