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Musculoskeletal complaints are among the most frequent reasons for children to present to a primary care office, walk-in clinic, or emergency room. While the child and parents may be focusing on what they perceive to be a localized problem, complaints involving the musculoskeletal system (e.g., arthralgia, myalgia, joint swelling, poorly localized extremity pain, limping, or refusal to walk) may be associated with a long list of potential systemic illnesses. Children or their parents rarely arrive in the clinic expressing a concern for “arthritis” or “patellofemoral syndrome.” Instead, they typically describe symptoms such as pain, swelling, limping, or other limitations of activity and function. These children might have complaints as a result of chronic inflammatory arthritis or an associated systemic rheumatic disease, a traumatic or overuse condition, a mechanical or anatomic problem, or a pain syndrome, among other possible explanations.
The differential diagnosis of extremity pain is extensive ( Table 44.1 ). For many of these diagnoses, the history and physical examination are sufficient to confirm a diagnosis; for others, specific laboratory tests, imaging studies, or rarely tissue biopsy will additionally be required to confirm a suspected diagnosis. Musculoskeletal symptoms may indicate pathologic processes isolated to a single extremity or joint, disease restricted to the musculoskeletal system, or a systemic illness of which the joint symptoms may be just one feature.
TABLE 44.1
Conditions Causing Arthritis or Extremity Pain
| Rheumatic and Inflammatory Diseases |
|
| Infectious Illnesses |
|
| Hematologic Disorders |
|
| Immunodeficiencies |
|
| Congenital and Metabolic Disorders |
|
| Orthopedic Disorders |
|
| Neuropathic Disorders |
|
| Neoplastic Disorders |
|
| Reactive Arthritis |
|
| Pain Syndromes |
|
| Miscellaneous Disorders |
|
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 one of the following: tenderness, warmth, or pain on motion. Arthritis should be distinguished from arthralgia ( Table 44.2 ), myalgia, neuralgia, bone pain, cutaneous pain, and allodynia, because if arthritis is present, the diagnostic possibilities are limited to more specific categories of disease ( Fig. 44.1 ). Arthritis is not a specific disease; there are infectious, postinfectious/reactive, hematologic, metabolic, oncologic, and rheumatic causes of arthritis. The cause of the arthritis is determined by establishing the characteristics of the arthritis, including the number and location of the joints affected; the severity, degree of disability, and chronicity of the arthritis; and the pattern of any associated systemic signs and symptoms.
TABLE 44.2
Distinguishing Characteristics of Arthritis and Arthralgia
| 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 with minor variation | Symptoms variable, constant, or intermittent |
Algorithm for determining the cause of extremity pain based on the presence or absence of arthritis.
History
Although the parents and child are usually the principal historians, it is 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, as well as how disabling the symptoms have been, and may often help to confirm the reliability of the history. 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 these inconsistencies.
Pain Location
Pain directly over a joint or joints may indicate synovial inflammation (arthritis), arthralgia secondary to viral infection, or mechanical joint problems such as joint laxity or ligament trauma. 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. There are several possible sites of extremity pain ( Fig. 44.2 ). Pain may involve a whole limb or limbs, or isolated regions of a limb, in which case it may be secondary to neuropathy, myalgia, or a regional pain syndrome. Complaints of pain “all over” may suggest diffuse pain related to a systemic illness or, if chronic, an amplified or 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 (e.g., from infection or drug reaction) and is less consistent with trauma, tumors, osteomyelitis, or septic arthritis, except for the migratory polyarthritis-tenosynovitis-dermatitis seen in certain instances of disseminated Neisseria gonorrhoeae infection or endocarditis.
Pain Character
Arthritis is an aching discomfort that is usually not severe; some children with arthritis may not complain of pain at all. Complete disability secondary to arthritis is rare and should prompt a search for an alternative explanation. 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 psychologic and behavioral factors, such as stress, anxiety, or depression, contribute to the pain. Sharp, radiating, or throbbing pain is unusual for arthritis and suggests an alternative explanation such as neuropathic pain, trauma, or psychogenic pain.
Pain Timing
Arthritis usually causes consistent patterns of daily discomfort with minor variability from day to day. 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, a subtype of juvenile idiopathic arthritis (JIA), 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 swelling and discomfort in one 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 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 or chronic swelling, or limited range of motion.
Nocturnal pain that wakes children from sleep may be seen in conditions such as leukemia, bone tumors, or infections, but may also occur with less critical conditions such as growing pains, muscle cramps, or psychogenic pain. Children with benign causes of nocturnal pain will lack systemic symptoms, are well during the day, and have normal physical examination findings, whereas those with inflammatory illnesses typically have additional signs and symptoms.
Pain Acuity
Most chronic arthritis is insidious in onset 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, atraumatic hemarthrosis, 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 many months or years often have mechanical causes of their discomfort such as hypermobility syndrome or patellofemoral syndrome, psychogenic pain, or other relatively benign conditions such as growing pains.
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 signs of inflammation.
Disability
The chief complaint associated with arthritis may often be a disability such as limping, trouble running or climbing stairs, or difficulty dressing. Some children have associated pain and signs of inflammation, whereas others have little or no discomfort, instead presenting with an isolated 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 or bacterial 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; unilateral toe-walking because of inability to extend the knee; and 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 44.1 ). Endocrine disorders such as diabetes, hyperparathyroidism, and hypothyroidism may be 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 joint or periarticular symptoms, either via serum sickness–like reactions associated with immune complex arthritis 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 based solely on 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 caused by one 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 first-degree relative affected by lupus. Less common familial illnesses that may cause rheumatic complaints include familial Mediterranean fever and other autoinflammatory syndromes that cause periodic fevers, mucopolysaccharidoses, fucosidoses, 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 in adults and 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, and other physical activities? Is the 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 amplified pain syndromes in children are frequently associated with a history of psychosocial stress, anxiety, or depression.
Travel history is important in considering certain infectious arthritides. The spirochete Borrelia burgdorferi , the causative agent of Lyme disease , is transmitted by the bite of a deer tick that has a specific geographic distribution. Lyme arthritis characteristically causes episodic joint effusions in one 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, Illinois, and Wisconsin). Although these endemic areas have been gradually expanding, a child who does not live in or 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. Rickettsiosis and ehrlichiosis tend to produce arthralgia but occasionally result in frank arthritis; residing in or traveling to endemic regions should increase suspicion of these vector-borne infections. The geographic distribution of Chikungunya virus has been widening; in addition to established endemicity in Africa, Asia, regions of Europe, and areas within the Indian and Pacific Oceans, transmission has been documented throughout North and South America and the Caribbean. Acute infection is often accompanied by rash and, when present in combination with fever, small and large joint polyarthritis, arthralgia, and myalgia, may mimic systemic JIA. Some patients may go on to develop chronic joint symptoms; inquiring about travel to endemic regions may hint at the diagnosis in both the acute and chronic stages of infection. Other viruses confined to a specific geographic area include Zika (South America, Africa, Asia), Ross River (South Pacific), o’nyong-nyong (Africa), and Sindbis (Africa, Middle East, Philippines).
Review of Systems
Constitutional Symptoms
Some rheumatic diseases, including several forms of childhood arthritis, are generalized 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 JIA typically produces one or two high temperature spikes each day, with many afebrile hours in between ( Fig. 44.3 ). 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, cyclic 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.
Decreased appetite is common in many arthritides, but 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. Vasculitis, SLE, 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, polymyositis, dermatomyositis, 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. 44.4 ). These may be generalized or localized to the trunk or extremities. The macules usually appear with the fever spikes, are not pruritic, 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 , though only in 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 these 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: heliotrope rash is a violaceous discoloration of the upper eyelid, often accompanied by edema. The heliotrope may sometimes be accompanied by more widespread facial erythema ( Fig. 44.5 ). Gottron papules are erythematous plaques or papules that appear on the extensor surface of the metacarpophalangeal and proximal interphalangeal joints of the hands ( Fig. 44.6 ) in individuals with dermatomyositis. These are sometimes scaly, are sometimes pale or atrophic, and can be confused with psoriasis or eczema if not for the distribution. Lesions similar to the Gottron papules occasionally appear on the extensor surfaces of the elbows and knees and over the medial malleoli. In addition, erythematous patches may appear on the shoulders, chest, or face (see Fig. 44.5 C ), where the appearance can cause confusion with the malar rash of SLE.
Erythema migrans occurs in up to 80% of cases of Lyme disease in children and appears 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. 44.7 ). 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.
Various mucocutaneous findings are present in up to half of patients with acute Chikungunya virus infection. Rash tends to be a generalized morbilliform maculopapular eruption that spares the face and appears within several days of the onset of fever, before subsiding within a week. Patients may also experience areas of hyperpigmentation, often in the centrofacial region and restricted to the nose, a finding termed the Chick sign . Up to a third of patients with acute Chikungunya will develop a chronic arthritis that may mimic JIA; therefore, inquiring about a remote history of characteristic skin findings, as well as constitutional symptoms such as a brief febrile illness temporally correlated with travel to regions where Chikungunya is endemic, may prompt testing for prior exposure to Chikungunya.
The history of other types of rashes or skin lesions may suggest other diagnoses. Measles and parvovirus infections, for example, have characteristic rashes. A history of photosensitivity is suggestive of SLE. Petechiae may be seen with SLE, vasculitis, immune thrombocytopenia, or leukemia. Pallor or cyanosis of the digits, hands, and feet upon exposure to cold temperatures suggests Raynaud phenomenon , which is most often seen in those with no underlying systemic illness but may be associated with several rheumatic diseases, most commonly SLE, mixed connective tissue disease (MCTD), 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.
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 central nervous system 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 or with nonspecific orbital inflammation (also known as orbital pseudotumor) potentially associated with a number of rheumatic diseases. 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 in younger children with oligoarticular or polyarticular JIA and is usually asymptomatic. Sarcoidosis in children may be associated with both anterior and posterior uveitis. Ulcerations of the nose or hard palate may be present in SLE. Both uveitis and oral aphthous ulcerations can be seen with inflammatory bowel disease and also with Behçet disease, which can also include genital aphthous ulceration. Frequent sinusitis is often an early manifestation of granulomatosis with polyangiitis (GPA).
Chest pain that is worse when the patient lies supine and improves with sitting up and leaning forward may represent pericarditis, which is most commonly associated with SLE and systemic-onset JIA but may occur in rheumatic fever. 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, might suggest Henoch-Schönlein purpura (HSP), also known as immunoglobulin A (IgA) vasculitis, as well as inflammatory bowel disease, polyarteritis nodosa with vasculitis of the intestine, or the rare intestinal vasculitis associated with SLE or dermatomyositis. Testicular pain is seen with some forms of vasculitis, particularly IgA vasculitis (HSP) and polyarteritis nodosa. Peripheral edema, sacral edema, or periorbital edema may be present with illnesses causing glomerulonephritis, such as SLE and the antineutrophil cytoplasmic antibody (ANCA)-associated 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 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. Systemic-onset JIA is the only subtype of JIA associated with fever. Abnormalities in other vital signs are not expected with isolated arthritis and suggest that a systemic disease may be present. 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 involvement.
In any child with joint complaints, it is critical to examine all the joints, even those that are asymptomatic. Children or their parents may focus on the joint that is most painful or causes the most disability and are often unaware of the presence of arthritis in other joints. 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 in size, and there may be pain with opening and closing of the jaw or 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 internally rotate the arm, reaching behind the head to touch the contralateral scapula, and then to adduct and internally rotate 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, usually identified posteriorly, proximal to the olecranon. 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 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 wrist 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. 44.8 ). 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 the digits, attempting to touch the fingertips to the palm. To examine the first MCP and thumb interphalangeal joint, the child should try to touch the tip of the thumb to the base of the fifth finger. Grip strength is determined by having the child tightly squeeze two 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 then 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 (producing a “spongy” feel); or an effusion (often feels like a “water balloon”). Applying pressure in the suprapatellar area with one 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 lateral and medial to the patella. Small effusions may be detected by eliciting a bulge sign . This is done by milking the medial and lateral depressions around the patella superiorly 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 inferiorly, causing the area medial to the patella to bulge out. The popliteal fossa should be palpated, because fluid within the knee joint may track posteriorly as it accumulates, producing fullness in the popliteal fossa and sometimes a frank cyst.
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 displaces the patella inferiorly by pushing on the superior pole of the patella. 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 normally touch their heel to their buttocks and can hyperextend the knee slightly. 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 relaxes their legs in a fully extended position. If one knee is limited with extension, the patella on that side may appear 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 ankle may be appreciated between the Achilles 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 one hand and using the other hand to grasp the forefoot allows the examiner to move the forefoot superiorly (dorsiflexion) and inferiorly (plantar flexion) to evaluate the tibiotalar joint. The hand cupping the heel is then 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 (MTP) joints is palpated along with each of the toes. The MTP joints are flexed and extended noting any limitations or pain, and as with other joints, also noting any asymmetry with the contralateral MTP joints. 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 lateral lumbar indentations 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. Obtaining a Beighton score may help the examiner more objectively assess the degree of hypermobility (see Chapter 47 ).
Myofascial pain syndromes are often associated with the presence of specific 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 second cervical space anteriorly, the second 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 and an evaluation of muscle bulk 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 their head. Most children can 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. 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 44.3 ). 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 polyarticular rheumatoid factor–positive JIA. Thickening and tightening of the skin, particularly over the distal extremities and face, are suggestive of scleroderma. Nasal or palatal ulcers suggest SLE, whereas aphthous ulceration may be seen with inflammatory bowel disease or Behçet disease, the latter particularly if on the genitals in the absence of sexually transmitted infection. 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.
TABLE 44.3
Skin Manifestations of Rheumatic Disease
| Physical Finding | Possible Disease |
|---|---|
| Petechiae, purpura | Vasculitis (may be palpable) Leukemia Meningococcemia Other infections SLE |
| Erythema nodosum | Inflammatory bowel disease Streptococcal infection Sarcoidosis Drug reaction Tuberculosis Fungal infection |
| 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 |
JIA, juvenile idiopathic arthritis; SLE, systemic lupus erythematosus.
The remainder of the physical examination including head, eyes, ears, chest, heart, and abdomen should also be performed carefully, with attention to potential signs that might indicate systemic and/or organ-specific disease.
Laboratory Studies
Laboratory testing should be considered when the diagnosis is unclear and systemic disease is a concern. It is important to recognize that laboratory tests are not diagnostic of JIA. Tests frequently seen in “arthritis panels” such as those for antinuclear antibody (ANA), rheumatoid factor (RF), ESR, and CRP are not specific for arthritis and may be abnormal in healthy children or in those with infections and other coincidental diseases.
A CBC with manual differential is useful in decreasing the suspicion of an acute infection or leukemia as the etiology of bone pain, joint pain, or even frank arthritis. A normal CBC is reassuring, but it is also helpful to compare the platelet count to the ESR when concerned about leukemia. Because platelets are an acute-phase reactant, they should increase as the ESR increases. A normal or low platelet count in a child with markedly elevated ESR increases the suspicion of leukemia or another cause for platelet destruction or decreased bone marrow platelet production.
An elevated peripheral white blood cell (WBC) count is often present in septic arthritis or osteomyelitis but is neither sensitive nor specific for these infections. In systemic-onset JIA, the WBC count may be markedly elevated to 20,000 WBCs/mm 3 or greater and the hemoglobin may be as low as 6 or 7 g/dL; 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 and a mild thrombocytosis are common. SLE may be associated with anemia, leukopenia, and thrombocytopenia.
The ESR is helpful when physical examination is inconclusive for signs of inflammation. In children who are uncooperative or whose body habitus precludes adequate assessment, it may be difficult to detect small effusions or subtle limitations in the range of motion. In these instances, an elevated ESR increases the suspicion of arthritis, although a normal ESR does not exclude it. In children who clearly have rheumatic disease or infection, the ESR is not useful diagnostically, but it may be useful as a means of monitoring disease activity over time. CRP is often elevated in systemic-onset JIA, polyarticular JIA, and infectious arthritis but is often normal in oligoarticular arthritis. Procalcitonin is typically normal in JIA and elevated in bacterial osteoarticular infections.
Vasculitis or SLE may result in glomerulonephritis; proteinuria or red blood cell casts can be detected on urinalysis, and the serum creatinine level will be elevated if glomerulonephritis has resulted in renal insufficiency. Severe proteinuria will also lead to hypoalbuminemia. 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, elevations in aminotransferases often occur concomitantly with increased creatine kinase, lactate dehydrogenase, and aldolase levels.
Antinuclear Antibody
The ANA test is a sensitive screen for SLE or overlap syndromes that include features of SLE, being positive in approximately 99% of these patients. The ANA is not a useful screen for any other rheumatic disease, including JIA, because it is neither sensitive nor specific enough for these other conditions; furthermore, the ANA is positive in many healthy children and adults, and it may be positive in infections and other autoimmune and systemic illnesses ( Table 44.4 ). Therefore, it does not necessarily indicate the presence of disease and should only be ordered as a diagnostic screening test when there is a strong suspicion of SLE or an overlap syndrome.
TABLE 44.4
Autoantibodies in Children
| Test | Characteristics |
|---|---|
| Antinuclear antibody (ANA) | 99% sensitive in SLE; very nonspecific; present in healthy children, endocarditis, autoimmune hepatitis, JIA, Hashimoto thyroiditis, lymphoma, psoriatic arthritis, dermatomyositis, scleroderma, mononucleosis |
| Anti–double-stranded DNA (dsDNA) | Up to 80% sensitive for SLE; highly specific (nearly 100%) |
| Anti-Smith (Sm) | Up to 50% sensitive in SLE; nearly 100% specific |
| Anti-SSA (Anti-Ro) | Up to 50% sensitive in SLE; seen in asymptomatic children; present in Sjögren syndrome and scleroderma; can be associated with neonatal lupus |
| Anti-SSB (Anti-La) | Up to 15% sensitive in SLE; seen in similar conditions as anti-SSA; can be associated with neonatal lupus |
| Antiribonucleoprotein (RNP) | Up to 40% sensitive in SLE; also seen in mixed connective tissue disease |
| Antihistone | Drug-induced SLE-like syndromes |
| Rheumatoid factor (RF) | 30% of SLE patients; 5% of JIA; also seen in infections |
| Antiproteinase 3 (c-ANCA) | 90–95% sensitive and specific for granulomatosis with polyangiitis |
| Antimyeloperoxidase (p-ANCA) | 75% sensitive for microscopic polyangiitis; seen in other vasculitides, inflammatory bowel disease, other inflammatory diseases |
| Anti-RBC membrane (Coombs positive) | Up to 50% sensitive in SLE; nonspecific, seen also in Evans syndrome, isolated hemolytic anemia |
| Anticardiolipin | Seen in SLE; nonspecific, seen in asymptomatic children and in those with antiphospholipid syndrome |
ANCA, antineutrophil cytoplasmic antibody; JIA, juvenile idiopathic arthritis; RBC, red blood cell; SLE, systemic lupus erythematosus; SSA and SSB, Sjögren syndrome type A and type B.
Those with SLE and overlap syndromes usually have high ANA titers, typically with values of 1:640 or higher, although there is no level of titer elevation that is sufficiently specific or sensitive enough to either diagnose or exclude the possibility of SLE, and further testing will be necessary in children with features of SLE and an elevated ANA. The pattern of the ANA is rarely helpful. Homogeneous and speckled patterns are the most common and are not specific. 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.
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