428 THE INFERIOR EXTREMITY 



At school age, injury in this region may take the form of a 

 separation of the epiphysis of the femoral head. The correct 

 diagnosis of this condition is extremely important, as unless 

 proper treatment is carried out the epiphysis unites in a faulty 

 position, and subsequent limitation of movement results. After 

 union has occurred no manipulations can separate the fragment 

 for the purpose of reposition in correct alignment. 



This injury is usually caused by violent rotatory movements 

 of the trunk while the body-weight is being supported on the 

 femur. When examined the limb is found to be powerless, 

 and there is marked eversion together with some slight shorten- 

 ing. The diagnosis should be confirmed by the X-rays. 



Dislocations of the Hip-Joint may be (i) Congenital, 

 (2) Traumatic, or (3) Pathological. 



(i) CONGENITAL DISLOCATION of the hip-joint occurs more 

 frequently in females than in males, and this incidence is possibly 

 due to the fact that in the female the acetabulum looks more 

 directly to the lateral side. 



The head of the femur is situated on the dorsum ilii just 

 lateral to the anterior inferior spine, and is enclosed within 

 the untorn but greatly stretched articular capsule. In these 

 cases it is doubtful whether the head of the bone has ever occupied 

 the acetabulum, which is usually rudimentary. The capsule 

 possesses its normal attachments, but, owing to the stretching 

 to which it has been subjected, it resembles an hour-glass in 

 shape. When the child begins to walk, the proximal part of 

 the capsule has to transmit the body-weight to the femur, and 

 the condition becomes more exaggerated. The child walks 

 with a heavy downward lurch to the affected side, and the 

 muscles connecting the trunk to the thigh become greatly 

 shortened. The longer the condition is allowed to remain un- 

 treated, the more difficult will it be to carry out remedial 

 measures and the poorer the subsequent result. 



Owing to the shortening of the muscles it may be difficult 

 to place the head of the femur in the acetabulum, but the 

 reduction does not involve the passage of the head through 

 a tear in the capsule, as in the case of a traumatic dislocation. 

 Since the Socket of the acetabulum may be undeveloped or 

 rudimentary, it is a matter of great difficulty to retain the head 

 of the femur in place after the reduction has been effected. 

 Further, the proximal part of the hour-glass shaped capsule 

 becomes nipped between the two articular surfaces. 



