Chronic Arthritis of Childhood
7 Apr 2010The fewer joint affected type of arthritis (oligoarticular) is characterised by having four or fewer joints affected, with the larger joints more typically affected such as the knees and ankles. These children usually appear well even though they may limp on walking. If only one hip seems affected this is very unusual for this type of arthritis and a different condition such as Perthes disease should be suspected. If the joints, such as the knees, are affected over a long period then the large extensor muscles of the thighs can weaken and waste, with tight hamstrings leading the flexion contractures of the knees. If the legs are affected asymmetrically then the length of the legs can develop a discrepancy.
The many joint affected type of disease (polyarticular) is characterised by having at least five joints affected, typically in a symmetrical pattern with the same joints affected on both sides. The child may have a low grade fever and if there are significant limits of joint movement this is associated with weakness of the relevant muscles and decreased normal function. A thorough physical examination of the child is very important for the correct diagnosis of juvenile arthritis as this will indicate where the problems lie and which kind of juvenile arthritis the patient has.
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.
In the many jointed polyarticular form of juvenile arthritis the weight bearing joints are typically affected in a symmetrical pattern, as are the small joints of the hand. There may be loss of the articular cartilage with areas of cartilage erosion and in some cases a fusion across the joint, with thickening of the synovial membranes and effusions within the joints. Long term changes in a joint which is arthritic can include partial dislocation, joint stiffness and contractures, bony enlargement and deformities, especially of the fingers. Other findings can be loss of bone stock around the joints and narrowing of the joint spaces due to cartilage loss.
Neck changes can include a limitation of cervical extension which is often not symptomatic but is an important issue because it indicates that the neck has arthritic changes within it which can progress to the joints partially dislocating in the high neck, a dangerous neck syndrome. The posterior neck structures may also fuse themselves due to the inflammation. The joints of the jaw (temperomandibular joints) can be affected by the arthritis process and this reduces the amount of growth in the jaw and limits the person’s ability to open their mouth wide. Eyes can also be affected.
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.
Surgery is not routinely indicated for most of these patients although joint injections with steroids may be employed for some. Polyarticular arthritis patients may suffer severe knee and hip arthritis which can be treated with knee and hip replacement once skeletal maturity has been reached and bone growth has stopped. Encouraging patients to be active is important as resting for long periods is not helpful and more active patients do better.
