376 



HUMAN ANATOMY. 



The ilio-femoral ligament may, in cases in which the thigh is adducted and 

 rotated inward at the time of application of the force, take the place of the acetabu- 

 lar rim as a fulcrum. In that position it is wound round the neck of the femur, and 



Fig. 



393- 



Luxation of the head of the femur onto the dorsum of the ilium. 



Fig. 394. 



when the flexed leg is used as a crank the head may be made to burst through the 

 lower and posterior part of the capsule. 



AUis * has shown that these conditions, easily demonstrated experimentally, are 

 reproduced in many forms of accident. It is obvious that they are all favorable to 

 a downward dislocation, and this, as is the case with the humeral head, is the direc- 

 tion primarily taken in the 

 vast majority of these luxa- 

 tions. If the thigh has been 

 rotated inward, either in ad- 

 duction or abduction, the 

 head of the bone will pass 

 outward and backward and 

 rest behind the acetabulum 

 on some part of the outer or 

 posterior plane of the pelvis. 

 If it lies upon the ilium, a 

 little above the acetabulum, 

 it constitutes the ' ' iliac' ' dis- 

 location, — "above the obtu- 

 rator tendon ;" if upon the 

 ischium, on a level with or 

 a little below the acetabulum, 

 it is the " ischiatic" or "sci- 

 atic" dislocation, — "below 

 the obturator tendon." This 

 obturator internus tendon 

 sometimes interposes an ob- 

 stacle to the upward passage 

 of the head, but its impor- 

 tance in this respect has been exaggerated. The degree of flexion of the limb at 

 the time of the accident is more likely to determine the level at which the head rests. 



' Reduction of Dislocations of the Hip, Philadelphia, 1896. 



;.</ 



Relation of the head of the femur to the innominate bone in 

 dorsal luxation. 



