Foot and Ankle Deformity

Benjamin Shore

Megan E. Johnson

• Introduction

Foot and ankle concerns are a common cause for evaluation in the pediatric patient. Fortunately, the majority of pediatric foot deformities are asymptomatic and do not require treatment or surgical intervention. This chapter will outline the clinically relevant congenital and physiologic conditions, which are common causes for orthopedic referral. Careful examination of the three segments of the foot (hindfoot, midfoot, and forefoot) is critical to help guide diagnosis and treatment. When it comes to describing the hindfoot, orthopedists will describe the hindfoot as being in varus (always abnormal) or valgus. Normal feet are in some degree of valgus, yet excessive valgus is abnormal (Figure 12.1).

• Congenital and Infantile Foot Deformities

Clubfoot

Introduction

Clubfoot (talipes equinovarus) occurs in approximately one of every 1000 live births and is a common cause for consultation in the nursery. Clubfoot is also one of the most common congenital deformities of the lower extremity. The ratio of idiopathic clubfoot among males to females is 2:1 and is consistent across ethnic groups. The majority of clubfoot cases are sporadic, indicating a complex multigene etiology. A careful examination of the three segments of the foot will help confirm the diagnosis of talipes equinovarus (Figure 12.2).

While the Ponseti method of correction was first developed in the early 1940s, the wide dissemination of this method has spread over the past two decades, whereby almost 95% of clubfeet are now initially corrected by the Ponseti method of serial casting¹ (Figure 12.3).

FIGURE 12.1 This figure demonstrates the difference between varus and valgus. The small trapezoid represents the foot while the longer one represents the shank of the tibia.

Clinical Significance and Natural History

Approximately 80% of clubfeet are considered idiopathic, while the remaining 20% are associated with neuromuscular conditions, genetic disorders, or syndromes. Left untreated, the idiopathic clubfoot is a significant disability. In many cultures, affected individuals will be
ostracized and restricted to a lifetime of poverty. The affected individual ends up walking on the dorsum of their feet and develops severe callosities. Their gastrocnemius muscle becomes very atrophic as there is little meaningful power at toe off (Figure 12.4).

FIGURE 12.2 This newborn has bilateral clubfoot deformity.

History and Physical Examination

Clubfoot can often be detected during routine second trimester prenatal ultrasounds; ultrasounds in the third trimester may not be specific for clubfeet as isolated metatarsus adductus can be detected by ultrasound (Figure 12.5).

Clubfoot has a distinct clinical appearance at birth, consisting of midfoot cavus and forefoot adduction as well as hindfoot equinus and varus. This foot position is often accompanied by internal tibial rotation with abnormalities existing at the midtarsal and subtalar joints. One can appreciate and describe the unique clinical appearance at birth with the anacronym “CAVE” (Figure 12.6).

Hindfoot equinus can be difficult to appreciate in clubfoot as well as in other conditions with a tight heel cord such as congenital vertical talus. In cases of hindfoot equinus, the examiner will notice that when the heel pad is palpated, there is no palpable bone as a result of the tight tendo-Achilles that pulls the calcaneus up and the calcaneus is pitched plantarly (Figure 12.7).

The term plantarflexed implies that the long toe flexors are also tight. In the normal foot, the calcaneus is not elevated and the pitch points dorsal.

FIGURE 12.3 The Ponseti method of casting obtains initial correction in greater than 95% of idiopathic clubfeet.

Pitfalls in Diagnosis

General physical examination is critical in the evaluation of a newborn child with clubfoot. A detailed head and neck examination should look for the presence of torticollis. Spinal examination involves ruling out the presence of scoliosis (with shoulder asymmetry) or spinal dysraphism such as a hairy tuft or sacral dimple. Focused examination of the lower extremities should confirm normal hip and knee examination. The

practitioner will examine both legs and perform a detailed neurologic examination, testing for active muscle control, especially ankle and toe dorsiflexion. Patients with inability to dorsiflex the toes may have a neurologic clubfoot (

Video 12.1).

FIGURE 12.4 This 19-year-old Honduran man has uncorrected clubfeet. He walks on the tops of his feet and has extensive calluses and tough dorsal skin.

FIGURE 12.5 Prenatal ultrasound of a child later born with clubfoot deformity.

FIGURE 12.6 Clubfeet have four features consisting of cavus, which is a high arched midfoot with a plantar crease. Adductus is medial deviation of the forefoot, which results in a curved lateral border of the foot (yellow line). Varus is noted when the foot is rolled in and the plantar aspect of the foot faces medial. Equinus is noted when the foot is not easily dorsiflexed to 90° (red line).

FIGURE 12.7 This treated clubfoot appears to be fully corrected. Yet if the examiner were to carefully palpate the heel pad, they would notice the calcaneus is not present at the point of the heel. This is due to the tight tendo-Achilles (yellow line) which elevates the calcaneus (dashed red line). In addition, one will notice the toes are plantarflexed implying the long toe flexors are also tight. In the normal foot, the calcaneus is not elevated and the pitch points dorsal.

The diagnosis of clubfoot is made clinically and is fairly reliable based on the clinical examination noted above. It is important to realize anatomic variants associated with clubfoot such as an increased prevalence of an absent dorsalis pedis artery. Reduced muscle mass has been seen in the affected lower leg of children with clubfeet and may be the result of genetic induced fibrosis of the muscle-tendon units.

Differential Diagnosis

Metatarsus adductus should not be confused with talipes equinovarus. In metatarsus adductus, there is isolated adductus of the midfoot without evidence of cavus, varus, or equinus. The deformity is typically flexible where a clubfoot tends to be more rigid.

Syndromic clubfoot (arthrogryposis) should not be confused with the idiopathic clubfoot. Atypical clubfeet appear fat with short metatarsals, and severe rigid cavus with a hallmark deep transverse plantar crease. Often, these atypical feet require a different casting technique for manipulation (Figure 12.8).

Diagnostic Tests or Advanced Imaging

Clubfoot diagnosis is based on physical examination and radiographs are not routinely indicated. If a syndromic clubfoot is suspected, then genetic testing and neurological consultation are indicated.

FIGURE 12.8 This child with arthrogryposis has severe clubfoot that is stiff and difficult to treat with standard casting.

Treatment

The Ponseti casting method has become recognized over the last several decades as the treatment of choice for idiopathic clubfoot. This method involves serial casting of the foot over successive weeks, gradually stretching and correcting the foot in a stepwise sequence. The deformities are corrected in the CAVE sequence: cavus is corrected first, adductus and varus are corrected simultaneously, and
equinus is the last deformity. To prevent recurrence, the child is then placed in an abduction orthosis for nighttime use over the next 2 to 4 years of life. Final success with the treatment is directly related to compliance of brace wear.

When to Refer

If a clubfoot is suspected, it is best to refer early. Ideally, treatment for clubfoot typically begins in the first several weeks of life. Yet even if the child is older, the Ponseti method is indicated; colleagues have successfully casted children with untreated idiopathic scoliosis as old as 9 years of age.

Metatarsus Adductus

Introduction

Metatarsus adductus is a common foot deformity in the newborn. Some have confused this with “clubbed feet”; yet, the informed practitioner knows that metatarsus adductus is just one of four deformities seen in clubfeet. The incidence of isolated metatarsus adductus is similar to clubfeet—one in 1000 live births with 50% being bilateral. While clubfeet are suspected to have a genetic etiology with some effect from external factors, the etiology of isolated metatarsus adductus is thought to be related to increased intrauterine crowding.² The deformity consists of medial deviation of the infant forefoot leading to a “bean”-shaped foot. Toddlers who present with metatarsus adductus walk with an internal foot progression angle, and “intoeing” may have been the reason for the original referral. It is important to evaluate for other causes of intoeing, such as internal tibial torsion which is a common cause for intoeing in older toddlers.

Clinical Significance and Natural History

Metatarsus adductus is thought to be caused by foot deformation due to intrauterine positioning. Most cases will resolve at least partially on their own without intervention. If the metatarsus adductus is flexible, resolution may be facilitated with parental stretching (Figure 12.9A). Surgery is rarely indicated unless the deformity is severe and rigid.²

History and Physical Examination

Metatarsus adductus can be associated with other “packaging disorders,” such as torticollis and developmental dysplasia of the hip (DDH). The incidence of DDH in children with metatarsus adductus may be as high as 1 in 25. Given the association with DDH, a thorough examination of the hips should be performed.

The foot will generally be “bean” shaped, with the forefoot medially deviated on the hindfoot. The medial border of the foot is concave. The base of the fifth metatarsal may be prominent and there may be a wider than normal space between the first and second toes. The arch of the foot often appears higher than normal.

The heel bisector line can be used to document the severity of the metatarsus adductus. With the patient prone, a line drawn from the middle of the heel down the foot should land between the second and third toes. With metatarsus adductus, the line will fall lateral to this with greater deviation implying greater deformity.

The flexibility of the deformity can be assessed and may be prognostic. In mild cases, the deformity will correct when the lateral border of the foot is stimulated. In intermediate cases, the foot will not spontaneously correct when stimulated, but the deformity is passively correctable by the examiner. Rigid cases will not correct at all and may have a soft tissue crease along the medial border and/or a noticeable medial soft tissue contracture.

Pitfalls in Diagnosis

Metatarsus adductus can be a feature of other foot deformities, such as clubfoot (hindfoot in varus) or skewfoot (hindfoot in excessive valgus). It is important to recognize these other pathologies if present. In clubfoot, there will also be hindfoot varus and equinus with cavus in the midfoot. The deformity will not be flexible. Skewfoot will demonstrate hindfoot valgus along with forefoot adductus.

FIGURE 12.9 A, This 6-month-old boy has moderate stiff metatarsus adductus. The family is taught to stretch the forefoot by abducting the forefoot (yellow arrow) against a fulcrum against the cuboid (red arrow). B, Despite the use of home stretching, the family wanted to try casting to obtain improvement. At 10 years of age, he is doing well despite residual mild adductus.

Differential Diagnosis

Whenever evaluating a child with metatarsus adductus, one should consider whether or not a more complex foot deformity is present, such as clubfoot or skewfoot. Patients with metatarsus adductus will often present with the chief complaint of intoeing. It is therefore important to rule out other causes of intoeing, such as femoral anteversion and tibial torsion.

Diagnostic Tests or Advanced Imaging

Radiographs are generally not indicated in cases of mild, flexible metatarsus adductus. If the deformity is severe, rigid, or persists past 2 to 3 years of age, and/or surgery is planned, radiographs of the affected foot/feet may be indicated.

Treatment

Most cases of mild, flexible metatarsus adductus will correct spontaneously before 6 months. The family can be instructed to perform serial stretching during this time. Another significant portion will resolve as the child starts to walk. If the deformity is more rigid, serial casting can be done to obtain a straight lateral border of the foot (Figure 12.9B).

An orthosis may be utilized to maintain correction, including reverse-last and straight-last shoes, as well as other off-the-shelf orthoses. For refractory cases with severe deformity that persists after 3 years of age, surgical treatment may be considered.³

When to Refer

If the deformity is flexible, it is reasonable to treat metatarsus adductus with observation with or without serial stretching for the first 6 months, as most cases will resolve on their own without further treatment. If the deformity persists past 6 months, or the foot is rigid, referral to a pediatric orthopedic surgeon for further evaluation is indicated.

Skewfoot

Introduction

Skewfoot is defined as a congenital or acquired valgus deformity of the hindfoot with concomitant adductus of the forefoot. Clinically, it appears similar to the name with the hindfoot going in one direction and the forefoot going in the opposite direction.

Clinical Significance and Natural History

Early on in childhood, skewfoot is frequently confused with metatarsus adductus, and some consider it a more significant variant of metatarsus adductus. There can be many etiologies associated with skewfoot, the most common is idiopathic, followed by iatrogenic (from previous casting or bracing) and associated with an underlying neuromuscular condition or chromosomal abnormality. The natural history is not well documented, but most people function well without pain or arthrosis. On occasion, shoe wear can be difficult.

History and Physical Examination

On clinical examination, one should look for a medial midfoot concavity (navicular/midfoot) and the adjacent lateral convexity (head of the talus). It is important to break the foot down into segments for examination. The hindfoot is in valgus and everted. The midfoot is adducted and the forefoot is pronated. The longitudinal arch may be variable in presentation depending on the underlying etiology. Typically, the ankle is in neutral position (Figure 12.10).

Diagnostic Tests or Advanced Imaging

Radiographs demonstrate a medial deviated talar head on the anteroposterior (AP) view, but on the lateral view, the talus is not plantarflexed. As the child ages, the midfoot deformities accentuate and the longitudinal arch drops leading to hindfoot valgus and equinus in some children. The adolescent skewfoot looks very close to a flat foot to the unexperienced examiner (Figure 12.11).

Treatment

One can consider serial casting early in a similar fashion to metatarsus adductus. In older children with symptomatic pain or callosities a lateral calcaneal lengthening, osteotomy coupled with a medial opening wedge osteotomy can help correct the hindfoot valgus and midfoot adductus (Figure 12.12A and B).

FIGURE 12.10 This 4-year-old girl has a skewfoot. It has the same forefoot adduction (red arrow) seen in metatarsus adductus. Yet, the hindfoot has significantly more valgus than usual (yellow arrow).

When to Refer

Skewfoot is a relatively uncommon foot condition and should be referred to a pediatric orthopedic surgeon. As a general practitioner, the skewfoot diagnosis is elusive and is often confused with typical pes planus (flatfoot). A foot that seems severe in its clinical appearance or a young child who appears to have more than one foot deformity should trigger the referral.

FIGURE 12.11 This 15-year-old high school football star has a skewfoot deformity. The forefoot is medially deviated on the midfoot, and the midfoot is laterally deviated on the hindfoot. Some have termed this a “serpentine foot”; despite the ominous name, the boy is asymptomatic and is the fastest runner on his team.

FIGURE 12.12 A, The child in Figure 12.10 is having difficulty with shoe wear and the family desires correction. Midfoot osteotomy was suggested. B, Three years after surgery, shoe wear has improved and the patient is asymptomatic despite persistent hindfoot valgus that was not corrected.

Congenital Vertical Talus

Introduction

Congenital vertical talus (CVT) is a rare foot deformity, with an estimated prevalence of 1 in 10,000 live births. Anatomically both clubfoot and CVT have a tight heel cord; but the CVT foot is flat with dorsal dislocation of the navicular on the talus with the hindfoot in valgus, while a clubfoot is a cavus foot with the navicular medially displaced on the talus head and the hindfoot is in varus. It is important to remember that the navicular is the last bone in the foot to ossify (3-4 years); thus it is impossible to see on radiographs prior to this period. In CVT the displacement of the navicular is confirmed it when the first metatarsal axis and the talus axis is displaced (the talus-first metatarsal axis is normally colinear). Fifty percent of cases are bilateral. The condition occurs equally in males and females. While major reconstructive surgery was once the mainstay of treatment, like clubfoot, CVT can now be treated successfully with serial manipulation/casting and minimally invasive surgery.⁴,⁵

Clinical Significance and Natural History

The etiology of CVT is considered idiopathic in half of cases and associated with neuromuscular or genetic conditions in the other half. Therefore, it is essential that a thorough history and physical examination be performed to rule out the presence of any associated conditions. It is important to recognize CVT as this can cause disability if left untreated.

FIGURE 12.13 Pathophysiology of congenital vertical talus. The talus is vertically positioned (dashed yellow line) and is not colinear with first metatarsal (dashed red line). This is due to contracture of the Achilles tendon (yellow arrow) and the dorsal tendons of the foot (red arrow).

History and Physical Examination

The physical appearance and anatomic orientation are a result of two forces pitted against each other and resulting in midfoot dislocation at the talonavicular joint. The anterior tendons (toe extensors and tibialis anterior tendons) are contracted leading to a dorsiflexed navicular and an abducted/everted forefoot, while the hindfoot is being pulled into equinus and valgus by the Achilles and peroneal tendons (Figure 12.13).

The CVT foot has a distinct “rocker-bottom” appearance due to the dorsal dislocation of the navicular on the talus. This causes a convex appearance to the plantar surface of the foot; age-old descriptions have compared this foot to a Persian slipper (Figure 12.14).

The head of the talus is palpable along the plantar medial aspect of the midfoot, contributing to the rocker-bottom appearance of the foot. The key factor that determines the difference between CVT and other flat feet (calcaneovalgus foot, oblique talus, or flexible flat foot) is the presence of Achilles contracture in CVT.⁵

Features to Confirm

A thorough physical examination should be performed to rule out an associated neuromuscular or genetic condition. Particular attention should be paid to the presence of abnormal appearing facies and other congenital anomalies, such as upper extremity deformities, multiple joint contractures, limb deficiencies, etc. Examination of the hips should be done to evaluate for hip dysplasia. Spinal examination should also be done to rule out the presence of scoliosis and a hairy tuft or a presacral dimple can signify spinal dysraphism such as a tethered cord.

FIGURE 12.14 Clinical appearance of congenital vertical talus.

Pitfalls in Diagnosis

Most cases of CVT can be diagnosed by clinical examination based on the appearance of a “rocker-bottom” foot that is usually rigid and with an empty heel pad signifying an equinus contracture. There is a less severe variant of CVT, known as an oblique talus, which can have a similar appearance, but is less rigid. With an oblique talus, the navicular will reduce (Noted by reduction of the talus-first metatarsus axis on a plantarflexion lateral radiograph of the foot.) with plantar flexion, while it remains rigidly dislocated in a foot with CVT. This can be determined both on clinical examination and also with radiographs. Practitioners must also consider an underlying neuromuscular diagnosis in children presenting with CVT.

Differential Diagnosis

A calcaneovalgus foot can be easily mistaken for CVT. A foot with calcaneovalgus deformity is severely dorsiflexed with the dorsal surface of the foot resting on the anterior surface of the lower leg. The calcaneovalgus foot will be much more flexible than one with a CVT due to the absence of any true equinus contractures. The calcaneovalgus deformity almost always corrects on its own in the first 6 months of life, while a foot with a CVT requires special treatment.

Diagnostic Tests or Advanced Imaging

When the diagnosis of CVT is not clearly based on the physical examination, radiographs (AP and lateral views in maximum plantar and dorsiflexion) can be used to help make the diagnosis. It is important to remember that the navicular does not ossify until 2 to 3 years of age; thus, the position of the cartilaginous navicular is inferred by using the longitudinal axis of the first metatarsal. In calcaneovalgus and oblique talus, the first metatarsal axis is not colinear with the axis of the talus on the forced dorsiflexion lateral radiograph. Yet with the oblique talus, this will reduce on the maximum plantar flexion lateral radiograph (Figure 12.15).

In CVT, the first metatarsal axis (and the navicular) will remain dorsally displaced and not aligned with talus on the forced plantar flexion lateral (Figure 12.16).

Treatment

Treatment of CVT has shifted away from extensive soft tissue releases to a more minimally invasive method utilizing serial casting, called the “reverse Ponseti method.” Weekly manipulation of the foot is performed with the goal of stretching the foot into plantar flexion and adduction, while pushing the talus dorsally and laterally. A long leg cast, similar to the Ponseti type used for clubfoot, is applied while the foot is being stretched. Casting is initiated in the first few months of life and continued weekly until reduction of the talonavicular joint has been achieved. In the final cast, the foot is positioned into
extreme equinovarus, resembling a clubfoot. After application of the final cast, the patient is scheduled for surgical stabilization of the talonavicular joint with a k-wire and a percutaneous tenotomy of the Achilles tendon. The patient then uses a shoe and bar brace system, similar to that used to treat club foot, full time for several months and then at night only for several years⁴ (Figure 12.17).

FIGURE 12.15 This child with an oblique talus has a vertically positioned talus as a result of Achilles contracture (yellow arrow). In plantar flexion, the talus and the first metatarsal are colinear.

FIGURE 12.16 This child has congenital vertical talus as the talus and the first metatarsal do not align with a forced plantarflexion lateral.

When to Refer

A patient with suspected CVT should be referred as early as possible. Evaluation and treatment are best performed by a fellowship trained pediatric orthopedic surgeon. While awaiting evaluation, gentle stretching and manipulation of the foot by the child’s family members can be done.

Calcaneal Valgus Foot

Introduction

A calcaneovalgus foot is another common diagnosis made in the newborn nursery or during the first couple of pediatrician visits. Clinically, a calcaneovalgus foot is associated with hyperdorsiflexion with valgus deformity of the hindfoot; the foot itself can almost appear to touch the anterior aspect of the tibia. The deformity is likely related to positioning in the womb.

Clinical Significance and Natural History

Thankfully, 100% of these feet correct without any intervention and reassurance to the family is necessary (Figure 12.18).

FIGURE 12.17 This boy with bilateral congenital vertical talus underwent the reverse Ponseti method as described by Dr Matt Dobbs. At 9 years, he has an excellent clinical result.

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