One or two guiding principles are important:—
1. Having made up your mind at what point you are to cut the metatarsal, if the amputation be a partial one, or as to the exact position of the joint, if you intend to disarticulate, commence your dorsal incision (Fig. v. 3) at a point fully half an inch higher up than the selected spot, as free access is of the very last importance.
2. Whenever it is possible, cut the bone through its continuity rather than disarticulate. Specially is this important in the case of the metatarsal bone of the great toe, that the insertion of the tendon of the peroneus longus may be saved. If, however, the terminal branch of the dorsalis pedis artery be wounded, it may be necessary to disarticulate the first metatarsal to secure it rather than trust to compression to stop the bleeding.
3. In cutting through the first and fifth metatarsals, remember to apply the bone-pliers obliquely, not transversely, so as to avoid unseemly projection.
4. As far as possible avoid cutting into the sole at all.
The plantar cicatrix is almost a fatal objection to a plan of removing the first and fifth toes and their metatarsals which has much otherwise in rapidity and elegance to recommend it. In the great toe, for example, it is performed as follows:—Seizing the soft parts of the inner edge of the foot in his left hand, the surgeon draws them inwards, transfixes just at the tarso-metatarsal joint, and, keeping as close as possible to the inner edge of the metatarsal bone, cuts the flap as long as to the middle of the first phalanx; then the soft parts of the foot being drawn as far outwards as possible by an assistant, the surgeon enters his knife between the first and second toes, and succeeds in entering his former incision so as to separate the metatarsal bone without removing any skin. All that remains is to open the tarso-metatarsal joint. It is a very neat-looking operation, leaves a very good covering for the parts, and is performed with extreme rapidity. This last is not so much required in these days of anæsthetics, and the cicatrix in the sole is a very formidable objection to it.
The simplest and shortest rule that can be given for the amputation of a toe, with the part or whole of its metatarsal, is to make one dorsal incision, commencing about a quarter of an inch above the spot at which you intend to divide the bone or to disarticulate, extending downwards in a straight line to the metatarso-phalangeal articulation, and then bifurcating so as to surround the base of the toe at the normal fold of the skin. The soft parts are then to be cleared from the metatarso-phalangeal joint, and the toe still being retained on the metatarsal bone, it should be carefully dissected up, avoiding any pricking of the soft parts below, till the joint is reached, or the spot at which the bone-pliers are to be applied is fully cleared.
Amputation of the anterior portion of the Foot at the Tarso-metatarsal Joint—Hey's Operation.—This operation, which is now comparatively rarely performed, has been invested with a halo of difficulty and complexity which is to a great extent unnecessary.
There is no doubt that the anatomical conformation of the joints involved, especially the manner in which the head of the second metatarsal (Fig. v. C) projects upwards into the tarsus, and is locked between the cuneiform bones, renders disarticulation in the healthy foot rather difficult; but it must be remembered that in cases where for accident we have to deal with previously healthy tissues, it is quite unnecessary to disarticulate, a better result being attained by simply sawing the foot across in the line of the articulation; and again, where we have to operate for disease, the tissues are so matted, and the bones so soft, that complete removal of the metatarsus is much easier than it appears when practising on the dead subject.
Very various plans of incision have been proposed. Mr. Hey's original procedure has not been much improved upon. His short account of it has at once surgical value and historical interest:—