214 OPERATIONS ON BONES. 



me7it, when the facts justify this description. Again, a fracture 

 may be intror-articular or extra^artlcular, as it extends within a 

 joint or otherwise, and once more, intra-periosteal, when the j)eri- 

 osteum remains intact. And, finally, there is no absolute Hmit to 

 the use of descriptive terminology in the case. 



The condition of displacement is largely influential in deter- 

 mining the question of treatment, and as affecting the final result 

 of a case of fracture. This, however, is dependent npon its loca- 

 tion or whether its seat be in one or more of the axes of the bone, 

 in its length, its breadth, its thicknsss, or its circumference. An 

 incomplete fracture may also be either simple or comminuted, the 

 periosteum, in the latter case when it is intact, keeping the frag- 

 ments together, the fracture in that case belonging to the intra- 

 periosteal class. At times there is only a simj^le fissure or spht 

 in the bone, making a condition of much difficulty of diagnosis. 



Two varieties of originating cause may be recognized in cases 

 of fracture. They are the predisposing and the occasional. As 

 to the first, different species of animals differ in the degree of their 

 liability. That of the dog is greater than that of the horse, and, in 

 horses, the various questions of age, the mode of labor, the season 

 of the year, the portion of the body most exposed, and the existence 

 of ailments, local and general, are all to be taken into account. 



Among horses, those employed in heavy draught work or that 

 are driven over bad roads, are more exposed than light-draught 

 or saddle horses, and animals of different ages are not equally 

 liable. Dogs and young horses, with those which have become 

 sufficiently aged for their bones to have acquired an enhanced 

 degree of frangibility, are more Hable than those which have not 

 exceeded the time of their adult prime. The season of the year 

 is undoubtedly, though in an incidental way, an imj^ortant factor 

 in the problem of the etiology of these accidents, for though they 

 may be observed at all times, it is during the months when the 

 shppery condition of the icy roads renders it difficult for both 

 men and beasts to keep their feet, that they occur most frequently. 

 The long bones, those especially which belong to the extremities, 

 are most frequently the seat of fractures, from the circumstance of 

 their superficial position ; their exposure to contact and collision, 

 and the violent muscvdar efforts involved both in their constant 

 rapid movement and their labor in the shafts or at the pole of 

 heavy and heavily laden carriages. 



