General Diseases of Bones ^ Joints and Muscles. 399 



INTXAMMATION. AETHEITIS. SYNOVITIS. 



Here agaiu the most common lesion is inflammation 

 from which most of the others follow as consequences. 

 This may begin in the bones as a restilt of concussion, 

 blows, etc., and extend through the cartilage and ligaments 

 to the sjraovial membrane ; or it may origiaate in tha 

 ligaments as a consequence of sprains or other injuries 

 or in the synovial membrane from wounds opening the 

 joint and exposing it to the air; or it may be a local 

 manifestation of some constitutional disease such as rheu- 

 matism, tubercle, glanders, farcy, etc., or finally it may be 

 due to plugging of the blood-vessels in consequence of 

 pus, ichor or fibrinous clots washed on through the vessels 

 from some distant seat of disease. In all cases the whole 

 of the joint structures tend to be involved and the symp- 

 toms are similar. 



The succession of changes may be as follows : the 

 inflamed synovial membrane throws out a serous fluid 

 filling the joiat to excess; the ligaments and adjacent 

 connective tissue also throw out a semi-liquid exudation 

 which forms a yielding swelling around the joint, suscep- 

 tible of indentation with the fingers ; the cartilage covering 

 the ends of the bones softens and is changed iato a fibrous 

 material or is even absorbed, leaving the bone bare ; the 

 bone exposed in this way may ulcerate, if that has not 

 previously commenced, or it may be partially repaired by 

 the deposit of a dense ivory-like layer (eburnation), the 

 smooth glistening surface of which ghdes smoothly on 

 that of the opposite bone; lymph may be exuded from 

 the exposed surface of the bone and from the interior of 

 the synovial membrane, and this, as well as what is out- 

 side the joint, may be developed into fibrous tissue re- 

 stricting the movements of the joint, or more frequently 

 into bone which binds the bony structures together and 

 abolishes aU movement (stiff-joint, anchylosis); in very 

 severe cases the lymph inside and outside the joint de- 

 generates into pus, and this makes its way through the 



