PARTIAL AMPUTATIONS OF THE FOOT

This name should be applied to amputations in which the mobility of the ankle joint is retained, i.e. Chopart's amputation (midtarsal disarticulation), Lisfranc's amputation (tarso metatarsal disarticulation), amputation of several toes with their metatarsal bones, or amputation of all five toes.

1. The amputations of Chopart and Lisfranc.—Chopart's amputation has a grave defect: the anterior muscles have not sufficient leverage to oppose this gastrocnemius and soleus, and the posterior tarsal bones tilt forward so that the patient walks, not on the lower surface of the os calcis and the plantar skin, but on the head of the astragalus and of the os calcis and on a painful cicatrix. If certain precautions are taken (careful preservation of the fibrous plantar flap and suture to it of the anterior tendons) this defect is not invariably present, and it is an exaggeration to say that Chopart's amputation "has never given anything but disappointment." It should, however, only be practised if the technique is well understood, and even then it is rarely indicated, because it demands almost as much plantar skin as Lisfranc's amputation.

Nevertheless I have seen some good Chopart stumps the result of operations by myself or by other surgeons; they should be fitted like the stumps resulting from Lisfranc's operation.

With regard to the latter, they can be easily and comfortably fitted, provided that the scar is dorsal and is not stretched over prominent bones.

If the first cuneiform is not well covered it can simply be removed, no functional disability results. It is mainly upon the plantar surface of the stump that pressure is borne, but pressure comes also upon the anterior surface when the foot is tilted downwards.

The fore part of the foot which constitutes the prosthetic apparatus consists of a block of wood, which reaches forward as far as the middle of the metatarsus and ends in a vertical plate in front of the stump. This block of wood is carved to the shape of the stump and lined with felt. It is attached to the leg by a leather gaiter which laces in front.

Anteriorly it is prolonged into an artificial toe piece similar to that already described for the artificial limb for amputation through the thigh.

This appliance is not indispensable. It is sufficient to use a piece of cork shaped to the anterior surface of the stump and filling up the anterior part of the boot, its advantage, however, is that once the patient is fitted with this appliance he can wear an ordinary boot.

2. Partial Amputation of the Fore Part of the Foot.—These are—

Transverse amputation through the metatarsal bones.

Disarticulation of one or more toes with their metatarsal bones.

Disarticulation of one or more toes.

For any of these amputations all that is required is an ordinary boot, fitted with a cork, which is shaped to fit the stump and which fills up the space left by the amputation.

In order that the patient may walk well the scar should be dorsal and should not be tense.

We consider that the difficulty of maintaining equilibrium after removal of the head of the first metatarsal, or even of the whole of this metatarsal bone, has been much exaggerated.

Removal of a marginal metatarsal bone (either alone or with its neighbour), tends to make the foot tilt into varus or valgus; so that the boot needs to be stiffened and the sole thickened to avoid this.