Is Nothing Sacrum? Identification and Treatment of Sacral Insufficiency Fractures

Abstract

Sacral insufficiency fractures are an overlooked etiology of back pain that can also be difficult to diagnose radiographically. Advanced imaging, including MR and scintigraphy, are useful modalities for diagnosis, as these fractures are frequently missed on plain films. Management is often conservative to avoid surgical fixation, a rarely performed surgery due to its high morbidity. Radiologists are also able to provide symptomatic relief via sacroplasty, a minimally invasive, percutaneous, image-guided procedure first described in 2002. The most common sites of pelvic insufficiency fractures include the sacral ala and parasymphyseal region of the os pubis. The butterfly or “H-shaped” pattern is a classic sign of this fracture on scintigraphy, best appreciated posteriorly. MR is considered the gold standard in diagnosing insufficiency fractures and is characterized by low T1 band-like signal intensity with corresponding high T2/T2 short-tau inversion recovery (STIR) signal intensity. Such fractures can be treated via sacroplasty by carefully injecting polymethylmethacrylate bone cement via one or more trocar needles. Knowledge of sacral anatomy is critical during the procedure to not violate specific sacral zones or traverse any of the neural foramina.