Deviations From The Healthy Condition of the Articulations of the Pelvis, and Solutions of the Continuity of its Bones. - There are various circumstances under which the synchondroses are liable to become more or less loose. Not only may they be torn asunder by considerable mechanical violence, but, in pregnancy, the firmness with which they connect the bones is slightly diminished, the fibro-cartilages becoming succulent, soft, (and vascular?): in the act of parturition the fibro-cartilages may be very much stretched, and even partially separated from the bone. When puerperal diseases of a very malignant type come on after labor, the cartilages may be partly or entirely removed by the destructive suppuration, and the bones thus separated from one another.

On the other hand, the bones of the pelvis may be too closely connected together, and anchylosis may take place between them. It is usually effected by bridge-like processes of bone which pass from the margin of the articular surface of one bone to that of the other, and as it were enclose the fibro-cartilage in a kind of capsule; it very rarely happens, that there is any union of the articulating surfaces themselves; and it is not ascertained whether, when that is the case, the fibro-carti-lages themselves ossify, or whether, as is more probable, new osseous matter is formed on the articulating surfaces of the old bone, whilst the fibro-cartilage is absorbed. Anchylosis of the sacro-iliac joint is met with now and then, but it is rarely found at the pubes.

Fractures of the pelvis do not generally take place without very considerable external violence, such as a fall from a great height, being run over, or buried beneath falling earth. They seldom unite without permanent displacement of the fragments.