56 THE SURGICAL ANATOMY OF THE HORSE 



FRACTURE OF THE FEMUR 



It will be seen, from the above description, that the femur is well 

 protected. Its anterior and lateral aspects are clothed by the thick 

 quadriceps extensor cruris muscle. Posteriorly we have the entire thick- 

 ness of the powerful hamstring muscles. The parts which may be felt 

 to be superficially placed are the external or third trochanter, the great 

 trochanter, and the distal epiphysis. Fracture of the third trochanter 

 sometimes occurs as a result of a fall on the broadside. In such cases 

 the fracture may be detected by palpation, particularly if the case be 

 seen before there is much swelling of the part. Fracture of the summit 

 of the great trochanter may result from a severe blow or kick received 

 over the part. These fractures are not very serious since they do not 

 affect the animal's ability to stand on the limb. The parts concerned, 

 however, give attachment to the superficial and middle gluteal muscles 

 and with the action of these there is, therefore, interference. Fracture 

 through the neck of the femur is rare in the horse. This is due to the 

 strengthening of the neck outwardly where it passes almost insensibly 

 into the non-articular area between the head and great trochanter. The 

 neck is thus more ill-defined and the head is not drawn out from the 

 shaft of the bone to such degree as it is, for instance, in the human 

 subject, and some of the smaller domesticated animals. 



The most common fractures of the femur pass through the diaphysis, 

 and these may be due to a severe blow received over the part, or the 

 fracture may arise as a complication when the animal is cast for an 

 operation. In the latter case fracture is said to be most likely to occur 

 when the leg is fixed with the stifle in a condition of flexion, the fracture 

 being the result of vigorous efforts on the part of the quadriceps muscles 

 to extend the joint. When the fracture passes through the inferior 

 third of the shaft fatal hemorrhage not infrequently occurs, due to 

 laceration of the femoral artery, which, it will be remembered, is here in 



