Orthopaedic surgeon using an arthroscope to examine a knee joint. An arthroscope is a type of rigid endoscope, a steel tube containing optical fibres, a lens and light-source that allows the surgeon to examine the interior of a joint. Some arthroscopes have a channel which allows surgical instruments to be inserted down the tube. A small scalpel, for example, might be used to shave and re-shape a damaged knee cartilage.