FORT WORTH, Texas -- Southwest of Fort Worth this summer, children with special medical needs gather for weeklong camps.

The philosophy of Camp John Marc is to feel totally normal -- when disease often makes youngsters feel completely different.

"Camp Joint Adventure" is the theme for the camp for children with arthritis, a disease often associated with old age.

"For some reason the body turns its immune system on and it doesn't turn off," explains Shirley Henry, a registered nurse at Texas Scottish Rite Hospital in Dallas. "And as a result of that it begins to attack the joints. And kids have a lot of swelling and limitations. Children are so good at adapting to whatever the condition they're in, so often it's overlooked even by the parents."

"Before I had arthritis, I could run really fast," says 9-year-old Jackson. "Now I can't run as well."

Jackson, my son, was diagnosed with juvenile rheumatoid arthritis a year ago.

No one knows what causes JRA, why it can affect a single ankle on one child, or dozens of joints on others.

For 14-year-old Rayveus, it is crippling.

"I have to be in a wheelchair when I go long distance," says Rayveus, "Because my joints swell up or I get stiff if I don't sit down."

This camp helps youngsters - who might not feel like they fit in all the time - feel completely normal, by doing ordinary camp activities. A joint effort on the ropes course takes on new meaning when 8-year-old knuckles and knees feel more like 80.

"A lot of kids at school, they don't have arthritis and they don't know what it's like," says 10-year-old Maddy. "Kids here they all know what it's like and there's no reason to make fun of you. It's just a lot easier than school."

Thanks to advances in medicine, kids with JRA can climb mountains or wiggle their hips doing the hula hoop -- without too much pain.

"You see children who have no limitations," says Henry, who volunteers each year at the camp.

"You see children who do not focus on the things that they can't do but rather the things that they can do. And as a result of that I think you see children who leave from this setting with a more profound sense of self and a heightened awareness of what they can do and who they can be in the future," he added.

E-mail jstjames@wfaa.com.