Abstract: A measuring adapter (1) for a measuring instrument for use in connection with hip prosthesis surgery is provided. The measuring adapter (1) comprises a measuring head (2) and a connector (3); the measuring head (2) comprises a front end (2a), a rear end (2b) and an upper surface (4a). The upper surface (4a) is convex. The measuring head (2), along an axial direction of the measuring adapter (1), further comprises a central through-going bore (5) adapted to receive an actuating rod (8). The measuring head (2) is adapted to expand from a relaxed state to an expanded state when the actuating rod (8) is axially displaced in the central through-going bore (5); and the measuring head (2) is divided into at least two separate sections (6). The connector (3) is hollow and slotted at one end in axial direction of the measuring head (2) into a number of legs (7), the number of legs (7) corresponding to the number of the at least two separate sections (6) of the measuring head (2).