| 主权项 |
1. A uniplanar bone anchor comprising:
a housing having a bore with a longitudinal axis, the bore extending through the housing to a lower opening, the housing having a channel disposed therein and extending transverse to the bore for receiving an elongate member, the housing further comprising a single mating element spaced from the lower opening of the housing and extending transverse to the longitudinal axis of the bore from an inner surface of the housing into the bore along an entire circumference of the inner surface of the housing to define an upper chamber and a lower chamber, the mating element having an opening therein defining two opposing planar surfaces extending parallel to the longitudinal axis of the housing, the opposing planar surfaces separated by opposing curved surfaces; and a bone screw having a longitudinal axis and including a head and a shank extending from the head, the bone screw configured to extend through the bore with the head positionable in the housing and the shank extending from the lower opening of the housing, the head having a substantially spherical surface with first and second opposing planar side surfaces, wherein the entire first and second side surfaces are planar and define outermost side surfaces of the head, wherein the first and second opposing planar side surfaces cooperate with the two opposing planar surfaces of the mating element to restrict angular movement of the bone screw to a single plane relative to the longitudinal axis of the bore. |
