468 



The Hip-Joint 



thinning and an absorption of these tissues, and so escape through the 

 ischio-rectal fossa, or by the rectum and anus. 



Occasionally the matter escapes by the perforation in the front of 

 the capsule^ finding its way into the bursa beneath the psoas, in which 

 case it may become extravasated upwards beneath the psoas and iliacus 

 and so give rise to secondary pelvic abscess and to caries. 



Often when disease has passed away, the hip-joint is synostosed, 

 the femur being flexed and inverted. . The limb can then be brought 

 straight down only by tilting the pelvis forwards and arching the 

 loins (lordosis). The exact amount of the deformity is calculated by 

 correcting the lordosis, by raising the thigh, making the line which 

 connects the anterior iliac spines pass at right angles to the middle 

 line of the body (' squaring the pelvis] as it is called), and noting the 

 position which the limb thus assumes. If the ankylosis be in a very 

 faulty position, the limb may be brought straight by dividing femur 

 subcutaneously, below the great trochanter, with a keyhole saw. 



Rectangular ankylosis following hip disease ; A, lordosis, thigh being brought down ; B, lor- 

 dosis effaced by raising thigh. (ERICHSEN.) 



As the joint-disease advances, and ulceration attacks the femur and 

 acetabulum, the child finds that he can get greatest rest and quiet 

 when the flexed knee is steadied over the other thigh, and protected 

 from muscular startings and accidental movements by the other leg 

 and foot, with which he lifts and arranges the damaged member. 

 Thus the thigh becomes persistently flexed and inverted. 



Dislocation of the femur, in the proper sense of the term, in hip- 

 joint disease never occurs. It sometimes seems to have taken place 

 when examination is made by Bryant's or Ne'laton's (p. 447) method, 



