An implant device for spinal interbody fusion surgery has a shape substantially similar to a human excavated disc space, and includes a first modular end section, at least one modular middle section disposed adjacent to the first modular end section, a second modular end section disposed adjacent to the modular middle section and wherein when the first end section, the middle section and the second end section are placed adjacent to each other, the implant device has a shape with is substantially oval, viewed from top, and a cross section which is bi-convex. The preferred embodiment of the implant device is manufactured from human bone material that has been formed into the shape of the modular components. Alternative embodiments are manufactured from non-human material such as hydrooxyapetite, ceramics, coral and other biodegradable material. Non-resorptable plastic and metal can be used as internal structural members of the implant modules.