An expandable cannula includes a proximal end portion having a substantially constant diameter therethrough, and a distal end portion, coupled to the proximal end portion and having a proximal end and a distal end. The distal end portion includes a plurality of panels hinged by “living hinges” to the proximal end portion, and a locking mechanism that stabilizes the distal end portion in one of a contracted position and an expanded position. The locking mechanism may be a strut pressed overcenter during expansion distal portion to expanded configuration, or may include a locking ring and a catch for stabilizing the ring in a configuration where it holds the panels in expanded configuration.
