Arthroscopy, ahr THROS kuh pee, is the technique of using an arthroscope to examine a joint of the body. An arthroscope is a straight, tubelike instrument with a series of lenses and optical-fiber bundles. It comes in sizes from 1/12 to 1/5 inch (2 to 5 millimeters) in diameter. It can be inserted into a joint through a small incision. A light transmitted by the optical fibers to the tip of the arthroscope illuminates the joint. Using an arthroscope, a doctor can thoroughly examine a joint and perform certain surgical operations.