Patent ID: 7803191

Claim:
A spacer for insertion between two vertebrae, said spacer having a variable axial length and comprising: a first member having a hollow interior and a tubular wall; and a second member having a hollow interior and a tubular wall, the second member being slidable within the first member in an axial direction for adjusting an overall length; wherein at least the first member or the second member comprises at its free end a first ring of prongs and at least a second ring of prongs within the first ring of prongs for fixation in the vertebral body, wherein each ring of prongs is formed by a tubular member, wherein at least the first member or the second member comprises an access opening in its wall, the opening having a size which is adapted for inserting bone graft through the opening into the interior, wherein at least the first or the second member comprises a plurality of second openings in the wall, the openings being smaller than the access opening in such a way that they do not permit the introduction of bone grafts.