These fractures are a combination of a posterior column and posterior wall fracture. The posterior column component is often nondisplaced, and the wall fracture is the more obvious component.
The posterior wall fractures involve the rim of the acetabulum, a portion of the retroacetabular surface, and a variable segment of the articular cartilage.
Posterior column fractures originate at the greater sciatic notch, pass through the roof or weight bearing dome and exit through the obturator ring. The result is a complete detachment of the posterior column. The fracture is usually displaced posteriorly, medially, and in internal rotation.
Posterior column and wall fractures may be associated with femoral head fractures.