A fluid operated retractor for use in surgery. The retractor has a portion which is expandable upon the introduction of fluid under pressure. The expandable portion is made of a material strong enough, and is inflated to enough pressure, to spread adjoining tissues within the body. The retractor is especially useful in fiber optic surgery because it can be inserted percutaneously through a small opening then expanded to a much larger dimension when in the desired location, to retract tissue from within. The retractor may be used to spread a joint such as a knee joint or a shoulder joint, or may be used to separate tissue planes generally, to improve visualization and create a working space for the surgeon.