PRACTICAL CONSIDERATIONS : THE PELVIS. 



347 



produce fracture of the horizontal or the descending ramus of the pubes, the ramus 

 of the ischium, or of the iha external to the sacro-iliac junction. 



If the accident has been a fall upon the feet, the injury will probably be confined 

 to the acetabulum or to the pubes. In young subjects the acetabulum may be sep- 

 arated into its three anatomical components (Fig. 355), or a portion of the rim may 

 be broken off, or in rare cases the head of the femur may be driven through into the 

 pelvic cavity. 



If the traumatism has been a crush in the antero-posterior direction, the pubes 

 .will probably first fracture ; if the force is continued, the protection afforded by the 

 " tie arch" having been withdrawn, the pressure comes upon the main arches, which 

 tend to open out. A portion of one of these arches may then give way, and a sec- 

 ond fracture may occur through the ilium into the sacro-sciatic notch, or vertically 

 through the sacrum itself. More commonly, however, the anterior sacro-sciatic 

 ligaments give way and a certain amount of disjunction of that joint occurs. Even 

 if the crushing force is applied laterally, it is usual to find the pubes again fractured 

 from indirect violence. If the application of the force is continued, the strain comes 

 upon the posterior sacro-iliac 



ligaments, which may rupture, "^• 



but are more likely to with- 

 stand the violence, which then 

 may result in the tearing away 

 of a portion of the bone into 

 which the ligament is inserted. 



The pubic fracture is dis- 

 coverable by the usual means. 

 The vertical fracture of the 

 ilium or the disjunction of the 

 sacro-iliac synchondrosis an- 

 teriorly should be suspected 

 if there is pain in the region 

 supplied by the superior glu- 

 teal, the lumbo-sacral, the 

 upper sacral nerves, or the 

 obturator, — i.e., in the sacral 

 region, the buttock, the back or inner part of the thigh, or the knee, — on account 

 of the relation of these nerves to the anterior surface of the joint. 



Marked ecchymosis, swelling, and tenderness over the sacro-iliac regions pos- 

 teriorly indicate tearing of the posterior ligaments or the fracture by arrachement 

 that has been described. 



In all these cases the gravity of the injury depends upon the presence or absence 

 of visceral complications. If a double vertical fracture exists, extending through 

 the rami of the pubes and ischium in front and through the ilium near the sacro- 

 iliac junction posteriorly, it is obvious that there will be one large fragment of the 

 pelvis more or less movable, to which the femur on that side is connected. This 

 condition may be associated with upward displacement of the fragment, carrying the 

 femur with it, and it may give rise to a mistaken diagnosis of fracture of the neck of 

 the femur. It should be remembered, as Tillaux has pointed out, that in the pelvic 

 lesion the relation of the greater trochanter to the anterior superior iliac spine is 

 normal, and the real length of the limb on the affected side is the same as that on 

 the sound side. 



2. Other fractures, as those through the lateral expansions of the ilia, and 

 epiphyseal separations involving the pelvis, have relation more especially to its 

 function as affording a means of moving the trunk upon the lower limbs. The 

 epiphyses chiefly separated are those of {a) the iliac crest, (3) the anterior superior 

 spine, (<:) the posterior superior spine, and (^) the anterior inferior spine. 



The first three of these are often united in one long epiphysis, but portions of 

 this may be detached separately by muscular action or by direct violence. Cases of 

 separation of the anterior superior spine by the action of the abdominal muscles 

 and by that of the sartorius have been reported. 



Lines of fractures of the pelvis. 



