THE HIP-JOINT 435 



the limb, provided that a posterior dislocation is not present. 

 It may also be utilised \yhen operative interference is necessary 

 in congenital dislocations. 



Attitude of the Lower Limb in Disease of the 

 Hip-Joint. Semi-flexion is the position of rest assumed in all 

 joints. Consequently this is the position which the limb first 

 takes up when there is effusion into the hip- joint, since in this 

 attitude the tense ilio-femoral ligament is relaxed. 



The commencement of tuberculous disease in the femoral 

 neck, associated with a simple effusion into the joint, is sufficient 

 to cause flexion and slight lateral rotation. When the synovial 

 membrane is attacked the thigh becomes abducted in addition. 

 As a result of the position assumed by the limb, the pelvis is 

 tilted downwards to the affected side to enable the foot to reach 

 the ground, and a compensatory adduction of the sound limb 

 becomes necessary to restore the parallelism of the two limbs. 

 Scoliosis of the lumbo-thoracic region restores the centre of 

 gravity (p. 434). As a result there is apparent lengthening of 

 the diseased limb, but the real condition is readily discovered 

 by measurements and the examination of the relative positions 

 of the anterior superior iliac spines. 



As the disease progresses the existing flexion increases, and 

 the pelvis becomes tilted forwards to accommodate itself to the 

 altering conditions. To prevent the centre of gravity from being 

 thrown too far forwards the lumbar curve is greatly exaggerated, 

 constituting the condition of lordosis. At the same time the 

 sound limb must also take up a flexed position. The inter- 

 vertebral joints of the lumbo-sacral region acquire a greater 

 degree of mobility, and passive movements carried out upon 

 the diseased joint are transferred to them at once owing to the 

 rigidity and spasm of the surrounding muscles. Under anaesthesia 

 and during sleep the muscles become relaxed. In the latter 

 case this allows some movement between the diseased articular 

 surfaces, and the consequent irritation of the exposed nerve- 

 endings produces the " starting pains." 



In order to reduce the amount of tilting of the pelvis, com- 

 pensation is sometimes gained by flexing the knee and extending 

 the ankle on the diseased side, so that the patient walks on the 

 balls of the toes. 



The condition in which the limb is flexed, adducted, and 

 rotated medially is commonly found in tuberculous disease, and 

 it is often described as a later stage of the preceding condition. 



