Apparatus is provided including an implant structure (22, 122, 1122), a rotatable structure (2900) coupled to the implant structure (22, 122, 1122) in a vicinity of a first portion thereof, and a flexible member (30). At least a first portion of the 5 flexible member (30) is disposed in contact with the rotatable structure (2900), and at least one end portion of the flexible member (30) is not disposed in contact with the rotatable structure (30). In response to rotation of the rotatable structure (2900) in a first direction thereof, successive portions of the flexible member (30) contact the rotatable structure (2900) to pull the at least one end portion of the flexible member 0 (30) toward the first portion of the implant structure (22, 122, 1122), and responsively to draw the first and second portions of the implant structure (22, 122, 1122) toward each other. Other applications are also described.