A medical device for implantation in a hip joint of a human patient, the natural hip joint having a ball shaped caput femur as the proximal part of the femoral bone with a convex hip joint surface towards the centre of the hip joint and a bowl shaped acetabulum as part of the pelvic bone with a concave hip joint surface towards the centre of the hip joint, wherein the caput femur has a centrally placed longitudinal extension, extending through the center of the caput and collum femur, aligned with the collum femur, defined as the caput and collum femur center axis, the medical device comprising; an artificial acetabulum, comprising a concave surface towards the centre of the hip joint, wherein said artificial concave acetabulum is adapted to, when implanted, a. be fixated to the femoral bone of the human patient, and b. be in movable connection with an artificial caput femur fixated to the pelvic bone of the patient, wherein: i. said medical device comprises a fixating portion adapted to be; stabilized by the cortical bone of the caput femur, from the outside of the caput femur, or stabilized by the cortical bone of the collum femur, from the outside of the collum femur, ii. wherein the caput or collum femur comprises a most proximal portion, and wherein said fixating portion is adapted to pass beyond the most proximal portion, on the outside thereof, thus partially be placed more distal than the most proximal portion of the caput or collum femur, characterized in that the fixating portion is adapted to clasp a portion of the caput or collum femur, said fixating portion thereby assisting in the fixation of the medical device to the caput or collum femur. a. be fixated to the femoral bone of the human patient, and b. be in movable connection with an artificial caput femur fixated to the pelvic bone of the patient, wherein: i. said medical device comprises a fixating portion adapted to be; stabilized by the cortical bone of the caput femur, from the outside of the caput femur, or stabilized by the cortical bone of the collum femur, from the outside of the collum femur, ii. wherein the caput or collum femur comprises a most proximal portion, and wherein said fixating portion is adapted to pass beyond the most proximal portion, on the outside thereof, thus partially be placed more distal than the most proximal portion of the caput or collum femur, characterized in that the fixating portion is adapted to clasp a portion of the caput or collum femur, said fixating portion thereby assisting in the fixation of the medical device to the caput or collum femur. i. said medical device comprises a fixating portion adapted to be; stabilized by the cortical bone of the caput femur, from the outside of the caput femur, or stabilized by the cortical bone of the collum femur, from the outside of the collum femur, ii. wherein the caput or collum femur comprises a most proximal portion, and wherein said fixating portion is adapted to pass beyond the most proximal portion, on the outside thereof, thus partially be placed more distal than the most proximal portion of the caput or collum femur, characterized in that the fixating portion is adapted to clasp a portion of the caput or collum femur, said fixating portion thereby assisting in the fixation of the medical device to the caput or collum femur.