Pivotable bone anchor assembly with independent locking by insert side compressing member

A receiver of a pivotal bone anchor assembly configured for independent locking with a vertically-translating insert side compressing member prior to securing an elongate rod to a bone of a patient with a closure top, the receiver comprising:

• a receiver body having a longitudinal axis, a base, and a pair of upstanding arms extending upwardly from the base to define an open channel configured for receiving the elongate rod, the base including a receiver cavity in communication with a bottom of the receiver body through a lower opening and with the open channel to define a central bore centered about the longitudinal axis, the upright arms having opposed interior surfaces, top surfaces defining a top of the receiver body, opposite front and back surfaces, and a closure top mating feature formed into the opposed interior surfaces adjacent the top surfaces, the receiver body having outer side surfaces opposite the opposed interior surfaces of each upright arm and extending downward across the base to the bottom of the receiver body;
• a horizontally-elongated upper tool engaging groove formed into the outer side surface of each upstanding arm, spaced an equal and symmetrical distance below the top surface, and extending to the front and back surfaces to define an upper portion of the upright arm above the upper tool engaging groove;
• and
• a vertical tool-engaging groove formed into the outer side surface of each upright arm, the vertical tool-engaging groove extending downward from the top surface through the upper portion of the upright arm and the upper tool engaging groove to a level below the upper tool engaging groove.

A receiver assembly of a pivotal bone anchor assembly configured for independent locking with a vertically-translating insert side compressing member prior to securing an elongate rod to a bone of a patient with a closure top, the receiver assembly comprising:

• a receiver having a longitudinal axis, a base, and a pair of upstanding arms extending upwardly from the base to define an open channel configured to receive the elongate rod, the base including a receiver cavity in communication with a bottom of the receiver through a lower opening and with the open channel to define a central bore centered about the longitudinal axis, the upright arms having opposed interior surfaces, top surfaces defining a top of the receiver, opposite front and back surfaces, outer side surfaces opposite the opposed interior surfaces and extending downward from the top surface across the base to the bottom of the receiver, and a closure top mating feature formed into the opposed interior surfaces adjacent the top surfaces, the outer side surface of each upright arm further comprising;
• a horizontally-elongated upper tool engaging groove spaced an equal and symmetrical distance below the top surface and extending to the front and back surfaces to define an upper portion of the upright arm above the upper tool engaging groove, each upper tool engaging groove including a downwardly-facing upper surface, an upwardly-facing lower surface, and an outwardly-facing inner surface;
• and
• a vertical tool-engaging groove extending downward from the top surface through to a level below the upper tool engaging groove;
• and
• an insert configured for positioning within the central bore of the receiver, the insert having a center opening and upward facing outer engagement surfaces positioned radially outward from the center opening configured for engagement by the insert side compressing member,
• wherein the outer engagement surfaces of the insert are configured to remain uncovered by the elongate rod or by the closure top when the elongate rod is received within the open channel of the receiver and locked with the closure top.

A method of assembling a receiver assembly of a pivotal bone anchor assembly configured for independent locking with a vertically-translating insert side compressing member prior to securing an elongate rod to a bone of a patient with a closure top, the method comprising:

• positioning an insert within the central bore of a receiver, the insert comprising a center opening and upward facing outer engagement surfaces positioned radially outward from the center opening configured for engagement by the insert side compressing member, the receiver comprising a longitudinal axis, a base, and a pair of upstanding arms extending upwardly from the base to define an open channel configured to receive the elongate rod, the base including a receiver cavity in communication with a bottom of the receiver through a lower opening and with the open channel to define the central bore, the upright arms having opposed interior surfaces, top surfaces defining a top of the receiver, opposite front and back surfaces, outer side surfaces opposite the opposed interior surfaces, and a closure top mating feature formed into the opposed interior surfaces adjacent the top surfaces, the outer side surface of each upright arm further comprising:
• a horizontally-elongated upper tool engaging groove spaced an equal and symmetrical distance below the top surface and extending to the front and back surfaces to define an upper portion of the upright arm above the upper tool engaging groove, each upper tool engaging groove including a downwardly-facing upper surface, an upwardly-facing lower surface, and an outwardly-facing inner surface;
• and
• a vertical tool-engaging groove extending downward from the top surface through to a level below the upper tool engaging groove,
• wherein the outer engagement surfaces of the insert are configured to remain uncovered by the elongate rod or by the closure top when the elongate rod is received within the open channel of the receiver and locked with the closure top.