- by Dr Gowher Yusuf
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- Apr 04 2017
Dispelling the Myths: Joint disease in children
(Source: Iain Goff, Helen Elisabeth Foster, Sharmila Jandial Arch Dis Child. 2013; 98(3):168-169)
Children frequently present to primary care, emergency departments and paediatricians with musculoskeletal (MSK) problems, and hence all of these professionals should be competent to perform a MSK assessment Many of these children will have self-limiting illness/injury, however some will be presenting with chronic or life-threatening disease. The challenge is to reassure those with self-limiting disease, while identifying those presenting for the first time with new inflammatory arthritis such as juvenile idiopathic arthritis (JIA), or other serious conditions which can present with MSK features, such as malignancies, infections and neuromuscular diseases.
There is a growing acceptance that early diagnosis and aggressive management of JIA leads to improved functional outcomes, while early access to therapies for non-inflammatory MSK disease reduces recovery times and prevents progression to pain amplification syndromes. This evidence stands in stark contrast to the reality experienced by many children with MSK disease, who still suffer long delays between disease onset and referral to a specialist service. Part of this delay is undoubtedly due to the paucity of training about MSK disease. This paper aims to dispel some of the myths that have developed regarding the diagnosis of joint disease in children.
Children With Musculoskeletal Disease Present With Joint Pain
Although pain is the most common MSK symptom encountered by frontline paediatric clinicians, it is unusual for this to be the principal presenting feature of serious MSK disease. The majority of children with JIA present with stiffness, joint swelling, limp or functional impairment, with pain either not apparent or not verbalised. More frequently, parents notice abnormalities in an uncomplaining child such as clumsiness, a change in mood or avoidance of activities or play that were previously enjoyed. There may be regression in achieved motor milestones and teachers may observe a change in the child's abilities at school. Inflammatory MSK disease often results in stiffness and manifests as reluctance to weight-bear especially in the mornings and after periods of rest ('gelling').
Children presenting with MSK pain as their main complaint however, often turn out to have overuse disorders or soft tissue injuries, though sudden onset joint pain or recurrent night waking should be assessed urgently to rule out conditions such as septic arthritis and malignancy.
Suggestion Ask specifically about joint stiffness, joint swelling and functional impairment and refer if these are present—even in the absence of pain.
Investigations Need to be Abnormal to Diagnose JIA
The diagnosis of JIA is made on clinical grounds in a child presenting with symptoms of inflammatory joint disease and with examination features of joint or systemic inflammation—there is no diagnostic test. JIA is a diagnosis of exclusion and investigations such as blood tests and imaging are helpful to exclude other causes of joint symptoms. Antinuclear antibody (ANA) and rheumatoid factor are not diagnostic of JIA but are used to identify individuals with specific subtypes of JIA; rheumatoid factor positivity confers increased risk of continuation into adulthood, while ANA associates with a higher risk of asymptomatic uveitis, which can result in blindness.
Although it is useful for specialists to have access to blood results at the child's initial assessment, referrals should not be delayed pending the results. Approximately 50% of patients with JIA are ANA negative, with this subset recognised as experiencing longer waits for referral than those who are ANA positive, possibly because of false reassurance clinicians draw from negative tests. Acute phase reactants (erythrocyte sedimentation rate (ESR)/C-reactive protein (CRP)) can also be normal in JIA and similar delays are encountered by children with a normal ESR level at presentation.
Similarly imaging investigations are of limited value in the diagnosis of early inflammatory joint disease. Classical radiographic features such as erosions are very rare in children and appear late in established disease; in early disease changes are subtle if present at all. Ultrasound and gadolinium enhanced MRI are emerging as useful imaging modalities, particularly for detecting very early subclinical joint inflammation, however the availability of MSK ultrasound is variable, and the need for sedation/anaesthetic limits the routine use of MRI.
Suggestion In children with suspected inflammatory joint disease do not delay referral while awaiting investigation results.
A Thorough History Leads to Most Diagnoses - Examination and Investigations are Used to Confirm Suspicions
The perception that medical history is the key component to a clinical assessment does not hold true within paediatric rheumatology. Although useful in pointing toward inflammatory versus non-inflammatory disease, history has proved to be poor at revealing the true extent of MSK disease, even when performed by paediatric rheumatologists. As a consequence, a thorough clinical examination is essential, and will often detect joint involvement that is seemingly asymptomatic, especially in young children. Unfortunately MSK examination skills are particularly deficient in undergraduate and postgraduate training, with doctors in primary and secondary care admitting to low confidence in their paediatric MSK clinical skills.
The paediatric gait, arms, legs and spine (pGALS) MSK examination was developed in order to integrate rapid MSK assessment into the routine evaluation of paediatric patients. pGALS has been shown to be effective at identifying joint abnormalities in various paediatric populations and to be acceptable to children and parents. It is easy to learn, and quick to perform (2–3 min), even when performed by non-specialists in paediatric rheumatology.
Suggestion In a patient with suspected MSK disease always perform a basic "top-to-toe" MSK examination as part of their assessment.
Joint Swelling Must be Present in Order to Diagnose JIA
Although joint swelling is one of the cardinal abnormal clinical findings in JIA, detection of joint swelling in clinical practice can be difficult, especially if the changes are mild and symmetrical. Young children and toddlers are particularly difficult to assess as symptoms and signs may be vague and difficult to localise from the history alone. Restriction of joint movement is very common in JIA, and because of this it is essential that clinicians are aware of the normal range of joint movement expected at various ages. If in doubt then carry out a minimum check for asymmetry, and compare range of movement with your own joints—children's joints will usually have a greater range of movement than adults.
Where children do present with joint swelling it is frequently in the context of trauma. In JIA it is often the case that the trauma has merely aggravated or drawn attention to, a pre-existing joint disease. A history of the injury should reveal whether the event was severe enough to lead to a joint effusion; the natural flexibility of children's joints means that a higher degree of trauma is necessary to damage intrinsic joint structures than is required in adults. Other clinical features to look for include joint tenderness, gait abnormality, limb length discrepancy, muscle wasting, rash and fever.
Suggestions Joint swelling is not the only important clinical finding—care must be taken to look for other physical signs. Joint swelling associated with trauma may be a "red herring"—put the injury in context of the history and physical findings.
Inflammatory Joint Disease in Children is Rare
MSK disorders are common in children affecting 4–30%, with limp alone accounting for approximately 1 in 60 acute paediatric presentations to emergency departments. The prevalence of JIA is cited at 1 in 1000 in the UK (based on 1989 to 1991 UK national registry figures), although this is generally felt to be an underestimate. The international prevalence varies widely, however, with one Australian community study finding a prevalence of over 1 in 250 children. In comparison with other chronic diseases of children, the prevalence of type 1 diabetes in children in the UK is estimated at 1 per 700–1000 and epilepsy at 1 in 200–500. When other chronic rheumatic diseases are included, it is clear that inflammatory MSK disease is more common that many realise.
Suggestion Consider inflammatory joint disease as one of the more common chronic diseases in children and the young.
Many myths have arisen around paediatric MSK disease, and these need to be addressed if earlier diagnosis and treatment is to become a reality. MSK diseases are among the more common chronic illnesses of childhood, and can present with a variety of symptoms to a range of clinicians. Only through better awareness of our misconceptions can we hope to address the delays in referral experienced by children with MSK disease. Improving the education of medical students and junior clinicians must begin with senior clinicians addressing their own knowledge gaps.
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