End caps and end cap and end plate assemblies for use with a cage or mesh, for use in surgical vertebral fusion procedures are described. A first end cap comprises an annular body and a projection extending from an outer side wall of the body to limit the travel of the end cap into the cage. At least a first and a second flexible member extend from an under side of the body. Each flexible member has a grip on an outer facing surface to retain the end cap on the end of the cage. A second end cap comprises an annular body having an uppermost surface, a projection extending from an outer side wall of the body and a formation adapted to mate with a formation in an end plate, the end plate having a vertebra engaging surface, such that the outermost surface of the body is flush with the vertebra engaging surface of the end plate. When inserted in an end of the cage in use, the projection engages an edge of the cage in more than one location to limit the travel of the end cap into the cage.