327 



will greatly assist in settling a case of differential diagnosis, and this is 

 the existence or lack of crepitation. It has no place or cause in a mere 

 dislocation; it belongs to a fracture, if it is a cou!i)lete one. If there is 

 crepitation with a dislocation then it proves that there is a fracture 

 also. 



The prognosis of a luxation is comparatively less serious than that of 

 a fracture, though at times the indications of treatment may prove to 

 be so difiBcult to apply that complications may arise of a very severe 

 character. 



The treatment of luxations must of course be similar to that of frac- 

 tures. Eeduction, naturally, will be the first indication in both cases, 

 and the retention of the replaced iiarts must follow. The reduction in- 

 volves the same steps of extension and counter-extension, performed 

 in the same manner, with the j)atient subdued by anesthetics. 



The difference between the reduction of a dislocation and that of a 

 fracture consists in the fact that in the former the object is simply to 

 restore the bones to their true normal position, with each articular sur- 

 face in exact contact with its companion surface, the apparatus neces- 

 sary afterwards to keep them in situ being similar to that which is em- 

 ployed in fracture cases, and which will usually require to be retained 

 for a period of from forty to fifty days, if not longer, before the ruptured 

 retaining ligaments are sufficiently firm to be trusted to perform their 

 office unassisted. A variety of manii^ulations are to be employed by 

 the surgeon, consisting in pushing, pulling, pressing, rotating, and 

 indeed whatever movement may be necessary, until the bones are forced 

 into such relative positions that the muscular contraction, operating 

 in just the right directions, pulls the opposite matched ends together 

 in true coaptation, a head into a cavity, an articular eminence into a 

 trochlea, as the case may be. The "■ setting" is accorajjanied by a pe- 

 culiar snapping soiind, audible and significant, as well as a visible re- 

 turn of the surface to its normal symmetry. 



Special dislocations. — While all the articulations of the body are liable 

 to this form of injury, there are three in the large animals which may 

 claim a special consideration, viz: 



The slioulder joint. — We mention this displacement without intending 

 to imply the practicability of any ordinary attempt at treatment, which 

 is usually unsuccessful, the animal whose mishap it has been to become 

 a victim to it being disabled for life. The superior head of the arm 

 bone as it is received into the lower cavity of the shoulder blade is so 

 situated as to be liable to be forced out of place in four directions. It 

 may escape from its socket, according to the manner in which the vio- 

 lence affects it, outwards, inwards, backwards, or forwards, and the 

 deformity which results and the effects which follow will correspond- 

 ingly differ. We have said that treatment is generally unsuccessful. 

 It may be added that the difficulties which interpose in the way of re- 

 duction are nearly insurmountable, and that the application of means 



