Abstract: A bone cavity sealing gasket which can be fitted over the resected end of a bone (2) to be provided with bone cement in its axial cavity, includes a sealing plate (10, 40) which has a quantity of a resiliently deformable material on its lower face to enable a seal to be created between the plate (10, 40) and the upper edge of the bone, and an opening (12, 42) extending through it. A plug (14, 30, 44) can be received in the opening (12,42) in the sealing plate (10, 40). The plug (14,30,44) has an injection port (26, 32) extending through it aligned with the opening (12, 42) in the sealing plate (10, 40) in which the injection nozzle (16) of bone cement delivery apparatus can be received.