Tumbling Bullet Sign - Orthopaedia

Location	Multiple
Diagnosis	Post traumatic bone cyst
Discussion	Two sets of frontal and lateral radiographs, separated only by time, which reveal the "tumbling bullet sign"--which is simply a bullet which changes its location and orientation within a solitary bone cyst. This sign serves two purposes. It is documentation of the evolution of a solitary bone cyst as a corollary of trauma, and reveals the free movement of the foreign body within the confines of the lesion establishing its cystic rather than solid nature. It is similar to the fallen fragment sign.
Reference	Taxin RN, Feldman R.: The tumbling bullet sign in a post-traumatic bone cyst. Am J Roentgenol Radium Ther Nucl Med 1975 Jan;123(1):140-3.