2. It is the most perfect stump that can be made, in fact the only one in the lower extremity which can bear pressure enough to support the weight of the body; all the others require the weight to be distributed over the general surface of the limb by means of apparatus. A good ankle-joint stump can bear the whole weight of the body, as when the patient hops on it without any artificial aid, or without even the interposition of a stocking between the stump and a stone floor. More than this, I have seen a patient who had both his feet amputated at the ankle-joint run without shoes or stockings on the stone passages, without even the aid of a stick, and with very great swiftness.
The reason of this may be found in the nature of the flap itself, originally intended to bear the weight of the body, there being no cicatrix at the part on which pressure is borne. I have noticed that perfection in walking on an ankle-joint stump has a certain relation to the freedom of movement which the pad has over the face of the bone. This ought to be pretty considerable. It is explained by the new attachments formed by the tendons, and is under the control of the patient, being elicited when he is told to move his toes.
It has been objected to this operation that the flap is apt to slough. When improperly performed, as when the flap is scored transversely in its separation, and especially when the flap is cut too long (as has been already noticed), this may occur; but that there is nothing whatever in the position or condition of the flap itself that at all necessitates its sloughing, is thoroughly proved by the following remarkable case, given by Mr. Syme in his volume of Observations in Clinical Surgery. I quote it entire:—
"P.C., aged thirty-three, was admitted into the hospital on the 25th July 1860, in the following state:—He had been treated in the Manchester Infirmary for popliteal aneurism by pressure, so decidedly applied that it had caused an ulcer, of which the cicatrix remained; but without producing the effect desired. The femoral artery was then tied with success, in so far as the aneurism was concerned, but with the unpleasant sequel, some months afterwards, of mortification in the foot, which was thrown off, with the exception of the astragalus and os calcis with their integuments, a large raw surface being presented in front where the bone was bare. Although the patient was extremely weak, and the parts concerned might be supposed more than usually disposed to slough, I did not hesitate to perform the operation, with the speedy result of a most excellent stump and complete restoration to health."—Pp. 49, 50.
The modifications of Mr. Syme's original operation have been very various. It will be unnecessary even to name them all. One or two may require notice. Retaining Mr. Syme's incisions in their integrity, some operators prefer not to disarticulate the foot, but remove it by sawing through the tibia and fibula at once, while still in connection with the foot. That most excellent surgeon and first-rate operator, Dr. Johnston of Montrose, used to prefer this method.
In cases where the pad of the heel has been destroyed by disease or accident, so as to be partially or entirely unavailable for the flap, the late Dr. Richard Mackenzie[41] practised the following operation by internal flap:—With the foot and ankle projecting from the table with their internal aspect upwards, he entered the point of the knife ([Plate I.] fig. 14) in the mesial line of the posterior aspect of the ankle, on a level with the articulation, carried it down obliquely across the tendo Achillis towards the external border of the plantar aspect of the heel, along which it is continued in a semilunar direction. The incision is then curved across the sole of the foot, and terminates on the inner side of the tendon of the tibialis anticus, about an inch in front of the inner malleolus. The second incision ([Plate III.] fig. 4) is carried across the outer aspect of the ankle in a semilunar direction, between the extremities of the first incisions, the convexity of the incision downwards, and passing half an inch below the external malleolus.
Precisely the same principle might supply the flap from the outer side in cases where the internal flap as well as the heel was deficient, but probably the nutrition of the external flap would be more doubtful. Neither the one nor the other is nearly so good as the true heel flap, and they are both only very poor substitutes for it when it cannot be had.
The modification devised by Dr. Handyside does not seem to have any advantages over the original operation, and has not been adopted.
The modification invented by Professor Pirogoff involves a much more important principle than any of the preceding. Instead of dissecting the flap from the posterior projecting portion of the os calcis, and removing the tarsus entire, he sawed off the posterior portion of the os calcis obliquely, leaving it in contact with the pad of skin, which is retained. Immediately after making the cut which defines the posterior flap and divides the tissues down to the bone, he opens the joint in front, disarticulates, and then putting on a narrow saw immediately behind the astragalus and over the sustentaculum tali, he saws the os calcis obliquely downwards and forwards till he reaches the first incision; then removes the ends of the tibia and fibula and brings up the slice of os calcis into contact with them.
Advantages.—It is easy of performance, saving the dissection from the heel, which some find so hard. It leaves a longer limb. It is said to bear pressure better, and there is certainly not so much chance of bagging of pus, and the mortality is exceedingly small, Hancock's collected cases giving only 8.6 per cent.; in cases of injury it is quite a warrantable operation.