[Subtotal Segment Resection, Augmenting Angle-Stable Plate Osteosynthesis and Allogenic Bone Graft as Treatment Option for Juxtacortical Osteosarcoma in the Knee Region].

Juxtacortical osteosarcomas are a group of rare primary bone tumours. They differ from medullary osteosarcomas in their anatomic location (outside of the corticalis), low metastasis rate and better prognosis. The only evidence-based treatment of juxtacortical osteosarcomas is the wide surgical resection. In this technical report we will introduce a new surgical technique, including the subtotal resection of the tumour-bearing bone segment, defect reconstruction by means of an augmenting fixed-angle plate osteosynthesis and homologous cancellous bone graft. If necessary, a subsequent plastic coverage of the soft tissue defect was performed. The technique will be presented by means of three illustrated cases of young patients with juxtacortical osteosarcomas in the proximity of the knee joint. Following diagnostic confirmation by means of an incision biopsy and tumour staging, the three patients underwent this new surgical technique. In the postoperative follow-up and re-staging, two to seven years after surgery, all patients were under complete remission, had functionally restored knee joints (Karnofsky score 90 % or higher) and showed good aesthetic results. The surgical technique described may therefore be an adequate alternative to the complete resection of the tumour-bearing bone segment with prosthetic reconstruction and should be considered on the basis of the illustrated functional results in individual cases.