An orthopedic instrument comprises a shell configured to be inserted into a cup-shaped site, a liner configured to be received within a cavity of the shell, wherein the liner has an aperture and a mating feature adjacent to the aperture, and a modular screw configured to be received within the aperture of the liner. The modular screw can include a first component that is positionable adjacent to a first side of the mating feature and a second component that is positionable adjacent to a second side of the mating feature. When assembled, the modular screw can be configured to rotate relative to the liner.