Introduction
Although children with musculoskeletal complaints may present with what appears to be an isolated, localized problem, complaints involving the musculoskeletal system (e.g., arthralgia, myalgia, joint swelling, poorly localized extremity pain, limping, refusal to walk) may be associated with a long list of potential illnesses. Children or their parents rarely arrive in the clinic with a complaint of arthritis or patellofemoral syndrome. Instead, they have symptoms such as extremity pain, joint swelling, or limitations of activity and function. These children may have chronic inflammatory arthritis or an associated systemic rheumatic disease, a traumatic condition, a mechanical problem, or a pain syndrome, among other possible explanations.
The differential diagnosis of extremity pain is extensive ( Table 33.1 ). For many of these diagnoses, the history and physical examination are sufficient to confirm a diagnosis; for others, specific laboratory tests or imaging studies will confirm a suspected diagnosis. Musculoskeletal symptoms may indicate pathologic processes localized and restricted to a single extremity or joint, or localized symptoms may be a component of a systemic illness.
| Rheumatic and Inflammatory Diseases |
| Juvenile idiopathic arthritis |
| Systemic lupus erythematosus |
| Juvenile dermatomyositis |
| Polymyositis |
| Polyarteritis nodosa |
| Scleroderma |
| Sjögren syndrome |
| Behçet disease |
| Overlap syndromes |
| Granulomatosis with polyangiitis |
| Microscopic polyangiitis |
| Sarcoidosis |
| Kawasaki disease |
| Henoch–Schönlein purpura |
| Chronic recurrent multifocal osteomyelitis |
| Infectious Illnesses |
| Bacterial arthritis (e.g., Staphylococcus aureus , Streptococcus pneumoniae , Kingella kingae , Neisseria gonorrhoeae , Haemophilus influenzae ) |
| Lyme disease |
| Viral illness (e.g., parvovirus, rubella, mumps, Epstein–Barr virus, hepatitis B, Chikungunya fever) |
| Fungal arthritis |
| Mycobacterial infection |
| Hematologic Disorders |
| Hemophilia |
| Hemoglobinopathies (including sickle cell disease) |
| Immunodeficiencies |
| Hypogammaglobulinemia |
| Immunoglobulin A deficiency |
| Human immunodeficiency virus |
| Common variable immunodeficiency |
| Congenital and Metabolic Disorders |
| Gout |
| Pseudogout (calcium pyrophosphate dihydrate crystal deposition disease) |
| Mucopolysaccharidoses |
| Glycogen storage diseases |
| Thyroid disease (hypothyroidism, hyperthyroidism) |
| Hyperparathyroidism |
| Vitamin C deficiency (scurvy) |
| Vitamin D deficiency (rickets) |
| Hereditary connective tissue disease (Marfan syndrome, Ehlers–Danlos syndrome) |
| Fabry disease |
| Farber disease |
| Orthopedic Disorders |
| Trauma |
| Patellofemoral syndrome |
| Hypermobility syndrome |
| Osteochondritis dissecans |
| Avascular necrosis (including Legg–Calvé–Perthes disease) |
| Hypertrophic osteoarthropathy |
| Slipped capital femoral epiphysis |
| Osteolysis |
| Benign bone tumors (including osteoid osteoma) |
| Histiocytosis |
| Neuropathic Disorders |
| Peripheral neuropathies |
| Carpal tunnel syndrome |
| Charcot joints (neuropathic osteoarthropathy) |
| Neoplastic Disorders |
| Leukemia |
| Neuroblastoma |
| Lymphoma |
| Bone tumors (osteosarcoma, Ewing sarcoma) |
| Histiocytic syndromes |
| Synovial tumors |
| Reactive Arthritis |
| Acute rheumatic fever |
| Postinfectious |
| Serum sickness |
| Transient synovitis of the hip |
| Postimmunization |
| Pain Syndromes |
| Fibromyalgia |
| Growing pains |
| Depression (with somatization) |
| Anxiety |
| Stress |
| Complex regional pain syndrome |
| Myofascial pain syndromes |
| Miscellaneous Disorders |
| Pigmented villonodular synovitis |
| Plant-thorn synovitis (foreign body arthritis) |
| Myositis ossificans |
| Eosinophilic fasciitis |
| Tendonitis (overuse injury) |
| Raynaud phenomenon |
| Erythromelalgia |
Arthritis is a specific sign indicating objective inflammation of the joint, and can be defined as (1) swelling of the joint or (2) limitation of motion combined with 1 of the following: pain on motion, tenderness, or warmth. Arthritis should be distinguished from arthralgia ( Table 33.2 ), bone pain, myalgia, and neuralgia, because if arthritis is present, the diagnostic possibilities are limited to more specific categories of disease ( Fig. 33.1 ). Arthritis is not a specific disease; there are infectious, postinfectious/reactive, hematologic, metabolic, oncologic, and rheumatic causes of arthritis. The precise diagnosis is determined by 1st establishing the characteristics of the arthritis with respect to the number and location of joints involved, severity, degree of disability, and chronicity. The clinician combines these characteristics with the history and the pattern of any associated systemic signs and symptoms to determine the specific cause of arthritis.
| Arthritis | Arthralgia |
|---|---|
| Prominent swelling | Minimal or no swelling |
| Morning stiffness | No morning stiffness |
| Symptoms improve with activity | Symptoms are exacerbated by activity |
| Stiffness follows rest | Pain constant or improves with rest |
| Limited range of motion | Normal or excessive range of motion |
| Warmth of joint | No warmth |
| Symptoms usually daily, consistent | Symptoms variable, constant, or intermittent |
(See Nelson Textbook of Pediatrics, p. 1162.)
History
Although the parents and child are usually the principal historians, it is often helpful to determine whether other adults have seen signs or have been aware of the child’s symptoms. Have daycare providers reported problems to the parents? Has the school staff, coach, or physical education teacher noticed any problems similar to those seen at home? Obtaining consistent information from several observers in different settings determines the frequency and consistency of the symptoms, how disabling the symptoms have been, and the reliability of the history. Adolescents have a tendency to either underreport or overreport their symptoms, making the history especially challenging within this age group. If there are inconsistencies, it becomes increasingly difficult to formulate a diagnosis, and information from the physical examination, along with potential laboratory and imaging studies, may be needed to resolve the inconsistencies.
Pain Location
There are several possible sources of extremity pain ( Fig. 33.2 ). Pain directly over a joint or joints may indicate synovial inflammation, arthralgia secondary to viral infection, or mechanical joint problems such as ligament trauma, meniscal tears, or hypermobility. Pain near a joint may represent disease in the muscle, bone, tendon, enthesis (tendon insertion sites), or bursa, or may be referred from a nearby joint. Pain may involve a whole limb or limbs, or isolated regions thereof, in which case it may reflect neuropathy, myalgia, or a regional pain syndrome. On occasion, children complain of pain “all over,” which may suggest diffuse myalgia related to a systemic infection, or if chronic, a myofascial pain syndrome. Intense pain localized to a single small area is seen with infection, trauma, fracture, or tumor. Migrating arthritis or arthralgia is more suggestive of diagnoses such as acute rheumatic fever or immune complex–mediated disease, and is less consistent with trauma, tumors, osteomyelitis, or septic arthritis, with the exception of septic arthritis secondary to Neisseria gonorrhoeae infection.
Pain Character
Arthritis is an aching discomfort that is usually not severe enough to cause crying or screaming. Some children with arthritis may not complain of pain at all. Very severe pain should increase the suspicion of a pain syndrome or bone disease such as osteomyelitis, leukemia, metastatic neuroblastoma, fracture, or bone tumors. Sporadic episodes of extreme pain interspersed with pain-free intervals are seen with pain syndromes such as growing pains, myofascial pain, and complex regional pain syndrome, or in situations in which psychogenic and behavioral factors contribute to the pain. With some pain syndromes, children often rate their pain as 10 on a scale of 0-10 and also may state that the pain is constant. Some patients may demonstrate “la belle indifference,” an incongruity between their affect and their complaint; they may be smiling or laughing while they are describing the presence of excruciating discomfort. Sharp, radiating, or throbbing pain is very unusual for arthritis and suggests an alternative explanation such as neuropathic pain, trauma, or psychogenic pain.
Pain Timing
Arthritis usually causes consistent patterns of discomfort. Symptoms are present daily, though with day-to-day variability in severity. Stiffness or pain-related discomfort occurs on awakening in the morning or after other periods of inactivity, such as prolonged sitting in class or taking a long car ride. The stiffness may last for hours, but generally improves with activity during the day. Some forms of arthritis, such as Lyme arthritis or enthesitis-related arthritis, may be more episodic. Lyme arthritis classically causes symptoms for days to weeks, usually in a single knee, interspersed with periods of improvement. Enthesitis-related arthritis can cause sudden increases in swelling and discomfort of 1 or more joints for several weeks to months at a time, followed by gradual spontaneous improvement.
Discomfort that occurs with activities and improves with rest is more suggestive of mechanical pain such as that associated with patellofemoral syndrome, hypermobility, tendonitis, overuse, or muscle strain. Affected children do not have significant symptoms in the morning or after naps, and these conditions are generally not associated with signs of significant inflammation such as warmth, prominent swelling, or limited range of motion.
Nocturnal pain that wakes children from sleep may be seen in potentially serious conditions such as leukemia, bone tumors (including benign tumors such as osteoid osteoma), or infections, but may also occur with benign conditions such as growing pains, muscle cramps, or behaviorally mediated pain. Children with benign causes of pain tend to lack systemic symptoms, are well during the day, and have normal physical examination findings, whereas those with more serious illnesses typically have additional symptoms to suggest the diagnosis.
Pain Acuity
Most chronic arthritis is insidious, and affected children often have symptoms for weeks to months before they seek medical attention. If the onset is sudden and severe, the evaluation should focus on excluding diagnoses that require urgent treatment, such as trauma, fracture, septic arthritis, or osteomyelitis. Acute rheumatic fever, reactive arthritis, and viral-associated arthritis or myositis may also manifest suddenly.
Children who describe having extremity pains “for years” often have mechanical causes of their discomfort such as hypermobility syndrome or patellofemoral syndrome, psychogenic or behavioral causes of pain, or other relatively benign conditions such as growing pains. It is very rare for such children to have an unrecognized arthritis.
Signs of Inflammation
The swelling and warmth of arthritis are often apparent to the child and parents. Exceptions may include the shoulder and hip, in which the joints are too deep for these signs to be visible, and the spinal, temporomandibular, and sacroiliac joints, in which the articular surfaces are small in relation to the surrounding soft tissues. In these areas, physical examination may reveal tenderness or limitation of motion in the absence of reported signs of inflammation.
Disability
The chief complaint may often be a disability such as limping, trouble climbing stairs, or difficulty writing. Some children will have associated pain and signs of inflammation, whereas others have little or no discomfort and it may be that they or their family have simply noticed a decrease in functional ability.
If the chief complaint is the disability, it is helpful to localize the source of the disability to the joint, the bones, the muscles, or the nerves. Muscle or nerve disease manifests primarily as weakness, although some children with sensory neuropathies or myositis, particularly acute viral myositis, will also have pain. Dermatomyositis and polymyositis cause symmetric proximal weakness in the upper and lower extremities. The characteristic symptoms are difficulties climbing stairs, rising from the floor, taking the big step onto a bus or into the family minivan, and washing or combing the hair, as well as fatigue and poor endurance. Isolated lower extremity or asymmetric weakness should increase suspicion of neurologic disease.
Disabilities from arthritis are caused by limited range of motion or discomfort in the joint rather than weakness. Limping, particularly in the mornings, toe-walking because of inability to extend the knee or Achilles tendon, and having difficulty running and jumping are seen with lower extremity arthritis. The child with hand or wrist arthritis has difficulty opening bottles, turning doorknobs, manipulating buttons or snaps on clothing, and gripping pencils or utensils.
Medical History
Numerous genetic syndromes and metabolic diseases are associated with arthritis and arthropathy (see Table 33.1 ). Endocrine disorders such as diabetes, hyperparathyroidism, and hypothyroidism are associated with arthropathy, periosteal inflammation, and muscle weakness, respectively. Arthritis is more frequent in patients with psoriasis and inflammatory bowel disease. Bone pain is common in hemoglobinopathies such as sickle cell disease. Cystic fibrosis and other chronic pulmonary diseases increase the likelihood of painful hypertrophic osteoarthropathy: the clinical triad of arthritis, digital clubbing, and ossifying periostitis of the long bones. Arthritis or arthralgia may occur after viral diseases or immunization, particularly with immunization against rubella and hepatitis B, presumably secondary to immune complex deposition in the joint.
Medications
Medications may directly cause symptoms, either via serum sickness-like reactions or swelling related to anaphylaxis. Response to medications may also provide further insight into the etiology of arthritis. In most children, an adequate dose of nonsteroidal antiinflammatory drugs (NSAIDs) improves the discomfort of arthritis to some degree. In rheumatic fever, NSAIDs often result in dramatic improvement in symptoms. Conversely, the patient who continues to have severe pain despite adequate doses of antiinflammatory and analgesic medication is more likely to have an infection, a fracture, a tumor, or psychogenic pain.
Family History
For some diseases, a positive family history increases the likelihood that other individuals in the family have that disease, but the genetics of the rheumatic diseases are complex, and none of the genetic associations are strong enough to confirm or eliminate a diagnosis solely on the basis of the family history. Within the rheumatic diseases, the family history is most helpful when diagnostic possibilities include enthesitis-related arthritis, psoriatic arthritis, or lupus. Ankylosing spondylitis, reactive arthritis, or inflammatory bowel disease in the family increases the likelihood that the child’s arthritis is related to 1 of these entities. The presence of the human leukocyte antigen (HLA)-B27 in these family members may increase the likelihood of enthesitis-related arthritis in the child. Approximately 30% of patients with lupus will have a 1st-degree relative affected by lupus. Less common familial illnesses that may cause rheumatic complaints include familial Mediterranean fever, mucopolysaccharidoses, hemophilia, and muscular dystrophies. A family history of adults with osteoarthritis or other forms of degenerative arthritis is generally not helpful, since these entities are relatively common and very rarely relevant to a child’s joint symptoms.
Social History
Determining the extent to which the problem has limited usual activities helps to gauge the severity of the problem. Has the child missed school because of their symptoms? Has the child been able to participate in physical education, organized sports, or other physical activities such as dancing, swimming, and gymnastics? Is the older child participating in social activities with friends? In some instances, the limitations are directly related to discomfort or disability from arthritis, but school absences and the discontinuation of sports and social activities may also be secondary to depression or psychogenic pain. It is helpful to ask the parents whether the child’s mood or personality has changed recently and whether there have been any recent known psychosocial stressors such as problems at school or with friends or discord within the family. Chronic pain syndromes in children are frequently associated with a history of psychosocial stress as well as depression.
Travel history is important in considering Lyme disease because the causative agent, the spirochete Borrelia burgdorferi , is transmitted by the bite of a deer tick that has a restricted geographical distribution. Lyme arthritis characteristically causes episodic joint effusions in 1 or several large joints, most commonly the knee. A small percentage of patients develop chronic arthritis. In the United States, endemic regions include the northeast (Connecticut, Rhode Island, and Massachusetts), mid-Atlantic (Long Island, New York City suburbs, New Jersey, southeastern Pennsylvania, Delaware, and Maryland), and the upper Midwest (parts of Minnesota and Wisconsin). Although these endemic areas may be gradually expanding, a child who has not traveled to these areas is unlikely to have Lyme disease. Arthritis may be the only symptom of Lyme disease, and may not appear until up to 2 years after the tick bite; a history of the classic rash (erythema migrans) is helpful but not necessary for a diagnosis of Lyme disease.
Review of Systems
Constitutional Symptoms
Some rheumatic diseases, including several forms of childhood arthritis, are systemic illnesses and cause fevers, poor appetite, weight loss, and fatigue. The absence of these symptoms helps eliminate specific illnesses as diagnostic possibilities. When fevers are present, establishing the pattern of fever is important. Systemic juvenile idiopathic arthritis (JIA) typically produces 1 or 2 high temperature spikes each day, with many afebrile hours in between ( Fig. 33.3 ). More persistent fevers tend to be seen with infections or Kawasaki disease. A periodic fever pattern, in which fevers occur for several days, followed by weeks without fever, is seen in familial Mediterranean fever, cyclical neutropenia, the syndrome of periodic fever, aphthous stomatitis, pharyngitis, and adenopathy (PFAPA), and other autoinflammatory syndromes. Systemic lupus erythematosus (SLE), vasculitis, rheumatic fever, serum sickness, inflammatory bowel disease, sarcoidosis, leukemia, and neuroblastoma may cause fevers associated with arthritis or extremity pains. These illnesses do not cause specific patterns of fever.
A decline in appetite is common in many arthritides, though when associated with documented weight loss may indicate more severe or systemic illness. Although most children with JIA do not have significant appetite changes, those with systemic JIA may have substantial appetite and growth disturbances. Severe polyarticular JIA may cause some appetite changes and mild weight loss. Children with Crohn disease or ulcerative colitis, both of which are often accompanied by abdominal pain and diarrhea, may demonstrate poor appetite and failure to thrive. SLE, vasculitis, scleroderma, malignancies, and chronic infections such as tuberculosis are additional causes of significant weight loss. An increase in weight should raise the suspicion of hypothyroidism or fluid retention.
Fatigue is common with any systemic illness, and it may be present in systemic or polyarticular JIA, SLE, hypothyroidism, rheumatic fever, and chronic pain syndromes. The clinician should attempt to distinguish between generalized fatigue and specific muscle weakness. The presence of proximal muscle weakness, often associated with fatigue and poor endurance, is characteristic of polymyositis and dermatomyositis.
Skin Changes
Systemic JIA is nearly always accompanied by evanescent pink or salmon-colored macules, often a few centimeters in diameter or smaller but sometimes coalescing to form larger patches ( Fig. 33.4 ). These may be generalized or localized to the trunk or extremities. The macules are usually not pruritic, appear with the fever spikes, and may resolve completely when the fever is absent. Sometimes parents do not notice the rash because of its fleeting nature. Acute rheumatic fever is associated with a specific rash, erythema marginatum , in only approximately 5% of cases. Erythema marginatum is also a fleeting rash, changing in distribution over time, and consists of erythematous patches with serpiginous borders that tend to migrate, usually over the trunk and proximal extremities. Because of their changes in distribution, families often confuse both of these rashes with urticaria. The malar rash of SLE is a fixed, erythematous, nonblanching patch over the cheeks and nasal bridge that tends to spare the nasolabial folds. SLE may also cause vasculitic rashes, as well as nonspecific erythematous macular or papular lesions. Vasculitic rashes consist of palpable purpura and can sometimes be ulcerative. The characteristic skin lesions in dermatomyositis are pathognomonic: a heliotrope rash is a purpuric discoloration of the upper eyelid, often accompanied by edema ( Fig. 33.5 ); Gottron papules are erythematous plaques or papules that appear on the extensor surface of the metacarpophalangeal and proximal interphalangeal joints of the hands ( Fig. 33.6 ). These are sometimes scaly and can be confused with psoriasis or eczema, were it not for the distribution. Lesions similar to the Gottron papules occasionally also appear on the extensor surfaces of the elbows and knees and over the medial malleoli at the ankle. In addition, erythematous patches may appear on the shoulders, chest, or face, where the appearance can cause confusion with the malar rash of SLE.
Erythema migrans occurs in up to 80% of cases of Lyme disease, days to weeks after the tick bite. The lesion expands, beginning as a small papule and then forming a large erythematous, circular patch, usually at least 5 cm in diameter and often with some clearing in the center to produce a target-like appearance ( Fig. 33.7 ). If Lyme disease is left untreated, the lesion usually lasts for several weeks and then gradually resolves. If dissemination occurs, some individuals develop multiple secondary lesions that appear similar to the primary lesion.
The history of other types of rashes or skin lesions may suggest other diagnoses. Measles and parvovirus infections, for example, have characteristic rashes. Petechiae may be seen with SLE, vasculitis, immune thrombocytopenia, or leukemia. Pallor or cyanosis of the digits, hands, and feet in association with cold temperature suggests Raynaud phenomenon , which is most often seen in those with no underlying systemic illness, but may be associated with several rheumatic diseases, most notably SLE and scleroderma. Scleroderma causes tightening, thickening, and the development of a waxy texture to the skin, and it frequently begins on the hands, feet, and face. A history of photosensitivity is suggestive of SLE.
Additional Symptoms
Questioning the parents about cognitive difficulties, including declining school performance or memory loss, helps screen for the possibility of subtle central nervous system involvement that may be associated with SLE or vasculitis. Seizures or frank psychosis may also occur in these illnesses. Alopecia is frequently seen with SLE and may also occur with hypothyroidism. Ocular symptoms, such as pain or redness of the eye, may occur with uveitis. Acute anterior uveitis (involving the iris and/or ciliary body) can be seen with reactive arthritis and enthesitis-related arthritis . Chronic anterior uveitis is most common with oligoarticular JIA and is usually asymptomatic. Sarcoidosis in children is usually associated with posterior uveitis, although anterior uveitis also occurs. Ulcerations of the nose or hard palate may be present with SLE. Aphthous ulcerations can be seen with inflammatory bowel disease and Behçet disease. Frequent sinusitis is often a manifestation of granulomatosis with polyangiitis.
Pleuritic chest pain that is worse when the patient lies supine and improves with sitting up and leaning forward may represent pericarditis, which can be seen in systemic JIA and SLE. Dysphagia suggests esophageal dysmotility, which may occur with inflammatory myopathies and scleroderma. Asking whether the child needs to cut food into small pieces, needs to drink an unusual amount of fluid with meals, or takes a long time to complete a meal are helpful ways of assessing dysphagia. Abdominal pain, vomiting, and diarrhea are nonspecific, but if severe or associated with melena or hematochezia, suggest Henoch–Schönlein purpura (HSP), inflammatory bowel disease, polyarteritis nodosa with vasculitis of the intestine, or the rare intestinal vasculitis associated with dermatomyositis. Testicular pain is seen with some forms of vasculitis, particularly HSP and polyarteritis nodosa. A history of recurrent genital and oral ulcerations is highly suggestive of Behçet disease. Peripheral edema, sacral edema, or periorbital edema may be present with illnesses causing glomerulonephritis, such as SLE and some of the vasculitides.
Physical Examination
Observing the child ambulate or explore the examination room provides a sense of the severity of the illness and the degree of disability. Particularly with young, fearful children, this period of observation may give a better sense of the range of motion or the degree of discomfort in the joints than the formal examination, when the child may be uncooperative.
The examination begins by reviewing the vital signs. Fever, especially in the child with arthritis or localized extremity pain, may suggest an infectious process. Tachycardia may be caused by fever, anxiety, pericarditis, or myocarditis. Tachypnea suggests the presence of cardiac or pulmonary disease and hypertension increases the suspicion of renal disease.
In any child with joint complaints, it is important to examine all of the joints because arthritis may be detected in joints that have not had symptoms. The neck and the joints of the upper extremities are best examined with the child in a sitting position. Children with inflammation in the joints of the cervical spine usually have limitations in extension, lateral flexion, and rotation. This is tested by asking the child to look up at the ceiling, touch each ear to the ipsilateral shoulder, and touch the chin to each shoulder.
Arthritis of the temporomandibular joint is common with polyarticular JIA and might easily be overlooked. Children with chronic arthritis of these joints develop micrognathia and often retrognathia as a result of delayed mandibular growth. The oral opening is often decreased, and there may be pain with opening and closing of the jaw, and tenderness to palpation directly over the joint.
Shoulder arthritis is identified by detecting limited range of motion and pain with motion. With the upper arm abducted to 90 degrees and the elbow flexed to 90 degrees, the clinician can then rotate the upper arm superiorly and inferiorly (external and internal rotation of the humerus, respectively), noting any limitation or pain. Alternatively, the patient can be asked to abduct and extend the arm, reaching behind the head to touch the contralateral scapula, and then to adduct and extend the arm, reaching behind the back and upward, again touching the contralateral scapula. The acromioclavicular joints and the sternoclavicular joints are occasionally affected by arthritis and should be palpated, noting any swelling or tenderness.
In the elbow, arthritis often produces detectable swelling and warmth. Elbow extension and flexion should also be tested, along with supination of the forearm and hand. Many children can normally hyperextend their elbows, and the degree of extension is variable; therefore, it is helpful to compare the range of motion of each elbow to the contralateral side.
The wrists are inspected for swelling and palpated for warmth and tenderness. Many children with wrist arthritis develop swelling on the dorsal aspect of the wrist that may be fairly large but is usually nontender. Extension tends to be more limited than flexion in wrist arthritis, and radial deviation tends to be more limited than ulnar deviation. Children with arthritis frequently complain of pain or withdraw their arm with maneuvers to test flexion and extension of the wrist.
The metacarpophalangeal (MCP) joint and the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints should be individually palpated, and any swelling, tenderness, or warmth should be noted ( Fig. 33.8 ). The examiner should flex and extend the MCP joints, looking for limitations. To test the range of motion of the PIP and DIP joints, the child should try to supinate the hand and flex all of the digits, attempting to touch the fingertips to the palm. To examine the 1st MCP and thumb interphalangeal joint, the child should try to touch the tip of the thumb to the base of the 5th finger. Grip strength is determined by having the child tightly squeeze 2 of the clinician’s fingers. Arthritis of the wrist or any of the small joints of the hand decreases grip strength.
The child should next lie in a supine position, either in the parent’s lap or on the examination table so that the lower extremities can be examined. Each hip is taken through its range of motion, beginning with flexion by trying to bring the knee as close to the chest as possible. Any pain or limitation is noted. With the hip and knee each flexed to 90 degrees, internal and external rotation are tested by keeping the knee in a fixed position and turning the lower leg laterally and medially, thereby rotating the femur. The hip and knee are extended back to a neutral supine position and abduction is tested. With the child in the prone position, the examiner evaluates hip extension by placing a hand on the child’s ipsilateral iliac crest and lifting the child’s thigh posteriorly with the knee extended. Hip arthritis most often causes limitations with internal rotation and extension, usually in association with pain in the inguinal area.
The knee is inspected for effusions and other obvious deformities. Palpation of the knee assesses for warmth, a common finding in knee arthritis, synovial swelling, or an effusion. Applying pressure in the suprapatellar area with 1 hand while palpating on either side of the patella with the other allows for the detection of effusions more readily because this forces excessive joint fluid that has accumulated in the suprapatellar area into the synovial space. Small effusions may be detected by eliciting a bulge sign . This is done by milking the medial and lateral depressions around the patella superiorly in an effort to push the fluid into the suprapatellar space and then gently pushing either medially or laterally just superior to the patella. This releases the fluid back into the synovial space, causing the area medial to the patella to bulge out. The popliteal fossa should be palpated, because fluid within the knee joint tends to track posteriorly as it accumulates, producing fullness in the popliteal fossa and sometimes a frank cyst, identical to the Baker cysts seen in adults with rheumatoid arthritis.
Palpating around the edges of the patella causes pain in many adolescents with patellofemoral syndrome (also known as chondromalacia patellae), a common cause of knee pain in active adolescents. In another maneuver that elicits pain in this syndrome, the patient relaxes the quadriceps muscles while the examiner pushes the patella inferiorly. While the examiner maintains pressure on the patella, the patient contracts the quadriceps. In patients with patellofemoral syndrome, pain elicited by this maneuver is referred to as a positive patellar apprehension test , while a grinding sensation felt by the examiner constitutes a positive patellar grind sign . The tibial tubercle and patellar tendon should be inspected and palpated for swelling and tenderness associated with Osgood-Schlatter disease and patellar tendonitis , respectively.
Flexing and extending the knee tests range of motion. Most young children can touch their heel to their buttocks and hyperextend the knee. The examiner can detect subtle limitations in extension by standing at the foot of the table and lifting the heels of the child off the table as the child holds his or her legs fully extended. If 1 knee is limited with extension, the patella on that side may be slightly more elevated.
Swelling in the ankles is often best seen when inspecting and palpating the posterior aspect of the ankle, where fullness on either side of the Achilles tendon may be appreciated between the tendon and the malleoli. Warmth is common with ankle arthritis. Testing range of motion in the ankle should include both the tibiotalar ankle joint and the subtalar talocalcaneal joint. Cupping the heel with 1 hand and using the other hand to grasp the forefoot allows the examiner to move the forefoot superiorly (dorsiflexion) and inferiorly (plantar flexion). The hand cupping the heel is rocked laterally and medially to check inversion and eversion associated with motion at the subtalar joint. Holding the heel firmly with a cupped hand and gently rotating the forefoot with the other hand tests the joints of the midfoot. Each of the metatarsophalangeal joints is palpated along with each of the toes. The toes are inspected for the presence of swelling. The plantar fascia and the Achilles tendon are palpated, and any tenderness or swelling is noted.
The child should stand so that the examiner can evaluate the back. The sacroiliac joints are palpated, any tenderness is noted, and the child is asked to keep the knees extended and bend forward, touching the hands to the ground if possible. The lumbar spine should curve forward normally without flattening. The modified Schober measurement , which reveals whether the lumbar spine flexes normally, is done by marking the lumbar spine at a point where a horizontal line connecting the dimples of Venus intersects the spine. Then the examiner measures 10 cm above and 5 cm below that spot while the child is standing. When the child bends forward, the distance between the top and bottom marks should increase to at least 21 cm as the vertebral bodies separate during flexion. A shorter distance suggests limitation in mobility of the spine and potential spondylitis. Scoliosis is detected by noting any asymmetric elevation of the shoulder and upper back while the child bends forward.
Hypermobility is a very common cause of pain associated with sports and other activities; it tends to improve with rest. Hypermobility, patellofemoral syndrome, frequent ankle sprains, and pes planus are frequently seen together. The hypermobile child or adolescent can hyperextend the knees and elbows, appose the thumb to the forearm while flexing the wrist, hyperextend the MCP joints so that the digits are parallel to the forearm when the wrist is extended, and easily put the palms flat on the floor while bending forward from a standing position with the knees locked. Extreme hypermobility is seen in some individuals with Ehlers–Danlos syndrome or Marfan syndrome.
Myofascial pain syndromes are associated with the presence of trigger points , exquisitely tender, well-localized points often detected in the following locations: the occiput, trapezius muscles, medial borders of the scapula, upper outer quadrant of the buttocks, the 2nd cervical space anteriorly, the 2nd costochondral space just distal to the lateral epicondyle on the forearm, the greater trochanter in the proximal leg, and the medial aspects of the knees. Their presence in the older child with diffuse pain, fatigue, and difficulty sleeping is highly suggestive of a myofascial pain syndrome.
Proximal muscle strength testing should be performed in any patient complaining of weakness or fatigue. The deltoids, biceps, triceps, psoas, quadriceps, and hamstrings are tested. Neck flexor weakness is common in dermatomyositis and polymyositis and is tested by having the child lie supine and lift only his or her head. Most children are able to lift and keep the head elevated, even if asked to resist pressure from the examiner’s hand against the forehead. To test proximal leg strength, the child rises from a sitting position on the floor. Muscle atrophy should be noted. Chronic knee arthritis or hip disease leads to atrophy of the ipsilateral quadriceps. Similarly, ankle arthritis causes the gastrocnemius to atrophy; wrist arthritis leads to wasting of the forearm muscles; and elbow contractures cause atrophy of the triceps muscle. Atrophy is easily overlooked, and it is sometimes helpful to measure the circumference of the thigh, calf, or upper arm to detect asymmetry.
The skin and mucous membranes should be examined carefully, as there may be clues to the presence of systemic disease ( Table 33.3 ). Systemic JIA, SLE, acute rheumatic fever, and dermatomyositis are associated with characteristic rashes. Petechiae or palpable purpura suggests vasculitis. Nodules are seen with acute rheumatic fever and some forms of JIA. Thickening and tightening of the skin, particularly over the distal extremities and face, are often present in scleroderma. Nasal or palatal ulcers suggest SLE, whereas aphthous ulceration may be seen with inflammatory bowel disease or Behçet disease. Alopecia, either localized or diffuse, may be apparent to the examiner without being recognized by the patient. The presence of peripheral or periorbital edema increases the suspicion of glomerulonephritis.
| Physical Finding | Possible Disease |
|---|---|
| Petechiae, purpura |
|
| Erythema nodosum |
|
| Gottron papules | Dermatomyositis |
| Alopecia | SLE, hypothyroidism |
| Calcification | Dermatomyositis, scleroderma |
| Subcutaneous nodules | Polyarticular JIA, rheumatic fever |
| Oral ulcers | SLE, Behçet disease, inflammatory bowel disease, reactive arthritis |
| Genital ulcers | Behçet disease |
| Digital ulcers | Vasculitis, SLE, scleroderma |
| Tight, thickened skin | Scleroderma |
| Livedo reticularis | Antiphospholipid syndrome, SLE, cutaneous polyarteritis nodosa |
| Nail dystrophy or pits | Psoriasis |
| Edema | SLE, vasculitis, scleroderma, eosinophilic fasciitis, serum sickness, Henoch–Schönlein purpura |
| Desquamation | Kawasaki disease, scarlet fever |
| Cyanosis | Raynaud phenomenon, hypertrophic osteoarthropathy |
Laboratory Studies
Laboratory testing should be considered when the diagnosis is unclear or when there is a suspicion of life- or limb-threatening disease such as leukemia, septic arthritis, or osteomyelitis. Laboratory testing alone does not establish a diagnosis of JIA. Tests frequently seen in “arthritis panels” such as those for antinuclear antibody (ANA), rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) are not specific for arthritis. However, if arthritis is detected on physical examination, laboratory testing aids in classifying the specific type of arthritis that is present.
A complete blood count (CBC) with manual differential is useful as a means of decreasing the suspicion of an acute infection or leukemia, which may manifest with bone or joint pain or even frank arthritis. A normal CBC is reassuring, but it is also helpful to compare the platelet count to the ESR. Because platelets are an acute-phase reactant, their number should increase as the ESR increases. A normal or low platelet count in a child with markedly elevated ESR increases the suspicion of leukemia.
An elevated peripheral white blood cell (WBC) count is often present with septic arthritis or osteomyelitis, but it is neither sensitive nor specific enough to change the diagnostic impression formulated after the history and physical examination. In systemic JIA, the WBC count may be markedly elevated at 20,000 WBCs/mm 3 or greater, the hemoglobin may be as low as 6 or 7 mg/dL, and the platelet count is typically significantly elevated. For many of the other inflammatory diseases that are associated with arthritis or extremity pain, a mild to moderate normocytic anemia as well as a mild thrombocytosis are common. SLE may demonstrate anemia, leukopenia, and thrombocytopenia.
The ESR is helpful when the physical examination is inconclusive regarding the presence or absence of an inflammatory condition. In uncooperative or obese children, it may be difficult to detect small effusions or subtle limitation in the range of motion. In these instances, an elevated ESR increases the suspicion of arthritis, although a normal ESR does not rule it out. In children who clearly have rheumatic disease or infection, the ESR is not diagnostically useful, but it may be used to monitor disease activity over time.
Urinalysis is an excellent screen for glomerulonephritis, which may occur in patients with vasculitis or SLE. Proteinuria or red blood cell casts suggest renal involvement. The creatinine level is elevated with renal insufficiency. Severe proteinuria leads to hypoalbuminemia, though hypoalbuminemia without proteinuria may also be seen in systemic JIA. Kawasaki disease is associated with sterile pyuria.
Serum aminotransferases are elevated in patients with hepatitis and occasionally in patients with SLE. In those with myositis, elevated aminotransferases, usually with the asparate aminotransferase (AST) elevated out of proportion to the alanine aminotransferase (ALT), often occurs concomitantly with increased creatine kinase, lactate dehydrogenase, and aldolase levels.
Antinuclear Antibody
The ANA test is a sensitive screen for SLE because it is positive in more than 95% of patients who also usually have high ANA titers, typically with values of 1 : 640 or higher. Lower ANA titers, usually in the range of 1 : 40-1 : 160, are seen in children with JIA, healthy children, or those with cross-reactive antibodies in the setting of a recent infection. The frequency of ANA positivity varies in the different forms of JIA. The pattern of the ANA is rarely helpful. Homogeneous and speckled patterns are the most common and are not specific for any particular illness. A peripheral or “rim” pattern is usually associated with anti–double-stranded DNA (anti-dsDNA) antibodies and is more specific for SLE. A nucleolar pattern suggests the presence of anti–Scl-70 antibodies, which may be seen in patients with scleroderma.
The ANA test is not specific and should not be ordered unless there is a strong suspicion of SLE or an overlap syndrome. It is not sensitive enough or specific enough to be diagnostically helpful for other diseases. A positive ANA finding is present in many asymptomatic healthy children, and in children with viral illnesses, other infections, other rheumatic and inflammatory diseases, and in relatives of those with autoimmune illnesses.
Rheumatoid Factor
The rheumatoid factor (RF) test is not diagnostic. Only 5% of children with JIA have a positive RF result, and this usually occurs in teenagers with adult-like polyarticular disease. RF is an immunoglobulin M antibody directed against immunoglobulin G. In children with polyarthritis, the presence of RF is a poor prognostic factor; these children have a high likelihood of developing chronic, erosive arthritis. A positive test result for RF can be seen with other illnesses associated with the formation of immune complexes, including rheumatic diseases such as SLE or vasculitis, and with infectious diseases such as bacterial endocarditis, infectious mononucleosis, and hepatitis B or C. It should not be ordered, and will not be helpful diagnostically, in individuals who do not have polyarthritis based on the history and physical examination.
Additional Antibody Testing
If the history and physical examination findings are suggestive of SLE, additional autoantibody testing is helpful ( Table 33.4 ). Anti-dsDNA antibodies and anti-Smith antibodies are highly specific for SLE. Antiribonucleoprotein (anti-RNP) antibodies may be seen in patients with SLE, and when present in isolation (without anti-dsDNA and anti-Smith antibodies), suggest mixed connective tissue disease, which has clinical features that are often a combination of those seen with SLE, dermatomyositis, and scleroderma. Anti-Sjögren syndrome type A (anti-SSA [also known as anti-Ro]) and anti-Sjögren syndrome type B (anti-SSB [also known as anti-La]) antibodies are occasionally seen in patients with SLE but are not specific. They are seen in Sjögren syndrome, an illness producing chronic inflammation of the salivary and lacrimal glands and resulting in xerostomia and xerophthalmia.
