THE HIP-JOINT 423 



Tuberculous disease may originate in any of the three com- 

 ponent parts of the acetabulum (p. 419); and in this case the 

 spread to the joint is prevented only by the articular cartilage, 

 i.e. no epiphysis intervenes between the joint cavity and the 

 tuberculous focus. 



The diaphyseal side of the epiphysis for the greater trochanter 

 constitutes a third site for the occurrence of tuberculous disease 

 in this region. Spread may take place (a) down the shaft, as 

 an osteo-myelitis ; (b) along the neck, ultimately involving the 

 joint ; or (c) through the periosteum in front of or behind 

 the trochanter, giving rise to abscess and sinus formation. 

 Tuberculous abscesses in the region of the hip, however, much 

 more commonly have their origin within the joint. 



When the disease becomes intra-synovial the pus eventually 

 perforates the capsule at its weakest points, which are found 

 (i) postero-laterally, and (2) anteriorly, between the ilio-femoral 

 and pubo-capsular ligaments. 



1. After perforating the postero-lateral part of the capsule 

 the pus gravitates distally and backwards to point near the 

 gluteal fold, but it occasionally travels forwards deep to the 

 glutseus maximus and the tensor fasciae latse to point in the 

 interval between the latter muscle and the sartorius (p. 398). 



2. The course taken by pus, after perforating the anterior 

 aspect of the capsule, is by no means constant, (a) If the joint 

 cavity communicates with the psoas bursa (p. 273) the pus 

 ascends within the bursa to the iliac fossa and the pelvis. It 

 may here be pointed out that a psoas abscess may infect the 

 bursa, and, spreading in the opposite direction, may involve 

 the hip-joint, (b) The pus may gravitate along the tendon of 

 the psoas major and then follow the course of the medial circum- 

 flex artery (p. 410). It reaches the dorsum above the upper 

 border of the adductor magnus and points in the gluteal fold. 

 (c) Sometimes, after following the psoas major tendon, the pus 

 passes laterally along the lateral circumflex artery and reaches 

 the surface in the gluteal fold or in the neighbourhood of the 

 greater trochanter. In the former case, the condition has to be 

 diagnosed from a tuberculous infection of the bursse underlying 

 the tendon of the glutseus maximus. 



3. More rarely the pus perforates the inferior aspect of the 

 capsule, and at once comes into relation with the obturator 

 externus (p. 410). By following this muscle to its insertion the 

 pus again reaches the gluteal fold, but if it tracks in the opposite 



27 c 



