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Metatarsalgia is a symptom rather than a disease and refers to pain and tenderness over the plantar heads of the metatarsals (the forefoot). Causes include foot deformities (especially with depression of the transverse arch), leading to painful strain, arthritis of the MTP joints, trauma, Morton neuroma, Freiberg disorder and entrapment neuropathy. However it can occur in normal feet after prolonged standing.
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Depression of the transverse arch results in abnormal pressure on the second, third and fourth metatarsal heads with possible callus formation. Repetitive foot strain, pes cavus and high heels may cause a maldistribution of weight to the forefoot.
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Treatment involves treating any known cause, advising proper footwear and perhaps a metatarsal bar. Flat-heeled shoes with ample width seldom cause problems in the metatarsal region.
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The aches or pains may be slow in onset or sudden
Common in dancers, especially classical ballet, and in unfit people taking up exercise
Examination is often unhelpful: swelling uncommon12
Routine X-rays often unhelpful
A bone scan is the only way to confirm the suspected diagnosis
Basis of treatment is absolute rest for 6 or more weeks with strong supportive footwear
A walking plaster is not recommended
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Avulsion fracture of base of fifth metatarsal
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Known also as a Jones fracture, it is usually a traumatic fracture but can be a stress fracture and associated with severe ankle sprains.
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March fracture of metatarsal
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Stress or fatigue fracture of the forefoot usually involves the neck of the second metatarsal (sometimes the third). Swelling typically occurs along the bone shaft. X-ray changes are often delayed. Treat conservatively with support from a firm elastic bandage; avoid painful activities. Resolution may take many months.
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Tarsals, especially navicular
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Stress fracture of the navicular, which is a disorder of athletes involved with running sports, presents as poorly localised midfoot pain during weight-bearing. Examination and plain X-ray are usually normal. It is a recently recognised serious disorder due to the advent of nuclear bone scans and CT scans. A protracted course of treatment can be expected.
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Stress fractures of the os calcis usually have an insidious onset. Osteoporosis is a predisposing factor, as is an increased training program.14
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Morton interdigital neuroma is probably misdiagnosed more often than any other painful condition of the forefoot. It is not a true neuroma but a fibrous enlargement of an interdigital nerve, and its aetiology is still uncertain. It is related to overuse and inappropriate footwear. The diagnosis is made on clinical grounds. An ultrasound examination may detect a neuroma.
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Usually presents in adults <50 years
Four times more common in women
Bilateral in 15% of cases
Commonest between third and fourth metatarsal heads (see FIG. 68.9), and second and third (otherwise uncommon)
Severe burning pain (sometimes sharp and shooting) between third and fourth or second and third toes
Worse on weight-bearing on hard surfaces (standing and walking)
Aggravated by wearing tight shoes
Relieved by taking off shoe and squeezing the forefoot
Localised tenderness between metatarsal heads
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Early problems are treated conservatively by wearing loose shoes with a low heel and using a sponge rubber metatarsal pad. An orthosis with a dome under the affected interspace helps to spread the metatarsals and thus takes pressure off the nerve. Any biochemical abnormalities of the foot should be corrected. Most eventually require surgical excision, preferably with a dorsal approach. A corticosteroid injection can be considered.
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This is a sprain of the first metatarsophalangeal joint caused by a forced hyperextension (occasionally hyperflexion) injury to the joint. It is common in football players and athletes, e.g. jamming or stubbing the great toe. There is pain, swelling and limitation of movement. Plain X-rays are unhelpful, but isotopic scans and MRI may help to diagnose the injury.
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Treatment is conservative with RICE, NSAIDs and relative rest. Surgical intervention may be required.
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Hallux valgus with associated bunion formation and splaying of the forefoot is common. It may be a consequence of poor-fitting footwear.
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A bunionette, also caused by pressure, may form over the fifth metatarsal.
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Pain, if present, may be due to shoe pressure on an inflamed bunion, a hammer toe, metatarsalgia or secondary arthritis of the first MTP joint.
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Hallux valgus with bunions should be treated by correcting footwear prior to any surgical correction. Systematic evidence-based reviews found that preventive orthoses and night splints were unlikely to be beneficial but absorbable pin fixation was likely to be beneficial.6
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Mainly involve the second toe with extended MTP joint, hyperflexed PIP joint and extended DIP joint. Painful corns will appear over the prominent joint. They respond well to surgery if problematic and are not helped by good footwear.
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Often follows polio. The feature is extended MTP joint, flexion PIP and DIP. Refer for surgical opinion.
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Calluses, corns and warts
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The diagnosis of localised, tender lumps on the sole of the foot can be difficult. The differential diagnosis of callus, corn and wart is aided by an understanding of their morphology and the effect of paring these lumps (see TABLE 68.2).
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A callus (see FIG. 68.10) is simply a localised area of hyperkeratosis related to some form of pressure and friction. It is very common under the metatarsal heads, especially the second.
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No treatment is required if asymptomatic. Remove the cause. Proper footwear is essential—wide enough shoes and cushioned pads over ball of foot. Proper paring gives relief, also filing with callus files. If severe, apply daily applications of 10% salicylic acid in soft paraffin with regular paring.
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A corn (see FIG. 68.11) is a small, localised, conical thickening. It is a horny plug of keratin in the epidermis. A corn develops in response to chronic irritation, usually over a bony prominence of the foot, e.g. outer distal fifth toe. It is associated with poorly fitting footwear, excessive activity or faulty intrinsic foot mechanics. It may resemble a plantar wart but gives a different appearance on paring.
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Remove cause of friction and use wide shoes to allow the foot to expand to its full width. Soften corn with a few daily applications of 15% salicylic acid in collodion or commercial ‘corn removers’ with salicylic acid and then pare. For soft corns between the toes (usually last toe-web) keep the toe-webs separated with lamb’s wool or a cigarette filter tip at all times and dust with a foot powder.
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A plantar wart (see FIGS. 68.12 and 68.13 and CHAPTER 124) is more invasive, and paring reveals multiple small, pinpoint bleeding spots.
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There are many treatments for this common and at times frustrating problem. A good rule is to avoid scalpel excision, diathermy and electrocautery because of the problem of scarring. One of the problems with the removal of plantar warts is the ‘iceberg’ configuration—not all the wart may be removed.
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Can be painful and the results are often disappointing.
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Topical chemotherapy:
— soak feet in warm water, then pare wart (particularly in children)
— apply Upton’s paste or salicylic acid (up to 27%) gel or cream to wart each night and cover
— review if necessary
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(Upton’s paste comprises trichloracetic acid 1 part, salicylic acid 6 parts, glycerin 2 parts.)
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Occlusion with topical chemotherapy: a method of using salicylic acid alone or in a paste under a special occlusive dressing is described.
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Cut two lengths of adhesive tape, one about 5 cm and the other shorter.
Fold the shorter length in half, sticky side out (see FIG. 68.14A).
Cut a half-circle at the folded edge to accommodate the wart.
Press this tape down so that the hole is over the wart.
Roll a small ball of the paste in the palm of the hand and then press it into the wart.
Cover the tape, paste and wart with the longer strip of tape (see FIGS. 68.14B).
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This paste should be reapplied twice weekly for 2–3 weeks. The reapplication is achieved by peeling back the longer strip to expose the wart, adding a fresh ball of paste to the wart and then recovering with the upper tape.
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The plantar wart invariably crumbles, and vanishes. If the wart is particularly stubborn, 50% salicylic acid can be used.
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Ingrown toenail (onychocryptosis)
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Ingrown toenail is a very common condition, especially in adolescent boys. Although not so common in adults, it may follow injury or deformity of the nail bed. It is typically located along the lateral edges of the great toenail and represents an imbalance between the soft tissues of the nail fold and the growing nail edge. The basic cause is a redundant skin fold. It is exacerbated by faulty nail trimming, constricting shoes and poor hygiene. A skin breach is followed by infection, then oedema and granulation tissue of the nail fold.5
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Initial management on presentation14
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First-line management should be conservative. Gently lift the nail edge and pack moistened cotton wool soaked in 70% alcohol beneath the nail. Remove any nail spicules. Pack daily until healed. If bacterial infection, treat with a topical antiseptic, e.g. povidone–iodine 10% ointment under occlusion. Oral antibiotics will be required for infection such as cellulitis or suppuration.
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Treat any granulation tissue with curettage or electrocautery (under local anaesthetic) and/or a silver nitrate cautery stick.
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All patients should be instructed on correct foot and nail care. Foot hygiene includes foot baths, avoiding nylon socks and frequent changes of cotton or wool socks. Cotton wool pledgets can be placed beneath the nail edge to assist separation.
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It is important to fashion the toenails so that the corners project beyond the skin (see FIG. 68.15). The end of the nail (not the corners) should be cut squarely so that the nail can grow out from the nail fold. Then each day, after a shower or bath, use the pads of both thumbs to pull the nail folds as indicated.
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Treatment—the spiral tape method15
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This simple technique involves the application of strong adhesive tape such as Elastoplast or Leukosilk 12.5 mm to retract the skin off the ingrowing nail. At first, use the thumb pads, despite the discomfort, to retract the skin. The tape is then passed around the plantar surface to anchor the tape in loops around the proximal aspect of the toe (see FIG. 68.16). The application of Friar’s Balsam to the distal ‘anchor’ gives a better grip. This process is repeated 2–4 times weekly until the problem settles.
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Excision of ellipse of skin. This ‘army method’ transposes the skin fold away from the nail. The skin heals, the nail grows normally and the toe retains its normal anatomy.
Electrocautery. This is similar in principle to the preceding method but is simple, quick and very effective with minimal after-pain, especially for severe ingrowing with much granulation tissue. Under digital block the electrocautery needle removes a large wedge of skin and granulation tissue so that the ingrown nail stands free of skin (see FIG. 68.17).
Skin wedge excision. Another similar method under digital block is to dissect away all the skin fold adjacent to the nail, starting from the nail base, extending proximally for about 4 mm and then sweeping around the side of the nail to under its tip, using a 3–4 mm margin all the way.
Wedge of nail excision and phenolisation. This method uses 80% phenol (concentrated solution) to treat the nail bed following excision with scissors of a wedge for about one quarter of the length (rather than a standard wedge resection) of the ingrown nail. A cotton wool stick soaked in phenol is introduced deep into the space of the nail bed.
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Warning: Take care not to spill the phenol onto the surrounding skin as it is very corrosive.
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antiseptic (e.g. Betadine-soaked) dressing
elevation of nail fold to drain pus
application of petroleum gauze dressing
antibiotics if extensive or cellulitis developing
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Sometimes the nail requires avulsion to establish free drainage of a periungual abscess. Refer to CHAPTER 127.
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Practice tips
Good-quality X-rays are mandatory in all severely sprained ankle injuries.
If in doubt about the diagnosis of a painful foot, X-ray.
Children rarely sprain ligaments. All joint injuries causing pain and swelling in children need to be X-rayed.
Think of the rare problem of a dislocating peroneal tendon if a sharp click and stab of pain is experienced just behind and below the lateral malleolus.
Paraesthesia of part or whole of the foot may be caused by peripheral neuropathy, tarsal tunnel syndrome, mononeuritis (e.g. diabetes mellitus), rheumatoid arthritis or a nerve root lesion from the lumbosacral spine.
Avoid giving injections of corticosteroids into the Achilles tendon.
Avoid invasive procedures such as surgical excision, diathermy or electrocautery for plantar warts. Be aware of the limitations of liquid nitrogen.
High-resolution ultrasound can help diagnose Achilles tendon disorders.
Keep in mind the possibility of pain around the sesamoid bones of the first metatarsal.
Beware of acral lentiginous melanoma on the sole of the foot, especially if amelanotic (see CHAPTER 125).