Torsional Phenomena

Torsional phenomena occur in at least half the infant and toddler population, varying considerably in degree. In a child whose feet turn inward, you must first decide whether it is the feet, femora, or tibias that are responsible. Does the torsion originate above or below the knee?

Internal femoral torsion (femoral anteversion)

When children have internal femoral torsion, the patellas show internal strabismus (Fig. 15–1). Gently rotate the knees so that the patella face forward. If internal femoral torsion is the problem, the feet suddenly and miraculously point directly forward.

FIGURE 15–1 Internal femoral torsion: internal strabismus of the patellas.

Once you understand the in-toeing mechanism, it becomes obvious that special orthopedic shoes, mistakenly prescribed as corrective, usually exaggerate the in-toeing because of their sheer weight. Perfectly normal shoes almost invariably also exaggerate in-toeing. It usually helps to demonstrate this phenomenon to the parents by having the child walk with and without shoes, after which they frequently realize that the problem is really not as bad as it seems.

Internal tibial torsion

Internal tibial torsion is a normal phenomenon seen in children 6 to 18 months old. It is noticed especially when they begin to walk and can vary greatly in degree. If the patellas point directly forward and the feet appear normal in a child with in-toeing, the likely cause is tibial torsion. As with femoral anteversion, the deformity typically appears worse when the youngster puts on shoes and may cause the child to stumble a bit more than average. Reassure the parents that this phenomenon disappears in most children by age 2.

Bowleg (genu varum) and knock knees (genu valgum)

Mild lower extremity bowing is the norm in infants and young children (Fig. 15–2). Internal tibial torsion often accompanies physiologic bowing and accentuates the bowed appearance. No treatment is necessary. By age 2 years, physiologic bowing spontaneously corrects itself in most children. Many healthy children, including those who have had physiologic bowing as toddlers, gradually convert to develop some degree of genu valgum after age 2 years (Fig. 15–3), which usually disappears spontaneously by age 8 years.

FIGURE 15–2 Genu varum (nonrachitic bowing of the legs), a transient normal variant requiring no treatment.

FIGURE 15–3 Physiologic knock knee, a self-correcting condition that requires no treatment.

In a few children, physiologic bowing or knock knee may be quite marked, raising concerns about possible underlying disease. If bowing increases after the child begins to walk, you should rule out pathologic causes, such as Blount disease, rickets, and metaphyseal dysplasia. Genu valgum may also develop in extremely obese children, the result of bearing excessive weight. It may also occur in pathologic conditions, such as metabolic bone disease (rickets or renal osteodystrophy).

Metatarsus varus (forefoot adduction)

In metatarsus varus, the forefoot turns inward in relation to the long axis of the heel (Fig. 15–4). The critical clinical issue is to determine whether the foot deformity is fixed or flexible. Mild to moderate flexible metatarsus varus usually corrects itself, because it is the result of intrauterine position, or packing. A severe or fixed metatarsus varus may require serial casting or an orthotic device. If you are in doubt about the severity of this condition in a child, consult a pediatric orthopedist.

FIGURE 15–4 Metatarsus varus. The key clinical issue is the extent of flexibility of the deformity.

Toeing-out

Toeing-out, sometimes quite marked, is noted when some perfectly healthy youngsters begin to walk. This eversion of the legs, not the feet, may look peculiar but does not interfere with walking and generally corrects spontaneously 6 to 12 months later. It is usually due to the external rotation of the hips or to the external tibial torsion. When it is due to the external rotation of the hips, rotating the hips to a normal position during the examination corrects the abnormality and helps the parents understand its nature. No treatment is necessary.

Flat feet

Flat feet are the norm in children younger than ages 2 to 3 years and in older children who show greater than average joint mobility. Usually asymptomatic, this normal variant is often simply part of generalized hypermobility. In such children, the normal body weight is sufficient to cause flattening of the feet. When the youngster sits on a table, the longitudinal arch miraculously reappears as the feet are suspended in space (Fig. 15–5).

FIGURE 15–5 With flexible flat feet (A), the longitudinal arch miraculously reappears when the child is not weight bearing (B).

Toe-walking

The most common condition that causes pathologic Achilles tendon tightening and gastrocnemius spasm is spastic cerebral palsy, but toe-walking can also be seen occasionally in perfectly normal children who favor their toes in the early months of walking before they develop a mature heel-toe gait. Toe-walking in normal children tends to be intermittent, and they tend to rest with their feet flat on the floor when they stop walking. By contrast, children with cerebral palsy have persistent toe-walking and also often circumduct their legs while walking; they also have increased muscle tone, hyperreflexia, and tight heel cords. Although a congenitally short Achilles tendon does occur, it is rare. Proximal muscle weakness, as in muscular dystrophy, and a tethered spinal cord also must be excluded in the child with toe-walking.

Hip pain

Knee pain

Knee pain in children is often due to one of the following causes:

Foot pain

Poorly fitting footwear is a common cause of foot pain in children. Other causes are tarsal coalition (a coalition between the tarsal bones characterized by a rigid flat foot), Köhler disease (avascular necrosis of the navicular bone), and Freiberg disease (avascular necrosis of the second metatarsal head).

Back pain

Consider osteomyelitis of a vertebral body, discitis, or tumor in all children who present with back pain. Other causes are discussed here.

Trauma

Whether accidental or inflicted, trauma can cause localized pain wherever it occurs. Always determine whether the child’s complaints and physical findings are compatible with the extent of injury reported.

Infection

Bacterial infections, such as septic arthritis and osteomyelitis, usually affect a single joint or bone, particularly the knee or hip; however, multiple sites are occasionally involved. If a child is febrile and has marked pain with movement of a joint or marked bony tenderness, you should suspect infection. Redness overlying the tender area should heighten your suspicion of bacterial infection. Specific infections and postinfectious illnesses may give rise to particular patterns of joint involvement as described here. Acute rheumatic fever produces a postinfectious migratory arthritis affecting any single joint for approximately 1 week or less. Lyme disease (a tick-borne infection) causes arthritis that usually affects a few joints, particularly the knee, shoulder, and elbow. Viral infections may be associated with acute pain in joints, muscles, or both, that usually resolves rapidly with symptomatic treatment.

Tumors

Juvenile idiopathic arthritis

Arthritis is defined by the American College of Rheumatology as the presence of joint swelling or two or more of the following findings:

Although any joint may be affected, certain types of JIA involve specific joints predominantly, providing essential diagnostic clues.

Oligoarticular JIA involves four or fewer joints during the first 6 months of disease, most commonly the knees, ankles, or elbows but not the hip joint. It primarily affects young girls ages 1 to 3 years and is frequently associated with asymptomatic uveitis and a positive antinuclear antibody test result. In a 2-year-old girl who has hip pain, other causes should be sought, such as septic arthritis and leukemia.

Polyarticular rheumatoid factor (RF)-negative JIA involves five or more joints during the first 6 months of disease, most often the knees, wrists, elbows, and ankles. The cervical spine and temporomandibular (TM) joints are also often involved.

Polyarticular RF-positive JIA also involves five or more joints in the first 6 months of disease and often has symmetric small-joint disease of the hands. Without aggressive treatment, this subtype, which is equivalent to adult rheumatoid arthritis, will cause joint damage and deformities. Fortunately, this subtype makes up only about 5% of all JIA.

Systemic JIA is characterized by high spiking fevers, an evanescent rash, variable internal organ inflammation that may lead to hepatosplenomegaly, lymphadenopathy, pericarditis, other serositis, and chronic arthritis. Either an oligoarticular or polyarticular pattern of arthritis may be seen. You must always exclude infection and malignancy before making a diagnosis of systemic JIA.

Enthesitis-related arthritis commonly affects the large joints below the waist, particularly the knees, ankles, and hips. Boys older than 8 years who carry the genetic marker HLA-B27 are more likely to be affected. Buttock pain due to sacroiliitis and back pain may also occur but usually appear later in the course of disease. Enthesitis resulting in pain in the heels, over the tibial tuberosities at the knees, and under the feet, is also characteristic of this subtype of JIA.

Psoriatic arthritis may affect a few or many joints in a child who has psoriasis or a strong family history of psoriasis. Dactylitis or a sausage-shaped finger or toe should make you think of psoriatic arthritis. Depending on the age at which it starts, the arthritis may look like oligoarticular JIA in younger children or more like enthesitis-related arthritis in older children.

Other rheumatic diseases

The connective tissue diseases, including systemic lupus erythematosus (SLE), juvenile dermatomyositis, mixed connective tissue disease, and scleroderma, may manifest as arthritis, arthralgia, myositis, myalgias, or tenosynovitis that causes musculoskeletal pain. Most of these disorders will have characteristic findings that allow you to make the diagnosis. The exception is SLE, which sometimes presents with arthritis and fatigue as the only initial symptoms. An index of suspicion, particularly in the adolescent girl with joint complaints, as well as appropriate use of serologic testing, can lead to the correct diagnosis. The various forms of primary systemic vasculitis may also manifest as arthritis. Of these, Henoch-Schönlein purpura and Kawasaki disease are by far the most common in children.

Growing pains

So-called growing pains have no connection with growth (aside from their occurrence in growing children). The term growing pains is used to describe limb pains that follow a characteristic pattern and are found by careful physical examination not to be associated with any detectable disease. They most commonly occur in children between ages 2 and 6 years. The limb pains occur mainly at night, often after intensive physical activity, and can cause severe leg pain. Typically, affected children are asymptomatic during the day, and their gait is normal.

Many children who experience growing pains go to bed without complaint but wake up 1 to 3 hours later complaining of leg pain that is often severe enough to make them cry. Most complain of bilateral calf, shin, or thigh pain, or, more vaguely, of pain in the entire leg. The trunk and upper extremities are rarely affected. Commonly, a parent of such a child experienced similar pains in childhood. Affected children often find relief from a single dose of acetaminophen or from massage, in contrast to children with an underlying pathologic cause of pain, who almost never ask their parents to rub their legs. A hot bath immediately before bed seems to help prevent pains in some children. If the history is atypical or if the child has a limp, joint swelling, or bone tenderness, do not label the problem as growing pains.

Benign hypermobility

Benign hypermobility syndrome is a common cause of joint pain, particularly in the knees, ankles, and fingers. Occasionally, the affected joints appear swollen for brief periods, but the swelling resolves spontaneously. The symptoms are episodic and may be exacerbated by exercise. The clinical findings that allow you to make a diagnosis of hypermobility are listed in Box 15–1.

Diffuse idiopathic musculoskeletal pain

Diffuse idiopathic musculoskeletal pain is a poorly understood condition characterized by chronic widespread musculoskeletal aching and stiffness that occurs predominantly in healthy teenaged girls. Patients often complain of fatigue, poor sleep, and awakening unrefreshed. They may have associated chronic headaches or irritable bowel syndrome. In some patients, physical examination reveals exquisite tenderness at characteristic soft tissue sites, meeting the criteria for fibromyalgia. The cause of fibromyalgia is unknown. Fibromyalgia may be primary or secondary, superimposed on a recognizable painful condition or underlying disease. The diagnosis, which is suggested by the history and the finding of specific tender points on physical examination, requires exclusion of other causes of widespread aches and pains, including hypothyroidism and depression.

Localized idiopathic musculoskeletal pain

Localized idiopathic musculoskeletal pain is typically constant, severe pain that can involve any part of the body. The leg is more commonly affected than the arm, and distal involvement is more common than proximal. The pain often significantly interferes with normal functioning and is frequently accompanied by allodynia (pain generated by stimuli that are not normally painful). The pain may or may not be associated with symptoms and signs of autonomic dysfunction, including cool temperature, mottled purple discoloration, increased sweating or marked dryness, and diffuse swelling of the painful area. Minor injury not infrequently precedes the onset of pain, but progressive disability follows that is not consistent with the inciting event. The disorders reflex sympathetic dystrophy and chronic regional pain syndrome types 1 and 2 are encompassed in the category localized idiopathic pain. As in the child with diffuse idiopathic pain, other diseases that could reasonably explain the symptoms must be excluded before this diagnosis is made.