58 DISEASES OF THE SYNOVIAL MEMBRANES AND ARTICULATIONS. 



its greatest effort to rise the limb (or limbs) is carried outwards and the 

 body comes to the ground on the udder or groin. 



Inspection discovers a depression where the great trochanter should 

 be. On applying the open hand over the hip joint, whilst an assistant 

 who grasps the pastern moves the limb in different directions, one can 

 feel and hear, in spite of the mass of muscle covering the part, a modified 

 crepitation due to sero-sanguinolent effusion in and around the joint. 

 This crepitation can also be detected by pushing the hand as high up as 

 possible on the internal surface of the thigh, and thus exploring the 

 neighbourhood of the luxation. 



Diagnosis. The j)Osition which the animal assumes when one 

 endeavours to make it rise is characteristic. Diagnosis of progressive 

 luxation, however, is more difficult. 



Prognosis. The prognosis is extremely grave ; for, even though 

 reduction can be effected, one is practically unable to ensure that the 

 parts shall remain in position. 



Treatment. Treatment comprises reduction of the luxation and 

 fixation of the parts. Reduction can be effected without very much 

 difficulty by casting the animal on the affected side, placing a block 

 of w^ood, or a pail, between the thighs, and manoeuvring the limb 

 in the desired direction. As, however, subluxation is the condition 

 most commonly seen, there is frequently no reduction to effect. More- 

 over, fixation of the joint after reduction is almost impossible in such 

 heavy subjects, and luxation is very liable to recur. From an economic 

 standpoint, slaughter is advisable or imperative. 



LUXATION OF THE PATELLA. 



Luxation of the patella is not uncommon in working oxen, and is 

 occasionally seen in cows as the result of a slip when entering or leaving 

 the byre, the reason being the peculiar anatomical arrangement of the 

 femoro-patellar articulation. 



The internal lip of the trochlea of the femur is very high, the external, 

 on the other hand, being only slightly developed. The patella itself is 

 smaller than that of the horse, and possesses a small cartilaginous 

 prolongation, principally on its inner face, in marked contrast with the 

 large cartilage found in the horse. As in the latter animal, the out- 

 ward displacement of the patella is only prevented by the internal patellar 

 ligament and the femoro-j)atellar aponeurosis. Under the influence of 

 varying causes to which the joint is exposed, these supporting structures 

 often prove insufficient to prevent the patella being displaced outwardly. 



Causation. From an anatomical standpoint, luxation inwards seems 

 impossible. It certainly must be very rare and be preceded by rupture 

 of the external ligament. On the other hand, as in the horse, it seems 



