chap, xxi.] THE KNEE JOINT. 441 



stands upright and when he is not concealing any of 

 the deformity by rotating the limb. 



The progress of genu-valgum may be divided into 

 three stages. In the first stage there is a yielding or 

 elongation of the internal lateral ligament, and of the 

 fascial structures on the inner side of the joint. That 

 the yielding of this ligament alone will permit of a 

 lateral movement at the articulation being accomplished 

 is illustrated by cases of sprains of the knee, where the 

 ligament has been torn, and where much lateral bend- 

 ing has been in consequence permitted. It is probable 

 that the crucial ligaments yield also a little, and it is 

 upon the posterior band attached to the internal con- 

 dyle that the strain possibly first comes. In the 

 second stage there is a contraction of the tissues on the 

 outer side of the joint, that have been relaxed by the 

 new position of the limb. These structures are the 

 ilio-tibial band of the fascia lata, the external lateral 

 ligament, and the biceps tendon. This contraction 

 tends to give permanency to the deformity. In the 

 third stage the bones become changed. On the outer side 

 of the joint the external condyle and the outer tuber- 

 osity of the tibia are pressed together, and through these 

 bones the greater part of the weight of the body will 

 be transmitted. As a result of the continual pressure 

 the parts waste a little, and by their atrophy contribute 

 not only to the extent of the deformity but also to its 

 permanency. On the inner side the internal condyle 

 tends to become separated from the tibia, and an 

 interval to develop between the two bones as the 

 deformity advances. This interval is prevented 

 from actually existing by the development of the 

 condyle, which enlarges, and so still maintains its con- 

 tact with the tibia. Mikulicz has pointed out that 

 " the alteration in length on the inner side of the 

 femur arises not from alteration of the epiphysis, but 

 is confined to the lowest part of the diaphysis." This 



