VOL. LI.] PHILOSOPHICAL TRANSACTIONS. 4gQ 



head of the bone, pressing it downward. As soon as the extension began Mi;. 

 Y. perceived plainly the bone sink under his hand, which he had hardly time to 

 say before it gave a snap, which was felt by the patient, and heard by them all, 

 and the bone was reduced. 



In about 6 or 7 days he was easy, and able to walk over the room with crutches, 

 and bear a considerable weight of his body on the right leg: and from this time 

 he recovered strength very fast, and had long been as strong in that leg and thigh 

 as in the other, without any even the least difference in length, or any other 

 respect. 



Mr. Y. was induced to send to Dr. Huxham the above case of John Down, 

 because it is asserted by some surgeons, and among those of the greatest cha- 

 racter too, that a luxation of the head of the femur is little less than impossible; 

 and that what is generally taken for a luxation of this joint, is a fracture of the 

 bone at its neck. 



A fracture of the neck of the bone probably happens more often than a dislo- 

 cation. But the above case has proved that it may happen, and that without 

 any extraordinary violence, provided the force is aptly applied. Indeed any force 

 applied in the direction of the thigh downward can hardly have any tendency to 

 dislocate it at all : and any force from below upward will be sustained by the head 

 of the femur bearing against the upper part of the acetabulum, till the neck, the 

 weakest part, gives way. 



But though it may not be possible that the femur should be luxated by any 

 force applied in a direction parallel to that of the thigh, in an erect posture of 

 the body, it is not equally impossible it should be dislocated by a force applied in 

 a contrary direction. For in the above case the blow was received on the upper 

 and hinder part of the thigh, in a direction forward, from the wheel of the 

 chaise, which must necessarily have a tehdency to drive it round forward, and 

 consequently cant the head of the femur out of the acetabulum backwards, where 

 it is less deep than it is either above or below. On the fore part of the aceta- 

 bulum it is yet more shallow, and therefore less force is required to dislocate it 

 that way, and more especially as there is on that side less strength of muscles 

 to resist. 



It was probably a fortunate circumstance for this man, that Mr. Y. thought 

 himself mistaken in his first opinion of its being a dislocation; for had that been 

 clearly the case, he would have used every method, and every assistance to be 

 had, to have reduced it immediately; and most likely, while the muscles remained 

 in their full strength, and contracting involuntarily, and that violently too, as 

 they will sometimes do on attempting an extension of them, and under which 

 circmnstance, the muscular fibres oftentimes rather break than give way, should 

 have failed of being able to reduce it; and in that case the man must have re- 



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