Abstract: An anchor for boring into a deformable substance which includes an elongate shaft adapted for disposition in the deformable substance is provided. The anchor has proximal and distal end portions and a central longitudinal axis. A handle is carried by the proximal end portion for causing rotation of the shaft about the axis. A drive screw is carried by the distal end portion for moving the shaft in opposite first and second longitudinal directions when the shaft is rotated in respective opposite first and second rotational directions about the axis. The anchor also includes a disengagement assembly carried by the shaft for deactivating the drive screw so that the shaft can rotate relatively freely without longitudinal movement thereof. The drive screw has an outer surface with a helical screw thread formed thereon and is rotatably mounted to the shaft distal end portion for rotation about the axis.