(48) HISTORT of the SOCIETr. 



Ac-mmtof tlic cavitv it fomied for itfelf in diflocation, but is made to prefs 



W. Hamilton. ' . ^ , ^ . • j 1^ 



on the furrounding parts, lo that if the force is continued to be 

 exerted in the fame diredlion, a new paffage mufl be torn for it. 

 This, like the laft, may be avoided, by attending to the mofl 

 probable pofition of the limb when the accident happened. We 

 have attempted to prove, that, in general, diflocation is moft apt 

 to happen when the arm is raifed ; and therefore that this pofi- 

 tion is the preferable one for redudion, I fufpedt in many 

 cafes, where improper attempts to reduce the bone have been 

 made, that the difficulty is increafed by the bone tearing a paf- 

 fage for itfelf in a new dire(5lion, and thus, by twifting the muf- 

 cles, preventing redudlion from being accomplillied. 



" The lafl obflacle is from the burfal ligament. As in no 

 cafe of diflocation the head of the bone can pafs out without la- 

 cerating it, fo, in redticlion, it cannot be replaced, unlefs it is 

 brought through the fame opening by which it went out ; for 

 if we attempt to bring the humerus over the glenoid cavity in a 

 wrong diredlion, the ligament will get between it and the fca- 

 pula, and thus, when apparently redxiced, the bone will return 

 to its old fituation, as foon as the ann is let loofe. This can 

 be avoided only by the pofhure of the limb ; and here alfo, in 

 the xaifed flate of the arm, the bone will return Hioft readily 

 tliraugh the opening in the ligament, as being put into the fame 

 pofition in which it w^as luxated. 



" Tkese three great difBculties in reduction, then, are to be 

 remedied by a proper pofitioii of the patient and of his arm ; and 

 this, 1 think, there can be no doubt, is by placing him fo, that 

 the extenfion may be made wh.en his arm is raifed. In order to 

 this, I make hiin fit on the ground, the fcapula, with the glenoid 

 cavity upwards, being kept fixed by two afliftants who are pla- 

 ced behind him. I put a towel round the humerus, immediate- 

 ly above the elbow, both to give me .a firmer hold of the part, 

 iind likewife, tliat, if neceffary, I may have.a place for an afliftant 



or 



