 The described investigation will clarify whether the theoretical advantages that have hitherto been demonstrated by clinical and biomechanical study normal weight transfer, bone sparing and bone-keeping in the short and long term, also obtained by applying the newly developed prosthetic component. If so, there will then be able to especially younger patients with osteoarthritis of the hip joints better chance of achieving good clinical outcomes and long-term sustainability by eventual replacement surgery, typically 10-20 years after primary surgery. 