LUXATION OF THE FEMUR. 931 



extended, and the phalanges fixed in a position of marked plantar flexion. 

 It is uncertain, however, whether these symptoms were exclusively dependent 

 on rupture of the ligamentum teres. Wyman and Lusk saw complete 

 luxation of the femur in a mule. 



Amongst the causes are violent movement of the limb on the 

 hip-joint, excessive flexion or extension in falling, and sometimes 

 excessive lateral movement (ab- and ad- duction). The head of the 

 bone, in quitting the acetabular cavity, does not always move in 

 the same direction, but may take a variety of positions, giving rise 

 not only to peculiarities in the symptoms, but influencing prognosis 

 and treatment. 



Symptoms. The displaced limb is sometimes lengthened, 

 sometimes shortened, sometimes fixed in a position of adduction, 

 sometimes in one of abduction. Its mobility in certain directions 

 may be limited, whilst in certain others it may be abnormally increased. 

 This resistance to manipulation distinguishes luxation from fracture, 

 a distinction which is strengthened by the absence of crepitation. 

 In any case, freedom of movement is lost. Luxation is always 

 accompanied by marked lameness when the limb is carried (swinging 

 leg lameness), though there is also more or less inability to sustain 

 weight. 



After a time the hip-joint appears swollen, though occasionally 

 swelling is replaced by a depression, whilst the upper trochanter 

 appears displaced, being sometimes more prominent, sometimes 

 sunk in the masses of muscle. The skin over and around the hip- 

 joint is either very tense or abnormally loose. When the bone is 

 displaced into the obturator foramen, its head may be felt from the 

 rectum or sheath, and is especially distinct when the limb is moved. 



Prognosis is always doubtful, and in large animals generally 

 unfavourable. Only during the first three days is reduction usually 

 possible, and then is effected with the greatest difficulty. If attempted 

 early, it sometimes succeeds in small animals. After rupture of 

 the ligamentum teres in large animals, relapses are very common ; 

 recovery is then exceptional, and the animal's usefulness is seldom 

 restored. In old-standing cases, muscular contraction furnishes 

 a further impediment to reduction. 



Cunningham succeeded in replacing the bone in three cows ; recovery 

 followed. In the case of two horses, however, he was unsuccessful. Teetz 

 reduced a luxation of the femur in a goat, although treatment only com- 

 menced three weeks after the injury. 



Treatment. Large animals are cast on the sound side and 

 anaesthetised ; and, as the operator's strength is not sufficient to 



