The management of pain whether acute being pain lasting less than 3 to 6 months, or pain that is directly related to tissue damage; or chronic being one or both types of the following; chronic pain due to an identifiable pain generator (e.g. an injury), and chronic pain with no identifiable pain generator. The term "chronic pain" is generally used to describe pain that lasts more than three to six months, or beyond the point of tissue healing. Chronic pain is usually less directly related to identifiable tissue damage and structural problems. Examples of chronic pain are: chronic back pain without a clearly determined cause, failed back surgery syndrome (continued pain after the surgery has completed healed), and fibromyalgia.