hip joint prostheses are disclosed for permanent anchoring in the human hip joint of a ball unit in the neck of a human femur . the prosthesis include a first cylindrical fixture portion for extending from the collum femoris toward the outer side of the femur and a second cylindrical fixture portion for placement in the cancellus bone of the collum femoris , both of these portions including outer cylindrical surfaces with external self - tapping threads , and in which the first and second cylindrical fixture portions are joined into a single portion for insertion into a bore hole provided in the femur in a single operation .