A fusion implant apparatus, in for the replacement of a vertebra or an intervertebral disc, having at least one biocompatible structure. The structure is made of a composite material having reinforcing fibers, and has a first and second face to engage adjacent bone structures to be fused, struts extending between the first and second faces, and a hollow interior space for reception of bone growth inducing substances. The fibers are long fibers and the majority of these long fibers have a direction that follows the longitudinal forces upon the first and second faces, which is the direction of trabecular structures of the adjacent bone structure, so that a majority of long fibers are essentially an extension of these trabecular structures.