chap, xix.] DISLOCATIONS OF THE HIP. 411 



(c) If the position of the limb at the time of the 

 accident be considered, it will be seen that the femur 

 will in every case be displaced downwards. There is, 

 indeed, but one primary dislocation of the hip, a 

 luxation downwards. The four forms given above 

 are all secondary, the bone having in each instance 

 first passed downwards before it moved to any of 

 the positions indicated. This point has been ably 

 demonstrated by Mr. Henry Morris, whose account 

 of the anatomy of hip dislocations is most valu- 

 able. The head having left the acetabulum, its 

 ultimate destination will depend upon the character 

 of the dislocating force. "If the limb be flexed on the 

 pelvis, and rotated inwards, or the pelvis be corre- 

 spondingly moved on the thigh at the moment of 

 displacement, the head of the femur will take a 

 backward course, and rest on the dorsum ilii or some 

 part of the ischium. On the other hand, extension 

 and outward rotation will cause the head of the bone 

 to travel upwards and forwards, and what is called a 



dislocation on to the pubis will occur If the 



dislocation is neither accompanied nor followed by 

 rotation, or fixed flexion or extension, the head of the 

 femur will remain below the acetabulum, and will 

 occupy the foramen ovale, if it takes a slightly forward 

 direction in its descent, or some position near the 

 tuberosity of the ischium if it leaves its socket in a 

 backward and downward direction " (Henry Morris). 



(d) The Y ligament is never torn in any "regular" 

 dislocation. It is saved by its great density, and the 

 circumstance that it is probably more or less relaxed 

 at the time of the luxation. The method of reducing 

 these dislocations by manipulation depends for its 

 success mainly upon the integrity of the Y ligament, 

 which acts as the fulcrum to a lever of which the 

 shaft of the femur is the long arm, and the neck the 

 short. In the backward luxations the head is behind 



