Medical bone screw and implant system

An implant system comprising at least a medical bone screw and a hip-joint acetabular implant having at least one first clearance hole through which the medical bone screw can be inserted in such a way that the medical bone screw can be pivoted at least in one direction of the at least one first clearance hole, wherein

• the medical bone screw has a shaft-shaped bone thread part for fastening the hip joint acetabular implant to a patient bone, which has a core diameter and an outer-thread diameter and at the proximal end of which a two-part, angle-adjustable head part is connected,
• the two-part, angle-adjustable head part is formed from a head piece, which is formed in one piece with the bone-thread part, which is preferably rotationally symmetrical, more preferably partially spherical, and a head piece provided separately from the bone-thread part,
• the head piece provided separately from the bone-thread part has an upper side and a lower side, and a second clearance hole having an undercut or a funnel shape or tulip shape is formed therein, and
• the second clearance hole has a proximal clearance-hole diameter at the upper side and a distal clearance-hole diameter at the lower side,
• wherein
• the second clearance hole furthermore has an inner thread with an inner-thread diameter between the upper side and the lower side, the inner thread corresponding to the outer thread of the shaft-shaped bone-thread part,
• wherein the inner-thread diameter is greater than the outer-thread diameter and the distal clearance-hole diameter is greater than the core diameter, and
• by screwing the shaft-shaped bone thread part into the second clearance hole, the shaft-shaped bone-thread part is inserted into the head piece provided separately from the bone-thread part, in such a way that the head piece formed in one piece with the latter rests in an axially fixed manner on the undercut or in the funnel shape or tulip shape, but a pivoting movement of the shaft-shaped bone thread part with respect to the separate head piece is allowed in at least one or exclusively one pivoting plane.