Expandable push-in interbody spinal fusion implant

Fusion implant between vertebral insertable and expandable for linear insertion bodies, at least partially covering at least the height of the disc space between two adjacent vertebral bodies of the spine, which implant comprises: an upper element (102, 402, 602 ) having a top surface (104) adapted for placement toward one of the adjacent vertebral bodies and contacted therewith, from within the disc space, said upper (104) in a non-arcuate along a substantial part of the length of said implant (100, 200, 400, 600, 800, 1000), having said upper surface (104) at least one opening (110) adapted to communicate with one of the adjacent vertebral bodies, having said element upper (102, 402, 602) a proximal end and a distal end.