404 GENERAL ANATOMY. 



smallest extent, and those which take place between the longest 

 bones, are those which are most frequently luxated. Thus, 

 the shoulder-joint furnishes of itself more examples of luxa- 

 tions than all the others together. 



638. Anchylosis,* or the uniting of the diarthrodial articu- 

 lations, consists, when it is complete, of an intimate union, a 

 real continuity between bones which were previously in con- 

 tact. The spongy substance communicates from the one bone 

 to the other. The compact plates, the diarthrodial cartilages, 

 the synovial membrane and the synovia, which separated the 

 spongy part of the two bones, have disappeared. Immobility 

 continued for a great length of time, but especially a certain 

 degree of inflammation, whether originally in the synovial 

 membrane, or at first in the ligaments and the other surround- 

 ing parts, induce these changes. Sometimes they commence 

 by an agglutination of the synovial membrane, and the forma- 

 tion between its surfaces of cellular tissue or fibrous bridles 

 which may become ossified at a later period. Sometimes the 

 articulation being laid open by a wound or the effect of an 

 abscess, it is by suppurative granulations that the agglutination 

 is established. In both cases, the diarthrodial cartilages are 

 gradually absorbed before the osseous union takes place. All 

 the diarthroses are susceptible of anchylosis, but the ginglymi 

 more than the others. 



Anchylosis sometimes affects several articulations. All the 

 diarthroses and amphiarthroses have even been seen to be suc- 

 cessively affected by it, and the skeleton has thus become a 

 single inflexible mass. M. Percy has deposited in the Mu- 

 seum of the Faculty of Paris a skeleton which presents this 

 general anchylosis of all the articulations. 



639. At other times, the causes of alteration of which we 

 speak determine the superficial necrosis or wearing out of the 

 articular surfaces. It is in cases of this kind that excision of 

 the articular extremities of the bones has been practised.! At 



J. Th. Van de Wympersse. De Ancyksi, &e. Lugd. Bat. 1783. Idem. 

 De Jlncybseos PathoL et Curat. Lug-d. Bat. 1783. J. Cloquet, in Diction- 

 naire de Mcdecine, vol. ii. 



f H. Park. Account of a New Met/tod of Treating Diseases of the Knee 



