[Anatomic characteristics of the pelvic girdle]

The most recent methods of investigation (CT osteoabsorptiometry) were applied in an attempt to reconstruct from their morphological structure the way in which connections between the bones of the pelvic girdle undergo stress. Thus, both sacroiliac articulation and symphysis pubis show characteristic distribution of the subchondral bone density and layout of the tensile collagen fibrous material as expression of a strongly varying qualitative pattern of stress during walking. In the region of sacroiliac articulation are the highest subchondral densities, both at the cranial and caudal edges, whereas the central part of the two auricular surfaces is less heavily mineralized. This distribution matches the thickness of the hyaline cartilage of the joint. There are striking sexual differences in the distribution of the subchondral bone density at the bordering surfaces of the symphysis pubis. During walking, all components of sacroiliac articulation and the symphysis pubis are apparently subjected to sudden changes in stress. Independent of this, the os sacrum is constantly exposed to torque on account of the weight of the upper body, and this is balanced out by the sacrospinal and sacrotuberal ligaments.