Uniplanar bone screw

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
• 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 that define outermost side surfaces of the head;
• an insert received within the housing, the insert comprising a concave inner annular surface engaging the head of the bone screw and an outer surface engaging an inner surface of the housing and comprising opposing planar surfaces separated by opposing curved surfaces, wherein the opposing planar surfaces of the insert, when aligned with the first and second opposing planar side surfaces of the head enable the head and insert to fit within the bore of the housing and wherein, when positioned in the bore of the housing, the first and second opposing planar side surfaces of the head cooperate with opposing planar surfaces of the inner surface of the bore to restrict angular movement of the bone screw to a single plane relative to the longitudinal axis of the bore.

A bottom loading 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
• 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;
• and
• an insert received within the housing, the insert comprising a concave inner annular surface engaging the head of the bone screw and an outer surface engaging an inner surface of the housing and comprising opposing planar surfaces separated by opposing curved surfaces, wherein the opposing planar surfaces of the insert, when aligned with the first and second opposing planar side surfaces of the head enable the head and insert to fit within the bore of the housing.

A bottom loading 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
• 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;
• an insert received within the housing, the insert comprising a concave inner annular surface engaging the head of the bone screw and an outer surface engaging an inner surface of the housing and comprising opposing planar surfaces separated by opposing curved surfaces, wherein the opposing planar surfaces of the insert, when aligned with the first and second opposing planar side surfaces of the head enable the head and insert to fit within the bore of the housing and wherein, when positioned in the bore of the housing, the first and second opposing planar side surfaces of the head cooperate with opposing planar surfaces of the inner surface of the bore to restrict angular movement of the bone screw to a single plane relative to the longitudinal axis of the bore.