An osteogenic fusion device is provided that includes opposite end pieces with an integral central element. The end pieces are sized to maintain the height of an intervertebral disc space. The central element has a smaller diameter so that the fusion device forms an annular pocket around the central element. An osteogenic material is disposed within the annular pocket between the opposite end pieces. The osteogenic material is in direct contact with the adjacent vertebral bone. The inventive osteogenic fusion device reduces stress-shielding and minimizes the radiopacity of the implant so that growth of the fusion mass can be continuously assessed. The osteogenic fusion devices of the present invention may be combined with other fusion devices to form an implant system. Methods of promoting fusion bone growth in the space between adjacent vertebrae utilizing devices and systems of the invention are also described.