PELVIS. 



207 



Ankylosis 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 cause of pelvic ob- 

 struction and protracted labour, and as such 

 has been before adverted to. Meckel de- 

 scribes ankylosis of the coccyx to" 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 de- 

 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 mention whether this process takes place 

 without previous inflammation, or follows the 

 analogy of other joints, in which pain, inflam- 

 mation and absorption of the cartilages, usually 

 precede the ankylosis. The instances of in- 

 complete ossific union mentioned by him to 

 be most common have most probably a rheu- 

 matic origin, like the smaller exostoses pre- 

 viously referred to, and arise from os-sific 

 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 rig/it 

 side, and is to be accounted for by the greater 

 pressure borne upon the right leg! He 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 ofmkjtoaeApnbicgymptytu 

 described by J. P. Mitchell, and given by Hull 

 in his 2nd Letter, the whole of the fibro- 

 cartilaginous disc wis 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 Kgamentum arcuatum is 

 also mentioned as sometimes interfering with 

 the urethra. Cases of imperfect ankylosis 

 of the pubic joint are also mentione'd by 

 Siebold, Voigtel, Walter, and Bonnard.f 

 All writers agree that ankylosis of this joint 

 is rare. Dr W. Hunter had never seen an 

 instance of it. 



Ossification of the sacro-sciatic ligaments 

 is mentioned by Meckel as sometimes exist- 

 ing, and even more commonly than that of 

 the pubic symphysis. Such a condition, if 

 present in the female during parturition, 

 would offer great obstruction to the passage 

 of the head through the inferior strait, from 

 its unyielding nature, and resistance to the 

 extension of the coccyx. It is, however, not 

 sufficiently common to be enumerated as one 

 of the ordinary obstacles to parturition. 



A different result of inflammatory change in 

 the pelvic joints, is that which gives rise to 

 the separation of the bones at their articular 

 surfaces. This, as a pathological process, 

 takes place most frequently by deposits of pus, 

 as a consequence of puerpal fever, which may 

 entirely destroy -the joint, and separate the 

 bones. From its more exposed position and 

 more open structure, this change has been 

 most frequently observed in the symphvsis 

 pubis. A case of this kind is described" by 

 Dr. W. Hunter, and many others have been 

 observed. 



A more remarkable separation of the pelvic 

 joints is to be ascribed to a congenital origin. 



It is one in which the pubic bones and with 

 them, in a minor degree, the sacro-iliac auri- 

 cular surfaces, are separated, mere or less 

 widely, and held together by a ligamentous 

 band. Instances in which this occurs to the 

 extent of a third of an inch, are mentioned 

 by Professor Otto, as being pretty frequent.J 



Probably one of the most extreme cases of 

 this kind is seen in a preparation at present in 

 the Hunterian Museum. It is the pelvis of 

 a woman, which was presented, as I am in- 

 formed, by Mr. Mayo, of Winchester, and 

 taken from a case which died in the infir- 

 mary of that town. The pubes are separated 

 to the great distance of 4f inches; and con- 

 nected by a ligamentous band of about the 

 width, in its present dried state, of from 

 i to ^ of an inch. The pubes are more ele- 

 vated than normal, with their articular ex- 

 tremities turned outward, and the symphy- 



* Observ. Anat. Path., b. i. p. 115., tab. 8. 



t Journal de Med. de Paris, 1778. t. xxxix. p.433. 



J Compend. of Human and Comp. Anatomy. 



