DISLOCATION OF BONES. 487 



important branch of practice, but is less so in the horse : 

 not that these separations do not sometimes occur, but the 

 immensity of the muscular resistance is such, and our sur- 

 gical machinery at present is so little calculated to make 

 any resistance to the power thus exerted, that few reduc- 

 tions have been attempted. 



Dislocated Patella. — This accident is of rather common 

 occurrence. The bone, however, is always dislocated out- 

 wards ; the form of the lower end of the femur, the strength 

 of the ligaments, and the power of the muscles on the out- 

 ward side, all prevent the bone from being dislocated in- 

 wards. It sometimes happens from weakness, when mere 

 motion will be sufficient to reduce it. Nevertheless, in 

 other instances, surgical aid is needed. In such cases proceed 

 as follows : — in the first place, have the leg drawn forward, 

 if necessary, by means of a rope passed over a beam or 

 rafter, and around the fetlock ; then push violently against 

 the dislocated bone, the position of which will be accurately 

 told by the swelling it produces. It will generally fly back 

 with some noise ; and having got it in its proper situation, 

 partially release the drawn-up leg, and have an assistant 

 to hold the bone justly, by pushing against it for several 

 hours ; afterwards blister the part, to render the animal 

 averse to using it. 



The Signs of a Dislocated Patella are the rigid deter- 

 mination of the limb backwards ; exactly as might be ex- 

 pected from the loss of the moving pulley into which the 

 extensor muscles of the thigh are implanted. The flexor 

 muscles, moreover, having no antagonists, the limb is 

 drawn downwards, and remains firmly flexed, the toe drag- 

 ging on the ground. The displacement of the patella itself 

 is less a guide than might be imagined ; but the complete 

 determination of the limb backwards, and the flexion of the 

 pasterns and foot, will serve to distinguish it ; it can at 

 once be detected by grasping the condyles of the femur. 

 An examination of both limbs will make clear the loss of 

 the protuberant patella in its natural situation, and enable 

 us to see the bone towards the outer edge of the thigh ; but 

 sometimes so deeply imbedded within the muscles of the 

 part, particularly in coarse fleshy horses, as to almost 

 escape cursory observation. This occurs from the powerful 



