Chulalongkorn Medical Journal


Background : Pelvic insufficiency fracture (PIF) is one of the commoncomplications in patients who have received pelvic irradiation.If clinicians and/or radiologists misunderstand the pathophysiologyand associated radiographic findings, the diagnosis of thiscondition is delayed or misdiagnosed as pathologic fracturesfrom metastasis.Objective : To evaluate prevalence and distribution of pelvic insufficiencyfracture in patients who have been investigated by CT or MRIfor pelvis or bone scan after pelvic irradiation.Design : Retrospective study.Setting : Department of Radiology, Faculty of Medicine, ChulalongkornUniversity.Materials and Methods : We retrospectively reviewed 260 patients with known history ofprimary pelvic cancer who received external beam radiation(40 - 64 Gy). The imaging findings were retrospectively reviewedon the PACS system and nuclear medicine workstation by anexperienced radiologist, nuclear medicine physician andresearcher. The prevalence of pelvic insufficiency fracture,frequency of distribution sites and average patients’ age werecalculated and analyzed.Results : Twenty of 260 patients (7.69%) showed pelvic insufficiencyfracture after pelvic irradiation. Ninety-five percent of the fracturesites are the sacral alar. The second most frequent fracture sitesare the upper sacral body (55%) and pubis (55%). Seventy-fivepercent of the cases showed more than one fracture sites inthe pelvis, either symmetric or asymmetric. Among them, 65%had bilateral symmetric lesions in the sacral alar. A single lesionwas noted in five cases (25%), at the sacral alar and the leftparasymphyseal region.Conclusion : Our study found the prevalence of pelvic insufficiency fracturein patients investigated by CT or MRI for pelvis or bone scanafter pelvic irradiation at King Chulalongkorn Memorial Hospitalis about 7.69%. The most common site involved is the sacralalar followed by the upper sacral body and the pubis which areweight bearing areas. Most cases had multiple sites ofinsufficiency fractures, usually bilateral involvement.

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