326 LUXATION OF THE PATELLA. 
lump upon the outer side of the thigh; it cannot, for three sufficient 
reasons, be drawn to the inner part of the leg. The inner condyle of 
the humerus, over which the patella plays, is sufficiently large to oppose 
any unnatural motion in that direction; the inner ligaments are the 
weakest, and are, therefore, most readily stretched in the outward direc- 
tion; the circumstances permit the bone to be displaced from the inside 
of the leg. Then, moreover, the muscles are altogether more powerful 
upon the outer side. Any force acts more energetically as debility 
increases, and, to favor it, there is less resistance in the direction oppo- 
site to which the force pulls; for these reasons the bone is invariably 
luxated upon the outer side of the animal’s haunch. 
The symptoms denoting luxation of the patella are: the leg thrust out 
behind, and remaining fixed; the horse’s entire frame is affected; the 
head is erect; the muscles quiver; the 
pastern of the protruded leg is violently 
flexed; there is an unnatural swelling 
upon the outer and lower part of the 
buttock. If the animal be forced to 
move, it can only imperfectly hop upon 
three legs; such an accident may occur 
at any time, and never be repeated. It 
may, however, become so common as to be 
mistaken for a species of habit; for lux- 
(Se ation of the patella, when by frequency 
THE PATELLA, OR WHIRL-BONE DISPLACED. confirmed, will take place upon the 
slightest possible cause. 
In stinted colts the most trivial motion will often give rise to this 
accident; the creature can hardly move without its leg being thrust out 
behind it. The cure is, in these cases, anything which may flurry the 
animal. A noise, made by moving the hand quickly and rather ener- 
getically from side to side within a hat, the crack of a whip, or any 
sudden and loud sound, will occasion the bone to return, with apparent 
ease and the utmost rapidity, to its natural situation. The colt, however, 
may the next moment exhibit the misfortune which, in young life, can 
only be cured by kindly treatment and liberal sustenance. 
Probably the author will best describe the nature of the affection in 
old animals, by narrating a case which a few years ago happened to 
himself. 
At the request of a friend he visited one of those auction marts for 
the sale of horses which in London are somewhat notorious. The object 
of his visit being, if possible, to purchase, his attention was directed to 
certain animals. As usual, a glance enabled him to pass by all the 
