teenagers can get certain forms of the condition , Klippel said . The Arthritis Foundation reports two-thirds of people with doctor-diagnosed arthritis are under age 65 . Watch more on arthritis fact and fiction Â '' Stephens was in her late 30s when she developed osteoarthritis after injuring her knees running and playing volleyball . She felt a sharp pain and recalled , `` It was downhill after that . '' Researchers do n't know the exact cause of arthritis , but they do know what puts people at risk . Klippel said that while the disease is associated with aging , other risk factors include heredity , joint injury , obesity and lack of fitness . Common myth 2 : Cracking your knuckles causes arthritis Despite what your grandmother told you , experts say cracking your knuckles is not a risk factor for arthritis . `` It 's annoying -- it 's certainly not good for the joints , but on the other hand , it does n't cause arthritis , '' Klippel said . Common myth 3 : Predicting the weather `` Boy , there 's a good myth , '' Klippel said with a chuckle . ``
-LRB- CNN -RRB- -- The bad economy and downturn in the housing market are n't the only painful things for Realtor Anne Stephens . Her knees , hips and ankles hurt from arthritis . Anne Stephens , 61 , was in her late 30s when she was diagnosed with osteoarthritis . `` I ca n't sit too long . I ca n't stand too long , and I ca n't walk too long , '' said Stephens , 61 , from Conyers , Georgia . Stephens is among the 27 million Americans who suffer from the most common form of arthritis called osteoarthritis . `` I think people tend to think of this as more of a nuisance , '' said Dr. John Klippel , president and CEO of the Arthritis Foundation . `` They think of it as only aches and pains and not the serious problem that it actually is -- the leading cause of disability in this country . '' Klippel said part of the misconception has to do with all the myths surrounding the disease . Common myth 1 : Arthritis is a disease of the elderly While older people do develop arthritis , children and