When a smaller number of joints are affected (the oligoarticular type) there are four or fewer joints exhibiting arthritic symptoms with the larger joints being preferentially affected. Such children do not present as unwell although they may limp when questioned to walk. Arthritis may be confined to one hip but if the symptoms are limited to this joint then an alternative diagnosis should be sought as this is much more common, with Perthes disease a typical outcome. Arthritis over some time develops weakness and loss of bulk in the main knee muscles and a knee bend contracture partly due to tightening of the hamstrings. A discrepancy in length of legs can develop if arthritis affects only one leg.
The polyarticular type of juvenile arthritis, which has a larger number of joints affected, is indicated by five or more joints becoming inflamed in a symmetrical manner, the same joints being inflamed on both sides. A low level fever may be present and if the joints are terribly limited in terms of range of motion there is likely to be weakness of the associated muscles and a limitation in function. Examining the patient thoroughly is crucial to determine if they do have the diagnosis of juvenile arthritis, where they have particular difficulties and which form of arthritis they possess.
The definition of arthritis for the examination is the presence of swelling inside the joint (often called an effusion), along with limited joint motion and perhaps pain, warmth and redness of the joint area. It is not possible to determine swelling of some joints such as the hips but they do exhibit pains and limited ranges of movement. A definitive diagnosis may take time to establish as the arthritis may develop at the same time as the fever and the rash but can occur some months later. The lymph nodes and the liver may be enlarged and muscles may be tender to palpation. In the fewer joint form of juvenile arthritis there is often only one joint affected.
A symmetrical occurrence of arthritic changes in the major weight bearing joints and in the hand small joints is a typical finding in the polyarticular form of juvenile arthritis. The cartilage lining the joints can narrow in thickness, develop eroded areas and can form a fusion in some cases bridging the joint. Chronic changes over longer periods can include chronic joint effusions and thickened synovial membrane, subluxed joints, stiff joints and contractures, enlargement of the bone around the joint and bony deformities (often of fingers). Bone density can also reduce around the joints and the cartilage thinning can cause joint space narrowing.
A reduction of extension in the neck may not produce any symptoms but it is vital to identify this as it can indicate arthritic changes in the cervical spine which can lead to partial dislocation (subluxation) of the upper neck bones, a potentially perilous situation. The neck bones can also fuse together along the posterior structures. The jaw joints, the tempero-mandibular joints, may also be affected and lead to reduced amount of growth in the lower jaw with inability to open the mouth as wide as normal. There may also be involvement of the eyes in the inflammatory process.
The management of children with juvenile arthritis works best as a team process as many aspects need to be considered such as medication, physiotherapy, occupational therapy, family education and school function. Individual treatments on their own will not be successful. Seeing the patient for regular examinations allows the medication to be regularly reviewed and changed, aiming at a reduction in morning stiffness and the number of joints involved until the number of affected joints drops to zero. The team will likely consist of a paediatric rheumatologist, a nurse, a physiotherapist and occupational therapist and social workers to help with family and school issues.
These patients do not routinely require surgical care although steroid injections into some joints can be useful. Knee and hip arthritis in polyarticular arthritic patients may be managed by joint replacement once bone growth has stopped at skeletal maturity. Resting for long periods is unhelpful and patients should be encouraged to keep active for a better end result.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapy, back pain, orthopaedic conditions, neck pain, injury management and Physiotherapists in Croydon. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
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