Abstract: The present application relates to an endoprosthesis including a first member which is connected to a patient's bone; a second member which is adjustably coupled to the first member by a coupling device; wherein the coupling device is configured to generate a movement of the second member relative to the first member. The present application also relates to an artificial joint including such an endoprosthesis and to an endoprosthesis placement system including such an endoprosthesis or artificial joint and a projection device which is configured to project visible light markings, acquired from pre-operational and/or intra-operational patient data, onto the patient and/or the endoprosthesis, thus enabling visible alignment markings of the endoprosthesis to be aligned with respect to projected visible light markings so as to allow a proper adjustment of the endoprosthesis.