Comminuted fractures of the posterior wall of the acetabulum. A biomechanical evaluation of fixation methods.

Reproducible simple fractures and osteotomies of the posterior wall of the acetabulum were created in twenty paired hemipelves from fresh human cadavera. Comminution was created with an additional fracture line that was either parallel (concentric comminution) or perpendicular (transverse comminution) to the posterior rim of the acetabulum. Under simulated weight-bearing, the stiffness of fixation of the transversely comminuted fractures that had been achieved with use of a reconstruction plate and screws was significantly higher than that achieved with fixation with screws alone (p < 0.05). The load to failure of the fixation of transversely comminuted fractures treated with a reconstruction plate and screws was also significantly higher than that of fixation of such fractures with screws alone (p = 0.05). The load to failure of the fixation of concentrically comminuted fractures was significantly higher when a reconstruction plate and accessory spring plates had been used than when a reconstruction plate alone had been employed (p < 0.05).