TARGETED treatments may be needed for children with arthritis, Melbourne researchers say, after discovering that cartilage inside children's joints breaks down in a different way to adults.
In a study published in the journal Arthritis and Rheumatism, researchers from the Murdoch Childrens Research Institute analysed components of cartilage in the fluid inside the joints of children with juvenile arthritis.
They found the pattern of components was different to that found in adults with arthritis, suggesting that different enzymes were damaging the cartilage, in a finding that indicates juvenile arthritis is a distinct condition. About 5000 children in Australia have juvenile arthritis, a chronic disease that causes persistent inflammation in the joints and can result in long-term damage to bone and cartilage. Current treatments are designed to manage and ease inflammation in affected joints, but there are no treatments to manage or prevent cartilage erosion.
While such treatments are being developed for adults - which could mean the need for joints to be replaced is avoided - lead researcher Amanda Fosang said her study showed they may not work in children. ''The findings support a need to understand more about the mechanisms driving cartilage erosion in patients with juvenile arthritis, because the cartilage-sparing drugs currently in development for adult therapies might not be useful for preventing cartilage erosion in children,'' she said.
Royal Children's Hospital rheumatologist Jonathan Akikusa said despite major improvements in anti-inflammatory treatments for children with arthritis over the past decade, cartilage erosion leading to irreparable joint abnormalities remained a long-term risk for some young patients.
''For some forms of arthritis, cartilage loss can be a significant problem, particularly in the hips,'' he said.
''We certainly have a few teenagers every couple of years who need to have their hips replaced because they have lost their hip cartilage, despite the fact their arthritis has been relatively well-controlled.
''If we had the ability to add in a drug that doesn't act on the arthritis so much but acts on cartilage breakdown, we may be able to slow that down and potentially allow those kids to keep their hips into young adulthood and beyond.
''There is definitely a sub-group of kids with arthritis where the ability to modify the loss of cartilage may have a huge impact on their quality of life.''
Connie Parker, whose four-year-old daughter Annabel was diagnosed with juvenile arthritis when she was about 17 months old, said it was encouraging researchers were discovering more about the condition. She said doctors initially thought swelling in Annabel's right knee, which caused her to limp as a toddler, was due to an infection, but she was diagnosed with arthritis a few months later.
The condition is now controlled with anti-inflammatory medication - allowing Annabel to do all her favourite things, including ballet - and doctors are hopeful she will have no long-term joint damage.
