Osteoarthritis can be very painful. An article on WebMD.com discusses the causes and treatments for knee pain caused by osteoarthritis. Cartilage loss is not the only cause of osteoarthritis knee pains. It is also caused by the lack of shock that is able to be absorbed by the joint fluid. One of the best treatment options for this condition is a viscosupplement injection. This injection supplements your natural joint fluids providing the natural lubricant that it needs to relieve knee pains caused by osteoarthritis.