DISEASES OP BONES 167 



geon restores tlie displaced fragments to their normal position 

 or as close to it as possible 



3. By retaining the fragments in position. 



How is a fracture reduced ? 



1. By extension ; that is, the surgeon exerts steady trac- 

 tion upon the lower fragment. 



3. By counter-extension. This means the fixing of the 

 upper fragment. 



3. By cog,ptation, by "which is understood the adjustment 

 of the fragments to their proper position. 



Why are these steps necessary ? 



Absolute rest to the broken bone and proper adjustment 

 of the fragments are essential to the normal development of 

 a callus. 



Can you reduce the fractures in all animals this way ? 



In the dog and other small animals, as a rule. The 

 larger animals offer great difficulties. In such fractures as 

 those of the pelvis and ribs, the reduction of a fracture by 

 extension and counter-extension, etc., is out of the question; 

 also when fragments of bone get between the ends when 

 muscles are pinched in, when the broken bones can't be 

 grasped or fixed. 



Why do you employ extension and counter-extension in 

 reducing a fracture ? 



It is done to overcome the contraction of muscles and the 

 elasticity of fascise, tendon, etc. 



How do you proceed for this pv/rpose f 



The smaller animals may be given a dose of morphine 

 and are then laid upon a table, where, with the help of one 

 or two assistants, the upper fragment is firmly held, while 



