CHAPTER XL 



DISEASES OF THE JOINTS. 



CLASSIFICATION OF THE JOINTS — ANCHYLOSIS OF THE VERTEBRJ: 



ACUTE SYNOVITIS CHRONIC SCROFULOUS SYNOVITIS — CALCIFICA- 

 TION OF THE SYNOVIAL FRINGES — RHEUMATOID ARTHRITIS — • 

 MORBID CONDITION OF CARTILAGE — TRAUMATIC INFLAMMATION 

 OF THE JOINTS — HYDROPS-ARTICULORUM — ANCHYLOSIS. 



Joints are complex in their structure, consisting of bones, arti- 

 cular cartilage which covers their extremities, synovial mem- 

 brane, capsular and binding ligaments, fat, blood-vessels, and 

 nerves. Owing to these various component parts possessing 

 different degrees of organization and vitality, it will be easily 

 understood that the diseases of the joints are both numerous and 

 important, more especially when the extensive motion they are 

 called upon to perform is taken into consideration. 



The joints are divided into three classes, namely, the immove- 

 able, the moveable, and the mixed. The immoveable joints, or 

 sutures, are those connecting flat bones together, as in the bones 

 of the head, and are subject to no special diseases ; it is there- 

 fore with only the two latter classes that we have to deal. 



In the mixed joints the ends of the bones are not covered bj 

 cartilage of incrustation, nor is there a true articular cavity 

 lubricated by synovia ; the bones, joined together by powerful 

 binding ligaments, are yet separated from each other by a thick 

 broad pad or disc of fibro-cartilage. This simple kind of articu- 

 lation is subject to but one form of disease, namely, chronic 

 inflammation, causing the gradual conversion of the fibro-carti- 

 laginous pad into bony tissue. In this manner the vertebral 

 column, which is extremely elastic and mobile in its entirety, is 

 converted, more especially in the lumbar and dorsal regions, 

 into a stiff; unyielding structure, rendering the movements of 



