3?6 SUKCICAL APPLIKD A.VA TOMY. [Chap. XVIlt. 



fragment (which is almost always carried forwai-ds) 

 as to be nearly closed. 



Special parts of the pelvis. Sympliysis. 



Separation of the bones at the symphysis without 

 fracture has occurred from severe violence. Malgaigne 

 reports three cases where the separation was brought 

 about by muscular violence only, by extreme action 

 of the adductor muscles of the two sides. The 

 Sigaultean operation consisted in dividing the sym- 

 physis pubis in cases of contracted pelvis, with the 

 idea of obtaining more room during labour, and of so 

 avoiding Csesarian section. It has been shown, how- 

 ever, that to gain half an inch in the aiit-ero-posterior 

 diameter the bones must be separated to the extent 

 of two inches. Such a separation involves laceration 

 of the sacro-iliac ligaments, and more or less damage 

 to the attachments of the pelvic viscera. 



The sacro-iliac sycliondrosis may be the seat 

 of disease. formally, there is no movement at this 

 joint, but when the ligaments are softened by disease, 

 and eflusion occurs between the opposed bones, some 

 movement may be demonstrated. As this joint lies 

 in the line of the great arches of the pelvis, it follows 

 that when inflamed much pain is felt in the part, 

 both when the patient is standing or sitting. When 

 abscess forms it tends to come forwards, owing to the 

 fact that the anterior ligaments are less dense than 

 the posterior. Having reached the pelvic aspect of 

 the joint, the pus may occupy the iliac fossa, or gain 

 the ilio-psoas sheath. Or it may follow the lumbo- 

 sacral cord and great sciatic nerve and point in the 

 thigh behind the great trochanter, or it may be 

 guided by the obturator vessels to the inner side of 

 the thyroid foramen, and ultimately appear at the 

 inner side of the thigh. The abscess may, however, 

 proceed backwards, and point over the posterior aspect 

 of the joint. 



