Prevalence of pelvic insufficiency fracture in patients investigated by CT or MRI for pelvis or bone scan after pelvic irradiation at King Chulalongkorn Memorial Hospital (KCMH)

Abstract

Background : Pelvic insufficiency fracture (PIF) is one of the common complications in patients who have received pelvic irradiation. If clinicians and/or radiologists misunderstand the pathophysiology and associated radiographic findings, the diagnosis of this condition is delayed or misdiagnosed as pathologic fractures from metastasis.

Objective : To evaluate prevalence and distribution of pelvic insufficiency fracture in patients who have been investigated by CT or MRI for pelvis or bone scan after pelvic irradiation.

Design : Retrospective study.

Setting : Department of Radiology, Faculty of Medicine, Chulalongkorn University.

Materials and Methods : We retrospectively reviewed 260 patients with known history of primary pelvic cancer who received external beam radiation (40 - 64 Gy). The imaging findings were retrospectively reviewed on the PACS system and nuclear medicine workstation by an experienced radiologist, nuclear medicine physician and researcher. The prevalence of pelvic insufficiency fracture, frequency of distribution sites and average patients’ age were calculated and analyzed.

Results : Twenty of 260 patients (7.69%) showed pelvic insufficiency fracture after pelvic irradiation. Ninety-five percent of the fracture sites are the sacral alar. The second most frequent fracture sites are the upper sacral body (55%) and pubis (55%). Seventy-five percent of the cases showed more than one fracture sites in the pelvis, either symmetric or asymmetric. Among them, 65% had bilateral symmetric lesions in the sacral alar. A single lesion was noted in five cases (25%), at the sacral alar and the left parasymphyseal region.

Conclusion : Our study found the prevalence of pelvic insufficiency fracture in patients investigated by CT or MRI for pelvis or bone scan after pelvic irradiation at King Chulalongkorn Memorial Hospital is about 7.69%. The most common site involved is the sacral alar followed by the upper sacral body and the pubis which are weight bearing areas. Most cases had multiple sites of insufficiency fractures, usually bilateral involvement.