LAMENESS, FROM VARIOUS CAUSES. 343 



811FLE Out (Dislocation or Luxation op tftv Stifla 



Bone). 



The patella of the horse, or stifle bone, as it is familiarly known, 

 corresponds to the knee-pan of man, and answers the same pur- 

 DCje ; that is, to facilitate motion, and protect the two extrcmitiea 

 c>f the bones which compose the stifle-joint. It is retained in situ 

 at the anterior part of the inferior extremity of the thigh bone and 

 superior extremity of the tibia. 



A I. accident of this character is generally accompanied with con 

 r.iderable pain and uneasiness ; but the most notable symptom is, 

 the bone is thrown ofi* its pulley-like articulatory surface,*and thus 

 tlie recti and vasti muscles (the latter being direct extensors of the 

 leg or thigh, and the action of the former being similar) are, for 

 the time being, paralyzed ; that is to say, their action is suspended. 

 If they act at all, it is under great disadvantage, and at the expense 

 of their muscular integrity. The liability to luxation of the stifle 

 bone (patella) is not so great as some persons would have us be- 

 lieve. The bone is secured in its position by a number of strong 

 ligaments — has a complete articulatory joint of its own, whose 

 capsular ligaments have strong attachments to surround them. The 

 muscles, tensor vaginse, rectus, vasti faschia, panniculus carnosus, 

 subcellular substance and integument, all operate favorably against 

 the chances of luxation. The accident, however, does sometimes 

 occur — not, perhaps, from any disarrangement of the mechanical 

 order of the parts by violence, such as might be operative in dis- 

 location of the thigh or arm bones, but often from spasm, cramp, 

 etc., of certain muscles in the immediate vicinity of the parts. 



" I think his stifle is out," is a very common complaint made 

 by horse-owners when a horse becomes lame, and the " neighbors" 

 can not discover the exact location of the same. They hastily 

 conclude, if the lameness is in the hind extremity, that the " stifle 

 is out " (luxated). Here is a case in point. I received a message 

 some time ago, to visit a horse said to have " his stifle out." On 

 making examination of the foot on the lame side, I found it much 

 hotter tlian its fellow on the opposite side. The owner, at the 

 moment, remarked that there was " no trouble in the foot." He, 

 however, was nietaken; for I found that a nail had entered the 

 josterior part of the cleA of tie frog, which I extracted, and this 

 was the sole cause of lameness. I av.ght relate a number of mis* 



