posterior wall fractures

Anatomy

Unusual anatomic convergence of ilium, pubis and ischium

- covered entirely by hyaline cartilage

- except at acetabular fossa, which is the site of attachment of the ligamentum teres

- deepened by peripheral fibrocartilage labrum

2 column theory (Letournel and Judet)

Anterior Column 

- superior pubic ramus

- anterior acetabular wall, anterior dome

Incidence

Young men

Posterior / Anterior 9:1

Aetiology

High velocity injury

- head direction at impact decides direction of dislocation

Anterior Dislocation 

Externally rotated & abducted leg

- flexion = inferior dislocation