Extremity pain is a common complaint in primary care pediatric practice. Up to 16% of school-aged children report at least 1 episode of activity-limiting extremity pain annually.
There is some evidence that extremity pain is more common in obese children Overall, approximately 6% of pediatric office visits are related to extremity pain. Fortunately, most of these visits involve
pain caused by minor trauma, overuse syndromes, and normal skeletal growth variants.
Occasionally, however, limb pain is the presenting complaint of a systemic illness, a neoplasm, an infectious process, a nutritional derangement, a specific orthopedic disorder, or a rheumatologic disease.
The challenge for the physician is to determine when the pain is significant without exposing the child to excessive diagnostic studies and without delaying treatment or referral. For the most part, this determination is based on the history and physical examination alone.
A thorough history from patients and parents often reveals the cause of extremity pain in children.
- Pain described as aching or cramping is likely to be muscular in origin.
- Bone pain is often described as deep.
- Nerve pain as burning, tingling, or numbness.
- Referred pain is common in children; thus, although usually helpful, the location of pain may be deceiving.
- Migrating extremity pain is less likely to occur after trauma and is more typical of systemic illnesses such as leukemia, acute rheumatic fever, disseminated gonorrhea, and arthralgia or arthritis associated with inflammatory bowel disease.
- The mode of onset, variability, duration, and frequency of pain also help in determining its cause. - - Activities associated with worsening or relief of pain can also lead to a diagnosis.
- Similarly, color change associated with extremity pain may indicate inflammation (faint red), infection (intense red), or autonomic dysfunction (pallor, cyanosis, and erythema).
- Stiffness, especially with clinical evidence of arthritis not associated with trauma, should prompt concern about a rheumatologic process.
A history specific to trauma associated with extremity pain can be helpful. If the physical findings of trauma are greater than would be expected from the history, then physical abuse must be considered.
The child’s general health history completes the picture of extremity pain. For example, the differential diagnosis changes with age.
- Toxic synovitis of the hip is a common diagnosis in a child younger than 10 years;
- a slipped capital femoral epiphysis is more likely in an overweight adolescent.
As a screen for systemic disease, all systems should be reviewed briefly. Particular attention should be paid to a history of fever, recent weight loss, sweating, rashes, and gastrointestinal symptoms.
A history of recent medications is important and might reveal a serum sickness–like illness. Even a short course of systemic steroids can cause aseptic necrosis of the hip or can result in demineralization of bone.
Immunizations, particularly for rubella, may cause joint or extremity pain, and a history of exposure to viral illness might explain myalgia or arthralgia.
The patient’s family history may reveal a tendency toward autoimmune disease or recent exposure to infectious diseases. The family history is particularly helpful in identifying hemoglobinopathies.
- A family history of sickle cell anemia in a 6- to 24-month-old child whose hands and feet are painfully swollen may lead to the diagnosis of hand-foot syndrome and previously undiagnosed sickle cell disease. A sickle cell pain crisis must always be considered in a black child or a child of Mediterranean origin who has a painful extremity.
Extremity pain may be a symptom of a functional disorder and can serve as an entry to the physician’s office. One large group of pediatric rheumatologists has estimated that 11% of their new patients suffer from psychosomatic musculoskeletal pain. In cases of functional
pain, the history may be either quite dramatic or highly understated. Pain in a nonanatomic distribution or that disturbs only unpleasant activities (waxing on school days and waning on weekends) should raise suspicion of a functional disorder. Eliciting a history of recent events at home, recent school performance, and other social history can be essential to determining the diagnosis.
A brief general physical examination is worthwhile even if the history points to extremity pain from minor local trauma.
- Abnormalities in blood pressure, heart rate, or growth pattern can reveal an endocrine cause.
- An elevated resting heart rate is associated with rheumatic fever.
- Pallor, fever, lymphadenopathy, or organomegaly may be clues to systemic disease.
- A rash may be particularly helpful.
- Dermatomyositis occurs with muscle pain and proximal weakness associated with a vasculitic rash on the extensor surfaces of knuckles, knees, and elbows (Gottron papules).
- Palpable purpura and extremity pain are associated with Henoch-Schönlein purpura.
- A photosensitive rash in a child who has limb pain might point to systemic lupus erythematosus, dermatomyositis, or parvovirus infection.
- Nail pitting is associated with psoriasis.
- In a child with unexplained extremity pain, a thorough eye examination by an ophthalmologist
- may detect uveitis, sometimes associated with juvenile idiopathic arthritis.
- Photophobia, eye injection, or pain with accommodation associated with extremity pain warrants a consultation with a rheumatologist and ophthalmologist.
A complete physical examination can reveal generalized joint laxity and hyperextensibility, diff erentiating benign hypermobility syndrome from a focal ligament injury.
- In benign hypermobility syndrome (Ehlers-Danlos syndrome type III), the joint laxity allows chronic hyperextension, which can cause pain, typically in weight-bearing joints. The pain often is worse in the evening.
- Dancing and gymnastics may exacerbate arthralgia, as can any other joint-impacting activity.
Because referred pain is common in children, the physical examination should include areas proximal and distal to the site of the complaint.
- A slipped capital femoral epiphysis and Legg-Calvé-Perthes disease, both of which affect the hip, can produce knee or thigh pain, whereas an abscess of the psoas muscle may cause hip pain.
- Appendicitis and other intra-abdominal processes can also cause pain that is referred to a lower extremity.
Examination of a painful extremity should include assessment of peripheral vascular status, muscle strength, soft-tissue swelling, and skeletal injury.
- Disruption of joint integrity may be shown by demonstration of abnormal range of motion of the joint with passive movement.
- Peripheral vascular status is assessed by palpating the pulses and determining the capillary refill time distal to the pain.
- Skin color and warmth, tenderness to palpation, and the extent of passive and active range of motion should all be assessed.
- Swelling, warmth, and erythema over a joint are signs of arthritis.
- Point tenderness over a bone raises suspicion of a fracture.
- Point tenderness in the absence of a clear history of trauma may indicate osteomyelitis.
- Comparing the opposite limb is helpful when assessing swelling, muscle wasting, or joint mobility. Observing the patient’s gait or use of the painful limb when the patient is unaware of the observation helps in diagnosing a functional process.
- Isolated distal weakness is likely to be of neurologic origin, whereas proximal weakness is most likely from muscular disease.
Finally, with chronic extremity pain, serial examinations of the patient over the course of weeks can be the key to diagnosis.