Traumatic posterior fracture-dislocation of the fifth lumbar vertebra: report of two cases with review of literature.

Posterior fracture-dislocation of fifth lumbar vertebra (L5) is a rare injury pattern. Existing Aihara classification system lacks its mention. We report two cases of posterior fracture-dislocation of L5 with comminuted fracture of body that presented with cauda equina syndrome. The smaller anteroinferior vertebral body fragment of L5 had its relationship maintained with sacrum, whereas the larger posterosuperior fragment of the body was retropulsed. Decompression and instrumented fusion through posterior approach yielded good clinical outcome. We also present literature review with special emphasis on fracture characteristics and suggest its possible inclusion as a separate sub-type in existing Aihara classification.