LESIONS OF THE PELVIC ARTICULATIONS.
Relaxation of the Symphyses.
After having been admitted, then contested, then demonstrated by Sew6rin Pinaud, in 1869, upon the body of a woman recently confined, the softening of the inter-articular cartilages and the consequent relaxation of the pelvic symphyses is to-day granted by all obstetricians. But this softening is usually moderate, and remains, so to speak, within physio logical limits. Sometimes, however, it is so extreme as to become patho logical. Going still farther, Zaglas has recently demonstrated that there is, in man, a perceptible movement of the ossa innominata, antero-poste riorly, or around an imaginary transverse line traversing the second sacral vertebra. So we may consider the sacrum as having a movement of rotation around an imaginary transverse axis, the promontory advancing forward and downward, while the apex moves in an opposite direction and vice versa.
Matthews Duncan calls attention to the presence, on the posterior arti cular surface of the iliac bones, of an irregular bony prominence, which often has the form of a massive angle in relief. There is a cavity corre sponding to this eminence upon the opposite side of the sacrum, and the cavity is analogous, as regards some of its functions, to a cotyloid cavity. The movements of the iliac bones occur at the level of these surfaces, which are, generally, opposite the upper part of the second sacral vertebra. While they offer no resistance to the movements of flexion and extension of the ilia upon the sacrum, they oppose vertical movements between the bones, such as would necessarily be prejudicial to stability in the erect posture. In the latter half of pregnancy, the soft parts entering into the formation of the joints are always softened, and the articulations are con sequently relaxed. The softening of these tissues is generally accompanied by increase in their thickness, which produces separation of the bony sur faces and widening of the pelvic diameters. In some cases, this thicken ing is extraordinary. Boyer, Chaussier, Bovin, Smellie, Dimerbroeck and Denman, have reported separations of the bones, even to the exten of from one-half inch to an inch. Matthews Duncan, thus regards the
softening and thickening of the ligaments as the cause of sepamtion of the joint surfaces, as a wedge of dry wood, becoming moistened by the absorp tion of water, splits stones into which it is driven. Lenoir thinks that, at a later stage, the relaxation depends solely on the serous infiltration of the pelvic ligaments, due to pregnancy. This does not produce separation of the articular surfaces, but renders it possible under the influence of an effort tending to produce it. In the late stages, a hypersecretion of synovia is added to the softening, distends the cavities and separates the bones. Then, the mobility is very great, and if, in the cadaver, one opens the joints, a viscid abundant fluid escapes, as Morgagni saw in one case.
Trousseau, Ferdinand Martin, and Tarnier have again called attention to this relaxation of the pelvic joints, and Bonrhis and Dubois have studied it with care.
For Stoltz, this relaxation is either the effect of softening of the liga ments, or of violence exerted upon the tissues holding the pelvis together; during operations undertaken to deliver the woman: He thus makes two classes of relaxations. 1. The slow and progressive relaxation; 2. The violent and sudden relaxation. This latter also bears the name of rup ture of the symphyses.
Korsch, in the laboratory of Professor Slavjansky, at St, Petersburg, examined thus forty-five pelves, of which there were: Pelves of women dead after labor at term, 18; before term, 8; after an abortion, 3; before labor, 1. Pelves with uterine and ovarian tumor, 4; pelves of wotnen not pregnant, 6 ; pelves of men, 5. The following are his conclu sions: 1. The influence of pregnancy and of large uterine and ovarian tumors manifests itself, not only by softening of the ligaments of the joints, but by .enlargement of the dimensions of the inlet, and, particularly, of the out let.