An acetabular cup assembly for a prosthetic hip joint includes an outer shell for attachment to the acetabulum. The outer shell has an inner surface receiving an adaptor. Complimentary coupling features are provided on the inner surface of the outer shell and the outer surface of the adaptor for coupling the bearing insert to the outer shell. A plurality of adaptors are provided having inclined outer surfaces for engaging an inner surface of the outer shell and having an inner surface for receiving the bearing insert. Each shell has at least one radial extending strap or flange for engaging the bone surrounding the acetabulum. The straps or flanges may be of different sizes and shapes and may be at different locations on the shell. The inner surface of the adaptor includes coupling features be able to receive different design bearing inserts.