lameness: tts causes and treatment. 363 



THE SHOULDER JOINT. 



AVe mention this displacement witlinut intending:: to imply the 

 piiu-ticability of any onlinaiy attempt at treatment, whieh is usually 

 unsuccessful, the animal whose mishap it has been to become a victim 

 to it being disabled for life. The superior head of the arm bone as 

 it is received into the lt)\ver cavity of the shouhler blade is so situ- 

 ated as to be liable to be forced out of place in four directions. It 

 may escape from its socket, according to the manner in which the 

 \ iolence atl'ects it — outward, inward, backward, or forward — and the 

 deformity which results and the effects which follow will correspond- 

 ingly differ. "We have said that treatment is generally unsuccessful. 

 It may be added that the diHiculties which interpose in the way of 

 reduction are nearly insurmountable, and that the application of 

 means for the retention of the parts after reduction would be next to 

 impossible. The prognosis, from any point of ^■iew, is sufficiently 

 grave for the luckless animal with a dislocated shoulder. 



THE HIP JOINT. 



This joint partakes very much of the characteristics of the humero- 

 scapular articulation, but is more strongly built. The head of the 

 thigh bone is more separated, or prominent and rounder in form, and 

 the cup-like cavity, or socket, into which it fits is much deeper, form- 

 ing together a deep, true ball-and-socket joint, which is, moreover, 

 reenforced by two strong cords of funicular ligaments, which unite 

 them. It will be easily comprehended, from this hint of the anatomy 

 of the region, that a lu.xation of the hip joint must be an accident of 

 compaiatively rare occurrence: yet cases are recorded in which the 

 head of the bone has been affirmed to slip out of its cavity and assume 

 various positions — inward, outward, forward, or backward. 



The indications of treatment are tho.se of all cases of dislocation. 



When the reducticm is accompli.shcd the surgeon will be appri.sed 



of the fact by the peculiar, snapping sound usually heard on such 



occasions. 



pseudo-luxatio.ns of the patella. 



This is not a true dislocation. The stifle l)one is so peculiarh' 

 articulated with the thigh bone that the means of union are of suffi- 

 cient .strength to resist the causes which u.sually give rise to luxation.s, 

 yet there is sometimes discovered a peculiar, pathological .state in the 

 hind legs of animals, the effect of which is clo.sely to simulate the 

 manifestation of many of the general .symptoms of dislocations. 

 This condition (uiginates in muscular crami)s, the action of which 

 is seen in a certain change in the coaptation of the articular sur- 

 faces of the stifle and thigh bone, resulting in the exhii)ition of a 



