SWOLLEN JOINTS
History
Zoe is a 3-year-old girl referred to children’s outpatients. For the past 7 weeks she has been generally off-colour and miserable. Having loved nursery she is increasingly reluctant to get up in the morning and is taking ages to get dressed. She says she feels ‘stiff all over’. As the day goes by, her stiffness improves unless she has been sitting for a while, but she is still easily tired and lacks energy. When encouraged to walk, she does so very slowly and wants to be carried or use the buggy. Zoe has also been complaining that her knees and ankles hurt and her parents report intermittent but definite swelling of her left knee and right ankle. Her symptoms are helped by ibuprofen. There are no reports of injury. She had a sore throat 2 months ago but has not had any fevers since, or any rashes. Zoe has no significant past medical or family history. She has a healthy 9-month-old brother.
Examination
Zoe is a quiet but generally healthy girl sitting on her mother’s knee. She would not walk into the consulting room. Her height is on the 75th centile and her weight is on the 50th. She is not clinically anaemic or clubbed and there is no lymphadenopathy. She is afebrile. There are no rashes. Both knees and her right ankle are mildly swollen and feel warm to touch, but there is no overlying skin change. The left knee seems most affected. There is pain and a decreased range of movement. There are similar findings in the proximal interphalangeal joint of the left index finger. The remainder of her joints, including the hips, appear normal. Examination of the cardiovascular, respiratory and abdominal systems is normal with no hepatosplenomegaly.
INVESTIGATIONS
Normal
Haemoglobin 11.8 g/dL 11.5–15.5 g/dL
White cell count 9.2 109/L 6.0–17.5 109/L
Platelets 395 109/L 150–400 109/L
Erythrocyte sedimentation rate (ESR) 19 mm/hour 0–10 mm/hr
Urea and electrolytes Normal
Liver function tests Normal Bone chemistry Normal
C-reactive protein (CRP) 21 mg/L 6 mg/L
Anti-nuclear antibody (ANA) Mildly positive Negative
Rheumatoid factor Negative Negative
Questions
• What is the differential diagnosis?
• Which of these is most likely?
• What else needs to be formally examined?
• What are the principles of management?
Medicine
Zoe has a polyarthritis – pain, swelling, warmth and restricted movement of several joints. The much commoner arthralgia is joint pain without the other features.
Differential diagnosis of chronic polyarthritis
• Connective tissue disorder – juvenile idiopathic arthritis (JIA), systemic lupus erythematosus, dermatomyositis, psoriatic arthritis
• Infection – bacterial causes are unlikely with this chronic history. Viruses such as hepatitis and also Lyme disease should be excluded
• Malignant disorders – children with leukaemia can have joint pain due to metaphyseal marrow expansion months before peripheral blood count changes. A bone marrow examination may be indicated
• Inflammatory bowel disease – can present with arthritis
• Vasculitis – Henoch–Schönlein purpura
Zoe has other features in the history that make JIA the most likely diagnosis. There has been an insidious onset of early morning stiffness, ‘gelling’ (stiffness) after inactivity, slow walking and progressive joint involvement. Juvenile idiopathic arthritis is a group of conditions in which there is a chronic arthritis lasting 6 consecutive weeks before the age of 16 years. Infection and other causes must obviously be excluded. Her sore throat 2 months earlier is probably incidental although a reactive arthritis following Streptococcus tonsillitis is well recognized and the anti-streptolysin O titre (ASOT) should be assayed. Juvenile idiopathic arthritis is classified according to its onset as systemic, polyarticular ( four joints) or oligo(pauci)articular ( four joints). Zoe has oligoarticular JIA, the commonest subtype, which typically affects the knees and ankles and less often the elbows or a single finger joint in young children 6 years, particularly girls. In systemic or polyarticular JIA, there is often laboratory evidence of chronic inflammation with anaemia, thrombocytosis and an elevated ESR and C-reactive protein, but in oligoarticular JIA these may be normal or only mildly abnormal. Patients with oligoarticular JIA have an increased risk of one of the complications of JIA, chronic anterior uveitis, and this is increased still further in girls who are ANA-positive. She therefore needs formal ophthalmology screening and frequent regular review. The course of the uveitis is independent of the joints.
Principles of management
• Pain control with non-steroidal anti-inflammatory drugs (NSAIDs)
• Physiotherapy, hydrotherapy and occupational therapy. Splints may help prevent contractures and deformities
• Intra-articular depot corticosteroid injections to reduce swelling and deformity
• Disease-modifying drugs are needed if not controlled with NSAIDs, e.g. methotrexate, sulphasalazine. Cytokine inhibitors (e.g. anti-tumour necrosis factor) may be needed for refractory polyarticular or systemic JIA. All of these need careful monitoring in a specialist setting
• Regular monitoring of growth and nutrition as for any chronic disease
• Multidisciplinary team approach, including psychosocial support. The impact of all forms of JIA is significant, although the prognosis for oligoarthritis is generally better than for other groups
KEY POINTS
• Juvenile idiopathic arthritis can only be diagnosed after 6 continuous weeks of arthritis and after the exclusion of other causes.
• The management of JIA requires a multidisciplinary team with as much emphasis on the therapies as on drug interventions.
need an explanation for this answer? contact us directly to get an explanation for this answer