*7.2.1 Intra-articular contact characteristics*

Several studies have focused on the alteration of contact area and stresses in the joint as a result of the fracture [28–32]. All fracture patterns showed a change from a uniform contact pattern to one of increased contact area and peak pressures in the superior acetabulum.

Letournal introduced the concept of "secondary congruence" in both column fractures of the acetabulum. In this group, the complete separation of all articular acetabular bony fragments can lead to an extra anatomical orientation around the femoral head with the possibility of healing in secondary congruence. In contrast, Levine et al. found an increase of the mean pressure and peak pressure in the acetabular roof area, whereas the contact area and mean pressure between femoral head and acetabular surface was decreased significantly in the anterior articular region and on a lesser degree in the posterior region.
