CHAPTER 114

In-toeing and Out-toeing: Rotational Problems of the Lower Extremity

Kier Maddox Blevins, MD, and Andrew K. Battenberg, MD

Benign rotational variations of the lower extremities, such as in- toeing and out-toeing, occur in many healthy children. Although rotational problems that produce in-toeing and out-toeing may initially be physically alarming, spontaneous resolution occurs in most cases. Such problems are a common cause of parental or caregiver concern during infancy and childhood, but they rarely result in physical limitation. Most of these children can be managed adequately by primary care physicians and do not need orthopedic referral. A thorough understanding of the normal rotational variations that occur in children younger than 10 years of age is essential to proper treatment as well as patient and parent or caregiver education. More importantly, a general understanding is imperative to identify more serious underlying structural problems.

Specific terminology is used to describe limb positioning. Version is normal variation in limb rotation, whereas torsion refers to abnormal conditions (ie, >2 standard deviations above or below the mean). Adduction is movement toward the midline, whereas abduction is movement away from the midline. Varus angulation is deviation toward the midline, whereas valgus angulation is deviation away from the midline. An inverted foot is one turned toward the midline on its long axis. An everted foot is one turned away from the midline on its long axis.

Epidemiology

In neonates or young infants, in-toeing is most likely the result of clubfoot (ie, talipes equinovarus), isolated metatarsus adductus, or metatarsus primus varus. The prevalence of clubfoot is 1 in 1,000 live births, with a male to female ratio of 2:1. The condition is bilateral in approximately 50% of patients. Metatarsus adductus, which is much more common than clubfoot, occurs in approximately 1 in 500 live births. It is often bilateral. Internal tibial torsion is the primary cause of in-toeing in the second year after birth, and femoral torsion accounts for most cases of this condition during early childhood.

Physiologic out-toeing is classically evident in infants who have not yet begun to walk and is the most common cause of bilateral out-toeing. In older infants and children, however, lateral tibial torsion is believed to be the most common cause of out-toeing.

Clinical Presentation

Children with congenital clubfoot, metatarsus adductus, and metatarsus primus varus present with in-toeing during infancy. Typically, congenital clubfoot is evident at birth. A severe medial, midline, plantar crease is present, and the foot appears C-shaped, with both the heel and forefront turned inward (Figure 114.1). The affected foot is small, wide, and stiff, and the lower leg appears small because of hypoplasia of the calf muscles. In contrast to clubfoot, in metatarsus adductus and varus only the forefoot turns inward.

Figure 114.1. Congenital clubfoot.

Tibial torsion is apparent during the second year after birth. In affected children, the feet turn inward during ambulation, but the knees are straight because the deformity is distal to the knee. Medial femoral torsion is evident at 3 to 4 years of age and usually affects girls. Affected children can sit in the “W” position with both legs behind them. As these children walk, both the knees and the feet appear to turn inward because the deformity is proximal to the knee.

Physiologic out-toeing is seen in infancy. Classically, parents or caregivers note that when they hold their child in a standing position, both feet turn outward. Approximately 5° of out-toeing is normal after age 3 years. Further degrees of out-toeing may be the result of lateral tibial torsion.

Pathophysiology

Several factors are involved in the etiology of rotational conditions. Most of these deformations are caused by intrauterine positioning. Genetics are also believed to play a role in the development of rotational problems, because parents may often have the same rotational deformity as their children. Other contributing factors include bony and neuromuscular abnormalities in clubfoot and certain sleeping and sitting positions in metatarsus adductus and medial tibial torsion. For example, sleeping in the prone position with the legs internally rotated may worsen internal tibial torsion or metatarsus adductus.

During the early intrauterine period, internal rotation of the lower extremity brings the big toe to the midline. During the later intrauterine period, infancy, and childhood, however, external rotation predominates. Alterations in this normal lateral process are caused by genetic and environmental factors, including intrauterine molding and sleep positions. Conditions influenced by intrauterine position, such as metatarsus adductus and developmental dysplasia of the hip, sometimes occur in the same child. Additionally, children with rotational deformity should undergo careful screening for other anomalies associated with intrauterine positioning as well, such as torticollis.

Typically, congenital clubfoot is an isolated birth defect and is considered idiopathic. Two major etiologies have been proposed: (1) a germline defect in the talus results in abnormal bony development, resulting in plantar flexion, inversion, soft tissue contractures, and hypoplasia of the calf muscles and the bones of the foot and (2) clubfoot represents the final common pathway of disruption anywhere along the neuromuscular unit, including the central nervous system, peripheral nerves, and muscles. Additionally, genetics are believed to play a major role because 25% of all cases are familial and there is 33% concordance of identical twins. Environmental factors, including intrauterine position and molding, are also thought to contribute.

In-toeing is usually caused by benign conditions, such as metatarsus adductus, excessive internal tibial torsion, and excessive femoral torsion. Less frequently, patients have pathologic conditions such as clubfoot, skewfoot, hip disorders, and neuromuscular diseases. Typically, out-toeing is caused by external rotation contracture of the hip, external tibial torsion, or external femoral torsion.

Conditions Associated With Rotational Variations in Children

In-toeing

Metatarsus Adductus, Metatarsus Primus Varus, and Skewfoot

Metatarsus adductus, with or without internal tibial torsion, is the most common cause of in-toeing from birth to 1 year of age. It is a functional deformity in which the forefoot is adducted with respect to the hindfoot with a neutral or slightly valgus heel. It is the most common pediatric foot problem referred to orthopedic surgeons and occurs in 1 in 500 live births and in 1 in 20 siblings of patients with metatarsus adductus. The rate is higher in males than females, twin births than singleton births, and preterm babies than term infants. Numerous theories exist as to the cause of metatarsus adductus, including in utero positioning, sleeping position of the baby, muscle imbalance, and medial cuneiform abnormality.

Presenting symptoms include cosmesis, in-toeing gait, and excessive shoe wear. On physical examination, the foot appears C-shaped with a concave medial border and convex lateral border. The forefoot can be brought into the neutral position either by stroking the lateral border of the foot or by gently straightening it. Metatarsus adductus can be classified as flexible or inflexible based on physical examination. Flexible metatarsus adductus typically resolves spontaneously and does not require splinting, bracing, or special shoes. However, the patient with rigid metatarsus adductus should undergo early casting; surgery is rarely necessary, and then only to manage resistant cases.

Congenital metatarsus primus varus is a bony abnormality that is characterized by an isolated adducted first metatarsal. Unlike flexible metatarsus adductus, metatarsus primus varus is a fixed deformity. The foot cannot be brought into the neutral position, and a deep vertical skin crease is evident along the medial border of the tarsometatarsal joints. Because it is a more rigid deformity, early casting is recommended; surgery is necessary to address persistent deformity.

Skewfoot, also known as serpentine metatarsus adductus, is characterized by adducted metatarsals combined with a valgus deformity of the heel and plantar flexion of the talus. It is theorized that improper casting of metatarsus adductus or clubfoot may result in a skewfoot; however, most cases are idiopathic. Patients present with pain or callus formation under the head of the talus and base of the fifth metatarsal. Some feet undergo spontaneous correction, but surgery is indicated for the persistently symptomatic foot.

Dynamic Abductor Hallucis

Dynamic abductor hallucis (ie, searching toe), also known as “wandering toe” or “atavistic toe,” can cause in-toeing. Children with a searching toe have a big toe that points medially when they walk. Unlike the other causes of in-toeing, which are structural and present at rest, this condition is a dynamic deformity. Searching toe results from the contraction of the abductors of the big toe during the stance phase of gait, which pulls the toe toward the midline. Typically, it resolves with age and subsequent development of fine motor coordination.

Clubfoot

Congenital clubfoot is a pathologic deformity of the foot that may be identified at birth (Figure 114.1). Clubfoot may be an isolated deformity or may occur in association with other neuromuscular anomalies, such as arthrogryposis, myelomeningocele, amniotic band syndrome, cerebral palsy, and poliomyelitis.

The diagnosis of congenital clubfoot is made at birth based on 3 conditions: forefoot varus, heel varus, and ankle equinus. Clubfoot can range in severity from a rigid deformity, in which the forefoot cannot be passively abducted into a neutral position, to nonrigid deformities, in which the forefoot can be gently brought toward the midline. Normal dorsiflexion of the ankle helps distinguish severe forms of metatarsus varus from clubfoot.

Internal Tibial Torsion

Internal tibial torsion is the most common cause of in-toeing from ages 1 to 3 years, is thought to be caused by intrauterine positioning, and is usually first noticed by parents or caregivers when their child begins to walk. Parents or caregivers often report that the child is clumsy and trips frequently. Internal tibial torsion is bilateral in two-thirds of affected children; when unilateral, the left leg is most commonly affected. Observation of gait reveals that the knees point forward but the feet turn inward. Because the knees are straight, the site of the rotational deformity lies below this joint. If the feet are normal and no metatarsus adductus or varus is present, the rotational deformity can be isolated to the lower leg. It is important to measure the thigh-foot axis and transmalleolar axis in the physical examination. Expectant observation is recommended, because the natural history of internal tibial torsion strongly favors spontaneous resolution by 4 years of age.

Internal Femoral Torsion

Internal femoral torsion is the most common cause of in-toeing in children, presenting between 3 and 6 years of age; it tends to occur in females and is usually bilateral. Typically, a child is brought to a pediatrician for evaluation after a parent or caregiver notices worsening in-toeing in a child with no history of in-toeing. Although excessive medial femoral torsion may be present at birth, it is often masked by the external rotatory forces present during infancy. Children with excessive internal femoral torsion characteristically sit with their legs in the “W” position and run with an eggbeater-type motion. Although no association has been shown between internal femoral torsion and degenerative joint disease, some studies suggest an increased association between internal femoral torsion and knee pain. This knee pain is referred to as “miserable malalignment syndrome,” which results from a combination of internal femoral torsion and external tibial torsion. No treatment is necessary for most cases of femoral torsion, which usually resolves by 8 years of age.

Out-toeing

Physiologic Out-toeing

Out-toeing of infancy, which most commonly occurs in children who are just learning to walk, is caused by intrauterine positioning that results in external rotatory contractures of the soft tissues surrounding the hip. This condition may be perpetuated in children who sleep in the prone, frog-leg position, which holds the hips in external rotation and prevents normal stretching of the external rotators of the hip. Although both feet turn outward when the infant stands, the lateral rotation of both hips is normal on examination (Figure 114.2). More serious conditions, such as slipped capital femoral epiphysis, hip dysplasia, or coxa vara, are less common but should be considered.

Figure 114.2. Physiologic out-toeing of infancy.

External Tibial Torsion

This condition may be suspected in children 3 to 5 years of age, but detection often is delayed until late childhood or adolescence. External tibial torsion tends to be unilateral, most often affects the right side, and generally worsens over time. Increased external tibial torsion often is associated with neuromuscular conditions, such as myelodysplasia and poliomyelitis. As the condition progresses, patients can develop disability and pain in the form of patellofemoral pain and instability. Some studies have even shown an association between external tibial torsion and degenerative joint disease of the knee.

Adolescent Hallux Valgus

Hallux valgus is well-described in the adult population but is beginning to be seen more often in the adolescent population. It is far more common in females than males, and studies have shown that up to 75% of affected patients have an affected mother. Adolescent hallux valgus is thought to be the result of a triad of deformities: abnormal bone growth, or exostosis, over the medial side of the first metatarsal head; valgus deformity of the hallux; and associated metatarsus primus varus. The etiologic factors for development of this deformity are similar to those for adults. The main contributing intrinsic factor is increased ligamentous laxity of the foot. The most common extrinsic factor is improper shoe wear. It has long been accepted that shoes with a narrow toe box, especially shoes with high heels, are strongly associated with hallux valgus. Other extrinsic factors commonly associated with hallux valgus are neuromuscular disorders, such as cerebral palsy.

The most common presenting symptom is pain over the medial aspect of the great toe metatarsal head. This is usually the result of pressure and chronic friction over the area. This pain can result in gait abnormalities and limit the patient’s ability to participate in regular activity.

Differential Diagnosis

In-toeing and out-toeing may be classified according to anatomic level and usual age at presentation (Table 114.1). These conditions may be localized to 1 of 5 areas: toe, foot, tibia, femur, and hip. If in-toeing problems are placed in chronologic order by age of presentation, the affected area follows a toe-to-femur sequence.

Evaluation

History

The clinical history must delineate the onset, duration, and progression of any structural problems. The typical natural history of benign rotational conditions is one of improvement over time, whereas a more serious condition is marked by a more progressive deformity. Relevant family and birth history, including gestational age, length of labor, complications, Apgar scores, birth weight, and length of hospital stay, should be noted. These details may heighten suspicion for cerebral palsy or the presence of hereditary disorders, such as vitamin D-resistant rickets, mucopolysaccharidoses, achondroplasia, epiphyseal dysplasia, or metaphyseal dysplasia that may affect rotational profiles. A thorough developmental history is important, because developmental delays may be a sign of underlying neuromuscular or neurologic disorders (Box 114.1). It is also important to determine whether the rotational problems cause marked functional impairment in the patient; this includes problems with tripping or pain difficulties with shoe wear.

Physical Examination

Normal variability in the lower extremities of young children must be differentiated from more serious structural problems. A detailed physical examination, including assessment of gait and neurologic and musculoskeletal function, is essential for making the correct diagnosis. This evaluation should include examination of the hips for signs of hip dysplasia, which may be associated with metatarsus adductus (see Chapter 113). Observation of the child’s stature and leg-to-body ratio is also useful because short stature or disproportionate leg-to-body ratio may suggest a skeletal dysplasia.

Evaluation of postural conditions requires both static and dynamic physical examination. Static examination includes an overall evaluation of the patient and a rotational profile. The child’s rotational profile, as described by Staheli, consists of 5 components: internal and external hip rotation, thigh-foot axis, transmalleolar axis, heel-bisector angle, and foot progression angle during gait (Figure 114.3 and Figure 114.4).

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