PATHOLOGY OF THE PELVIC JOINTS.
The pelvic joints, like all other joints in the body, but much less frequently than many, are subject to inflammation and its conse quences in such structures —viz., ulceration, suppuration, and ankylosis. They are also, probably more frequently, subject to original malformation, coalescence, and anomalous constructions of a congenital origin.
Ankyosis is the most frequently seen in the sacro-coccygeal joint. It is also met with in the sacro-iliac, and sometimes, but most rarely, in the pubic symphysis. Anky losis of the coccyx is one CAUSC of pelvic ob struction and protracted labour, and as such has been before adverted to. Meckel de scribes ankylosis of the coccyx td be more frequent in males than in females, particularly in such as have long-continued equestrian habits.
Coalescence of the bones composing the sacro-lumbar articulations have been before described as producing deformed pelvis. This formation almost universally results from an original aberration of development, and not from ankylosis as a subsequent pathological result. Sometimes it occurs on both sides with hypertrophy and transformation of the last lumbar transverse process. In many of the instances recorded of six sacral pieces, and in the pelvis drawn after Murphy (see fig. 113.), a complete coalescence of this kind probably existed.
Ossification of the sacro-iliac joint has also been referred to in connection with the "pelvis oblique ovata." It is, however, by no means confined to pelves presenting that deformity.
In the 'Museum of King's College is a well formed male pelvis, with ankylosis of the sacro-iliac joint on the left side, the bones presenting no other traces of disease or tle• formity.
In the experience of Rokitansky, it is rare that the bony union in ankylosis of the pelvic joints extends through the whole of the op posed articulating surfaces, but generally takes place by bridge-like processes, passing from one margin of the joint surface to the opposing margin, so as to enclose the fibro cartilage in a kind of bony capsule. It is not ascertained whether the fibro-cartilage itself ossifies, or, as he thinks is most likely, be comes absorbed before the ossifying process from the adjacent bones. This author does
not rnention whether this process takes place without previous inflammation, or follows the analogy of other joints, in which pain, inflain 'nation and absorption of the cartilages, usually precede the ankylosis. The instances of in complete ossifie union mentioned by him to be most common have tnost probably a rheu matic origin, like the smaller exostoses pre viously referred to, and arise from ossific deposits in the circumferential ligaments, with out the interior structures being affected. Meckel describes ossification of the sacro iliac joints as those most frequently- seen, and that it most commonly occurs on the right side, and is to be accounted for by the greater pressure borne upon the right leg! Ile con siders, also, that ossifications of this joint usually take place without preceding inflam mation, from a gradual change in their sub stance and in the fibrous tissues around them.
In a specimen of ankylosedpubic symphysis described by J. P. Mitchell, and given by Hull in his 2nd Letter, the whole of the fibro cartilaginous disc w•ts converted into a smooth equable bony substance. A few other cases of complete ankylosis of this symphysis are recorded by Wagner. In a case described and figured by Sandifort#, the pubes were united on, their posterior and upper surfaces by an osseous bridge in the position of the ligaments, leaving a chink between the bones in front. In the same pelvis the right ob turator membrane was also extensively ossified, as well as a considerable portion of the right capsular ligament of the hip joint,— all these circumstances indicating a rheumatic origin. Ossification of the ligamentum arcuatum is also mentioned as sometimes interfering with the urethra. Cases of imperfect ankylosis of the pubic joint are also mentioned by Siebold, Voigtel, Walter, and Bonnard:I All writers agree that ankylosis of this joint is rare. Dr NV. Hunter had never seen an instance of it.