LATERAL LUXATION OF THE PATELLA. 
691 
Meyer grasps the patella with the whole hand and lifts it up whilst 
the animal is led forward. 
Reduction is assisted by passing a cord round the fetlock, lifting the 
toe from the ground, and drawing it forward, thus extending the stifle- 
joint. The animal is then thrust backward, and at the same moment the 
patella pushed back. Where the animal is lying, the limb can be drawn 
forward and fastened as for castration, replacement being attempted 
in this position. 
After successful replacement, it is important to rest the animal for 
three to five weeks. The application of blisters, setons, &c., is only 
useful in keeping the limb at rest. If the patella again slips out when 
the animal lies down or rises, slinging may be resorted to. Another 
useful device is the application of a patten shoe (see Dollar’s “ Horse¬ 
shoeing,” pp. 411 to 413), by which the limb is raised from the ground, 
and the stifle-joint is kept flexed so that the necessary conditions for the 
occurrence of luxation cannot well occur. 
Violet and others recommended dividing the inner straight ligament, 
and state having cured cases of momentary luxation which had been 
in existence for years. The operation is, however, by no means easy, 
because the inner straight ligament is in somewhat dangerous proximity 
to the capsule of the joint. From theoretical considerations it certainly 
seems feasible, inasmuch as it frees the inner surface of the patella, 
which is the part said to become fixed on the femur. Cavallan per¬ 
formed the operation with immediate and lasting success on both 
hind limbs of a cow, but further experience is required before a final 
judgment can be delivered. 
(b) - Lateral Luxation of the Patella.” 
In horses, oxen, and still more frequently in dogs, the patella is 
displaced laterally, and almost always towards the outer side. In dogs 
the disease is generally congenital and affects both limbs, being caused 
by arrest in the development of the condyles of the femur. Acquired 
luxations outwards are dependent on excessive strain or rupture of the 
inner lateral ligament. As the internal condyle of the femur is much 
the larger and projects further inward, luxation is very rare indeed in 
animals, though Stockfleth saw one case in a cow. Sometimes the 
patella still lies to some extent over the external condyle (incomplete 
luxation), though it is generally thrust on to its outer surface (complete 
luxation). Though in the horse the patella is certainly secured in 
position by a cartilaginous prolongation which curves over the inner lip 
of the trochlea, its displacement outwards is by no means impossible. 
Meyer saw luxation of this kind in two cows. 
Causes. The predisposing causes of lateral luxation are uprightness of 
the limb, obliquity of the quarters, and youth of the animal. The 
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