Beyond back pain, bad posture can aggravate other problems like joint degeneration and osteoarthritis. "Bad alignment predisposes you to joint and muscle stress, which may lead to back pain and arthritis," says Shirley Sahrmann, professor of physical therapy at the Washington University School of Medicine in St. Louis.
http://health.msn.com/general/ArticlePage.aspx?cp-documentid=100161886