Chapter 68: Pain in the foot and ankle

Pain in the foot (podalgia) and ankle problems are common occurrences in general practice. Various characteristics of the pain can give an indication of its cause, such as the description of gout by Thomas Sydenham. There are many traumatic causes of podalgia and ankle dysfunction, especially fractures and torn ligaments, but this chapter will focus mainly on everyday problems that develop spontaneously or through overuse. Forefoot pain is common especially in the elderly. The forefoot comprises the toes to the middle of the metatarsals and all of the supporting structures. Metatarsalgia is a term used to describe pain in the distal aspect of one or more of the metatarsal bones during weight-bearing.¹

A summary of the diagnostic strategy model is presented in TABLE 68.1.

Probability diagnosis

Common causes include osteoarthritis, especially of the first metatarsophalangeal (MTP) joint, acute or chronic foot strain, plantar fasciitis, plantar skin conditions such as warts, corns and calluses and various toenail problems.

Serious disorders not to be missed

The very important serious disorders to consider include:

• vascular disease—affecting small vessels

• diabetic neuropathy

• osteoid osteoma

• rheumatoid arthritis

• complex regional pain syndrome I

Vascular causes

The main problem is ischaemic pain that occurs only in the foot. The commonest cause is atheroma. Vascular causes include:

• acute arterial obstruction

• chilblains

• atherosclerosis, especially small vessel disease

• functional vasospasm (Raynaud)—rare

• claudication (rare in isolation)

• sensory disturbances, especially numbness at rest or on walking

• rest pain—at night, interfering with sleep, precipitated by elevation, relieved by dependency

For treatment refer to CHAPTER 67.

Complex regional pain syndrome I

Also known as reflex sympathetic dystrophy or Sudeck atrophy, regional pain syndrome is characterised by severe pain, swelling and disability of the feet. It is a neurovascular disorder resulting in hyperaemia and osteoporosis that may be a sequela of trauma (often trivial) and prolonged immobilisation. Complex regional pain syndrome I usually lasts 2 years and recovery to normality usually follows.

The clinical features include sudden onset in middle-aged patients, pain worse at night, stiff joints and skin warm and red. X-rays that show patchy decalcification of bone are diagnostic. Treatment includes reassurance, analgesics, mobility in preference to rest, and physiotherapy.

Osteoid osteoma

Osteoid osteomas are rare but important little ‘brain teasers’ of benign tumours that typically occur in older children and adolescents. Males are affected twice as often as females. Any bone (except those of the skull) can be affected but the tibia and femur are the main sites. Nocturnal pain is a prominent symptom with pain relief by aspirin being a feature.

Diagnosis is dependent on clinical suspicion and then X-ray, which shows a small sclerotic lesion with a radiolucent centre. Treatment is by surgical excision.

Pitfalls

There are many traps in the diagnosis and management of problems presenting with a painful foot. Common problems require consideration—these include gouty arthritis, chilblains, a stress fracture and a foreign body in the foot, especially in children. Nerve entrapment, as outlined in CHAPTER 66, is uncommon but Morton neuroma is reasonably common.

Less common disorders include complex regional pain syndrome, which is often misdiagnosed, the spondyloarthropathies (psoriasis, reactive arthritis, ankylosing spondylitis and the inflammatory bowel disorders) and osteochondritis of the calcaneus, navicular bone and metatarsal head. If there is an exquisitely tender small purple–red spot beneath a toenail, a glomus tumour (a benign hamartoma) is the diagnosis. It is worth noting that most of these conditions are diagnosed by X-rays.

General pitfalls

• Failing to order X-rays of the foot.

• Failing to order X-rays of the ankle following injury.

• Failing to appreciate the potential for painful problems caused by diabetes—neuropathy and small vessel disease.

• Neglecting the fact that most of the arthritides can manifest in joints in the foot, especially the forefoot.

• Regarding the sprained ankle in adults and children as an innocuous injury: associated injuries include chondral fractures to the dome of the talus, impaction fractures around the medial recess of the ankle, avulsion fractures of the lateral malleolus and base of fifth metatarsal.

• Misdiagnosing a stress fracture of the navicular which, like the scaphoid fracture, causes delayed union and non-union. Cast immobilisation for 8 weeks initially may prevent the need for surgery.

• Misdiagnosing a complete rupture of the Achilles tendon because the patient can plantar flex the foot.

• Overlooking tibialis posterior tendonopathy as a cause of ankle pain.

Seven masquerades checklist

The checklist has four conditions that should be considered, especially diabetes and spinal dysfunction. Diabetes may be responsible for a simple type of atherosclerotic pattern, possibly complicated by infection and ulceration. The neuropathy of diabetes can cause a burning pain with paraesthesia. It has a ‘sock’-type pattern as opposed to the dermatome pattern of nerve root pressure arising from the lumbosacral spine. The common S1 pain is experienced on the outer border of the foot, into the fifth toe and on the outer sole and heel of the foot.

Drugs and anaemia could indirectly cause pain through vascular insufficiency. The drugs that could cause vasospasm include beta blockers and ergotamine. An alcoholic neuropathy also has to be considered.

Psychogenic considerations

Any painful condition can be closely associated with psychogenic disorders, including depression.

History

This is very important, as always, since various characteristics of the pain can give an indication of its cause. Questions should address the quality of the pain, its distribution, mode of onset, periodicity, relation to weight-bearing, and associated features such as swelling or colour change. It is relevant to enquire about pain in other joints such as the hand and spine, including the sacroiliac joints, which might indicate that the foot pain is part of a polyarthritis. A history of diarrhoea, psoriasis, urethritis or iritis may suggest that one of the spondyloarthropathies has to be excluded.

Key questions

The practitioner should address the following questions:

• Does the pain arise from a local condition or is it part of a generalised disease?

• Is there a history of psoriasis, chronic diarrhoea or colitis, urethritis or iritis?

• Is pain also present in other joints, thus indicating the foot pain is part of a polyarthritis, such as rheumatoid arthritis?

• Is the problem related to unsuitable footwear?

• Does the nature of the pain point to the cause?

  • — throbbing pain → inflammation

  • — burning pain → nerve entrapment, diabetic neuropathy or regional pain syndrome

  • — severe episodic pain → gout

  • — pain worse at night → ischaemia (small vessel disease), regional pain syndrome, cramps or osteoid osteoma

  • — pain worse at night, relieved by aspirin → osteoid osteoma

  • — pain worse on standing after sitting and getting out of bed → plantar fasciitis

For ankle injuries it is important to ask about the nature of the injury:

• Did the foot twist in (invert) or twist out (evert)?

• Was the foot pointing down or up at the time of injury?

• Point with one finger to where it hurts (the finger-pointing sign).

• What happened immediately after the injury?

• Were you able to walk straight away?

• What happened when you cooled off?

If there has been a fall onto the foot from a height, consider the possibility of a fracture of the calcaneus or talus or disruption of the syndesmosis between the tibia and fibula. Also check the lumbar spine.

Examination

Inspection

Inspect the feet with the patient standing, sitting, walking (in shoes and barefooted) and lying down (note plantar surfaces). Inspect the footwear (normally, a shoe wears first on the outer posterior margin of the heel).

Note:

• any gait abnormalities, including limping and abnormal toe in or toe out

• deformities, such as hammer toes, bunions—medial (hallux valgus) and lateral (Tailor bunion)—and claw toes

• swellings, including callosities

• muscle wasting

• skin changes and signs of ischaemia

Palpation

Systematic palpation is very useful as most structures in the foot are accessible to palpation.

Movements (active and passive)

The joints to test are:

• ankle (talar) joint

• hindfoot (subtalar) joint

• midfoot (midtarsal) joint

Movements

• Plantar flexion (normal—50°) and dorsiflexion (20°) of foot (see FIG. 68.1)

• Inversion and eversion of hindfoot (mainly subtalar joint)—hold heel and abduct and adduct (see FIG. 68.2)

• Inversion and eversion of forefoot (midtarsal joint)—hold heel in one hand to fix hindfoot, hold forefoot in the other and abduct and adduct (rotation movement) (see FIG. 68.3)

• Test other joints individually (e.g. MTP, midtarsal)

Special tests

• Achilles tendon, including calf squeeze (Thompson or Simmond test)

• Compress MTP joints from above and below

• Compress metatarsals mediolaterally between thumb and forefinger

• Press upwards from sole of foot just proximal to third and fourth MTP joints—Morton test

• Check circulation—test dorsalis pedis and posterior tibial pulses

• Neurological examination, including tests for L4, L5 and S1 nerve root function

Investigations

The choice of investigations depends on the clinical features elicited by the history and examination. Select from the following list:

• for systemic diseases:

  • — blood glucose

  • — RA tests

  • — ESR/C-reactive protein

  • — HLA-B₂₇

• serum uric acid

• radiology:

  • — X-ray ± stress and weight-bearing views

  • — radionuclide scans (for bone or joint pathology)

  • — CT or MRI (especially helpful) scans

  • — ultrasound (operator dependent)

• nerve conduction studies

Note: High-resolution ultrasound is used to diagnose disorders of the Achilles and posterior tibialis tendons and to locate foreign bodies such as splinters of wood and glass.

Radionuclide scanning may detect avascular necrosis in bones, stress fractures, osteoid osteomas, inflammatory osteoarthritis and similar lesions.³

Apart from the common problem of trauma, special problems in children include:

• foreign bodies in the foot

• tumours (e.g. osteoid osteoma, osteosarcoma, Ewing tumour)

• plantar warts

• osteomyelitis/septic arthritis

• ingrowing toenails

• osteochondritis/aseptic necrosis

• osteochondritis dissecans of talus (in adolescents)

• pitted keratolysis and juvenile plantar dermatosis (adolescents)

• stress fractures

Think of osteoid osteoma in children with night pain.

Osteochondritis/aseptic necrosis

Three important bones to keep in mind are:

• the calcaneum—Sever disease

• the navicular—Köhler disease

• the head of the second metatarsal—Freiberg disease

Sever disease is traction osteochondritis, while the other disorders are a ‘crushing’ osteochondritis with avascular necrosis.

Sever disease of the heel

This is calcaneal apophysitis, which presents in a child (usually a boy) aged 7–15 years (average of 10 years) with a painful tender heel at the insertion of the tendoachilles. It is diagnosed by X-ray. The only treatment is to ensure that the child avoids wearing flat-heeled shoes and wears a slightly raised heel. Strenuous sporting activities should be restricted for 12 weeks and then reviewed.

Köhler disease of the navicular

This disorder causes a painful limp (usually mild) with some swelling and tenderness around the navicular in a child (usually a boy) aged 3–6 years, although it is seen sometimes in older children. Complete recovery occurs with temporary rest. Sometimes supportive strapping is helpful.

Freiberg disease

This problem affects the head of the second metatarsal (rarely the third), which feels tender and swollen on palpation. It is more common in girls aged 12–16 years and can present in young adults as pain aggravated by standing on the forefoot. Plain X-ray shows the characteristic collapse of the metatarsal head. The treatment is restriction of activity, protective footwear and protective padding.

Sprained ankle in a child

Children rarely sprain ligaments so it is important to assess apparent strains carefully, including an X-ray.

The little athlete

The ‘little athlete’ can suffer a variety of injuries from accidents and overuse. Diffuse heel pain, which is common, is most often related to Sever apophysitis of the calcaneum. Occasionally, a juvenile-type plantar fasciitis may occur. Little athletes can develop tendonitis around the ankle, either on the lateral side (peroneals) or medially (tibialis posterior). Occasionally, a stress fracture of the metatarsals or other bones can occur.⁴ Special attention must be paid to any developmental structural abnormalities and to footwear.

Foot problems are more prevalent in old age. Some are due to a generalised disease, such as diabetes or peripheral vascular disease, while others, such as bunions, hammer toes, calluses and corns, atrophy of the heel fat-pad and Morton neuroma, increase with ageing. The transverse arch may flatten out and the protective pads under the metatarsals may atrophy, resulting in painful callosities.

Unfortunately, many elderly people regard foot problems as a normal process but these problems actually require considerable care and attention, especially in the presence of peripheral vascular disease, diabetes or rheumatoid arthritis. Deformed toenails (onychogryphosis) are also common albeit not a painful condition.

Flat foot occurring in middle age is usually due to stretching or rupture of the tibialis posterior tendon.⁵

Sprained ankle

There are two main ankle ligaments that are subject to heavy inversion or eversion stresses, namely the lateral ligaments and the medial ligaments respectively. Most of the ankle ‘sprains’ or tears involve the lateral ligaments (up to 90%) while the stronger, tauter medial (deltoid) ligament is less prone to injury. It is important not to misdiagnose a complete rupture of the lateral ligaments.

Most sprains occur when the ankle is plantar flexed and inverted, such as when landing awkwardly after jumping or stepping on uneven ground. It is a very common sporting injury.

Clinical features (sprained lateral ligaments)

• Ankle ‘gives way’

• Difficulty in weight-bearing

• Discomfort varies from mild to severe

• Bruising (may take 12–24 hours) indicates more severe injury

• May have functional instability: ankle gives way on uneven ground

Physical examination

Perform as soon as possible:

• note swelling and bruising

• palpate over bony landmarks and three lateral ligaments

• test general joint laxity and range of motion

• a common finding is a rounded swelling in front of the lateral malleolus (the ‘signe de la coquille d’oeuf’)

• test stability in AP plane (anterior draw sign)

Is there an underlying fracture?

For a severe injury the possibility of a fracture—usually of the lateral malleolus or base of fifth metatarsal—must be considered. If the patient is able to walk without much discomfort straight after the injury a fracture is unlikely. However, as a rule, ankle injuries should be X-rayed according to the Ottawa rules.

Important causes of heel pain in adults (see FIG. 68.4)⁶ include:

• Achilles tendon disorders:

  • — tendonopathy/peritendonitis

  • — bursitis: postcalcaneal, retrocalcaneal

  • — tendon tearing: partial, complete

• bruised heel

• tender heel pad:

  • — usually atrophy

  • — also inflammation

• neuropathies (e.g. diabetic, alcoholic)

• tenosynovitis (FHL, FDL)

• ‘pump bumps’

• plantar fasciitis

• periostitis

• calcaneal apophysitis

• peroneal tendon dislocation

• nerve entrapments

  • — tarsal tunnel

  • — medial calcaneal nerve

  • — nerve to abductor digiti minimi

Ultrasound examination is useful to differentiate the causes of Achilles tendon disorders.

Achilles tendonopathy⁶

The pathology is a combination of degenerative and inflammatory changes due to overuse and may occur either in the tendon itself or in the surrounding paratendon. It presents with tendon pain during and after weight-bearing activities with a tender local swelling of the tendon. The latter is called peritendonitis rather than tenosynovitis because there is no synovial sheath.

Management

• Relative rest

• Course of NSAIDs for acute pain

• Heel padding

• Consider heel ‘raisers’

• Consider continuous topical glyceryl trinitrate as patches

• Physiotherapy for stretching and an eccentric exercise program⁶

• Physiotherapy

Complete rupture of Achilles tendon⁶

Clinical features

• Sudden onset of intense pain

• Patient usually falls over

• Feels more comfortable when acute phase passes

• Development of swelling and bruising

• Some difficulty walking, especially on tiptoe

Diagnosis

• Palpation of gap (best to test in first 2–3 hours as haematoma can fill gap)

• Positive Thompson test: compression of the calf muscles reveals an absent plantar reflex on the affected side

Treatment

• Early surgical repair (within 3 weeks)

Partial rupture

Similar history and clinical findings. Localised tenderness and very tender defect about the size of the tip of the finger.

Refer for evaluation—if gap, early surgical exploration and repair. Conservative treatment if no gap, including heel raise and crutches early.

Achilles tendon bursitis

Bursitis can occur at two sites:

• posterior and superficial—between skin and tendon

• deep (retrocalcaneal)—between calcaneus and tendon (see FIG. 68.4)

The former occurs mainly in young women from shoe friction and is readily palpated. Tenderness from the deep bursitis is elicited by squeezing in front of the tendon with the thumb and index finger: a swelling may be seen bulging on either side of the tendon.

Treatment

• Avoid shoe pressure (e.g. wear sandals)

• 1–2 cm heel raise inside the shoe

• Apply local heat and ultrasound

• NSAIDs

• Inject corticosteroid into bursa with a 25 gauge needle

Fat-pad disorders

A tender heel pad or cushion causes a dull throbbing pain under the heel. It is localised more proximal to that of plantar fasciitis. Once established, it is very difficult to treat.

The fat-pad, which consists of globules of fat encapsulated in multiple U-shaped septa, acts as a hydraulic shock absorber on heel strike. It also contains significant nerve endings.⁷ It can undergo atrophy, especially in the elderly, and also become inflamed.

Treatment

• Reduction of aggravating activity

• Weight loss (if applicable)

• Simple analgesics

• Orthotic (cushioning heel cup) ± foam insert

• Good footwear

Problems are treated with an orthotic or an insert and good footwear. Corticosteroids should be avoided as they can accelerate the atrophy.⁸

Plantar fasciitis

This common condition (also known as ‘policeman’s heel’) is characterised by pain on the plantar aspect of the heel, especially on the medial side; it usually occurs about 5 cm from the posterior end of the heel, although it can be experienced over a wide area beneath the heel. The pain radiates into the sole.

Clinical features

• Pain:

  • — under the heel

  • — first steps out of bed

  • — relieved after walking

  • — increasing towards the end of the day

  • — worse after sitting

• May be bilateral—usually worse on one side

• Typically over 40 years

• Both sexes

• Sometimes history of injury or overuse

• No constant relationship to footwear

Signs⁸

• Tenderness:

  • — localised to medial tuberosity

  • — may be more posterior

  • — may be lateral

  • — may be widespread

  • — not altered by tensing fascia (but this action may cause pain)

• Heel pad may bulge or appear atrophic

• Crepitus may be felt

• No abnormality of gait, heel strike or foot alignment

• Patient often obese

Treatment

Plantar fasciitis not associated with one of the spondyloarthritides tends to heal spontaneously in 12–24 months. It has a variable response to treatment with NSAIDs, injections, ultrasound and insoles. Rest from long walks and from running is important. Systematic reviews to date indicate that taping is effective for short-term relief. Plantar fascia-stretching exercises, when combined with prefabricated insoles and a short course of NSAIDs, are effective for short-term and long-term pain relief.⁹ Another systematic review supports a conservative approach based on maximising comfort during the 3-month period of considerable discomfort.¹⁰

Protection

Symptomatic relief is obtained by protecting the heel with an orthotic pad to include the heel and arch of the foot (e.g. Rose insole). Otherwise, a pad made from sponge or sorbo rubber that raises the heel about 1 cm is suitable. A hole corresponding to the tender area should be cut out of the pad to avoid direct contact with the sole. The aim is to get all of the foot to take the stress.

Injection technique

Disabling plantar fasciitis can be treated by injecting local anaesthetic and long-acting corticosteroid into the site of maximal tenderness in the heel. An alternative is to inject the corticosteroid into the anaesthetised heel—this is usually for temporary relief.

‘Cracked’ heels

• Soak feet for 30 minutes in warm water containing an oil such as Alpha Keri or Derma Oil.

• Pat dry, then apply a cream such as Nutraplus (10% urea) or Eulactol heel balm. Use hydrocortisone 0.5% cream for resistant cases.

• For severe cases, use sorbolene cream with 20% glycerol and 30% urea (test skin sensitivity first).

Arthritic conditions

Arthritis of the foot or ankle is a rather meaningless diagnosis and specificity is required. Typical sites of arthritic targets are shown in FIGURE 68.5.

Osteoarthritis

Osteoarthritis may occur in any of the joints of the foot, but it commonly involves the first MTP joint, leading to hallux rigidus. It can affect the subtalar joint, but the ankle joint proper is usually not affected by osteoarthritis.

Hallux rigidus

Osteoarthritis of the first MTP joint can lead to gradual loss of motion of the toe and considerable discomfort. Roomy protective footwear and relative rest is the basis of treatment, coupled with daily self-mobilisation (stretching toe into plantar flexion morning and night). Other measures include manipulation under general anaesthesia or surgery (arthrodesis or arthroplasty) for severe cases.

Rheumatoid arthritis

Rheumatoid arthritis is typically a symmetrical polyarthritis presenting with pain in the MTP joints. It may also affect the ankle, midtarsal and tarsometatarsal joints. The interphalangeal joints are seldom affected primarily. It causes pain and stiffness under the balls of the feet, especially first thing in the morning.

Gout

Gout typically affects the first MTP and should be considered with the sudden onset of pain, especially in the presence of redness, swelling and tenderness. It can affect any synovial joint and occasionally may be polyarticular. Gout is often dismissed by the patient as a ‘sprain’. A history of alcohol consumption or diuretic treatment is relevant.

Spondyloarthritides

This group of arthritic disorders (reactive arthritis, ankylosing spondylitis, psoriatic arthritis and arthritides associated with chronic bowel disorders) may involve peripheral joints. Other foot involvement includes plantar fasciitis, Achilles tendonitis and sausage-shaped toes due to tenosynovitis, and arthritis of the proximal interphalangeal joints.

It is not uncommon for people, especially the elderly, to present with the complaint of ‘burning’ feet. A careful history is needed to elicit exactly what they mean by ‘burning’—is it real pain, a cold sensation or paraesthesia?

A checklist of causes is as follow:

• vascular: ischaemic rest pain from small vessel disease, chilblains or other cold reaction, functional vasospasm (Raynaud phenomenon)

• diabetic neuropathy

• tarsal tunnel syndrome

• complex regional pain syndrome I or II

• Morton neuroma (localised pain between toes)

• psychogenic, especially anxiety

It is worth considering tarsal tunnel syndrome if there is anterior burning pain in the forefoot with associated aching in the calf. It is usually present in menopausal women and worse at night. It is caused by entrapment of the posterior tibial nerve near the medial malleolus, and may be associated with rheumatoid arthritis. Treat with physiotherapy, a medial arch support and a corticosteroid injection before contemplating surgery.

Foot strain

Foot strain is probably the commonest cause of podalgia. A foot may be strained by abnormal stress, or by normal stress for which it is not prepared. In foot strain, the supporting ligaments become stretched, irritated and inflamed. It is commonly encountered in athletes who are relatively unfit or have a disorder such as flat feet, or in obese adults.

Symptoms and signs

• Aching pain in foot and calf during or after prolonged walking or standing

• Initial deep tenderness felt on medial border of plantar fascia (see FIG. 68.6)

• Worse with new shoes, especially a change to high heels

Acute foot strain

Acute ligamentous strain, such as occurs to the occasional athlete or to the person taking long unaccustomed walks. It is usually self-limiting and recovers rapidly with rest.

Chronic foot strain

Foot strain will become chronic with repeated excessive stress or with repeated normal stress on a mechanical abnormality. A common consequence is an everted foot, leading to flattening of the longitudinal arch on weight-bearing. It is important to establish whether the symptoms commenced after the patient began wearing a different type of footwear.

Treatment

The treatment is basically the same as that of the adult flat foot. Acute strain is treated with rest and by reducing walking to a minimum. Try the application of cold initially and then heat. The management of chronic strain is based on an exercise program and orthotics, including arch supports, to correct any deformity.

• Avoid wearing high heels.

• Wear insoles to support the foot arch.

• Perform foot exercises.

• Soak the feet in a basin of warm water containing therapeutic salts (Epsom salts is suitable).

• Massage feet with baby oil followed by a special ribbed wooden foot massager.

Flat feet are normal in young children. No treatment is required in flat feet in which the arch is restored by standing on tiptoe (see CHAPTER 92). If painful, treat with exercises and insoles. Refer if concerned. Hind foot fusion can be performed for severe pain.

High foot arch is usually of congenital origin. It may be secondary to polio or various neurological conditions. The foot is inflexible and the toes may be ‘hammer’ or clawed. Treatment includes special orthotics with good shock-absorbing properties, appropriate footwear, foot exercises and padding under the metatarsal heads. Operative treatment involves soft tissue release or arthrodesis to strengthen toes.

Disorders of the ankle tendons

Inflammation of a tendon sheath surrounding the ankle may result from repetitive overuse, trauma such as a sprained ankle or unaccustomed stress, including sporting injuries.

Tenosynovitis commonly involves the tibialis posterior tendon over the medial compartment or the peroneal tendons over the lateral compartment. It may also affect the tibialis anterior and extensor digitorum longus tendons. Friction at the point where the tendons become angulated at the ankle causes the inflammation. The patient presents with pain, swelling and restricted movement. On examination there is swelling and tenderness where the tendon bulges out from behind and below the malleolus.

If necessary, the diagnosis can be confirmed by ultrasound or MRI imaging.

Complications include tenovaginitis, weakness, ganglion formation, subluxation or dislocation and rupture.

Treatment of tendonitis includes partial immobilisation (rarely in a cast) or an orthotic device to support the arch of the foot.

A carefully directed injection of corticosteroid into the tendon sheath can be very effective.

Peroneal tendonitis

This occurs along the course of the tendon from behind the lateral malleolus to the outer side of the foot and is common in athletes and ballet dancers. Pain is reproduced on palpation, on stretching the tendons by passive inversion of the foot or by resisting eversion of the foot.

Peroneal tendon dislocation

This is most commonly a dislocated leg tendon as a result of forceful dorsiflexion. An audible painless snapping sensation may be experienced. Surgical repair is necessary.

Tibialis posterior tendonopathy

This is a common problem, especially in middle-aged females, in ballet dancers and in those with pes planus with a valgus deformity. The tendon (see FIG. 68.7), which is an invertor of the foot, is attached to the navicular tuberosity.¹¹

Clinical features^6,11

• Pain and a feeling of weakness in the medial ankle and foot

• Pain aggravated by standing and walking

• Standing on toes is painful and difficult

• Pain on palpation anterior and inferior to the medial malleolus

• Pain on stretching into eversion

• Painful resisted active inversion

• May cause tarsal tunnel syndrome

Diagnosis

Ultrasound examination—but MRI is the gold standard for delineating tendon tears and inflammation.¹²

Treatment

This is basically conservative with a good outcome in 12–24 months.

• Orthotic correction (bilateral) with semi-rigid orthosis to support faulty arch

• Exercises under physiotherapist guidance

• Remedial massage

Consider ultrasonic guided injection of corticosteroids into tendon sheath (but best avoided) and a surgical opinion for failed conservative management.

Tibialis posterior tendon dislocation

This can occur with forceful ankle dorsiflexion and inversion. The patient usually experiences pain and cannot weight-bear. The dislocated tendon may be seen overlying the medial malleolus. Immediate surgical repair is recommended.

Tibialis posterior tendon rupture

Rupture of the tibialis posterior tendon after inflammation, degeneration or trauma¹³ is a relatively common and misdiagnosed disorder, especially in middle-aged females. It causes collapse of the longitudinal arch of the foot, leading to a flat foot.⁵

It is uncommon for patients to feel obvious discomfort at the moment of rupture. They may subsequently present with the sudden appearance of an ‘abnormal’ flat foot. There is gross eversion of the foot.

A simple test is the ‘too many toes’ test whereby more toes are seen on the affected side when the feet are viewed from about 3 m behind the patient (see FIG. 68.8).⁵

The single heel raise test is also diagnostic. The most useful investigation is an ultrasound examination. Minor cases can be treated conservatively with orthotics, but severe problems respond well to surgical correction.

Sesamoiditis¹

The two sesamoids that lie beneath the head of the first metatarsal may develop painful conditions such as chondromalacia, osteoarthritis and stress fractures. A special ‘sesamoid’ X-ray assists diagnosis. A painful callus can develop over here in the elderly. Well-designed insoles are usually effective, as is surgical excision for persistent problems.

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.

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.

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.

Stress fractures¹⁴

Clinical features

• 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

Avulsion fracture of base of fifth metatarsal

Known also as a Jones fracture, it is usually a traumatic fracture but can be a stress fracture and associated with severe ankle sprains.

March fracture of metatarsal

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.

Tarsals, especially navicular

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.

Calcaneum

Stress fractures of the os calcis usually have an insidious onset. Osteoporosis is a predisposing factor, as is an increased training program.¹⁴

Morton neuroma¹²

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.

Clinical features

• 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

Treatment

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.

‘Turf toe’

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.

Treatment is conservative with RICE, NSAIDs and relative rest. Surgical intervention may be required.

Hallux valgus

Hallux valgus with associated bunion formation and splaying of the forefoot is common. It may be a consequence of poor-fitting footwear.

A bunionette, also caused by pressure, may form over the fifth metatarsal.

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.

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

Hammer toes¹

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.

Claw toes

Often follows polio. The feature is extended MTP joint, flexion PIP and DIP. Refer for surgical opinion.

Calluses, corns and warts

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).

Calluses

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.

Treatment

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.

Corns

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.

Treatment

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.

Plantar warts

A plantar wart (see FIGS. 68.12 and 68.13 and CHAPTER 124) is more invasive, and paring reveals multiple small, pinpoint bleeding spots.

Methods of removal¹⁵

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.

• Salicylic acid 17%, lactic acid 17% in collodion:

  • — apply daily, dry and cover

• Liquid nitrogen:

  • — pare wart (a 21 gauge blade is recommended)

  • — apply liquid nitrogen

  • — repeat weekly for up to 3 weeks

Can be painful and the results are often disappointing.

• 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

(Upton’s paste comprises trichloracetic acid 1 part, salicylic acid 6 parts, glycerin 2 parts.)

• Topical chemotherapy and liquid nitrogen:

  • — pare wart

  • — apply paste of 70% salicylic acid in raw linseed oil

  • — occlude for 1 week

  • — pare on review, then apply liquid nitrogen and review

• Curettage under local anaesthetic:

  • — pare the wart vigorously to reveal its extent

  • — thoroughly curette the entire wart with a dermal curette

  • — hold the foot dependent over kidney dish until bleeding stops (this always stops spontaneously and avoids a bleed later on the way home)

  • — apply 50% trichloracetic acid to the base

Occlusion with topical chemotherapy: a method of using salicylic acid alone or in a paste under a special occlusive dressing is described.

Equipment

• 2.5 cm (width) elastic adhesive tape

• 30% salicylic acid in Lassar’s paste of plasticine consistency

Method

1. Cut two lengths of adhesive tape, one about 5 cm and the other shorter.

2. Fold the shorter length in half, sticky side out (see FIG. 68.14A).

3. Cut a half-circle at the folded edge to accommodate the wart.

4. Press this tape down so that the hole is over the wart.

5. Roll a small ball of the paste in the palm of the hand and then press it into the wart.

6. Cover the tape, paste and wart with the longer strip of tape (see FIGS. 68.14B).

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.

The plantar wart invariably crumbles, and vanishes. If the wart is particularly stubborn, 50% salicylic acid can be used.

Ingrown toenail (onychocryptosis)

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

Initial management on presentation¹⁴

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.

Treat any granulation tissue with curettage or electrocautery (under local anaesthetic) and/or a silver nitrate cautery stick.

Prevention

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.

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.

Treatment—the spiral tape method¹⁵

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.

Treatment—surgical¹⁵

1. 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.

2. 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).

3. 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.

4. 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.

Warning: Take care not to spill the phenol onto the surrounding skin as it is very corrosive.

Paronychia

Initial treatment:

• antiseptic (e.g. Betadine-soaked) dressing

• elevation of nail fold to drain pus

• application of petroleum gauze dressing

• antibiotics if extensive or cellulitis developing

Sometimes the nail requires avulsion to establish free drainage of a periungual abscess. Refer to CHAPTER 127.

Hand-out sheets from Murtagh’s Patient Education 7th edition:

• Bunions

• Calluses, corns and warts on feet

• Flat feet

• Ingrowing toenails

• Plantar fasciitis