An acetabular implant system , comprising: an acetabular shell including an inner surface and a lip portion defining an opening, wherein the acetabular shell comprises a hemispherical shape and the inner surface is centered on an apex of the hemispherical shape; a liner having an edge portion ; and a fitting ring having a fitting ring wall, an alignment portion and an engagement portion engageable to the edge portion of the liner such that the alignment portion extends radially outward from the liner ; wherein: the alignment portion is located on an exterior surface of the fitting ring , the alignment portion extending circumferentially around the fitting ring ; the engagement portion is located on an interior surface of the fitting ring and defines an opening for receiving the liner ; the alignment portion is engageable to the lip portion of the acetabular shell to position the liner within the opening at a predetermined distance from the inner surface ; and wherein when a driving force is applied along an axis (A-A) transverse to the apex , the liner is released from the fitting ring and the liner is pushed into engagement with the inner surface of the acetabular shell ; characterised in that the engagement portion is formed by a region of reduced radial thickness of the fitting wall, wherein the engagement portion is engageable to the edge portion of the liner . an acetabular shell including an inner surface and a lip portion defining an opening, wherein the acetabular shell comprises a hemispherical shape and the inner surface is centered on an apex of the hemispherical shape; a liner having an edge portion ; and a fitting ring having a fitting ring wall, an alignment portion and an engagement portion engageable to the edge portion of the liner such that the alignment portion extends radially outward from the liner ; wherein: the alignment portion is located on an exterior surface of the fitting ring , the alignment portion extending circumferentially around the fitting ring ; the engagement portion is located on an interior surface of the fitting ring and defines an opening for receiving the liner ; the alignment portion is engageable to the lip portion of the acetabular shell to position the liner within the opening at a predetermined distance from the inner surface ; and wherein when a driving force is applied along an axis (A-A) transverse to the apex , the liner is released from the fitting ring and the liner is pushed into engagement with the inner surface of the acetabular shell ; characterised in that the engagement portion is formed by a region of reduced radial thickness of the fitting wall, wherein the engagement portion is engageable to the edge portion of the liner . the alignment portion is located on an exterior surface of the fitting ring , the alignment portion extending circumferentially around the fitting ring ; the engagement portion is located on an interior surface of the fitting ring and defines an opening for receiving the liner ; the alignment portion is engageable to the lip portion of the acetabular shell to position the liner within the opening at a predetermined distance from the inner surface ; and wherein when a driving force is applied along an axis (A-A) transverse to the apex , the liner is released from the fitting ring and the liner is pushed into engagement with the inner surface of the acetabular shell ; characterised in that the engagement portion is formed by a region of reduced radial thickness of the fitting wall, wherein the engagement portion is engageable to the edge portion of the liner . <EOS>