Modular bone anchor system with bottom loaded shank heads having a single shank head shape

A modular bone anchor system for securing an elongate rod to a bone of a patient, the modular bone anchor system comprising:

• a plurality of bone anchors, each bone anchor comprising a longitudinal axis, a capture portion at a proximal end having a rounded shape, and an anchor portion at a distal end configured for fixation to the bone, the capture portion including a planar top surface at an upper end of the capture portion, a rounded outer side surface extending downward from the planar top surface to a neck portion integral with the capture portion and the anchor portion, and at least one helically wound upper threadform located on the rounded outer side surface and extending upwards toward an upper start structure with a concave surface adjacent the planar top surface;
• at least one multiplanar receiver sub-assembly comprising:
• a multiplanar receiver having an upper portion with a channel configured to receive the elongate rod, a base portion defining a lower portion of a central bore having a rounded lower seating surface adjacent a bottom opening and configured to receive and support a capture portion of a first bone anchor, and at least one helically wound lower threadform located on the rounded lower seating surface and extending downwards into the bottom opening toward a lower start structure adjacent the bottom surface, and
• a multiplanar insert positionable with the central bore of the multiplanar receiver above the capture portion, the multiplanar insert including a planar top surface positionable within the channel and configured for engagement by the elongate rod and a bottom surface configured to engage the capture portion of the first bone anchor while providing for multiplanar pivotal motion of the first bone anchor relative to the multiplanar receiver prior to locking the at least one multiplanar receiver sub-assembly with a closure, and
• at least one monoplanar receiver sub-assembly comprising:
• a monoplanar receiver having an upper portion with a channel configured to receive the elongate rod, a base portion defining a lower portion of a central bore having a rounded lower seating surface adjacent a bottom opening and configured to receive and support a capture portion of a second bone anchor, and at least one helically wound lower threadform located on the rounded lower seating surface and extending downwards into the bottom opening toward a lower start structure adjacent the bottom surface, and
• a monoplanar insert positionable with the central bore of the receiver above the capture portion, the monoplanar insert including a planar top surface positionable within the channel and configured for engagement by the elongate rod and a bottom surface configured to engage the capture portion of the second bone anchor while providing for monoplanar pivotal motion of the second bone anchor relative to the monoplanar receiver prior to locking the at least one monoplanar receiver sub-assembly with a closure,
• wherein the capture portion of each bone anchor in the plurality of bone anchors has a single predetermined size and shape common with the other bone anchors in the plurality of bone anchors and is configured for being threadably uploaded into either of the at least one multiplanar receiver sub-assembly or the at least one uni-planar receiver sub-assembly.

A method of assembling a modular bone anchor system configured for securing a fixation rod to a bone of a patient with a plurality of closures, the method comprising:

• uploading one of a plurality of bone anchors into a lower portion of a central bore of one of a plurality of pivoting and non-pivoting receiver sub-assemblies, each of the plurality of bone anchors comprising a longitudinal axis, a capture portion at a proximal end, an anchor portion at a distal end configured for fixation to the bone, and a neck portion integral with the capture portion and the anchor portion, each of the plurality of pivoting and non-pivoting receiver sub-assemblies including:
• a receiver having a vertical centerline axis, an upper portion defining a channel configured to receive the fixation rod, and a base defining the lower portion of the central bore formed around the vertical centerline axis and communicating with a bottom surface of the receiver through a bottom opening, the central bore extending upwardly from the bottom opening through the channel to a top of the receiver and including a guide and advancement structure mateable with a closure proximate the top of the receiver;
• and
• at least one of a capture portion-engaging retainer or a rod-engaging insert positioned within the central bore around the vertical centerline axis,
• wherein the capture portion of each bone anchor in the plurality of bone anchors has a single predetermined size and shape common with the other bone anchors in the plurality of bone anchors and is configured for being uploaded into either of the pivoting or non-pivoting receiver sub-assemblies through the bottom opening of the receiver.