Chronic knee pain can occur for a variety of reasons. In a common, age-related condition called osteoarthritis, the cartilage that cushions the knee joint's bones wears down and breaks up, causing pain and stiffness. If you'd prefer to avoid surgery or painkilling drugs for this problem, consider the following three alternatives. 1. Knee Pain Stem Cell Treatment The human body repairs and rebuilds its tissues by drawing on its supply of stem cells.