| 主权项 |
1. A facet screw system for surgical implantation into bone tissue, comprising:
a shaft, the shaft having a bone engaging portion and a compression member engaging portion; a compression member having a proximal end and a distal end, the compression member comprising:
a spherical head portion located at the proximal end and having a recess for engaging with a driving instrument; andan elongated coupling portion having internal threads for coupling with the compression member engaging portion of the shaft; and a washer having a ridge positioned on a top portion of the washer and plurality of bone engaging protrusions on a bottom portion, the washer being coupled to the spherical head portion of the compression member, wherein the washer comprises a plurality of slits extending along the top portion of the washer, wherein the slits extend to an edge of the top portion of the washer and enable engagement with the compression member, wherein the top portion of the washer including the slits is a flexible portion and the bottom portion of the washer is a bone-engaging portion, wherein an outermost diameter of the bone-engaging portion is greater than an outermost diameter of the top portion, wherein a transition from the outermost diameter of the bone engaging portion to the outermost diameter of the top portion is continuous around its entire periphery, wherein a diameter of the spherical head portion of the compression member is greater than a diameter of the bottom portion of the washer, wherein the ridge prevents the disengagement of the compression member from the washer, and wherein the washer is polyaxially rotatable with respect to the compression member. |
