US 12,458,410 B2
Method of assembling a pivotal bone anchor assembly with a downwardly displaceable collet insert
Roger P. Jackson, Prairie Village, KS (US); James L. Surber, Kansas City, KS (US); and Nathaniel D. Ginzton, Boise, ID (US)
Filed by Roger P. Jackson, Prairie Village, KS (US)
Filed on Oct. 31, 2024, as Appl. No. 18/933,954.
Application 18/933,954 is a continuation of application No. 18/055,399, filed on Nov. 14, 2022, granted, now 12,137,944.
Application 18/055,399 is a continuation of application No. 17/564,784, filed on Dec. 29, 2021, granted, now 11,497,533, issued on Nov. 15, 2022.
Application 17/564,784 is a continuation of application No. 16/686,122, filed on Nov. 16, 2019, granted, now 11,234,738, issued on Feb. 1, 2022.
Claims priority of provisional application 62/811,250, filed on Feb. 27, 2019.
Claims priority of provisional application 62/768,732, filed on Nov. 16, 2018.
Prior Publication US 2025/0057570 A1, Feb. 20, 2025
Int. Cl. A61B 17/70 (2006.01); A61B 17/86 (2006.01)
CPC A61B 17/7037 (2013.01) [A61B 17/7076 (2013.01); A61B 17/8605 (2013.01); A61B 17/864 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A method of assembling a pivotal bone anchor assembly intended for securing an elongate rod to a bone of a patient, the method comprising:
loading an insert into a central bore of a receiver,
the receiver comprising a base defining an internal cavity in communication with a bottom of the receiver through a bottom opening, a pair of upright arms extending upwardly from the base to define a first channel configured to receive the elongate rod, and the central bore centered around a vertical centerline axis and extending upward from the bottom opening through the internal cavity and the first channel to top surfaces of the upright arms, the central bore including a guide and advancement structure adjacent the top surfaces of the upright arms and interference abutment surfaces below the guide and advancement structure, the internal cavity including an upper capture region and a lower retaining region with an engagement surface adjacent the bottom opening,
the insert comprising a lower collet portion integrally formed with an upper portion defining a second channel configured to receive the elongate rod when the elongate rod is received in the first channel, a center opening alignable with the vertical centerline axis of the central bore, and opposite lateral protrusions extending radially outward in a direction transverse to the second channel, the lower collet portion defining a collet pocket and including a plurality of distal tip sections at a lower end thereof defining an expandable collet pocket opening;
positioning the insert into a first position in the central bore with the opposite lateral protrusions of the insert located adjacent to and at least partially above the interference abutment surfaces of the central bore and the lower collet portion contained within the upper capture region of the internal cavity;
with the insert in the first position, positioning a load ring into a non-overlapping friction fit engagement within the center opening of the insert, the load ring having an upper surface configured to engage the elongate rod when the elongate rod is received in the second channel;
uploading a head portion of a shank into the internal cavity of the receiver through the bottom opening and into the collet pocket through the collet pocket opening, the shank including a longitudinal axis and an anchor portion opposite the head portion configured for fixation to the bone;
capturing the head portion of the shank within the lower collet portion of the insert; and
forcibly downward displacing the insert within the central bore of the receiver with tooling so as to move the opposite lateral protrusions at least partially below the interference abutment surfaces and thereby inhibit the insert from moving back up within the receiver, and to move lower outer surfaces of the plurality of distal tip sections of the lower collet portion into engagement with the engagement surface of the lower retaining region to secure the head portion of the shank within the internal cavity the receiver.