An assembly for use in fixing a first component of a joint prosthesis, having a bone facing surface and an exposed surface which faces towards a second component of the joint prosthesis when implanted on a patient's bone. The assembly includes a skirt which can be temporarily fixed to the edge of the first component extending along the edge thereof from a remote portion of the edge to an accessible portion of the edge. The skirt provides at least one opening through which cement located between the bone facing surface of the component and the surface of the bone can be displaced. The opening is located so that cement is prevented from being displaced at the remote portion of the edge and is instead displaced at the accessible portion of the edge.