Modular bone screw

Patent metadata

Field	Value
Publication number	US-10588666-B2
Application number	US-201815947848-A
Country	US
Kind code	B2
Filing date	Apr 8, 2018
Priority date	Apr 10, 2017
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A modular polyaxial bone screw includes a poly-axial bone screw, a polyaxial tulip head, and a collet disposed within the tulip head, the collet interacting with the bone screw and tulip head providing an interference fit with the bone screw head to lock orientation of the tulip head on and relative to the bone screw. Inner configurations of the tulip head interact with outer configurations of the collet to lock axial and/or rotational position of the collet within and relative to the tulip head, and thus about the bone screw head. The collet also has a resilient, tapered base with a plurality of slots in and about its end that allow the end to splay outwardly over and upon the head of the bone screw to create a snap or frictional interference fit between the splayed collet and the bone screw head when a spine rod is fixed in the tulip head.

First claim

What is claimed is:

1. A modular polyaxial bone screw assembly for holding a spine rod in a fixed spatial orientation relative to vertebral bone, the modular polyaxial bone screw assembly comprising:
a polyaxial bone screw having a threaded shank and a globular head;
a tulip head disposed on the globular head of the polyaxial bone screw and configured to swivel about the globular head of the polyaxial bone screw before the tulip head is fixed in spatial orientation relative to the polyaxial bone screw, and to receive and hold a spine rod as the spatial orientation of the tulip head is fixed, the tulip head having a bore extending from a first end of the tulip head to a second end of the tulip head and defining a generally cylindrical interior with an upper cylindrical portion defining an upper inner cylindrical wall coinciding with and within the first end of the tulip head, inner threading on the upper inner cylindrical wall for threaded receipt of a set screw, and a lower generally cylindrical portion defining a lower inner generally cylindrical wall coinciding with and within the second end of the tulip head and sized to receive the globular head of the polyaxial bone screw in its entirety, and an inner configuration on the lower inner generally cylindrical wall, the inner configuration consisting of a ridge extending radially inward from the lower inner generally cylindrical wall; and
a collet disposed in the interior of the tulip head, the collet having a lower section of a first diameter with a first end resting about the globular head of the polyaxial bone screw and configured to splay about on the globular head of the polyaxial bone screw and fix a spatial orientation of the tulip head relative to the polyaxial bone screw through interference between the first end, the globular head of the polyaxial bone screw, and the tulip head when a spine rod is received in and affixed to the tulip head by the set screw, and an upper section of a second diameter that is smaller than the first diameter of the lower section, the collet having an outer configuration on an outer wall between the upper section and the lower section that cooperates with the inner configuration of the tulip head to fix axial and rotational position of the collet relative to the tulip head, the outer configuration consisting of a circumferential depression that receives the ridge of the tulip head whereby reception of the ridge of the tulip head in the circumferential depression retains the collet in its axial position.

2. A modular bone screw comprising:
a polyaxial bone screw having a threaded shank and a rounded head;
a tulip head disposed on the rounded head of the polyaxial bone screw and configured to swivel about the rounded head of the polyaxial bone screw before the tulip head is fixed in spatial orientation relative to the polyaxial bone screw, and to receive and hold a spine rod in spine rod notches disposed in a first end of the tulip head once the spatial orientation of the tulip head is fixed, the tulip head having a bore extending from the first end to a second end of the tulip head that also defines a generally cylindrical interior with an upper cylindrical portion defining an upper inner cylindrical wall coinciding with and within the first end of the tulip head, inner threading on the upper inner cylindrical wall for threaded receipt of a set screw, and a lower generally cylindrical portion defining a lower inner generally cylindrical wall coinciding with and within the second end of the tulip head and sized to receive the rounded head of the polyaxial bone screw in its entirety, and an inner configuration on the lower inner generally cylindrical wall, the inner configuration consisting of a plurality of projections each one of which extends radially inward from an inner circumference of the lower inner generally cylindrical wall; and
a collet disposed in the interior of the tulip head, the collet having a tapered first end resting about the rounded head of the polyaxial bone screw and having a plurality of cutouts configured to allow the tapered first end of the collet to splay about the rounded head of the polyaxial bone screw and fix a spatial orientation of the tulip head relative to the polyaxial bone screw through interference between the tapered first end, the rounded head of the polyaxial bone screw, and the tulip head when a spinal rod is received in and affixed to the tulip head by the set screw, the collet having a second end axially above the tapered first end and an outer configuration on an outer wall between the tapered first end and the second end that cooperates with the inner configuration of the tulip head to fix axial and rotational position of the collet relative to the tulip head, the outer configuration consisting of a plurality of depressions on a circumference of the outer wall whereby reception of the plurality of projections of the tulip head in the plurality of depressions of the collet retains the collet in its axial position.

3. The modular bone screw of claim 2 , wherein the plurality of radially inward projections comprise four radially inward projections.

4. The modular bone screw of claim 3 , wherein the four radially inward projections are disposed equally about the inner circumference of the inner wall.

5. The modular bone screw of claim 3 , wherein the plurality of depressions comprise four depressions.

6. The modular bone screw of claim 5 , wherein the four depressions are disposed equally about the circumference of the outer wall.

Assignees

• Life Spine Inc

Inventors

• Samuel Forrest
• Palagi Gregory

Classifications

• A61B17/863

  with thread interrupted or changing its form along shank, other than constant taper · CPC title

• A61B17/7037 Primary

  wherein pivoting is blocked when the rod is clamped · CPC title

• A61B17/8605

  Heads, i.e. proximal ends projecting from bone · CPC title

• A61B17/7032 Primary

  Screws or hooks with U-shaped head or back through which longitudinal rods pass · CPC title

• A61B2090/037

  with a frangible part, e.g. by reduced diameter · CPC title