A pedicle screw assembly , comprising: a bone fastener having a head at a proximal end and a threaded portion extending between the proximal end and a distal end ; a compression member having a cylindrical outer surface and a conical inner surface ; a locking member having an outer surface adapted to mate with the conical inner surface of the compression member , wherein the outer surface of the locking member has a proximal portion and a distal portion , the proximal portion being conically shaped and further comprising at least one of a circumferential groove and a circumferential flange , the locking member having a top edge and a bottom edge, the locking member being deformable and having a proximal portion further comprising a plurality of vertical slots , the slots extending from the outer surface to the inner surface and from a top of the proximal portion down to at least one of the circumferential groove and the circumferential flange in the distal portion , the slots being disposed around an outer circumference of the proximal portion ; and a receiving housing having a central bore extending from a proximal end to a distal end , wherein the distal end comprises a first opening sized to receive the head of the bone fastener and the proximal end comprises a second opening sized to receive the locking member and the compression member , wherein the receiving housing further comprises an intermediate portion extending between the proximal end and the distal end , and wherein the intermediate portion further comprises a retention mechanism extending from the intermediate portion of the receiving housing inwardly towards the central bore ; wherein the compression member is positioned below the retention mechanism and the retention mechanism inhibits the compression member from moving above the retention mechanism . a bone fastener having a head at a proximal end and a threaded portion extending between the proximal end and a distal end ; a compression member having a cylindrical outer surface and a conical inner surface ; a locking member having an outer surface adapted to mate with the conical inner surface of the compression member , wherein the outer surface of the locking member has a proximal portion and a distal portion , the proximal portion being conically shaped and further comprising at least one of a circumferential groove and a circumferential flange , the locking member having a top edge and a bottom edge, the locking member being deformable and having a proximal portion further comprising a plurality of vertical slots , the slots extending from the outer surface to the inner surface and from a top of the proximal portion down to at least one of the circumferential groove and the circumferential flange in the distal portion , the slots being disposed around an outer circumference of the proximal portion ; and a receiving housing having a central bore extending from a proximal end to a distal end , wherein the distal end comprises a first opening sized to receive the head of the bone fastener and the proximal end comprises a second opening sized to receive the locking member and the compression member , wherein the receiving housing further comprises an intermediate portion extending between the proximal end and the distal end , and wherein the intermediate portion further comprises a retention mechanism extending from the intermediate portion of the receiving housing inwardly towards the central bore ; wherein the compression member is positioned below the retention mechanism and the retention mechanism inhibits the compression member from moving above the retention mechanism . <EOS>