PRACTICAL CONSIDERATIONS : THE HIP-JOINT. 



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In both positions the iho-femoral ligament, which is almost invariably intact, 

 has now become the fulcrum. As the short arm of the lever— the head and neck — 

 has moved outward, the long arm — the shaft of the femur — must move inward ; hence 

 adduction is present in all cases of outward luxation in which the Y-ligament is not 

 lacerated, and is persistent because the head lying in contact with the outer wall of 

 the pelvis cannot be moved inward. Rotation inward, which is also present and 

 persistent, is due to the same tension upon the Y-ligament. This explains the 

 usual position of the limb with the line of the femur crossing that of the opposite 

 thigh a little above the knee and the 



great toe resting upon the instep of Fig. 395. 



the sound foot. Flexion of the thigh 

 is maintained partly by the tension on 

 the ilio-psoas. 



The muscles have a very minor 

 part in the production or maintenance 

 of the characteristic deformity. The 

 external rotators, the glutei and the 

 pectineus, are often lacerated. There 

 is shortening, and the trochanter is 

 above the level of Nelaton's line. 



In the rare cases in which the Y- 

 ligament — or its outer limb — is torn, 

 outward luxation with neither adduc- 

 tion nor inversion becomes possible. 



2. biward or Anterior Ltixations. 

 — These always occur with the thigh 

 in abduction, and are favored by out- 

 ward rotation, which carries the head 

 towards the lower anterior part of the 

 capsule. If it passes upward and rests 

 on the body of the pubis, it constitutes 

 the "pubic" luxation (Figs. 395, 

 396) ; if downward, it is in or opposite 

 the thyroid foramen, and is often called 

 an "obturator" or "thyroid" luxa- 

 tion (Figs. 397, 398). The ilio-femoral 

 ligament again becomes the fulcrum ; 

 the short arm of the lever has been 

 carried inward, necessitating a corre- 

 sponding outward movement of the 

 long arm ; hence abduction is present. 

 The exaggerated rotation outward is 

 maintained by the tension of the liga- 

 ment ; hence the eversion of the limb. 

 Neither abduction nor eversion can be 

 overcome, because the head is held 

 firmly against the pubo-ischiatic pelvic 

 plane. The gracilis, pectineus, and ad- 

 ductors are apt to be torn ; the stretch- 

 ing of the ilio-psoas, the glutei, and the 

 muscles inserted into the greater trochanter aids in maintaining both the flexion and 

 the eversion. The ilio-tibial band of fascia will be found relaxed ; the trochanteric 

 prominence disappears as the trochanter approaches the mid-line and is in a measure 

 sunk in the socket. There will be shortening on measurement from the anterior 

 superior spine to the condyle ; the head of the femur will be unduly prominent in 

 the pubic variety. 



With the patient in dorsal decubitus, it will be evident that the acetabula are 

 situated on a horizontal plane about midway between the pubes and the sacrum. 

 From this level the pelvis slopes upward to the symphysis and downward to the 



Luxation of the head of the femur onto the pubis. 



