A prosthetic acetabular liner including a wall that extends from an apex portion to a circumferential rim portion, the wall having: a convex outer surface; a threaded spigot extending outwardly from the apex portion; a concave inner bearing surface; and an opening surrounded by the circumferential rim portion. The liner is rotatably insertable into an acetabular outer shell having a corresponding threaded apical hole, and rotation of the liner in the shell causes the threaded spigot to engage the threaded apical hole and thereby draw the liner into the shell.