Abstract: A curved bur with an inner flexible member that is rotatably positioned within an outer tube. The curved bur has a design that constrains the flexible inner coil within the outer tube as the curved bur is rotated (without permitting the coil to stretch and to allow the bur tip to come out of the distal end of the outer tube). To ensure containment of the flexible coil within the outer tube, the outer tube is provided with a constraining neck feature at its distal end to allow the flexible inner assembly to be constrained within the outer tube, and to prevent bur extrusion. The constraining neck feature also centers the bur tip and prevents bur wobble. The curved bur may have a convex or concave bend configuration.