We measured the distribution of contact area and pressure between the
acetabulum and the femoral head of cadaveric pelves in three different
conditions: intact, with an operatively created fracture of the posterior
wall, and after anatomical reduction and fixation of the fracture with a
buttress plate and interfragmentary screws. The study involved eight
cadaveric hip joints from five pelves loaded to 2000 newtons in simulated
single-limb stance. Measurements were made with pressure-sensitive film.
The acetabulum was divided into three areas--the anterior wall, the
superior aspect, and the posterior wall--for the analysis of the data.
Creation of a fracture of the posterior wall was followed by an increase in
contact area, maximum pressure, and contact force in the superior aspect of
the acetabulum. A concomitant decrease in these parameters was observed in
the anterior and posterior walls. Anatomical reduction and fixation of the
fracture with a plate and screws did not restore the pattern of loading to
pre-injury levels.