The two bones of the leg united by the interosseous ligament form an elongated fossa in front which is closed in by the aponeurosis, and is larger at the union of its two superior thirds than at its extremities. The muscles being imbedded here are difficult to cut in circular amputations, at the same time that its depth prevents the formation of a good flap. Posteriorly, they form a gutter, or fossa, larger than the preceding, but also much more shal low, excepting at the lower part. Hence the deep muscles are easily comprehended in the flap in amputation. In the circular operation the section of the flesh, which can only be effected by passing the point of the knife transversely over the bottom of the interosseous fossa, is equally difficult in the flap method, in making the anterior flap, in consequence of the depth of the space in which the muscles are lodged. The difference of size of the two bones and the posterior relative situation of the fibula renders some precaution necessary in dividing them with the saw. The foot must be turned in, so as to bring the fibula a little forward, and care must he taken to commence the section upon the tibia as being the longest and strongest, but to finish the section of the fibula first, since it is too thin and mobile to support the movements of the saw without breaking at the termination. In amputation above the tubercle of the tibia, it has been held advisable to remove the head of the fibula from its joint, since this small portion of the bone is of no advantage to the stump and by its mobility may be some hindrance in the after treatment. (See KicEE-Joi yr.) The small size and moveable nature of the fibula constitutes some difficulty in the treat ment of fractures of the leg, since the appli cation of the ordinary bandages, &c., would have a tendency to press the bone inwards against the tibia, and we not unfrequently see, in old united fractures of these bones, this deformity to have been produced, in all proba bility, from want of due precaution in the ap plication of bandages. The defect may be obviated by proper care, that neither the splints DOT the cushions should take any bearing upon the fibula itself except at its two extremities, and great assistance may be derived from proper pressure, before and behind, upon the muscles, gently forcing them against the inter osseous ligament and bearing outwards the bone attached to it.
After amputation of the leg, the tibia pre sents a triangular surface, having the apex for wards. As the skin covering it is hereby in vested with the subcutaneous layer, it may, by pressure against this projection, ulcerate, or slough, and thus expose the bone. The great means for obviating this accident is to have a good supply of integument in the flap, so that, in bringing the parts together afterwards, they may not be drawn too tight over the bone. While this rule is attended to all will go on well, whereas when the integument is left scanty, nothing can prevent unpleasant consequences. It may often, however, be advisable to remove with the saw the projecting angle of bone, and as a matter of precaution we generally do this, though not attaching much importance to it.* In amputating above the tuberosity of the tibia, we run the risk of opening into the knee joint, as the synovial membrane is sometimes prolonged thus far. According to M. Lenoir the synovial cavity of the knee is continuous with that of the superior tibio-fibular articu lation, once in four times.t There are always three principal vessels to be tied in this ope ration : first, the anterior tibial, which is found, with its collateral nerve, close upon the inter osseous ligament; secondly, the posterior ti bial, in contact with the deep layer of the aponeurosis, and having its nerve to its outer side ; and, thirdly, the peroneal, which is found imbedded in the flexor longus pollicis muscle, and may be readily tied without fear of injuring any nerve. These three arteries
sometimes retract so far into the flesh after amputation, that to secure the anterior tibial it is necessary to cut through the interosseous ligament to the extent of some lines. This probably arises principally from the attachment of the muscles to the whole parietes of the interosseous fossa, while the vessels, enveloped by elastic cellular tiss4e, retract considerably.
It must be borne in mind, that in whatever situation the amputation may be performed, if it be the flap operation the arteries of the flap are much more difficult to be found and se cured, owing to the oblique nature of the sec tion, than where, as in the circular operation, the muscles and vessels are cut transversely through.
When the amputation is just below the tu berosity of the tibia, the nutritious artery has here sometimes a volume sufficient to require a ligature. With the exception of this last, the arteries to be tied will be nearly the same, in whatever part of the length of the leg the amputation is performed. The muscular branches seldom occasion much inconvenience from hwmorrhage.
It may not be out of place here to remark on the subject of amputations of the leg, that the division of the bones high up may often save the knee, and thus give a good bearing for a wooden leg, but that we are too often apt to act upon the principle that, in amputations below the knee, this joint must necessarily be the bearing point ; whereas we are convinced that a much more useful stump is gained by saving as much as possible of the leg, at least as far as half of its length, with the view of applying the wooden leg to the stump itself, and so preserving entirely the use of the knee joint. FVe have now adopted this plan, with the most perfect success, in several instances, and always to the great comfort and satisfaction of the patient. Indeed, the loss of the limb, which is thus remedied, is really little felt, when compared with the great inconvenience of making the knee the bearing point, and thus taking away all the benefit of it as a joint. The reason why this mode of operating has not been more generally adopted, appears to us to consist in the fear that the cicatrix of the stump is ill able to bear the weight of the body in walking, when pressed between the ends of the two bones and the artificial leg. But be sides that by the flap amputation in the middle of the leg, (the best possible situation for this operation, when practicable,) a soft cushion of muscle can be added to the integumental covering to obviate the effects of pressure, the fact is that in the application of the artificial leg to this stump, the bearing is not entirely upon the stump itself, but it is divided between this and some part of the anterior surface of the leg, generally falling most powerfully about the tubercle of the tibia. The bearing on the anterior part of the leg is so strong, that unless the precaution is taken of well padding that part of the wooden box, the pain occasioned by the pressure entirely pre vents the use of the wooden leg; but by the use of this precaution all inconvenience is ob viated, and by this support to the weight of the body a valuable help is found for the pre vention of injury to the cicatrix of the stump.