Surgery to revise scars is done while the patient is awake, sleeping (sedated), or deep asleep and pain-free (local anesthesia or general anesthesia). Massive injuries (such as burns) can cause loss of a large area of skin and may form hypertrophic scars. A hypertrophic scar can cause restricted movement of muscles, joints, and tendons (contracture). Surgical repair includes removing excessive scar tissue and a series of small incisions on both sides of the scar site, which create V-shaped skin flaps (Z-plasty) may be used. The result is a thin, less noticeable scar because the wound closure following a Z-plasty more closely follows the natural skin folds.