When I have a pediatric patient complaining of joint pain, I usually do three initial questions. These questions are: 1) Where is the pain located? 2) Is the pain present all the time? and 3) How long has it been present?
If the patient is complaining of only one joint, the etiology of the pain could be trauma, infection, or malignancy. If the patient has multiple joint or migratory pain, the cause could be growing pain or rheumatologic pain. If the patient indicates constant pain, then the cause could be trauma, infection, or malignancy, while if on–off, it could be growing pain or rheumatologic pain. If the patient has an acute complaint, it could be an infection, malignancy, or trauma. If the patient has been complaining for a long time without fever or weight loss, the pain is probably growing pain or has a rheumatologic etiology. The initial step in the evaluation of joint pain is the exclusion of malignancy and infectious causes.
After the history and an exhaustive physical examination, I order a complete blood cell count with a differential, erythrocyte sedimentation rate, and C-reactive protein. I also order a plain radiograph of the affected joint. If the plain radiograph is not diagnostic for the joint pain, I usually order magnetic resonance imaging. I agree with the Pediatrics in Review article “Juvenile Idiopathic Arthritis for the General Practitioner” (10.1542/pir.2021-005456) that antinuclear antibodies or rheumatoid factor blood tests are not recommended in the primary care setting.
Having a process for diagnosing these common complaints is critical. Every day we are faced with pediatric patients complaining of long-standing joint pain in our clinics. New knowledge and technologies allow us to identify early inflammatory conditions, like juvenile rheumatoid arthritis (JIA). JIA is the most common cause of inflammatory joint pain in children younger than 16 years, with a variable worldwide incidence. In Europe and North America, the incidence is approximately 7.8 to 8.3 per 1,000, with prevalence rates between 12.8 and 45 per 100,000.
The etiology of JIA is poorly understood and is thought to be a combination of genetic, immunologic, and environmental factors. Pathologically, there is synovial hypertrophy and hyperplasia of the synovial lining with dense infiltration of inflammatory cells.
The diversity of the clinical manifestations has forced us to differentiate juvenile arthritis (JA) into different categories to help with the diagnosis and treatments. The International League of Associations for Rheumatology (ILAR) proposed the most-used classification with seven separate categories. Oligoarticular JA is the most common form of JA, where its diagnosis requires the onset of inflammatory arthritis before age 16 years and is persistent for at least 6 weeks. It is further characterized as persistent (1-4 joints affected during the disease course) or extended (5+ joints involved after the initial 6-month period of disease). Uveitis will be present in 20% to 30% of children and is typically asymptomatic. The other categories are polyarticular arthritis (RF Negative), polyarticular arthritis (RF Positive), enthesitis-related arthritis, psoriatic arthritis, undifferentiated arthritis, and systemic-onset JIA. Each category has diverse patterns of clinical manifestations, laboratories results, and prognoses.
The most common complication is uveitis, followed by temporomandibular joint disease and macrophage activation syndrome. Uncontrolled chronic uveitis can lead to vision loss, and given its asymptomatic nature, continuous screening should be performed every 3 months and is necessary to prevent blindness.
Treatment plans have been developed by the consensus of North American research organizations such as the Childhood Arthritis and Rheumatology Research Alliance, which has provided treatment guidance that is commonly used by pediatric rheumatologists. The protocols have drastically changed over the years with the implementation of disease-modifying antirheumatic drugs (DMARDs) and biological medication. The indication of each medication depends largely on the number of joints involved at the time of diagnosis and the risk factors for aggressive disease.
The long-term outcomes of JIA depend on multiple factors, including time to diagnosis, category, presence of inflammatory markers at diagnosis, and development of or presence of uveitis. In the past, the long-term prognosis was highly pessimistic, but now with the implementation of biological medications and DMARDs, there is an improvement in the long-term results, and, as this Pediatrics in Review article emphasizes, the importance of early diagnosis of JIA to avoid delays in diagnosis and a subsequent delay in proper care that may lead to chronic disability due to progressive joint destruction.