An acetabular cup assembly implantable at an acetabular socket can include an acetabular cup defining a partially spherical bone engaging surface and having a uniform thickness. A spacer can include a body portion formed of porous metal and define a radial support surface. The porous metal can be adapted to receive bone ingrowth through interstitial space at pores defined therein. The spacer can further comprise a piercing portion adapted to be advanced into the acetabular socket. The spacer can bridge a gap defined between the acetabular socket and the acetabular cup. Filler can be disposed between the acetabular cup and the acetabular socket in areas adjacent to the spacer such that the spacer and the filler collectively define a continuous support surface adapted to support the acetabular cup at the bone engaging surface.