Pivotal bone anchor assembly with modular receiver and universal shank head

A pivotal bone anchor system for securing an elongate rod to a bone of a patient via closure tops, the pivotal bone anchor system comprising:

• a plurality of bone anchors, each bone anchor comprising a longitudinal axis, a capture portion having a rounded shape with a midsection defining a hemisphere plane perpendicular to the longitudinal axis, and a unitary anchor portion opposite the capture portion configured for attachment to the bone, the capture portion being without flat side faces and including an upper partial spherical outer surface above the hemisphere plane, a lower partial spherical outer surface below the hemisphere plane, and a horizontal capture recess extending into and circumferentially around the capture portion at the hemisphere plane;
• at least one multi-planar receiver sub-assembly comprising:
• a multi-planar receiver having a upper channel portion configured to receive the elongate rod and a lower base portion defining an internal cavity having a substantially continuous circumferential partial spherical seating surface proximate a bottom opening, and
• a multi-planar pivoting retainer having a circumferential partial spherical outer surface configured for multi-planar motion upon engagement with the seating surface of the internal cavity of the multi-planar receiver, and an inner surface configured to snap into the capture recess of a one of the plurality of bone anchors to capture the bone anchor within the internal cavity of the multi-planar receiver;
• and
• at least one uni-planar receiver sub-assembly comprising:
• a uni-planar receiver having a upper channel portion configured to receive the elongate rod and a lower base portion defining an internal cavity having a non-continuous circumferential partial spherical seating surface proximate a bottom opening with opposing pockets formed therein, and
• a uni-planar pivoting retainer having a non-continuous circumferential partial spherical outer surface with opposite pegs projecting outward therefrom, the partial spherical out surface and pegs configured for uni-planar motion upon engagement with the seating surface and opposing pockets of the internal cavity of the uni-planar receiver, respectively, and an inner surface configured to snap into the capture recess of another of the plurality of bone anchors to capture the bone anchor within the internal cavity of the uni-planar receiver,
• wherein the capture portion of each of the plurality of bone anchors is configured for capture by either of the at least one multi-planar receiver sub-assembly or the at least one uni-planar receiver sub-assembly without further modification or adjustment.