A bone anchor , comprising: a bone engaging member having a first end and a second end , the bone engaging member comprising: a first plurality of bone-engaging tines extending longitudinally towards the first end ; a second plurality of bone-engaging tines extending longitudinally towards the second end ; an expander , wherein the expander is positioned along a longitudinal axis ; wherein the expander is positioned between the first plurality of bone engaging tines when the expander is in a first position, wherein the expander is positioned between the first plurality of bone engaging tines and between the second plurality of bone engaging tines when the expander is in a second position; and wherein the expander is configured to expand both the first set of tines and the second set of tines outward upon movement of the expander relative to the bone- engaging member from a first position to a second position, wherein the expander comprises a cylindrical portion positioned directly between a first conical portion and a second conical portion , the conical portions both expanding in diameter from a second end to a first end of the expander , wherein the first conical portion is configured to radially expand the first set of tines , characterized in that the second conical portion of the expander is configured to radially expand the second set of tines when the expander is moved from the first position to the second position. a bone engaging member having a first end and a second end , the bone engaging member comprising: a first plurality of bone-engaging tines extending longitudinally towards the first end ; a second plurality of bone-engaging tines extending longitudinally towards the second end ; an expander , wherein the expander is positioned along a longitudinal axis ; wherein the expander is positioned between the first plurality of bone engaging tines when the expander is in a first position, wherein the expander is positioned between the first plurality of bone engaging tines and between the second plurality of bone engaging tines when the expander is in a second position; and wherein the expander is configured to expand both the first set of tines and the second set of tines outward upon movement of the expander relative to the bone- engaging member from a first position to a second position, wherein the expander comprises a cylindrical portion positioned directly between a first conical portion and a second conical portion , the conical portions both expanding in diameter from a second end to a first end of the expander , wherein the first conical portion is configured to radially expand the first set of tines , a first plurality of bone-engaging tines extending longitudinally towards the first end ; a second plurality of bone-engaging tines extending longitudinally towards the second end ; an expander , wherein the expander is positioned along a longitudinal axis ; wherein the expander is positioned between the first plurality of bone engaging tines when the expander is in a first position, wherein the expander is positioned between the first plurality of bone engaging tines and between the second plurality of bone engaging tines when the expander is in a second position; and wherein the expander is configured to expand both the first set of tines and the second set of tines outward upon movement of the expander relative to the bone- engaging member from a first position to a second position, wherein the expander comprises a cylindrical portion positioned directly between a first conical portion and a second conical portion , the conical portions both expanding in diameter from a second end to a first end of the expander , wherein the first conical portion is configured to radially expand the first set of tines , characterized in that the second conical portion of the expander is configured to radially expand the second set of tines when the expander is moved from the first position to the second position. <EOS>