Aneurysmal bone cysts of the pelvis.

Twenty-three cases of pelvic aneurysmal bone cysts treated at the Istituto Ortopedico Rizzoli were reviewed after a mean follow-up of 7 years. Eighteen cysts involved the anterior arch, four extended into the iliac wing and the anterior arch, and one invaded the entire hemipelvis. The acetabulum was involved in 56.5% of the cases. Fourteen patients were treated with surgery (curettage 11; resection 3), and five with radiation therapy; two patients had both modalities; two additional patients refused any treatment after biopsy. The overall recurrence rate was 13% (one case after curettage, one after radiation therapy, and one after combined treatment). Significant complications affected the final functional result in four of seven patients who received radiation therapy, while only one minor complication was seen in the surgical group.