The operation by the circular incision is performed by necessity in the thick part of the leg, and the bone is usually sawn through about four inches from the patella, so that, when the stump has healed, there may be sufficient length of bone left to support with steadiness the weight of the body on the knee, and that greater facility may be given to the motion of the leg, from the preservation of the insertion of the flexor tendons. The most eligible place for the application of the tourniquet, when used, is about one-third of the length of the thigh from the knee, on the inside, where the artery perforates the tendon of the triceps muscle, and where it can be most conveniently compressed against the bone by a small firm pad, the instrument being on the outside, or opposite the pad; or the compress may be placed between the hamstring tendons, a little distance from the hollow behind the joint, the instrument itself being on the fore part of the thigh. In this method the pad must be thicker, and the compression is more painful, and not more secure. The surgeon should stand on the inside of the leg to be operated upon, that he may more readily saw the fibula at the same time as the tibia, by which the chance of splintering the fibula is diminished; for this bone is held much more steadily under the saw when the tibia is undivided, whatever pains may otherwise be taken by the assistants to secure it. The limb should be a little bent, and the circular incision made with the smaller amputating knife through the skin and integuments to the bone on the fore part, and to the muscles on the outside and back part; and as the attachment of the skin to the bone will not readily allow its retraction, it must be dissected back all round, and separated from the fascia, the division of which in the first incision would avail nothing, from its strong attachments to the parts beneath. The muscles are then to be cut through, nearly on a level with the first incision, down to the bones. The interosseous ligament between the tibia and fibula is to be divided with the catlin; and as several of the muscles cannot retract in consequence of their attachment to the bones, they are to be separated with the knife; in the same manner the inter-muscular septa, or expansions running between them, are to be divided, as they would else prevent their retraction. The retractor with three slips is now to be put on, the center slip running between the bones, by which the soft parts may be pulled back to a sufficient distance, any adhering part being divided by the point of the knife. The bones are to be sawn through with the usual precautions, and the retractor removed, when the three principal arteries should be secured: the anterior tibial, on the fore part of the interosseous ligament, between the tibia and fibula; the peroneal artery behind the fibula; and the posterior tibial near it, more inward and behind the tibia; this artery will frequently, however, contract very much, and will only show itself on the compression being taken off the artery above. It in general causes more trouble to secure it than the others, and I have two or three times seen, even in London hospitals, the needle dipped round it in despair, when merely pulling out the artery with the tenaculum, and dissecting a little round it, would have shown the small retracted bleeding vessels arising from it, and have prevented, in all probability, a secondary hemorrhage. The tourniquet, if used, being removed, the smaller vessels tied, and the stump sponged with cold water and dried, the integuments and muscles should be brought forward as much as possible, and the strips of adhesive plaster applied from side to side—that is, the wound is to be closed vertically or nearly so, that the strips of plaster may not in any way press upon the fore part of the tibia, by which its protrusion will be avoided, an occurrence which almost invariably follows when the line of approximation is horizontal and the strips of plaster press upon the bone. If the spine of the tibia be sharp, it should be removed by the saw, whether the operation be done by the circular incision or by the use of flaps.
91. The flap operation, as performed by Mr. Luke, differs from that of the thigh in some particulars. There is a greater variety in the proportion which the soft parts in the posterior flap bear to those in the anterior, and the distance from the bones at which the limb is transfixed in the first step of the operation is subject to such variety that, when the calf is large, the mid-point for the introduction of the knife lies at some distance from the posterior aspect of the bones; in a small calf, it is close to it. The course of the knife through the limb is oblique instead of transverse, for the purpose of accommodating the line of incision to the plane of the two bones. The anterior flap is formed in the same way as in the thigh amputation, but it has proportionately more integuments and is thinner; yet its base and length are rendered equal to the base and length of the posterior flap, and may be adjusted evenly with it when the stump is dressed. In the circular division of the remaining soft parts, after the formation of the flaps, there is a necessary variation in the proceedings, from the circumstance of there being two bones united by interosseous membrane. It may, however, be accomplished by sweeping the knife around the more distant bone of the two, its point being afterward carried between the bones through the interosseous membrane. While the knife is between the bones, its edge may be so turned that the membrane may be divided longitudinally to any convenient extent for the easy introduction of a retractor, and the soft parts around the bone nearest to the operator may subsequently be divided by a sweep of the knife in a manner similar to that adopted for the division of parts around the more distant bone. The sawing of the bones and dressing of the stump are accomplished as in the thigh amputation; but more care is required to avoid pressure on the acute margin of the tibia, (which, when very sharp, should be removed,) and to prevent the pendulous state of the flaps.
A. The mid-point between B and C, at which the knife is introduced for carrying it across the limb.
A to D. The course of the incision to form the posterior flap, E.
F to g. The course of the incision to form the anterior flap.
When the nature of the injury renders amputation necessary at or immediately below the tuberosity of the tibia, the operation may be done with safety. Baron Larrey recommended the removal of the head of the fibula in such cases; I have done it with impunity, and thereby made a better stump than if it had not been done; but as the articulating surface of the head of the fibula does sometimes enter into the composition of the knee-joint, and as this cannot be known beforehand, the removal of this portion of the fibula is not advisable, neither must the tibia be sawn through above the tuberosity lest the capsular ligament be implicated. As an operation by which the knee-joint is saved, it is important; for although the stump is very short, it forms a solid support for the body, enables the patient to walk without the aid of a stick, and admits of the adaptation of an artificial leg. The skin, in these cases, must be saved in every direction by flaps, to form a covering. When in sufficient quantity, the operation may be done by the circular incision, as much muscle as possible being saved to aid in forming a covering on the under and outer sides. The posterior tibial artery will be found to have retracted behind the head of the bone, whence it, or others which may bleed, must be drawn out. The nerves should be cut as short as possible.
EXCISION OF THE ANKLE-JOINT.
92. This operation should be performed in the following manner: Begin the incision behind the external malleolus, an inch and a half above its lower extremity, and carry it downward and then forward across the front of the ankle-joint, then under the internal malleolus and upward, close behind this process, to the extent of an inch and a half; this incision should merely divide the skin, and should not, on any account, wound the subjacent parts. Raise the flap thus made, and, placing the leg on its inside, detach and turn aside the peronei tendons from the groove behind the external malleolus. Cut through the external lateral ligaments of the ankle-joint, keeping the knife close to the end of the fibula; then, with the large bone-scissors or nippers, cut through the fibula from one-half to three-quarters of an inch above its junction with the tibia, and, after dividing the ligamentous fibers connecting the two bones, remove the malleolus externus. Turn the leg on to its outer side, and cut through the internal lateral ligament close to the tibia, to avoid wounding the posterior tibial artery; this will allow the foot to be dislocated outward, and the lower end of the tibia to be brought well out through the wound. An assistant keeping the foot and tendons out of the way, the lower end of the tibia is to be removed by a fine saw to the same extent as the fibula, or as high as the injury or disease requires. The articulating surface, or injured part of the astragalus, is then to be removed, after which the foot is to be returned to its proper position, and the cut surfaces of the tibia and astragalus brought into close approximation, and so kept by suture, strapping, and bandage. The limb is to be placed on an outside leg-splint, having a foot-piece to it; and in order to prevent any matter oozing, an opening should be maintained on the outside of the joint, with a corresponding hole in the dressing and splint for this purpose, until the recovery is completed. The shot-hole will sometimes answer the purpose, when the injury is inflicted by a musket-ball. There are no vessels to tie, unless wounded accidentally.
REMOVAL OF THE OS CALCIS.
93. If this bone should be much shattered, and the injury nearly confined to it alone, it may be removed in the following manner: Make a semilunar incision down to the bone from the posterior angle of the inner malleolus, across the sole of the foot to the external malleolus, the convexity of the flap being forward. This flap being turned back, the tendo Achillis is brought into view, and is to be separated from its attachment or cut across above it. The point of junction between the calcis and astragalus having been ascertained, the ligamentous fibers are to be cut through and the joint between them opened, when the knife is to be carried from behind forward, in order to divide the interosseous ligament between them. Some ligamentous fibers passing between the calcis and cuboid bones are then to be cut through, when the os calcis may be dissected out without difficulty. The posterior tibial artery and nerve will be divided.