An assembly for use in arthroplasty. a liner (10) within the shell, the liner including: a generally concave inner surface (12), an outer surface (14) including a liner locking section (20) and a curved section (22) which includes a radial portion (25) having a radius. The curved section (22) extends tangentially from the liner locking section at a first transition point (28). A rim extends between the inner surface and the outer surface. The shell locking section (40) and the liner locking section (20) are self-locking tapers.
