When an acetabular cup used in hip replacement surgery is to be affixed to the acetabulum using screws, the drill guide instruments of the invention are used to position a drill bit so that the screw holes drilled in the acetabulum are properly placed for optimum implantation of the acetabular cup. The drill guide is locked into the acetabular cup by spring loaded pins which position the guide over holes in the cup which accommodate the screws. The guide is used to position the drill bits and allow drilling. After drilling the guide is removed.

In embodiments of the invention, an implant that anchors into bone may have a bone-facing region that comprises a plurality of interconnected struts. The interconnected struts may define local features such as engagement ridges, fins, crests, a macroscopic surface-interrupting feature, a divertor structure, and sawteeth in any combination. Such features may help resist translation or rotation of the implant, and may be conducive to bone ingrowth. Parameters such as local empty volume fraction and local average strut length can be varied, even within the features, by the design of the network of struts. Struts may be tapered. Cantilever struts may also be provided, which may point in a desired direction. The pattern of struts may be specified to the level of dimensions and location of individual struts. The implant may be manufactured by additive manufacturing methods. The mesh of struts may be generated by an algorithm using Voronoi tessellation.

In embodiments of the invention, an implant that anchors into bone may have a bone-facing region that comprises a plurality of interconnected struts. The interconnected struts may define local features such as engagement ridges, fins, crests, a macroscopic surface-interrupting feature, a divertor structure, and sawteeth in any combination. Such features may help resist translation or rotation of the implant, and may be conducive to bone ingrowth. Parameters such as local empty volume fraction and local average strut length can be varied, even within the features, by the design of the network of struts. Struts may be tapered. Cantilever struts may also be provided, which may point in a desired direction. The pattern of struts may be specified to the level of dimensions and location of individual struts. The implant may be manufactured by additive manufacturing methods. The mesh of struts may be generated by an algorithm using Voronoi tessellation.

When an acetabular cup used in hip replacement surgery is to be affixed to the acetabulum using screws, the drill guide instruments of the invention are used to position a drill bit so that the screw holes drilled in the acetabulum are properly placed for optimum implantation of the acetabular cup. The drill guide is locked into the acetabular cup by spring loaded pins which position the guide over holes in the cup which accommodate the screws. The guide is used to position the drill bits and allow drilling. After drilling the guide is removed.

In embodiments of the invention, an implant that anchors into bone may have a bone-facing region that comprises a plurality of interconnected struts. The interconnected struts may define local features such as engagement ridges, fins, crests, a macroscopic surface-interrupting feature, a divertor structure, and sawteeth in any combination. Such features may help resist translation or rotation of the implant, and may be conducive to bone ingrowth. Parameters such as local empty volume fraction and local average strut length can be varied, even within the features, by the design of the network of struts. Struts may be tapered. Cantilever struts may also be provided, which may point in a desired direction. The pattern of struts may be specified to the level of dimensions and location of individual struts. The implant may be manufactured by additive manufacturing methods. The mesh of struts may be generated by an algorithm using Voronoi tessellation.