A locking member for implantation in a hip joint of a patient is disclosed. The locking member is adapted to assist in the fixation of a medical device, having an artificial hollow caput femur surface, to the collum and/or caput femur, wherein the artificial caput femur surface comprises at least one extending portion adapted to clasp a portion of the caput and/or collum femur. The locking member comprises an element adapted to lock the artificial caput femur surface such that the caput femur remains clasped and restrained in the artificial caput femur surface.
