338 



motion over the limb — no muscular contraction can avail to cause it to 

 j)erform its various functions — but in the hands of the surgeon it may 

 be made to describe a series of movements which would be simply- 

 impossible with the joint in a state of integrity. Both fractures and 

 luxations are marked by deformity, but while in a fracture with dis- 

 placement there will usually be a shortening of the leg, a dislocation 

 maj^ be accompanied by either a shortening or a lengthening. Swell- 

 ing of the parts is usuallj^ a well-defined feature of these injuries. 



With all this similaritj' in the sj^mptomatology of luxations and 

 fractures, there is one sign which either by its j)resence or its absence 

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

 is the existence or lack of crepiiation. It has no place or cause in a 

 mere dislocation; it belongs to a fracture, if it is a complete one. If 

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

 fracture also. 



The jDrognosis of a luxation is comparatively less serious than that 

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

 to be so difficult to appl}- that complications may arise of a very severe 

 character. 



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

 tures. Reduction, naturallj", will be the first indication in both cases, 

 and the retention of the replaced parts must follow. The reduction 

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

 in the same manner, with the patient 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 

 surface in exact contact with its companion surface, the apparatus 

 necessary afterwards to keep them in situ being similar to that which 

 is emx)loyed 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 manipulations 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 con- 

 traction, operating in just the right directions, imlls the oi)posite 

 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 accompanied by a peculiar snapping sound, audible and significant, 

 as well as a visible return of the surface to its normal symmetry. 



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

 liable to tliis form of injury, there are three in the large animals which 

 may claim a special consideration, viz: 



Tlie shoulder joint. — We mention this displacement williout intend- 

 ing to imply the practicability of any ordinary attempt at treatment. 



