300 . DISEASES OF THE HOESE. 



will vary according to the kind of fracture and the bone which is 

 injured. For example, a fracture of the cannon bone without dis- 

 placement, or of one of the phalanges, which are surrounded and sus- 

 tained by a complex fibrous structure, is, in a certain degree, not 

 incompatible with some amount of resting on the foot. But, on the 

 contrary, if the shank bone, or that of the forearm be the implicated 

 member, it would be very difficult for the leg to exercise any agency 

 whatever in the support of the body. And in a fracture of the lower 

 jaw it would be obviously unreasonable to expect it to contribute 

 materially to the mastication of food. 



A fracture seldom occurs which is not accompanied with a degree 

 of deformity, greater or less, of the region or the leg affected. This 

 is due to the exudation of the blood into the meshes of the surround- 

 ing tissues and to the displacement which occurs between the frag- 

 ments of the bones, with subsequently the swelling which follows the 

 inflammation of the surrounding tissues. The character of the 

 deformity will mainly depend upon the manner in which the dis- 

 placement occurs. 



In a normal state of things the legs perform their movements with 

 the joints as their -only centers or bases of action, with no participa- 

 tion of intermediate points, while with a fracture the flexibility and 

 motion which will be observed at unnatural points are among the most 

 strongly characteristic signs of the lesion. No one need be told that 

 when the shaft of a limb is seen to bend midway between the joints, 

 with the lower portion swinging freely, that the leg is broken. But 

 there are still some conditions where the excessive mobility is not 

 easy to detect with certainty. Such are the cases where the fracture 

 exists in a short bone, near a movable joint, or in a bone of a region 

 where several short and small bones are united in a group, or even in 

 a long bone where its situation is such that the muscular covering 

 prevents the visible manifestation of the symptom. 



If the situation of a fracture precludes its discovery by means of 

 this abnormal flexibility, other modes of detection remain. There is 

 one method which is absolute and positive and which can be applied 

 in by far the most, though not in all cases. This is crepitation, or the 

 peculiar effect which is produced by the friction of the fractured sur- 

 faces one against another. Though discerned by the organs of hear- 

 ing it can scarcely be called a sound, for the grating of the parts as 

 the rubbing takes place is more felt than heard ; however, there is no 

 mistaking its import in cases favorable for the application of the test. 

 The conditions in which it is not available are those of incomplete 

 fracture, in which the mobility of the part is lacking, and those in 

 which the whole array of phenomena are usually obscure. To obtain 

 the benefit of this pathognomonic sign requires deliberate, careful, 

 and gentle manipulation. Sometimesthe slightest of movements will 



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