Osteonecrosis of the Iliac Wing and Sacral Insufficiency Fractures After Radiotherapy: Case Presentation

Iliac wing osteonecrosis coexisting with sacral insufficiency fracture rarely causes low back pain. Radiotherapy (RT) applied to the pelvic area is an important precipitating factor. Here, we present a patient who was referred to our outpatient clinic with mechanical lower back pain that was present for 3 months. The patient had received RT to the pelvic region due to colorectal cancer. Contrast-enhanced magnetic resonance imaging studies revealed iliac wing osteonecrosis and sacral insufficiency fracture. After ruling out the possibility of metastasis and making a definitive diagnosis, the patient was followed-up and bed rest and calcium and vitamin D supplementations were recommended. Despite these precautions, the patient still developed another sacral insufficiency fracture. Mechanical low back pain has a myriad of etiologies and standard X-rays may underdiagnose rarer causes of pain, such as osteonecrosis and insufficiency fractures. Clinical suspicion of these entities, especially in patients with a history of RT, may help in diagnosis and treatment.