DISLOCATIONS. 265 



boBe 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 originates in muscular cramjDs, the action 

 of which is seen in a certain change in the coaptation of the artic- 

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

 tion of a sudden and alarming series of symjitoms which have 

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

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

 haps with one of his hind 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 hock and no motion 

 at the stifle, while the cii'cular 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 str.iight 

 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 perhaps 

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

 less on the outside and upper part of the joint. 



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

 untn treatment is applied, or it may spontaneously and suddenly 

 terminate, leaving everything in its normal condition, but perhaps 

 to return again. 



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

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

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

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

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

 perhaps shpping when endeavoring to rise ; sometimes to weakness 

 in convalescing 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 si^asmodic 



