392 ON AMPUTATION 



as the diameter of the Hmb ; but when the soft parts are cut from without 

 inwards, a much shorter knife will answer the purpose, and should therefore 

 be preferred, as the movements of the smaller instrument can be directed with 

 greater precision and speed. For removing a finger or toe, something inter- 

 mediate between the tapering bistoury often used in France and the old round- 

 bellied English scalpel will be found to combine the advantages of both, without 

 the inconveniences of either, being equally adapted for piercing and cutting. 



In using the knife, the young practitioner will have to unlearn some of the 

 habits he has acquired in anatomical study. The object being now simply to 

 divide the resisting textures efficiently, the stroking and scratching movements 

 of the dissecting room must be changed for a free sawing motion : and for this 

 purpose the knife must be held firmly in the hand, instead of being kept in the 

 feeble position best suited for the investigation of delicate structures. 



There is another error to which the habits of dissection may lead, far more 

 serious than a cramped and awkward use of the knife, viz. that of directing the 

 edge of the instrument towards the skin in raising a flap of integument. Such 

 a practice, necessary in anatomy, in order to leave the subcutaneous structures 

 intact, will, if carried into amputation, most seriously endanger the vitality 

 of the flap, which derives its supply of nourishment from vessels ramifying in 

 the fat, and must perish if those vessels are extensively divided through scoring 

 of the tela adiposa. I am satisfied that integument designed to form a covering 

 for the stump is often made to slough for want of scrupulous attention to this 

 simple point. 



The skin should always be cut perpendicularly to its surface, for if it is 

 bevelled off to a thin edge, it is not only unsuited in shape for adaptation with 

 a view to primary union, but the margin may slough for lack of nutriment. 



In transfixing a limb, the direction of the knife must of course be changed 

 as it passes round the bone, in order that it may emerge at the opposite aspect ; i 



but it is desirable that this should be done in a continuous manner ; for if the 

 instrument be thrust in for a certain distance, and then partially withdrawn j 



and made to follow a new track, the punctured wound first made may cause 

 very troublesome haemorrhage, if a considerable arterial branch happen to be \ 



divided in it. j!' 



In passing the knife round a bony prominence, such as the shoulder, care 

 must be taken to hold the limb in such a position as shall relax the parts that are 

 to be pierced, otherwise what might be quite easy may prove impossible ; and 

 in the latter part of the process, when the point of the knife is advancing in 

 a greatly altered direction, it is important to keep the back rather than the edge 

 directed outwards, in order to avoid cutting the base of the flap. 



