Postpartum sacral insufficiency fracture

Abstract

A 32-year-old woman with inflammatory lower back and hip pain was admitted to the Radiology Department for investigation. The patient had a history of osteoporosis and underwent childbirth 2 months before. On the sacroiliac magnetic resonance image, the bilateral ventral subchondral sacral bone showed hypointensity on the axial T1-weighted image (Fig. 1A) and hyperintensity on the axial T2 (Fig. 1B) and coronal T2 fat-saturated image (Fig. 1C), which is compatible with bone marrow edema. In the central region of the bone marrow edema, a hypointense linear band was seen on the T2 short tau inversion recovery (Fig. 1C) and T1 selective partial inversion recovery (Fig. 1D) images, which was compatible with fracture lines. Treatment prescribed to the patient included Vitamin D, calcium replacement, pain control, bed rest, and physical therapy. One year after treatment, sacroiliac magnetic resonance image showed that the sacral bone marrow edema had disappeared, and bilateral symmetrical T1and T2-weighted hyperintensity (Fig. 2A, B) showed signal loss in fat-saturated images (Fig. 2C, D), which was compatible with fatty bone marrow changes. Fracture lines were not seen in the control images.