DISLOCATIONS. 265 



bone that the means of union are of sufficient strength to resist 

 the causes which usually give rise to luxations. Yet there is some- 

 times discovered a peculiar pathological state in the hind legs of 

 animals, the effect of which is closely to simulate the manifestation 

 of many of the general symptoms of dislocations. The peculiar 

 pathological condition origiaates in muscular cramps, the action 

 of which is seen ia a certaia change in the coaptation of the artic- 

 ular surfaces of the stifle and thigh bone, resulting ia the exhibi- 

 tion of a sudden and alarming series of symptoms which have 

 suggested the phrase of "stifle out" as a descriptive term. The 

 animal so affected stands quietly and firmly ia his stall, or per- 

 haps with one of his hiad legs extended backward, and resists 

 every attempt to move him backward, and if urged to move for- 

 ward he will either refuse, or comply with a jump, with the toe 

 of the disabled leg dragging on the ground and brought forward 

 by a second effort. There is no flexion at the hook and no motion 

 at the stifle, while the circular motion of the hip is quite free. The 

 leg appears to be much longer than the other, owing to the straight- 

 ened position of the thigh bone, which forms almost a straight 

 line with the tibia from the hip joint down. The stifle joint is 

 motionless, and the motions of all the joints below it are more or 

 less interfered with. External examination of the muscles of the 

 hip and thigh discovers a certain amount of rigidity, with perhajjs 

 some soreness, and the stifle bone may be seen projectiag more or 

 less on the outside and upper part of the joint. 



This state of things may continue for some length of time and 

 until treatment is applied, or it may spontaneously and suddenly 

 terminate, leaving everything ia its normal condition, but perhaps 

 to return again. 



Pseudo-dislocation of the patella is likely to occur under many 

 of the conditions which cause actual dislocation, and yet it may 

 often occur in animals which have not been exposed to the or- 

 dinary causes, but which have remained at rest in their stables. 

 Sometimes these cases are referred to falls ia a slippery stall, or 

 perhaps slipping when endeavoring to rise ; sometimes to weakness 

 ia convalesciag patients ; sometimes to lack of tonicity of structure 

 and general debility; sometimes to relaxation of tissues from 

 want of exercise or use 



The reduction of these displacements of the patella is not 

 usually attended with difficulty. A sudden jerk or spasmodic 



