LUXATIONS. 



143 



position with a clucking noise at every step the animal takes ; 

 very commonly both patellae are in the same condition. When 

 the luxation is complete, 

 the internal lateral liga- 

 ment must be ruptured 

 throuGjh its whole thick- 

 ness, and the patella 

 shps outwards. The limb 

 now becomes stretched 

 backwards ; there is total 

 inability on the part of 

 the animal to flex it, 

 owing to the action of 

 the vasti, rectus femoris, 

 crureus, &c., being inter- 

 fered with. 



Treatjnent. — Forcible 

 extension and keepinoj ^ ,« ^ n r ^-u r ^ •,^4-t.<. 



^ ^ Fig. 17. — Trochlea of the femur, showing the 



the limb m a forward effects of friction from luxation of patella, a, Ex- 

 position by means of a ternal, and 6, internal trochlea, d and c, Condyles 

 ■'■ "^ of the femur, 



strong cord round the 



foot. The leg must be kept in this position by the cord being 

 fastened round the neck of^ the animal for some hours ; a shoe 

 higher at the toe than at the heels should be put on, with a 

 projecting piece of iron at the toe, and a smart blister applied 

 to the stifle. Professor Dick used to say that this would per- 

 form a cure, even after the ligament had entirely given way, 

 provided the animal were kept at rest. 



If the dislocation has been existent for any time, the articular 

 cartilage on the surfaces of the trochlea and patella becomes 

 worn by attrition ; the articular laminal layer of bone is then 

 rubbed off, the cancellated tissue exposed, and there is a deposi- 

 tion of porcellaneous material (porcellaneous deposit) in the 

 opened-up Haversian canals, giving the articulating surfaces a 

 shining or glistening appearance. A restoration of the animal to 

 usefulness will be now a matter beyond possibility ; indeed it is 

 hardly conceivable that a complete dislocation with rupture of 

 the ligament can at any time be curable. 



