A method for arthroplasty includes using a self-locking prosthesis that has a member structured to transfer a load produced by the weight of a patient to a bone. An expandable bone-locking portion that is integral to the member includes a shape-memory material and expands to produce a locking force. A portion of the bone is removed to form an aperture in the bone. The bone-locking portion is inserted into the aperture, and a temperature increase causes a change from a contracted state to an expanded state resulting in expansion of the bone-locking portion so as to contact the inner surface. The expanding is sufficient to create a locking force at the junction between the inner surface and the bone-locking portion of the prosthesis and the majority of the locking force is applied at or above the metaphysis. The length/width ration of the prosthesis may be less than or equal to 5. The resulting reconstructed long-bone may have improved primary and long-term stability.