Simple bone cyst with fracture

One of the complications of a simple bone cyst is fracture. The fracture is often transverse and one sign that is touted is the "fallen fragment sign", due to fragments of bone that are seen in the dependent portion on erect images (Fig. 1) - usually in the inferior aspect of the cyst. Even on MRI, which is performed in the supine position, bone fragments may be seen in the inferior aspect (Figs. 2, 3).