<p>People typically think knee replacement surgery is only for older adults with arthritis. But the surgery is also used for young patients when joint damage has become severe.</p><p>Recently, researchers found knee replacements did not last as long in young patients with juvenile idiopathic arthritis (JIA) as they do in older osteoarthritis patients.</p><p>Still, the procedure can be a life-changer for many patients with JIA – a painful disease that affects children. In patients with JIA, about 92 percent of knee replacements lasted 10 years and a little over 75 percent lasted 20 years.</p>