I04 THE SURGICAL ANATOMY OF THE HORSE 



prevents anterior dislocation of the large metacarpal bone, and 

 luxation in this direction can only occur as a sequel to rupture of this 

 ligament. Similarly, to have lateral dislocation the lateral ligaments must 

 first be ruptured. At the back of the joint, however, we have no posterior 

 common ligament. Here are placed the sesamoid bones which are 

 articulated to the back of the lower extremity of the large metacarpal. 

 The slips of insertion of the suspensory ligament and the insertions of the 

 lateral fetlock ligaments into the sides of the sesamoids suspend the latter 

 in position. The tendons of the superficial and deep flexors of the digit 

 play over the posterior aspect of the sesamoids, and the manner in which 

 these tendons are bound down to the phalanges, causes them to exert 

 pressure on the sesamoid bones, and keeps the distal extremity of the large 

 metacarpal bone from slipping off the upper surface of the suffraginis 

 when weight is placed upon the limb. In cases of rupture of both flexor 

 tendons, luxation of the fetlock joint readily occurs in the posterior direc- 

 tion. Such cases are most frequently met with in race-horses. 



Little difficulty is experienced in diagnosis, since the altered position 

 of the bones is very evident upon manipulation. 



Cases of recovery are very rare, and the animal is usually destroyed. 



If it should be decided to treat the case, general principles should be 

 followed. To reduce the luxation it is usually necessary to place the 

 patient under a general anaesthetic. The replaced bones are then main- 

 tained in position by applying a splint or stiff bandage, and the animal 

 is then placed in slings. 



KNUCKLING AT THE FETLOCK 



In this affection the fetlock joint bulges forwards, the joint being 

 in a peculiar state of flexion. The long axis of the large meta- 

 carpal bone is disposed obliquely downwards and forwards, and that 

 of the suffraginis upwards and forwards. In some cases the articular 



