Juvenile idiopathic arthritis: Case

Framing the case

This three-year-old girl has the classic presentation of the oligoarticular juvenile idiopathic arthritis with the chronic anterior uveitis. The swollen knee for ten weeks, the morning stiffness that improves with activity, the single joint, the antinuclear-antibody positivity and the cells and the flare on the slit-lamp together make the diagnosis, and the framework that organises the case is the ILAR classification, the persistent-versus-extended split, the uveitis risk profile and the stepwise treat-to-target care. The first priority is the management of the uveitis and the joint, and the exclusion of the septic-arthritis mimic. [1][2]

Classifying and risk-stratifying the disease

The ILAR classification requires the arthritis of one or more joints for at least six weeks in a child under sixteen with the other causes excluded, and this child meets the criteria with the ten-week duration. She has one joint in the first six months, which assigns her to the oligoarticular category, the commonest subtype at about half to two-thirds of the cases. The oligoarticular disease splits at the six-month mark into the persistent, where the disease stays in four joints or fewer, and the extended, where further joints become involved after the first six months, and the split will be determined at the six-month review. The uveitis risk is the highest in the oligoarticular subtype, and she meets all four of the high-risk criteria: she is young, antinuclear-antibody positive, oligoarticular and within the first four years of the disease. [1][9]

Managing the uveitis

The chronic anterior uveitis is the silent sight-threatening complication, and it is detected on the slit-lamp as the cells and the flare. The high-risk profile mandates the three-monthly slit-lamp screening for the first four years, because the window of the highest uveitis incidence is the first four years. The management of the uveitis, guided by the SHARE initiative consensus of Constantin, begins with the topical corticosteroid and the mydriatic, and escalates to the methotrexate for the steroid-sparing and the anti-tumour-necrosis-factor, particularly the adalimumab, for the resistant disease. The eighteen-year Nordic outcome of Rypdal showed that the visual outcomes have improved with the modern screening and treatment but that the burden persists, and the ongoing slit-lamp is the reason it is sustained. [8][10]

The stepwise treat-to-target management

The management of the joint disease is stepwise and treat-to-target, with the goal of the Wallace clinically inactive disease. The first step is the non-steroidal anti-inflammatory drugs and the intra-articular corticosteroid injection of the right knee, with the triamcinolone hexacetonide for the longer duration, and the physiotherapy for the quadriceps wasting and the movement. For the oligoarticular child with the single joint and the active uveitis, the methotrexate is started early, at ten to fifteen milligrams per square metre once weekly subcutaneously, with the folic acid at one milligram daily, and the monitoring of the full blood count and the liver function. The methotrexate serves the double purpose of the joint disease and the steroid-sparing for the uveitis. [4][2]

If the disease is still active at three to six months of the methotrexate, the third step is the tumour necrosis factor inhibitor. The etanercept is zero point eight milligrams per kilogram once weekly to a maximum of fifty milligrams, and the adalimumab is twenty-four milligrams per square metre every two weeks to a maximum of forty milligrams, given with the methotrexate. The adalimumab is preferred when the uveitis is the active problem, because it has the added benefit for the uveitis. The TREAT trial of Wallace and the colleagues tested the early aggressive therapy and shaped the treat-to-target care. [5][6]

The septic-arthritis mimic

The examiner asks the candidate to describe the approach if the child becomes febrile, unwell and refusing to bear weight. The swollen joint in the febrile unwell child is the septic arthritis until proven otherwise, and the Kocher criteria, the fever, the inability to bear weight, the raised white-cell count and the raised erythrocyte sedimentation rate, probability-weight the diagnosis. The joint aspirate is the definitive test, and the urgent orthopaedic washout follows. The septic arthritis is the emergency that must not be missed, and the candidate who can pivot from the chronic JIA to the acute septic arthritis demonstrates the safety the boards reward. [2]

Communication and the family

The family is counselled on the chronic relapsing course, the methotrexate and the folic acid, the three-monthly slit-lamp, the school and the physical activity, and the transition to the adult rheumatology. The candidate names the diagnosis, explains that the oligoarticular disease carries the best prognosis and that many children achieve the inactive disease, and that the goal is the Wallace clinically inactive disease. The parents are introduced to the multidisciplinary team, given a written plan, taught the fever and the neutropenia emergencies, and supported by the social work and the school liaison. The candidate who holds the science and the humanity together in this conversation demonstrates the reasoning the boards reward. [6][7]