Systems and methods for the fixation or fusion of bone

1. A method comprising

identifying a bone site comprising a first bone segment, a second bone segment, and a joint between the first and second bone segments,

providing an elongated bone fusion device having a longitudinal axis and a rectilinear cross section transverse to the longitudinal axis and including an exterior surface treated to provide bony in-growth, the elongated bone fusion device including a lumen accommodating passage over a guide pin,

forming a bore in the first bone segment,

forming a bore in the second bone segment that faces the bore in the first bone segment across the joint, the bores in the first and second segments each being non-parallel to the joint and sized and configured to tightly engage the exterior surface of the elongated bone fusion device,

placing in the bore of the first bone segment a guide pin that extends across the joint into the bore of the second bone segment,

fusing the joint by passing the elongated bone fusion device over the guide pin across the joint and into tight engagement within the bores of the first and second bone segments, to thereby restrict movement of the elongated bone fusion device across the joint and provide bony in-growth within the bores along the exterior surface of the bone fusion device, and

removing the guide pin.

2. A method according to claim 1

wherein the rectilinear cross section of the elongated bone fusion device comprises a square.

3. A method according to claim 1

wherein the rectilinear cross section of the elongated bone fusion device comprises a rectangle.

4. A method according to claim 1

wherein the rectilinear cross section of the elongated bone fusion device comprises a triangle.