What is the reverse hamburger bun sign?
The “reverse hamburger bun” sign refers to the appearance of a dislocated facet joint on axial CT images where there is uncovering of the articular facet. The superior facet of the level below normally constitutes the top bun of the hamburger, the facet joint itself constitutes the meat patty, and the inferior articular facet of the level above constitutes the bottom bun. When there is facet dislocation, the meat patty is exposed without the top bun, also known as the “naked facet” sign.
