"I've tried to figure out why these implants failed, and I would say that in the 1980s and '90s, we were treating the worst cases," he says. "Our patients were on a lot of steroids, their bone quality was poor and deformities could be terrible. Many were in a very debilitated state by the time they came to us because no one wanted to operate on a 15- or 16-year-old. Now, there are better drugs and patients are functioning at a much higher level, and they tend to do better."

He adds that the standard implants typically used in young patients pose problems, too. "What I've seen over the years is that standard implants don't fit very well because of unusual deformities in bone shape and size. Arthritis causes the growth plate to grow abnormally, so we tend to custom fit many of the implants [for young patients]. The better the implant fits, the better it should function and the longer it should last. The problem now is that custom implants are much harder to get because of new FDA regulations." And, they are also five or six times more expensive than standard ones.

In addition to implant longevity, the study also looked at function while performing daily activities, such as walking and climbing stairs. Nearly half of participants could walk without restrictions, most could manage stairs and only a small number used a wheelchair.

Dr. Figgie says the purpose of the study was to make people aware of the difficulties inherent in treating JIA patients. "This is a challenging patient population with specific, and, I feel, unmet needs," he explains. "Standard implants may or may not be the best solution, so it's important to look at how well they've survived and functioned. Then we have to figure out why they failed and what we can do in the future to improve them."

Carol A. Wallace, MD, a professor of pediatrics and chief of rheumatology at the University of Washington School of Medicine and Seattle Children's Hospital, agrees that more needs to be done for children with JIA.

"This is an interesting but sad report," she says. "Although the 10-year survival rate of the implant was 92 percent and the 20-year survival 75 percent, the results weren't satisfactory for 20 percent of patients. Additional information that would be important to understand is the breakdown of the ages of the patients by decades, category of JIA, patient-reported outcomes and the status of arthritis in other weight-bearing joints."

Dr. Wallace, an expert on JIA, also agrees that the longevity of pediatric implants may be affected by bone quality, joint deformities and immunosuppressive medications – information not captured in the study.

Given these challenges, she says, “It is far better to treat JIA early and aggressively to prevent joint damage than to have joint replacements later."