An interspinous fusion device comprising: a first member having a ring with two or more anchor assemblies (83, 83a) projecting laterally from substantially opposite sides of said first member ring, the first member further comprising a first flange and a second flange that each extend transversely and from opposite sides of the first member ring, the two flanges (87, 87a) facing each other and biased toward one another, wherein each of said first and second flanges (87, 87a) comprises a series of teeth (91, 91a) protruding inwardly therefrom; a second member having a ring with two or more anchor assemblies projecting laterally from substantially opposite sides of said anchor member ring, the second member further comprising a barrel extending transversely from the second member ring wherein the barrel comprises a first column of recesses adapted to mate with the teeth of the first flange and a second column of recesses adapted to mate with the teeth of the second flange, wherein the barrel has openings (97a, 97b) on opposite sides of the barrel in between the first and second column of recesses (90, 90a) such that when the first member is mated with the second member there are no other mechanical components within the barrel such that an unobstructed passage is formed through which bone graft material can extend; wherein the first member is adapted to slide over the barrel of the second member such that the series of teeth of the first flange mates with the recesses in the first column of recesses of the barrel and the series of teeth of the second flange mates with the recesses in the second column of recesses of the barrel, the bias of the two flanges (87, 87a) further causing the two flanges (87, 87a) to compress down onto the barrel to form a lock with the barrel without the aid of a set screw, a pin or other mechanical component. a first member having a ring with two or more anchor assemblies (83, 83a) projecting laterally from substantially opposite sides of said first member ring, the first member further comprising a first flange and a second flange that each extend transversely and from opposite sides of the first member ring, the two flanges (87, 87a) facing each other and biased toward one another, wherein each of said first and second flanges (87, 87a) comprises a series of teeth (91, 91a) protruding inwardly therefrom; a second member having a ring with two or more anchor assemblies projecting laterally from substantially opposite sides of said anchor member ring, the second member further comprising a barrel extending transversely from the second member ring wherein the barrel comprises a first column of recesses adapted to mate with the teeth of the first flange and a second column of recesses adapted to mate with the teeth of the second flange, wherein the barrel has openings (97a, 97b) on opposite sides of the barrel in between the first and second column of recesses (90, 90a) such that when the first member is mated with the second member there are no other mechanical components within the barrel such that an unobstructed passage is formed through which bone graft material can extend; wherein the first member is adapted to slide over the barrel of the second member such that the series of teeth of the first flange mates with the recesses in the first column of recesses of the barrel and the series of teeth of the second flange mates with the recesses in the second column of recesses of the barrel, the bias of the two flanges (87, 87a) further causing the two flanges (87, 87a) to compress down onto the barrel to form a lock with the barrel without the aid of a set screw, a pin or other mechanical component.