There is disclosed an apparatus for the distraction of two tissue surfaces in a given direction within a spine, comprising: a plurality of elongated inserts (10,20A,20B) composed of biocompatible material configured to be consecutively stacked upon one another to form a structure extending in a given direction within a spine, each elongated insert having a generally planar top surface (14) having a first leading edge and a first trailing edge, a generally planar bottom surface (12) disposed generally parallel to said top surface and including a second leading edge and a second trailing edge, first and second side surfaces extending between said top and bottom surfaces, and a beveled surface extending from at least one of said first and second leading edges, said beveled surface configured to facilitate the successive stacking of said inserts to distract said two tissue surfaces in said given direction during consecutive insertion into said spine, each of said inserts having a length dimension defined by the distance between one of said first and second leading edges and the corresponding one of said first and second trailing edges, a width dimension defined by the distance between said first and second side surfaces, and a height dimension defined by the distance between said top and bottom surfaces, at least one of said inserts having a generally rectangular cross-section taken along a plane generally parallel to at least one of said top and bottom surfaces, such that said length dimension is greater than said width dimension.
