Sacral insufficiency fracture

Overview

 * Typically, patients present with groin, low back, or buttock pain.
 * Patients present with either no history of trauma or a history of low impact trauma.

Causes

 * Postmenopausal osteoporosis (most common)
 * Senile osteoporosis
 * Pelvic irradiation
 * Corticosteroid therapy
 * Rheumatoid arthritis

Plain film

 * The most common finding is a sclerotic band or line.
 * Lytic fracture line or cortical break rarely is observed.

CT

 * Sacral fractures typically are oriented vertically and located parallel to the sacroiliac joints.
 * Linear fracture line with surrounding sclerosis is observed.

MRI

 * Decreased signal on T1-weighted images and increased signal on T2-weighted images.
 * Signal changes are seen as linear bands within the sacral ala and body and are parallel to the sacroiliac joints.
 * On T2-weighted images, the fracture line may be seen if it is surrounded by adjacent marrow edema.

Nuclear Medicine

 * H or "Honda sign" which indicated horizontal involvement of the sacrum and vertical involvement of the sacral ala
 * The "dot and dash" pattern is another common appearance.

Images
Images courtesy of RadsWiki