Oncological and Functional Outcomes after Hemicortical Resection and Biological Reconstruction Using Allograft for Parosteal Osteosarcoma of the Distal Femur

Figure 1

Parosteal osteosarcoma (PAO) in a 16-year-old female (no. 6). Anteroposterior (a) and lateral (b) radiographs of the knee showing a parosteal osteosarcoma as a large-ossified opacity attached to the posterior cortex of the distal femoral metaphysis. Sagittal computerized tomography (CT) reformatted images, soft tissue window (c), and bone window (d) demonstrate the characteristic separation between the tumor and the intact femoral cortex (cleft sign) as well as the ossified thick stuck lytic areas are seen within the ossified mass which is surrounded by a thick hypodense rim representing cartilaginous tissue. A fat-suppressed T2w magnetic resonance image sagittal (e) and axial view (f) showing the densely ossified stuck centrally, the inhomogenous moderately, T2 hyperintense mass in the middle, and the hyperintense cartilaginous component in the periphery. There is no intramedullary extension of the tumor.