Popliteus muscle as a barrier to tumor spread: computed tomography and angiography.

We reviewed 14 patients with primary bone tumors of the proximal tibia whose plain radiographs suggested possible posterior soft tissue extension. Four tumors extended posteriorly and displaced the major vessels on angiography. However, high resolution computed tomography (CT) showed the normal popliteus muscle lying between the tibia and the major vessels in three instances. When CT was equivocal, angiography in the lateral projection with the knee flexed was helpful for further evaluation.