13.22 The foot in childhood

The limb buds appear 4 weeks after fertilization and form rapidly over the next few weeks. By 10 weeks, joint cavitation has occurred and ligaments and capsule have developed with forefoot ossification. Ossification proceeds progressively to the hindfoot and at birth, ossification centres are seen throughout the forefoot, the calcaneum, cuboid, and talus. The navicular ossifies last between 2–5 years. An additional ossification centre develops in the posterior aspect of the calcaneum at approximately 6 years and numerous other accessory ossification centres may be noted with growth (Box 13.22.1).

It is not uncommon for a problem to occur during fetal maturation. Failure of formation may be complete or partial and the anomalies classified as terminal transverse or longitudinal deficiencies involving either the preaxial or postaxial border. The foot anomaly may simply be part of a more generalized limb deficiency, such as fibular dysplasia, or it may be restricted to the foot but associated with similar anomalies in the hand. Such foot deformities include ectrodactyly (or lobster claw foot), absent or short metatarsals, syndactyly, and polydactyly (Figure 13.22.1).

The most significant congenital foot abnormality is the clubfoot or talipes equinovarus deformity which is discussed separately (see Chapter 13.21).

Genetic disorders can be inherited in either dominant or recessive modes and the associated anomalies may affect the foot alone or be part of a more generalized condition. Polydactyly and syndactyly are common examples of inherited conditions (Figure 13.22.2). Minor genetic variations, such as the number of phalanges in the fifth toe, often have little clinical significance. The common major chromosomal malformations are associated with foot abnormalities (Box 13.22.2).

Many conditions seen during the neonatal period are inherited and appropriate genetic counselling helps with management. In the older child, the history of onset of symptoms and deformity becomes more important. Clinical photographs and standard radiographs may help in documenting progression of deformity.

Pain becomes a more common complaint with increasing age. Severe unremitting night pain suggests a serious pathology. Pain occurring in a specific area during a specific activity suggests a mechanical cause whilst a burning pain in association with swelling may indicate an inflammatory condition. In children, the report of pain is often second hand and the parents’ and the child’s interpretation of the pain may be different. A child who truly has severe pain, even intermittently, is unlikely to behave normally at other times of the day.

At all ages, it may be difficult to conduct an adequate foot examination but the standing posture, gait, and function should be observed with a particular focus on lower limb alignment and asymmetry. A generalized neuromuscular examination should be performed in addition to a survey of all lower limb joints and the spine.

The simplest active movements of the foot and ankle are dorsiflexion and plantar flexion but this movement is not confined to one standard axis. In the hindfoot joints, all movement is around an oblique axis such that dorsiflexion includes elements of both external rotation (motion around a vertical axis) and pronation (motion around a longitudinal axis). Plantar flexion includes an element of internal rotation and supination. Inversion as an active movement not only has supination but also plantar flexion and internal rotation; eversion includes mainly pronation, dorsiflexion, and external rotation (Figure 13.22.3). All hindfoot joints contribute to these movements and loss of movement at one joint is often disguised by increased movement at another neighbouring joint. Assessment of the passive joint ranges at differing levels helps identify this.

The neonatal foot may be relatively easy to examine but careful observation is necessary to assess muscle activity and power. The neonate and young infant are best examined in an informal manner with the child supported on the parent’s knee and distracted by suitable activity. In the older child, a more formal structured examination becomes feasible.

Children over the age of 4 years can generally stand for AP and lateral weight-bearing radiographs that allow the foot to be seen in its fully loaded position. The site of deformity can be identified and measurements made with reference to the weight-bearing surface to document progressive deformity. Under this age, non-weight-bearing films are accepted. An oblique view may demonstrate abnormalities of the midtarsal and tarsometatarsal regions identifying accessory ossicles or coalitions.

In the child, bone scans can be helpful in isolating inflammatory and infective aetiologies, while computed tomography (CT) and magnetic resonance (MR) scans are useful in the diagnosis and assessment of anatomic abnormalities such as coalitions (Figure 13.22.4) and soft tissue disorders. Three-dimensional CT imaging has a potential role in planning surgical intervention (Figure 13.22.5).

These deformities arise in late pregnancy, in an otherwise normal limb, and are generally due to fetal crowding and consequent moulding secondary to oligohydramnios or a twin pregnancy. They are characterized by the lack of significant structural changes and the ease with which they correct, usually spontaneously, soon after birth. Their greatest significance lies in the increased joint laxity with which they may be associated.

This condition, the most common postural foot deformity, is ass ociated with other postural deformities such as torticollis, plagiocephaly, infantile skeletal skew, developmental hip dysplasia, and hyperextension deformity of the knee. It is more common in girls. The foot is dorsiflexed with a variable degree of eversion. Most feet are passively correctible and improve promptly but if the soft tissues over the dorsum of the ankle are tight, stretching exercises are advocated.

Metatarsus adductus is a common benign postural deformity. It is often bilateral and associated with DDH as part of fetal moulding. The child often presents with an in-toeing gait with the abnormality confined to the forefoot. The metatarsals are adducted at the level of the tarsometatarsal joint and the severity of the deformity is assessed by the curvature of the medial border and whether the deformity is correctible or not (Table 13.22.1) (Figure 13.22.6). The forefoot may be supinated as well as adducted. A stiff foot with a deep medial sulcus represents a severe deformity.

Plain radiographs of the foot are rarely needed but demonstrate the abnormal alignment of the forefoot compared to the hindfoot.

The vast majority of cases resolve by the age of 3 years. Although widely advocated, stretching exercises probably make little difference to the long-term outcome. Straight or reverse-last shoes have been recommended in children with flexible deformities and serial casting may be helpful in rigid deformities.

Significant persistent deformity beyond the age of 4 years may warrant surgical treatment. Up to the age of 6 years, soft tissue procedures (abductor hallucis recession, medial release, and tarsometatarsal release) may suffice. In older children with more rigid deformities, osteotomy of either the metatarsals or preferably the midfoot (lateral closing, medial opening wedge osteotomies) should be considered.

Isolated forefoot anomalies may occur but they are often associated with more proximal problems and the foot must be examined carefully to identify them. The most frequent hindfoot and midfoot abnormalities lead to a position that is planus (flatfooted) and valgus, or cavus (high arched) and varus.

Flexible flat feet are found in up to 30% of the adult population so it is important to differentiate between the healthy ‘normal’ flatfoot and the ‘pathological’ flat foot that becomes mechanically inefficient and therefore symptomatic.

The characteristic feature of the flatfoot is loss of the medial longitudinal arch. In the hindfoot there is plantar flexion and medial rotation of the talus that almost certainly becomes pathological at the point when the calcaneonavicular (spring) ligament fails, perhaps due to increasing laxity. This change in alignment has secondary effects: the calcaneum moves into valgus altering the line of pull of the Achilles tendon. This then becomes tight in its laterally displaced position limiting the ability of the heel to return to a neutral or varus position. In the normal foot the calcaneocuboid joint (CCJ) movement is approximately half that of the talonavicular joint, primarily because of its more complex anatomical shape. With hindfoot deformity, the CCJ becomes subluxed, effectively fixing the position of the forefoot; further deformity of forefoot abduction and supination can occur and if secondary contractures develop the deformity becomes fixed.

It is useful to consider whether the foot is primarily rigid or flexible. The ‘surgical sieve’ can be considered for each category. Asymmetry can indicate unilateral pathology as in the unusual event of a laceration of the tibialis posterior tendon or involvement of the subtalar joint with an inflammatory arthritis. The flexible foot may be normal or associated with excessive and generalized joint laxity commonly seen in conditions such as Ehlers–Danlos, Marfan, trisomy 21, and osteogenesis imperfecta. Other causes of acquired flatfoot are muscle imbalance, contractures, and arthritic conditions.

Flat feet may present with problems due to ill-fitting shoes or with concerns about abnormal shoewear. As the child progresses into puberty, particularly if he or she is obese, there may be aching discomfort. These minor problems settle at maturity. The flexibility of the foot is determined by watching the behaviour of the longitudinal arch in walking and during tip-toe standing. The latter should improve the longitudinal arch whilst the calcaneum swings into varus. Passive dorsiflexion of the first toe as the child stands (Jack’s test) should produce the same appearance.

Standing anteroposterior and lateral films identify the site of joint subluxation. Primary and secondary deformity can occur at any joint along the medial column but the talonavicular joint is the most common level. The navicular becomes abducted and dorsiflexed relative to the talus. Although the overall appearance is one of a pronated foot, differential dorsiflexion of the first ray and plantar flexion of the fifth ray may produce relative supination of the forefoot with respect to the hindfoot. The overall alignment of bones and joints can be measured and compared both with normal values and on serial films. Although these angles may illustrate the severity of the deformity, their main purpose is in monitoring its progression.

Several factors should be considered before treatment is advocated.

Treatment of the asymptomatic mobile flat foot is unnecessary. These children have a normal exercise tolerance. If abnormal shoewear is causing problems, insoles may improve matters.

Some flat feet, despite having mobile joints, are functionally rigid because of the severity of their joint laxity or because the muscles have undergone secondary contracture. Exercises that stretch the gastrocsoleus complex and strengthen the tibialis posterior muscle may be important: once the foot regains its flexibility, orthotic supports can be used to maintain the neutral foot position. This may prevent symptoms and the tendency for contractures to occur which place an increasing pressure on the foot to deform as it grows. Evidence suggests that a variety of customized devices can control foot position and some studies have shown additional benefits including pain relief and improvement in gait pattern. Other studies suggest that such benefits are only seen in the more severely deformed feet. It is probable that if this form of symptomatic treatment is to be successful, it must continue throughout the adolescent growth spurt.

It is inappropriate to consider surgery in the vast majority of children with a flexible flat foot. The small group of children who have a functionally rigid foot associated with increased joint laxity may be suitable for surgical treatment if their deformity becomes progressive and there is a functional deficit with symptoms. Pain is often felt medially due to strain of the tibialis posterior and the medial capsular structures or laterally secondary to impingement in the sinus tarsi or between the lateral malleolus and the calcaneum. Operative treatment should only be considered if all conservative methods have failed to relieve symptoms or prevent progressive deformity. Surgery may involve soft tissue procedures, osteotomies or fusion of selected joints.

In planning surgical management, several factors must be considered. Soft tissue procedures include those that aim to reef or tighten the medial ligamentous structures and those which seek to redirect the pull of various tendons in the foot, but they are rarely performed in isolation. Osteotomies correct the valgus position of the calcaneum or lengthen the functionally short lateral border of the foot. Arthrodesis of one or more of the hindfoot joints is a last resort.

The overall incidence of this condition is less than 1%. Occasionally they are associated with carpal coalitions. There is evidence to support an autosomal dominant inheritance for calcaneonavicular bars.

Coalitions are classified according to the site of involvement and whether they are part of a complex malformation or not. Coalitions may be complete or incomplete, or may be bony (synostosis), cartilaginous (synchondrosis) or fibrous (syndesmosis).

Although present from birth, they are rarely recognized before the adolescent growth spurt when the coalition becomes partially or completely ossified. This leads to a reduction in hindfoot movement that may be associated with pain, especially if the coalition is fibrous. Patients may also present with deformity. A planovalgus foot may be associated with peroneal muscle spasm (peroneal spastic flatfoot) whilst a heel with mild varus and reduced subtalar movement may present with symptoms of ankle instability.

As a simple screening test, the lack of a longitudinal arch when the flat-footed child stands on tip-toe is highly suggestive of a coalition. In the presence of a coalition, inversion/eversion may appear to be preserved but in reality the movement is often occurring at ankle level.

Initial anteroposterior, lateral, and oblique views may show talonavicular and calcaneocuboid coalitions (Figure 13.22.7). Talocalcaneal bars are the most difficult to diagnose radiologically: they may be seen on an axial view of the calcaneum and by the ‘C’ sign on a lateral view of the hindfoot (Figure 13.22.8). Imaging techniques such as CT and MRI scanning (Figure 13.22.4) are more helpful and will also reveal incomplete and fibrous coalitions.

Initially, activity restriction or a period of cast immobilization may help but if symptoms persist then surgical treatment is warranted (Box 13.22.7). The nature of the surgery will depend on the age of presentation and the type, site and extent of the coalition. The options lie between bar excision and fusion. Arthrodesis should only be considered for non-resectable bars, for joints with extensive involvement or in the older patient where there is evidence of joint degeneration. Bar excision results in good relief of pain but surgery does not usually lead to a significant improvement in joint motion.

This rare disorder has an equal sex distribution and the majority of cases occur bilaterally. It may occur as an isolated deformity or in combination with other congenital malformations.

The primary deformity is a dorsal dislocation of the navicular onto the talar neck effectively locking the talus in the vertical position. The secondary deformities of hindfoot equinus and forefoot dorsiflexion and eversion arise from this producing the typical rocker-bottom foot (Figure 13.22.9).

The sole of the foot is convex with the talar head prominent on its medial aspect. The forefoot is abducted and dorsiflexed while the hindfoot is in equinovalgus. The muscles of the anterior and lateral compartments are tight. The deformity is rigid such that there is no restoration of the longitudinal arch with any foot position. Passive correction of the deformity is not possible.

On plain lateral radiographs the talus lies vertically with its axis parallel to that of the tibia. The calcaneus is in equinus and the forefoot is dorsiflexed. In infancy, the cartilaginous navicular is not visible but later, when ossified, it can be seen lying on the dorsum of the neck of the talus (Figure 13.22.10).

The aim of treatment is to reduce the talonavicular joint dislocation and restore normal alignment of the forefoot on the hindfoot and the hindfoot on the tibia.

Non-operative treatment is with passive stretching, which should be started as soon as possible after birth. The principles of the Ponseti management of the talipes equinovarus deformity have been ‘reversed’ and used with some success for this equinovalgus deformity. Once the talonavicular joint has been reduced, it is stabilized with a K-wire. A tenotomy of the Achilles tendon is then performed to achieve ankle dorsiflexion. Foot abduction orthoses (‘boots and bars’) are used and supplemented with AFOs once the child is able to weight-bear.

If these measures fail to reduce the dislocation, operative management will be necessary. A full peritalar release is often required. Many surgeons transfer the tibialis anterior tendon to the talar neck in addition to reefing the tibialis posterior tendon and the stretched capsular tissues on the inferior aspect of dislocated joint. In syndromic cases, talectomy may need to be performed as a primary procedure although usually it has been reserved for management of the relapsed foot with significant recurrent deformity.

In older children, soft tissue procedures alone are unlikely to be successful, and excision of the navicular has been advocated. After the age of 6, open reduction is associated with a significant risk of avascular necrosis of the talus, and in children presenting at this late stage, it is better to delay surgery until a triple fusion is appropriate.

A variety of foot deformities present with a high longitudinal arch. This may be due to abnormalities in the hindfoot, the forefoot, or both and a significant number of children will have an underlying neurological abnormality.

Pes cavus is a high arched foot where the longitudinal arch fails to flatten with weight-bearing. A high arched foot has an angle of 150 degrees or less between the long axes of the first metatarsal and calcaneum on a standing lateral radiograph.

The calcaneum is dorsiflexed and often in varus. The forefoot deformity varies but frequently involves a degree of plantar flexion of the metatarsals. Claw toes are commonly seen in the cavus foot along with tightness of the plantar fascia. At the metatarsophalangeal joints (MTPJs), there is a range of deformity from fully mobile claw toes to toes that are dorsally dislocated.

The hindfoot varus may be due primarily to a stiff subtalar joint or, more commonly, it may be secondary to plantarflexion of the medial metatarsals relative to the lateral rays. This differential plantarflexion pronates the forefoot which can only be accommodated if the hindfoot goes into varus.

Feet with a cavus deformity can be classified according to the level of the aetiological insult within the neuromuscular system (Table 13.22.2). In children, dysraphism, cerebral palsy, undercorrected clubfoot, and arthrogryposis are the most common causes of cavus feet.

In children, the family history is crucial. The age of onset of the deformity may indicate the likely cause and predict the rate of progression. Evidence of progression must always be documented carefully. Each component of the foot (hindfoot, midfoot, forefoot) must be examined in turn to define the deformity and ascertain whether it is flexible or fixed. The Coleman block test is particularly important when assessing hindfoot varus. It tests the flexibility of the hindfoot in the presence of fixed forefoot deformity. The neurological examination must include assessment of the spine especially when there is asymmetrical foot involvement.

Standard weight-bearing radiographs are important in assessing the degree of deformity, monitoring its progression and planning treatment. If the calcaneal pitch, (the angle between the plantar surface of the calcaneum and the weight-bearing surface) is greater than 30 degrees, the calcaneum is excessively dorsiflexed. Spinal radiographs supplemented with MRI are often required to identify treatable causes of a progressive neurological lesion.

Other investigations may be necessary to identify the neurological cause.

Stretching exercises for the Achilles tendon, other long tendons, and plantar structures should be performed regularly. A flexible deformity can be held with an AFO or balanced with outside wedges on the shoes or by posting the outer border of an insole. Appropriate, customized shoewear can be used to accommodate a fixed deformity. The aim of treatment is reduce pain and prevent progression of deformity.

In childhood the deformity is usually mobile. Release of the soft tissues of the longitudinal arch in combination with tendon transfers may help to correct deformities and rebalance muscle pulls which should reduce recurrence.

Correction of claw toes can be achieved by soft tissue surgery in children. In the younger child with significant growth potential, the great toe can be corrected by a modified Jones procedure where the long extensor is used both to elevate the first metatarsal by transfer to the neck of the metatarsal and to tenodese the interphalangeal joint (IPJ). Alternatively, the long extensor can be transferred to peroneus tertius. The older child may undergo a more traditional Jones procedure where the IPJ is fused. The lesser toes can be treated by a variety of methods including tendon transfer although IPJ fusions are often required eventually.

If the deformity is fixed, bony surgery is usually necessary. In general, arthrodesis should not be performed in a growing foot. Midfoot and hindfoot osteotomies can be performed. Metatarsal or midfoot osteotomies may correct fixed plantar flexion. A calcaneal osteotomy will correct a varus heel. In adolescence, a triple arthrodesis can be considered in order to stabilize the foot in a plantigrade position.

This uncommon deformity is characterized by hindfoot valgus and forefoot adduction and supination. Historically, many such feet were a result of aggressive surgery for a congenital talipes equinovarus deformity. The primary deformity is felt to be medial subluxation of the tarsometatarsal joints leading to fixed forefoot adduction. The talonavicular joint is subluxed dorsolaterally.

In infancy, this condition must be differentiated from congenital talipes equinovarus and metatarsus adductus which both have an adducted forefoot with a medial skin crease. The distinguishing features are in the midfoot and hindfoot. In talipes equinovarus, the hindfoot is fixed in equinus and varus but in the skew foot the hindfoot is in valgus although this may be difficult to appreciate in the newborn. The midfoot changes differentiate skew foot from metatarsus adductus: the medial border of the foot is concave in metatarsus adductus but in the skew foot, there is a medial convexity at the level of the talonavicular joint proximal to the forefoot concavity (Figure 13.22.11).

Weight-bearing anteroposterior and lateral views reveal the hindfoot valgus and the forefoot adductus. The midfoot is shifted laterally with respect to the hindfoot. The lateral view may show a degree of midfoot cavus.

The natural history of the skew foot is unclear. While some may correct either spontaneously or with simple measures such as serial casting, others persist to cause long-term disability. Casting may correct the forefoot adductus, but will have limited effect on the hindfoot valgus. If the Achilles tendon shortens, the hindfoot valgus is accentuated.

Symptomatic skew feet generally require operative treatment. Stretching the Achilles tendon may benefit those with plantar heel pain. All components of the deformity must be addressed. A calcaneal lengthening osteotomy to correct hindfoot valgus has good long-term results but should be combined with a forefoot correction, which might entail a medially based opening wedge osteotomy of the medial cuneiform and a closing wedge of the cuboid. The Achilles tendon may need lengthening to allow full correction of the hindfoot deformity.

The hallux is in varus. It is important to establish whether this is an isolated abnormality or part of a more generalized condition. There is medial deviation of the proximal phalanx of the hallux.

Three types of hallux varus can be recognized. The first is an isolated or local type where the primary abnormality is a tight band of tissue extending along the medial side of the foot. The effect of this band is to pull the great toe further into varus with growth. A second group relates to patients who have a set of congenital deformities including a marked varus of the first metatarsal, which is also short and broad. There may be an adjacent medial accessory bone. This type may be due to a longitudinal epiphyseal bracket. Finally, it can occur in more generalized conditions such as diastrophic dysplasia. Plain radiographs will distinguish the different types of the condition.

Non-operative treatment has little or no effect. Surgical correction involves lengthening the tight medial structures and stabilizing the first MTPJ. Temporary K-wire fixation of the joint is needed. If there is varus deviation of the first metatarsal, a metatarsal osteotomy is indicated. In the second type, the growth disturbance of the first metatarsal may contribute to recurrence after surgery. In these cases, it may be necessary to syndactylize the first and second toes in order to prevent progressive deformity.

This is a relatively uncommon condition. The familial incidence is higher in adolescent hallux valgus compared to the adult onset type of hallux valgus. It is significantly more common in girls and its development may be influenced by footwear. Shoes with a narrow toe box force the hallux into a valgus position whilst high heels transfer weight from the lesser metatarsals medially and may also contribute to the deformity. There may be an associated primary varus angulation of the first metatarsal.

The foot should be examined weight-bearing to determine the true degree of valgus and pronation. As with all childhood foot deformities, a neurological cause must be excluded.

Weight-bearing anteroposterior radiographs are essential and various angular measurements should be made.

Initial management should be non-operative with shoewear modification. If the deformity is progressive or symptoms are severe, surgery may be warranted. Soft-tissue procedures alone are frequently unsuccessful. If the intermetatarsal angle between the first and second metatarsals is 15–20 degrees (metatarsus primus varus), a distal metatarsal osteotomy may suffice. Larger intermetatarsal angles require a more proximal osteotomy such as the Scarf combined with distal soft tissue realignment. Recurrence rates are higher than in mature feet.

This is a congenital, often bilateral, condition where there is marked lateral deviation at the IPJ of the hallux. In young children, the condition is generally asymptomatic. Local irritation over the IPJ may cause problems in adolescence in which case a medial closing-wedge osteotomy of the proximal phalanx will correct the deformity.

This rare congenital anomaly is characterized by absence of two or three of the central rays of the foot and inherited as an autosomal dominant trait with incomplete penetrance. It is bilateral and often associated with cleft hand and other anomalies. Unilateral cases are sporadic in nature. The incidence is reported to be 1: 90 000 live births (see Figure 13.22.1).

The hindfoot is normal but the central rays of the forefoot are absent to a variable degree. The classification system (Table 13.22.3) is based on degree of metatarsal deficiency. Types IV and V are the most common forms.

The foot usually functions well and no surgery is necessary in the milder forms. Surgery is usually indicated for cosmetic reasons and to improve shoe wear. The foot is narrowed by basal metarsal osteotomies and/or reduction of subluxed tarsometatarsal joints with closure of the cleft and soft tissue reconstruction. It is important to ensure that the resultant foot is supple and plantigrade. Surgery is usually performed between 1–2 years of age.

This common congenital condition affects one or more toes. It is usually bilateral, symmetrical and often familial. The affected toes (usually third and/or fourth) curl medially and tend to lie under the neighbouring toe. A tenotomy of all flexor tendons to the affected toe is often recommended for cosmetic reasons. An osteotomy performed later may be more effective in producing a lasting result.

This common familial abnormality is often bilateral. The toe is dorsiflexed and adducted, overlying the fourth toe. The MPTJ is subluxed due to capsular contracture. Symptoms develop in about 50% of cases. Non-operative treatment methods (stretching, strapping) are rarely successful. Surgical treatment is warranted for symptom relief or for cosmesis and is usually successful. Recurrence may occur but bony surgery such as proximal phalangectomy is rarely indicated and never in a child.

This is a rare deformity that may be secondary to neurofibromatosis (NF), haemangiomatosis, or congenital hyperplasia of the lymphatic and adipose tissue. The diagnosis of NF must be excluded by careful clinical examination. In true gigantism, there is an increase in size of all the elements of the toe. The degree of hypertrophy is variable: sometimes the deformity is static in that the increase in size is proportionate to growth but in others there is progressive disproportionate growth. If the appearance is unacceptable, surgery is indicated. Several procedures have been described, none of which is very successful. Simple debulking and epiphysiodesis is frequently followed by recurrence. Ray amputation may be indicated in severe cases of recurrence but may be complicated by the development of hallux valgus.

Polydactyly is a common deformity occurring in 2:1000 live births (see Figure 13.22.2). It is often inherited in an autosomal dominant fashion but sporadic cases do occur. There may be associated polydactyly of the hand or other major congenital malformations such as tibial aplasia. It is also seen in syndromes such as Ellis–van Creveld syndrome and chondroectodermal dysplasia.

The extra toe may be preaxial (15%), postaxial (80%), or central. The child must be assessed thoroughly to look for associated malformations. The extra digit may be either fully formed or rudimentary. Plain radiographs will show the level and extent of bony duplication.

The extra toe should be excised both for cosmetic reasons and for shoe fitting although some cultures are opposed to this. The operation is best performed when the child is around 9–12 months old. Generally the most peripheral toe is excised, although radiographic appearances must be considered.

Osteochondroses affect active growth areas and involve a defect in ossification in either an epiphysis or an apophysis. They generally occur soon after the ossific nucleus has appeared when the epiphysis is growing rapidly. Most are more common in boys.

Osteochondritis of the navicular occurs predominantly in children aged 3–6 years. Boys are more commonly affected and up to 33% are bilateral. The navicular is the last bone of the foot to ossify and may be subjected to significant pressures while still cartilaginous as it is the keystone to the longitudinal arch. Histologically, avascular necrosis is seen.

Clinically, there is pain, swelling, and tenderness around the navicular and the child limps. There may be surrounding warmth and erythema but the normal movement at the mid-tarsal and subtalar joints distinguishes this from inflammatory arthritides.

Radiographs show a small, sclerotic ossific nucleus and diagnosis rests on the combination of radiographic appearances and the clinical picture (Figure 13.22.12).

The condition is self-limiting and the prognosis good. Symptomatic improvement usually occurs within a few months. If symptoms are severe, a period of immobilization in a cast may be warranted.

Osteochondritis of the calcaneal apophysis affects boys predominantly between the ages of 8, when the apophysis first appears, and 12 years, when it fuses with the parent bone. It is a common cause of heel pain in the immature athlete, probably related to overuse. The diagnosis rests on clinical symptoms and signs. There is pain and tenderness around the insertion of the Achilles tendon to the calcaneum. Radiographs show sclerosis and fragmentation of the calcaneal apophysis, features which are consistent with normal apophyseal development.

Like the other osteochondritides, this is a self-limiting condition and symptoms abate once the apophysis has fused. Stretching the gastrocnemius and soleus with strengthening of the anterior muscles helps to reduce symptoms and activity should be reduced. A period of rest in plaster may be necessary to control symptoms.

Infraction of the metatarsal head occurs in adolescents, mainly girls, and may be bilateral. Although any metatarsal can be affected, it is most frequently the second, perhaps because it is the longest and subject to overloading of the MTP joint. Clinically, there is pain under the metatarsal head with swelling, tenderness and restriction of MTPJ movement particularly dorsiflexion. Radiographs shows flattening and irregularity of the metatarsal head with sclerosis and metatarsal shaft hypertrophy.

Initial treatment is conservative. Often all that is required is modification of shoewear and activity levels. A metatarsal bar may offload the joint. If symptoms persist, curettage and bone grafting of the defect is indicated. At skeletal maturity, if there are ongoing severe symptoms, a dorsiflexion osteotomy may be necessary. Debridement of the metatarsal head or resection of the base of the proximal phalanx is a salvage procedure.

Congenital constriction band syndrome (Streeter’s dysplasia) is believed to be due to constriction of the limb by amniotic bands. The bands may be either partial or complete. The clinical picture is variable but includes congenital amputations, syndactyly and equinovarus foot deformities (Figure 13.22.13). The bands can cause obstruction to venous and lymphatic drainage and Z-plasties may be required urgently in the neonatal period. The clubfoot deformity may be resistant to conservative treatment.

Almost a quarter of children have one or more accessory bones visible on radiographs. Many are unimportant but some may cause problems in childhood.

The accessory navicular represents a separate ossification centre for the navicular tuberosity. Three types have been described (see Table 13.22.4). Generally, the accessory centre fuses with the main ossific nucleus but in about 2% of people it remains as a separate ossicle. The tendon of tibialis posterior is therefore attached to the medial aspect rather than the inferior aspect of the navicular, weakening the support for the longitudinal arch, and the foot becomes planovalgus. Midfoot pain may develop after activity, together with tenosynovitis of the tibialis posterior tendon. Pressure from shoewear may lead to local pain, swelling and tenderness.

Anteroposterior and external oblique radiographs reveal the accessory navicular located on the proximal medial aspect of the navicular. Its smooth outline distinguishes it from a fracture (Figure 13.22.14). The bipartite navicular appears on the dorsal surface of the navicular as a separate comma-shaped segment and is a separate entity from the accessory navicular.

Non-operative treatment is indicated initially. An orthosis may be useful if there is a flexible hindfoot valgus. A short period in a plaster cast with or without a local anaesthetic injection of the synchondrosis may settle acute symptoms. Persistent symptoms may warrant surgery. The Kidner procedure involves excision of the accessory navicular and advancement of the tibialis posterior tendon onto the plantar surface of the navicular but simple excision of the accessory navicular with trimming of any residual prominence is a simpler and equally reliable alternative.

An os trigonum is seen in nearly 10% of the population. It represents failure of fusion of the posterolateral tubercle of the talus with the main ossific centre. Repetitive minor trauma may be an aetiological factor.

The main clinical features are pain around the posterior aspect of the ankle and limitation of plantar flexion and it is frequently seen in ballet dancers and gymnasts. It must be distinguished from flexor hallucis longus tendinitis, although the two conditions coexist. Radiographs reveal an ossicle at the posterior aspect of the talus. Non-operative treatment consists of limiting ankle plantar flexion. Local steroid injections may help control symptoms and open excision may be warranted for persistent symptoms.