(44) HISTORY of the SOCIETK 



w'Sihon. point out the changes that take place on the joint, when left un- 

 reduced, as being our proper guide in judging what line of prac- 

 tice^ is to be followed in fuch cafes. An unreduced luxation 

 may be defcribed in three fituations : The firfl, when the parts- 

 are little changed from the flate they are in, immediately after 

 diflocation happens. The fecond, where motion is beginning to- 

 take place, and when the foft parts become adapted to the di (lo- 

 cated flate of the bones. And the laft, when a new joint is 

 formed. After the head of the bone is lodged on fome part of 

 the fcapula, it is found to confolidate the cellular membrane 

 and mufcular fibres under it, fo as to form a kind of foft focket 

 for itfelf, which, by the prefTure of the cartilage on the end of 

 the humerus, and by the motion the arm admits of, gets a 

 fmooth fiirface. The burfal ligament torn on that fide next the 

 humerus, is pulled acrofs the glenoid cavity, and the mufcles 

 will be found in the flate I have already defcribed. 



" After the inflammation and fwelling, confequent upcm the 

 injury, have gone off, the patient will be plagued with pains in , 

 the llretched mufcles, and will be incapable of moving the joint^ 

 with eafe. The inflammation will however make the lacerated 

 parts grow together, fo as to obliterate the pafTage through 

 which the head of the bone efcaped from the joint. This may 

 be reckoned a luxation in a recent flate. After fome time the 

 mufcles begin to adapt themfelves to the flate of the bones, thofe 

 that were overftretched are lengthened, and the relaxed ones 

 Gontra<5l, fo that the perfon is capable of moving his arm, and 

 by degrees the motion becomes more confiderable. The burfal 

 ligament now gets adhefions to the edges of the glenoid cavity, 

 over which it lies, and the opening in it, through which tli« 

 bone pafTed, is filled up, fo that it embraces the humerus clofe- 

 ly. The torn pafTage in the foft parts has become as firm as if 

 no laceration had ever take place. The focket, formed in the 

 cellular fubftance, between the head of the hiimerus and the 



fcapula. 



