A clamp assembly for use in connection with an operating table rail is disclosed. The clamp assembly includes a top clamp member, a base clamp member and an operating lever to move the top clamp member relative to the base clamp member. The base clamp member and the top clamp member include complimentary V-shaped channels that allow the clamp assembly of the present invention to be installed on the sterile side of the surgical field. The base clamp member is provided with dual guide pins and an actuator pin, extending upwards from the base clamp member and through the top clamp member. The actuator pin is affixed with a fastening means to engage the top of the actuator pin and the base clamp member together. Further, the base clamp member includes apertures for receiving various surgical support fixtures.