64 THE SURGICAL ANATOMY OF THE HORSE 



A peculiar feature in connection with fracture of the tibia is that 

 this bone is the most common seat of what is known as deferred 

 fracture, by which term is meant a fracture in connection with which 

 displacement does not occur until some time after the injury to which 

 the fracture is primarily due, has been inflicted. Regarding the cause of 

 the delay in the displacement, there are two theories. One is that 

 the fracture is complete at the time of the injury, but that the fractured 

 pieces are held in position by the dense layer of deep fascia which covers 

 the part, displacement occurring later when some sudden strain is thrown 

 upon the limb. The other theory is that at the time of the receipt 

 of the injury the fracture is only partial, the bone being fissured 

 but not completely fractured. The fracture is completed by some 

 subsequent strain thrown upon the limb, aided by the pressure of the 

 inflammatory exudate which has been poured into the line of the partial 

 fracture. 



Little difficulty is experienced in diagnosing cases of complete 

 fracture with displacement, particularly when the inferior third of the 

 bone is affected, as the seat of the fracture may be readily located with a 

 little manipulation. Frequently it may be seen, and manipulation is 

 unnecessary owing to the pronounced lateral bend presented just above 

 the hock and the swinging of the limb below it. Cases of compound 

 fracture are, of course, still more apparent. In these cases there is, in 

 addition, considerable systemic disturbance. 



In cases of deferred fracture accurate diagnosis is much more difficult. 

 There is lameness, the degree of which varies considerably, and occasionally 

 attention is attracted by the presence of an abrasion of the skin over the 

 part. When the injury has been received some time before the surgeon 

 has been called in, the difficulty is increased by the swelling of the inner 

 aspect of the leg. In such cases the part should be carefully palpated, 

 when it is possible to trace out the painful area, which will indicate the 

 line of the fissure. 



These remarks apply only to fissures on the inner aspect of the bone. 



