Transarticular invasion of iliopelvic sarcomas into the sacrum. Radiological analysis of 47 cases.

Joint cartilage functions as a barrier against the extension of bone tumors. However, transarticular invasion by iliopelvic sarcomas across the sacroiliac (SI) joints into the sacrum sometimes occurs. We made a radiological analysis (CT and/or MRI) of 47 bone sarcomas which originated in the ilium and extended nearly to the SI joint 8 of 17 chondrosarcomas and 3 of 30 other sarcomas (2 of 23 Ewing's sarcomas and 1 of 7 osteosarcomas) invaded the sacrum through the SI joint.