Ghent University's Erik Witvrouw led a study that examined 550 soccer players ages 13 to 18. The teenagers stood with their feet together while researchers measured the distance between their knees. The longer the kids had played the game, the wider the gap grew. In young people, bowlegs are chiefly a cosmetic nuisance, though the condition can sometimes increase the risk of ligament damage. In later life, however, bowlegs can lead to arthritis.