A tool (410) for use with an implant (20) includes a housing (426) and a controller (440). The housing includes a tubular wall (428) that circumscribes a longitudinal axis； is dimensioned to house at least part of the implant； and defines a track (430) that follows a generally-helical path around the longitudinal axis. The controller includes a rod (442) that extends from a proximal part of the tool to the housing； and an actuator (444). The actuator is fixedly coupled to the rod, includes an engaging element (446) that engages the track, and is rotatable with respect to the housing. The controller and the housing mechanically cooperate such that rotation of the actuator with respect to the housing slides the housing longitudinally with respect to the actuator. Other embodiments are also described.
