A medical device for treating hip joint osteoarthritis in a human patient is provided, the hip joint comprises an acetabulum, being a part of the pelvic bone, and a caput femur, being connected to the collum femur and being the upper extremity of the femoral bone. The caput femur and collum femur further comprises cortical bone, the outer more sclerotic bone, and cancellous bone, placed in the bone marrow, said medical device comprising: an artificial caput femur surface, adapted to be in contact with the acetabulum surface or an artificial replacement therefor, and a fixating member adapted to at least partly be stabilized by the cortical bone of a stabilizing part of the collum femur.
