FRACTURES OF THE BONES OF THE KNEE. 803 



conjunction with wounds and injuries of the joint, i.e., they are 

 compound, and the fragments seldom unite ; but when this does 

 occur movement of the joint is more or less limited, or altogether 

 prevented by anchylosis. 



On account of its isolated position the pisiform bone is an exception 

 to the above rule, and Moller has repeatedly seen fracture of it in 

 race-horses. A case occurred in a draught-horse during heavy work, 

 the immediate cause being excessive contraction of the flexors of 

 the knee. One or another of the ligaments of the pisiform bone 

 may also be ruptured. 



The symptoms are, inability to bear weight on the limb which 

 is flexed, as in complete radial paralysis, and local pain. Abnormal 

 mobility of the pisiform bone and crepitation under pressure reveal 

 the character of the fracture beyond doubt. On the other hand, 

 fractures of the other carpal bones produce very ill-defined symptoms : 

 though in most cases the sudden appearance of severe lameness 

 (" supporting leg lameness ") and local pain about the knee-joint 

 sufficiently indicates the seat if not the exact nature of the lesion. 



Course. Union of fractures of the pisiform bone is difficult. The 

 fragments of bone are drawn upwards by the pull of the attached 

 muscles, and, as in fractures of the ulna, the conditions are 

 unfavourable to callus formation. A fibrous callus forms, generally 

 of insufficient strength, and if the animal be put to work too soon 

 there is danger of relapse. In other cases the knee shows marked 

 dorsal flexion. Even favourable cases last for two to three months ; 

 but many horses have to be destroyed in consequence of laminitis 

 in the other foot and of the resulting acute pain, fever, &c. Com- 

 pound fractures of the knee bones often end in suppurative arthritis 

 and death. Should recovery occur, there is usually extensive 

 callus formation and loss of function in the joint, so that the animals 

 are of little use except for stud purposes. 



Treatment. The animal should be placed in slings and reposition 

 attempted, though it is seldom successful. In quiet animals a 

 dressing may be applied, but it is useless in fidgety patients, which 

 can only be given a roomy stall or box, with plenty of bedding, and 

 allowed to lie down, thus preventing laminitis of the other foot. 

 Complete rest is always the first indication in treating fractures 

 of the carpal bones. Compound fractures call for the strictest 

 antiseptic precautions ; though frequently the animal has to be 

 slaughtered owing to anchylosis. 



