chapter 15 Musculoskeletal Examination

“It is easier to build strong children than to repair broken men.”

The 6-year-old boy who presents with a limp and no other complaints or the 18-month-old girl who has one swollen knee can pose a diagnostic dilemma. Although most children with musculoskeletal pains do not have a serious underlying problem, some do have a potentially life-threatening or debilitating disease that requires urgent recognition and treatment. The first step toward distinguishing between a condition that requires treatment and one that calls for studious neglect is to understand normal variants and their spontaneous evolution. This understanding avoids unnecessarily meddlesome and expensive treatments and soothes parents enormously. Common musculoskeletal concerns include the child with feet (one or both) that turn in or out, legs that appear bowed, flat feet, a peculiar gait, and occasional stumbling. Most are self-correcting variants of normal skeletal growth, sometimes traceable to intrauterine position or familial characteristics. They are not deformities and should not be labeled as such when you talk to parents.

Normal Musculoskeletal Variants

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.

Key Point

Special shoes are rarely indicated for treating children’s leg and foot problems, whether real or perceived. Internal femoral torsion, a normal developmental phenomenon, is the most common cause of in-toeing in children between ages 3 and 12 years.

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).

Key Point

Often, at least one parent has similar generalized ligamentous laxity and joint hypermobility. Checking both parents for joint hypermobility helps them understand the child’s “problem.”

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.

Important local causes of musculoskeletal pain

Musculoskeletal pain may be caused by local or generalized conditions. Local causes of hip, knee, foot, and back pain in children include many common orthopedic conditions, which are summarized here.

Hip pain

Transient Synovitis

Transient synovitis is an acute transient disorder of unknown etiology that frequently causes isolated hip pain in children younger than age 10 years. Typically, the child awakens with intense groin pain that causes him or her to limp or refuse to walk. The leg is often held in a flexed and externally rotated position. Although the range of motion in one hip is limited, physical examination is otherwise normal. The most important differential diagnosis is septic arthritis, which is suggested by fever, other signs of systemic illness, marked pain, reduction in hip movement, and an elevated erythrocyte sedimentation rate.

Legg-Calvé-Perthes Disease

Legg-Calvé-Perthes disease is the name used for idiopathic avascular necrosis of the femoral head, usually seen in children between ages 4 and 10 years. It manifests as either acute or insidious onset of hip pain with associated limp and decreased range of motion, particularly in internal rotation.

Slipped Capital Femoral Epiphysis

Slipped capital femoral epiphysis occurs in adolescents. Presenting symptoms include:

1. Hip pain that radiates to the groin, medial thigh, and knee

2. An externally rotated gait

3. Decreased hip internal rotation

4. A limp

Short, obese children with delayed puberty and children who have undergone a recent, rapid growth spurt are at particular risk for chronic slipped capital femoral epiphysis. An acute slip can occur after trauma.

Knee pain

Key Point

Never forget that knee pain may not originate in the knee. It may be referred pain originating in a diseased hip.

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

• Patellofemoral pain often occurs in adolescents, particularly girls, as a result of chronic injury to cartilage, secondary to subclinical instability related to malalignment. Typically, knee pain occurs with activity and is exacerbated by climbing or descending stairs, walking down hills, squatting, or jumping. The term chondromalacia patella is a pathologic diagnosis made when there is evidence of fragmentation of the articular cartilage on the posterior surface of the patella.

• Recurrent patellar subluxation or dislocation is suggested when a child’s knee periodically gives way in association with severe, sudden pain and the inability to straighten the knee. Treatment consists of a referral for physiotherapy.

• Synovial plicae are persistent remnants of folds of synovial membrane that divide the knee joint into three compartments during fetal development. A thickened synovial fold that runs over the medial femoral condyle may typically result in medial knee pain.

• Osteochondritis dissecans is a defect in the subchondral region of an epiphysis with partial or complete fragmentation of bone. The condition commonly affects the distal femur, causing acute or insidious knee pain in teenaged boys, with or without an intra-articular loose body. Complaints about a knee that aches, gives way, locks, and swells, characterize osteochondritis dissecans, although teenagers often complain of a knee that gives way or aches without any evidence of disease.

• Osgood-Schlatter disease is a common cause of knee pain that is localized to the tibial tuberosity in athletic teenagers. Tenderness and swelling occur at the tibial tubercle and patellar tendon insertion, which result from a microavulsion fracture due to repetitive injury.

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

Key Point

Always take seriously any back pain in a child, because an organic cause is commonly found, particularly in younger children.

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

• Spondylolysis is a stress fracture, usually unilateral, through the pars interarticularis (usually affecting L5). Spondylolisthesis occurs in the setting of bilateral spondylolysis when one vertebral body slips forward on the one beneath (such as L5 on S1). Both conditions may cause back pain in a child older than age 5 years.

• Scheuermann disease (idiopathic adolescent kyphosis), a disorder of unknown etiology, is characterized by increased thoracic spine kyphosis with abnormal wedging of at least three adjacent vertebral bodies at the apex of the kyphotic curve with the presence of Schmorl nodes. These are protrusions of the disc into the adjacent vertebra, which can be detected on a plain radiograph of the spine.

Generalized Causes of Musculoskeletal Pain

Case History

History. A 5-year-old boy is brought to your office with leg pain. His mother tells you that at least 2 nights a week Michael awakens from sleep and cries with pain below his knees. This has been going on for the past month. Michael has not had obvious pain during the daytime and seems to keep up with his friends playing soccer. Michael’s mother looks very worried as she tells you that her second cousin had complained of similar severe leg pains and was diagnosed with leukemia.

Eliciting the parents’ fears and concerns is a key step toward alleviating these worries and managing a child’s problem. Leg pain is a very common complaint in childhood. So called growing pains, which are benign leg pains that follow a characteristic pattern and are accompanied by a normal physical examination, may cause significant anxiety in the parent who is woken from sleep by a distressed child. Distinguishing benign forms of leg pain from the less common but serious causes of pain is an essential skill of the physician.

Besides the orthopedic disorders that cause pain in specific bones or joints, certain conditions may cause musculoskeletal pain in any location and must be considered in any child presenting with musculoskeletal pain. The pain may be localized to one or a few sites or may be generalized.

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

• Osteoid osteoma is a relatively common benign tumor causing localized bone pain, usually in the proximal femur or tibia, that worsens at night and is classically relieved by salicylates or other nonsteroidal anti-inflammatory drugs (NSAIDs).

• Leukemia is the most common malignancy causing musculoskeletal pain in children. Leg pain and fatigue on exertion may be among the earliest complaints of affected children. The pain is typically localized to the metaphysis of long bones, and the severity of pain is often out of proportion to other objective findings. The child may have associated swelling of a joint, most commonly the knee, which must be differentiated from oligoarticular juvenile idiopathic arthritis (JIA). Neuroblastoma is another important cause of bone pain in young children, the pain being due to bony metastases.

• Primary bone tumors often manifest as localized musculoskeletal pain. Osteosarcoma, the most common primary malignant bone tumor in children, typically occurs in the metaphysis of the distal femur, proximal tibia, or proximal humerus in adolescents. Ewing sarcoma is the second most common primary malignant bone tumor in children and also usually occurs in adolescents. It is often found in the diaphysis of the femur, humerus, or tibia but may occur in any bone, including those of the axial skeleton.

Juvenile idiopathic arthritis

Key Point

Juvenile idiopathic arthritis (JIA) is diagnosed if a child age 16 years or younger exhibits persistent arthritis for 6 weeks or more with no underlying cause.

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

1. Tenderness or pain on motion

2. Limitation of motion

3. Increased heat

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.

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.

BOX 15–1 Findings in Joint Hypermobility *

Passive opposition of thumb to flexor aspect of the forearm

Passive hyperextension of the metacarpophalangeal joints so fingers are parallel to extensor aspect of forearm

Hyperextension of elbows to >10°

Hyperextension of knees to >10°

Ability to touch floor with flat of hands without bending knees

^* The diagnosis of joint hypermobility requires the presence of three of these findings.

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.

The Child with a Limp

Key Point

A limp in a child must be taken seriously; usually, a cause is found. Observation of the gait often tells a great deal about the site and nature of the problem.

Causes of an abnormal gait may be divided into the following categories:

• Painful causes: injury, mechanical stress, inflammation, or a destructive process

• Painless causes: leg-length discrepancy, in-toeing or out-toeing

• Neuromuscular causes: weakness, spasticity, or coordination problems

A limp is frequently accompanied by pain in a child, although discomfort may not be the chief complaint (Table 15–1). Recent pain accompanied by worsening symptoms suggests trauma, infection, slipped capital femoral epiphysis, or transient synovitis. The more prolonged the symptoms, the more likely that an abnormality will be detected on imaging studies. A limp that is worse in the morning and improves as the day progresses may be due to inflammatory disease. Limping without pain occurs in conditions such as developmental hip dysplasia, leg-length discrepancy, and neurological disorders.

TABLE 15–1 Common Causes of a Limp in a Child

Cause	Underlying Conditions
Local causes
Hip	Developmental hip dysplasia,
	Legg-Calvé-Perthes disease (septic arthritis), transient synovitis, slipped capital femoral epiphysis
Knee	Osgood-Schlatter disease, osteochondritis dissecans, tumors
Tibia	Toddler’s fracture, stress fracture, fracture through a bone cyst
Foot	Tarsal coalition, Köhler disease, tight shoes
Back	Spondylolisthesis, osteomyelitis,
	Scheuermann disease
Short leg

Generalized disorders
Bone diseases	Rickets, infections, leukemia, primary tumors
Muscle diseases	Inflammatory, congenital, metabolic myopathies
Joint diseases	Juvenile idiopathic arthritis, septic arthritis
Neurological diseases	Cerebral palsy
Psychiatric diseases	Conversion disorder

The Child with a Single Swollen Joint

Six broad categories of monoarthritis are listed in Box 15–2. As with musculoskeletal pain, the location provides a diagnostic clue, particularly in rheumatic or orthopedic conditions.

BOX 15–2 Causes of Monoarthritis in a Child

Trauma

Infection

Rheumatic disorders

Hematologic disorders (hemophilia, hemangioma)

Mechanical and orthopedic conditions

Trauma is the most common cause of a single swollen joint in a child. Ask about a precipitating injury.

Infections, such as septic arthritis or osteomyelitis, must be considered. If the child has had a fever or recent documented infection and has recently received antibiotics, you should suspect infectious arthritis, especially if marked pain, redness, and increased heat are noted in a single joint. In an area endemic for Lyme disease, this infectious cause of swelling of one or more joints must be considered because antibiotics can cure the arthritis.

Consider malignancy in a child who presents with fever, weight loss, and malaise. Leukemia, lymphoma, and neuroblastoma are by far the most common possibilities.

Juvenile idiopathic arthritis is an important cause of monoarthritis in a child. About fifty percent of children with oligoarticular JIA present with monoarthritis, most commonly affecting one knee. Several other JIA subtypes may also start with a single swollen joint.

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