US 12,262,921 B2
Modular head assembly
Brittany Lang, Warrenton, VA (US); and Michael Barrus, Redondo Beach, CA (US)
Assigned to K2M, Inc., Leesburg, VA (US)
Appl. No. 18/011,612
Filed by K2M, Inc., Leesburg, VA (US)
PCT Filed Jun. 25, 2021, PCT No. PCT/US2021/039063
§ 371(c)(1), (2) Date Dec. 20, 2022,
PCT Pub. No. WO2021/263088, PCT Pub. Date Dec. 30, 2021.
Claims priority of provisional application 63/044,575, filed on Jun. 26, 2020.
Prior Publication US 2023/0233233 A1, Jul. 27, 2023
Int. Cl. A61B 17/70 (2006.01); A61B 17/56 (2006.01)
CPC A61B 17/7037 (2013.01) [A61B 17/7032 (2013.01); A61B 2017/564 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A spinal fixation device, comprising:
a bone screw including a head and a shank extending from the head;
a modular head assembly, comprising:
a housing having a proximal surface, a distal surface, and a throughhole formed through the housing from the proximal surface to the distal surface;
an anvil slidable within a portion of the throughhole;
a biasing member circumferentially surrounding the anvil to impart a distally directed force on the head of the bone screw;
an assembly cap secured to the housing, the assembly cap including an inner surface defining a cavity having a first portion and a second portion, the first portion having a first diameter and the second portion having a second diameter smaller than the first diameter, the anvil located entirely above the assembly cap;
a retaining ring positioned at least partially within the cavity of the assembly cap, the retaining ring transitionable between a first configuration in which the retaining ring is sized to receive the head of the bone screw and a second configuration in which the retaining ring is compressed about the bone screw,
wherein movement of the retaining ring from the first portion to the second portion compresses the retaining ring from the first configuration to the second configuration and secures the bone screw relative to the housing.