A ceramic acetabular cup (10) devoid of a separate liner comprises a part-spherical inner articulating surface (12) for non-captively receiving a femoral head, and an outer surface (14) for enabling direct to bone fixation. An inner radius at or adjacent to a rim (22) of the cup (10) extends to or adjacent to a surface edge of the inner articulating surface (12) to prevent or reduce undesirable effects of impingement of an associated femoral head and/or neck. An inner radius of the inner articulating surface (12) defines an active arc (A) over which an in use femoral head can articulate, and an uppermost portion of the rim (22) defines an offset datum plane (D). An offset (O) between an equatorial centre (E) of the inner articulating surface (12) and the offset datum plane (D) is in a range of around 1 mm towards a pole (24) of the inner articulating surface (12) and around 3.5 mm away from the said pole (24). The active arc (A) extends in a range from around (150) degrees to less than 180 degrees, and a distance between the inner articulating surface, (12) and outer surface (14) on a straight line from the said equatorial centre (E) and passing through the surface edge is equal to or less than 4 mm.
