The care of anaesthetic feet

A patient's feet are even more important than his hands. He may be able to work with a paralysed hand, but if he cannot walk, he will probably be unable to undertake the essential activities of daily life. All over the world, leprosy patients who are being adequately treated medically, are being allowed to walk about on ulcerated feet. The dressings that cover their ulcers do not prevent them from deepening, and widening, and involving the bones underneath. The quiet progressive destruction of these feet is not inevitable[md]and can be minimized. It may be a losing game, so play it as cleverly as you can, and try to retain the usefulness of a patient's foot as long as possible.

Ulcers can be caused by: (1) Constant mild pressure, which causes necrosis by impairing the blood supply to the tissues, as in paraplegic ulcers (64.13). In a normal person ischaemia soon causes pain, so that the ischaemic part is moved, and its blood supply restored. In an anaesthetic limb there is no pain, so that the ischaemic tissue is allowed to become necrotic and ulcerates. (2) A strong force which cuts, shears or tears the tissues. In the foot, the strength of the force is less important than the small area over which it is applied. (3) The frequent repetition of moderate forces, which cause inflammation that weakens the tissues. This is an important cause of ulcers, so try to keep the pressure on a foot low. (4) Forces which spread infection to soft tissues and bone. An infected foot is so painful to a normal person, that he has to rest it[md]a leprosy patient does not do this spontaneously. (5) A previous ulcer. This is the commonest cause. If a patient has never had an ulcer, he may escape without one[md]if he is careful. If however he has already had nine ulcers, he will probably get a tenth.

The key to preventing ulcers is: (1) To teach a patient how not to injure himself in the first place, and (2) to teach him ''self care' for any injuries he does receive, in their earliest stages. All primary care workers should be able to teach this. When his tissues have been damaged, they will usually heal, if he rests them completely. Surgery is much less important than rest, at the right time, and for the right length of time. Antibiotics without rest will not heal ulcers.

Ulcers commonly start in the deeper tissues, and develop slowly over several days, so teach him to recognize an ulcer as a ''hot spot' in its ''pre-ulcer' stage, before the skin over it has been broken. A hot spot is a warm area of skin, usually with swelling, that occurs after activity, and persists during at least 2 hours of rest. In an anaesthetic foot, a hot spot may be the only indication of some underlying pathology, such as a fracture, disintegrating bone, a strain, or an abscess. Any of these may break through to the surface, and form an ulcer. The patient, or a friend, must learn to look for hot spots, because they mean ''Stop!'' He must take them seriously, and rest his foot until all signs of inflammation have gone. Rest at the hot spot stage is the only way to avoid the serious damage that starts the downhill road to amputation.

The risk of an anaesthetic foot developing an ulcer depends partly on his shoe (if he has one), and partly on how much he walks. The less he walks the better. Perhaps he can ride a donkey, or a bicycle? The kind of shoe he needs depends on the state of his foot, as defined by the ''degree of risk' below. Many patients with moderate, or even high risk feet, can remain free from ulcers without moulded shoes if: (1) they practise self care, (2) they have microcellular rubber insoles in their sandals or shoes, (3) they limit their walking, and (4) they take small steps. Moulded shoes are more difficult to make, and many hospitals manage without them. With a little instruction a local cobbler should be able to make a suitable unmoulded shoe in the local style, with the necessary insoles and straps, and using only the local materials. If you want him to make a moulded shoe, he will need these special materials:

MICROCELLULAR RUBBER, 5 m['2][mu]10 mm only. This has a closed bubble structure, and is much more resilient than ordinary ''foam rubber'. Some shoe factories can provide it. It is not the same as the foam plastic used for cheap sandals, which is less resilient. Car tyres make good soles, and inner tubes can make uppers.

FOAMED P0LYETHYLENE, 1 cm thick, as ''Plastazote' (Smith and Nephew) 5 m['2] only. This is a light thermoplastic which a skillful cobbler can use to make a moulded shoe, for a moderate- or severe-risk foot. It resists wetting and is easily cleaned, but it does need an oven. Its main disadvantage is that it wears away in less than 6 months. Heat a piece of sheet to exactly 140[de]C in an oven and hold it at that temperature for five minutes: place it on a 10 cm polyurethane foam pillow; and then ask the patient to stand still on it until it is cool, or let him sit while you force his foot down on it, as in C, Fig. 30-5. It will not burn him, and will set in the shape of his sole, as in illustrations D, and E, in this figure. Be sure to support moulded ''Plastazote' with microcellular rubber, or cork and latex, built up to produce a flat sole; it is not resilient enough to make an insole by itself.

FOOTPRINT MAT, also called a Harris mat, rubber, (DOW Canada), two only of each thickness (optional). This is a mat with little rubber ridges which you ink. Place a piece of paper on the inked mat and ask the patient to walk on it. The greater the pressure, the blacker the ink impression. If you are really interested in the care of leprosy feet, get a footprint mat: its use is described in Paul Brand's book on insensitive feet (30.1).

LOOK FOR SWELLING AND REDNESS FEEL FOR ''HOT SPOTS' Fig. 30-4 FOOTWARE FOR FEET AT RISK can be made by any cobbler if you are prepared to teach him.

LOW RISK FEET. A, microcellular rubber distributes the pressure. B, hatching indicates the areas of increased pressure on walking. C, a car tyre sole applied.

MODERATE RISK FEET. D, the first layer of ''Plastazote''. E, a layer of microcellular rubber. F, a layer of car tyre.

HIGH RISK FEET. G, a layer of ''Plastazote' in a carved wooden clog distributes the weight evenly. H, when the patient walks, his foot does not flex, and weight continues to be spread evenly. I, the completed sandal.

J, a toe-raising strap for a dropped foot. [f10]This is a very helpful device for any dropped foot, so don't fail to fit one when it is needed. [f11]If necessary, use canvas or plastic straps and make the ''spring' from a car inner tube. K, a properly made shoe can protect a badly damaged foot. Note that it has no ulcers, even though it has lost its arches, and its toes are clawed and deviated. It has remained free from ulcers because the patient limited his activity, and because the shoe has a layer of microcellular rubber built up under a moulded ''Plastazote' insole. M, the foot belonging to the owner of the shoe; its arches have flattened, so has his calcaneus; even so, his shoe has managed to protect him. N, the simplest modification for an ulcerated foot is a metatarsal bar, stuck or stitched to the outside of the sole, just behind the metatarsal heads, proximal to the ulcerated area. From Bryceson A, and Pfaltzgraff RE, ''Leprosy' (2nd edn 1979), Figs 11.1 to 11.3. Churchill Livingstone, with kind permission.

FEET [s8]IN LEPROSY ''SELF CARE'. Teach a leprosy patient to: (1) Recognize that his anaesthesia is abnormal. (2) Care for his anaesthetic limbs, so that they are not injured. (3) Inspect his limbs daily, so that he can remove any thorns, and recognize and care for any wound, either open or closed, while it is still small, and before it gets worse. (4) Rest his limbs when they are injured. (5) Recognize and understand the seriousness of ''hot spots'. (6) Treat his first ulcer as the calamity that it really is.

CAUTION ! (1) Persuade him that it is injury to his anaesthetic feet and not the disease itself which leads to ulceration and loss of tissue. (2) He must limit his walking, if he has a hot spot, or an area of deep tenderness.

EXAMINING AN INSENSITIVE FOOT. Look for swellings, injuries and callositis. Are any of his toes pushed apart (with oedema from an injury)? Examine the arches of his feet as he stands, and look for flattening. Feel his whole foot. Warmth or swelling suggest active pathology, and the need for extra care. Press deeply over the common sites of ulceration in A, and B, Fig. 30-6. He may still feel deep pain, when he has lost all ordinary sensation.

Watch him walking barefoot. You can easily miss a dropped foot, if it is also short. Ask him to walk on his heels. He cannot do this if his anterior tibial or peroneal muscles are weak. Finally, don't forget to look at his shoes!

SKIN CARE. Denervation of the skin reduces its natural secretions and makes it dry, so that it more easily cracks, fissures, and becomes infected. Softening dry skin reduces these dangers, and may allow any fissures that have formed to heal. So ask him to get plain water, without detergents, into his dry feet (or hands) by soaking them for 15 to 20 minutes at least twice a day. Then ask him to cover his skin with petroleum jelly (''Vaseline'), or any kind of grease or oil (including car oil). It is the water that is important, not the grease which keeps it in.

If fissures are already well established, pare away the thick callus with a knife, or ask him to rub it away with a pumice or other stone. Remove rough callus regularly, because it may split and crack, or cause ulcers by pressure.

OTHER WAYS TO PREVENT ULCERS. When necessary remember to: (1) Correct deformities. If he has a dropped foot, fit a toe raising strap (J, 30-4). (2) Ask him to take short steps, which will reduce the pressure on the front of his foot and his heel. (3) Ask him to avoid any hard edges or knots in his shoes or socks. (5) Beware of newly healed ulcers. The scar will not have had time to become supple, and is in danger from any shearing force applied to it.

''PRE-ULCERS'. Try to recognize a ''pre-ulcer foot', because 3 days to 3 weeks of immediate bed rest at this stage may prevent a serious ulcer forming. Look for: (1) swelling of his sole, (2) separation of his toes, (3) necrosis blisters at the side of his foot, caused by fluid which has tracked from the necrotic area above his plantar fascia, as in G, Fig. 30-6, (4) ''hot spots', (5) redness, (6) pain (if he still has any sensation), especially pain on deep pressure.

FEET AT RISK [s7]FROM LEPROSY A LOW RISK FOOT is anaesthetic, but has little or no scarring. It needs protection and a resilient sole. The possibilities include: (1) A resilient insole in a well-fitting shoe, which is one size larger than one he usually wears. This may be enough. Don't make the insole too thick, and make sure his shoe is well fastened, so that it does not slip and produce blisters. (2) A car-tyre sandal with an insole of microcellular rubber.

A MODERATE RISK FOOT is anaesthetic, has multiple scars, and has lost some of the subcutaneous fat pad on its sole. A shoe for a foot like this needs to be moulded, to take the weight off the metatarsal heads, and spread it evenly over the entire sole. Such a foot will however do fairly well in a simple car- tyre and microcellular rubber sandal[md]if he keeps the callus well pared down. Or, make a piece of moulded ''Plastazote' as described above. When it has set firm, build microcellular rubber up underneath it, and then fit this to a car-tyre sole. If it is made as a sandal, it will need a retainer for the heel moulded into it. A shoe with a moulded sole is better than a sandal at preventing the foot slipping out, but it must have a well-fitting upper with buckles, laces, or straps, so that it remains in its correct relationship to the foot.

A HIGH RISK FOOT has, in addition, a mild deformity, such as flattening of the arches, and shortening, or loss, of toes. It needs a shoe which is moulded to conform to it completely, and has a rigid sole. Build microcellular rubber up under a sole of moulded ''Plastazote', and carve a wooden rocker clog to fit it; then fit this with a hard rubber sole. A clog is rigid, so its front end must be boat-shaped as in G, Fig. 30-4. Some of these feet do well in microcellular rubber sandals[md]if their owner looks after them carefully.

A DISINTEGRATED FOOT has a major bony deformity such as fragmentation of its tarsal bones, or is ''boat-shaped', or has a dislocated ankle. Rehabilitation is difficult; he may need reconstructive surgery and a proper orthopaedic boot. See also Section 30.6D.

PROTECTIVE FOOTWARE [s7]FOR LEPROSY Instruct a cobbler to make the footwear described above, and to follow the local styles where he can. Make the straps broad, and adjustable with buckles or laces, so as to allow for swelling or bandages. The simplest protection for an ulcerated foot is a metatarsal bar, stuck or stitched to the outside of the sole, just behind the metatarsal heads, as in N, Fig. 30-4.

CAUTION ! (1) Never use nails or wire to make or repair shoes for leprosy patients[md]glue and sew them. (2) If his foot is significantly inverted or everted, only major surgery will allow him to walk satisfactorily. (3) New shoes need special care. Warn him to walk short distances only until the leather has become adjusted to his foot[md]meanwhile he should use his old ones most of the time.

PARALYSIS [s7]OF THE FEET IN LEPROSY If paralysis developed quickly and is acute (and is still within 3 months, and perhaps up to 6 months, but certainly no more), he has probably been in reaction (Type One) and has some hope of recovery. Give him full antileprosy treatment and steroids for 6 to 12 weeks (30.1a). Treat him as described below.

If he has a posterior tibial nerve palsy, either: (1) Apply a firm bandage to limit friction at the back of his ankle. Combine this with a heel retainer, to minimize the use of the small muscles of his foot, and trauma to his anaesthetic sole. Or, (2) apply a padded plaster boot.

If he has an acute common peroneal nerve palsy, or a palsy of its branches, so that he has a flapping gait and foot drop, passive exercises will help to stretch his Achilles tendon and prevent a contracture: (1) Ask him to squat with his heels flat on the ground. (2) Ask him to stand erect about 70 cm from a wall, to keep his feet flat on the ground, and with the palms of his hands flat on the wall to do ''press ups' in the vertical position.

He also needs some protective device. Either: (1) By day, fit him with a toe-raising spring as in J, Fig. 30-4. If he is co-operative, this will be easier and cheaper, and will allow him to do some work. By night, apply a posterior slab to hold his ankle in neutral. Or, (2) apply a complete plaster cast, including his foot and leg up to the middle of his thigh, with 15[de] of flexion of his knee, and with his ankle in neutral, taking care that the cast does not press on the nerve. Leave it on for 6 weeks.

If his common peroneal nerve paralysis has persisted 6 months in spite of medical measures and physiotherapy, it is probably permanent. He may be helped by the lengthening of his Achilles tendon, and the transfer of his tibialis posterior tendon to the front of his foot to make it into a dorsiflexor (30.8). If this is impossible, or while waiting for surgery, fit him with a toe-raising strap.

If he also has plantar ulceration with his foot drop, be sure to use a posterior slab or a cast. If his ankle is not supported, his tendo Achilles is likely to contract on bed rest. Give him crutches while his ulcer heals, so that he does not even take one step on it.

If he has clawed toes, transfer his flexor longus tendon to the extensor expansion on each toe (N, and O, 30-9).

FIND A CAPABLE COBBLER AND HELP HIM TO HELP YOUR PATIENTS Fig. 30-5 PROTECTIVE FOOTWARE FOR LEPROSY. A, the right kind of microcellular rubber can be squeezed to half its thickness; if it is flatter than this it is too soft, if it is thicker it is too hard. B, a sheet of hot ''Plastazote' laid on soft foam. C, take the mould by applying even pressure and holding it for 3 minutes. Mark it out (D), and cut it (E), so as to project 0.5 to 1 cm in front of the patient's toes and behind his heel. Shape it (F), smooth it on an electric buff, and support it with a layer of microcellular rubber and stick it to a hard rubber sole. G, the completed shoe made from moulded ''Plastazote' supported by layers of microcellular rubber, and soled with car tyre. H, and I, a moulded shoe must be anchored to his foot and must not be allowed to move about. After Brand Paul,''Insensitive Feet: A Practical Handbook on Foot Problems in Leprosy'. The Leprosy Mission International, with kind permission.