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US 12,758,268 B2Granted
Polyaxial screw assembly
AssigneeSeaSpine Orthopedics Corporation
InventorsCorey Noel Gladieux, Leah Beyer Sherman
Life of this patent
Estimating the term…
Abstract
A polyaxial bone screw system and method for connecting a longitudinal rod to multiple bones or bone portions. The system may include a bone fastener having a shank and a shank head; a polyaxial body to receive the shank head; and a collet for applying force to exterior surface of the shank head when the collet is acted upon by a rod, which is pressed onto the collet via a set screw received in the polyaxial body. The force applied to the shank head by the collet is adequate to temporarily lock the desired orientation of the shank with respect to the polyaxial body.
Claims18
A polyaxial spinal fixation system comprising:
- a polyaxial head having an upper section and a lower section, the upper section having two upstanding members comprising internal threading therein;
- the lower section having a collet cavity having an upper portion and a lower portion, wherein the upper portion includes a collet retention groove and an upper ledge at a top portion of the collet retention groove;
- and wherein the lower portion includes a first section, a second section, and a third section;
- wherein the first section has a partially spherical concave surface;
- and the second section has a conical surface terminating in a lip;
- a bone fixation screw having a head and a threaded shank;
- a rod configured for insertion into the two upstanding members;
- a set screw having threads thereon configured to mate with the internal threading of the polyaxial head;
- and
- a collet configured for insertion into the collet cavity, wherein the collet further comprises a split-ring cylindrical body having a hinge thereon, and wherein the collet further comprises an upper portion and a lower portion, the upper portion including one or more tabs extending outwardly from an outer cylindrical surface, and the lower portion including multiple flanges separated by multiple slits, each flange of the multiple flanges having an external surface having a partially spherical convex surface and a conical surface, and an internal surface having at least one partially spherical concave surface, a cylindrical surface, and a conical surface,
- wherein the internal surface of at least one flange comprises a first partially spherical concave surface with a first radius and a second partially spherical concave surface with a second radius, wherein the second radius is smaller than the first radius.
8 more elements
A method for installing a polyaxial spinal fixation system comprising:
- inserting a bone fixation screw using an insertion tool;
- installing a collet having a lower portion of the collet having multiple flanges into a collet cavity of a lower section of a polyaxial head from a top by pushing down to compress each flange so that at least one flange passes through at least one relief cut defined within the polyaxial head to retain the collet;
- rotating the collet within the collet cavity to position one or more tabs within a collet retention groove but below an upper ledge to limit rotation of the collet within the polyaxial head;
- selectively translating the collet within the collet cavity between the upper ledge and a lip;
- attaching the collet to the bone fixation screw by contacting the lower portion of the collet with the head of the bone fixation screw such that the multiple flanges splay outwardly to accept the head within the lower portion wherein a first portion of each flange at least partially contacts a lower hemisphere of the head and a second portion of each flange at least partial contacts an upper hemisphere of the head to frictionally hold the head of the bone fixation screw within the collet;
- inserting a rod into a U-shaped channel of the polyaxial head;
- installing a set screw to engage with an internal threading within an upper portion of the polyaxial head;
- and
- tightening the set screw to direct the rod to interact with the collet to securely fix an angular orientation of the bone fixation screw with respect to the polyaxial head.
6 more elements
A polyaxial spinal fixation system comprising:
- a polyaxial head having an upper section and a lower section, the upper section having two upstanding members comprising internal threading therein;
- the lower section having a collet cavity having an upper portion and a lower portion;
- wherein upper portion includes a collet retention groove, and wherein the lower portion includes a first section, a second section, and a third section;
- wherein the first section has a partially spherical concave surface;
- and the second section has a conical surface terminating in a lip;
- a bone fixation screw having a head and a threaded shank;
- a rod configured for insertion into the two upstanding members;
- a set screw having threads thereon configured to mate with the internal threading of the polyaxial head;
- and
- a collet configured for insertion into the collet cavity, wherein the collet further comprises a split-ring cylindrical body having a first side and a second side separated at a first end by a separation and joined at a second end by a hinge, and wherein the collet further comprises an upper portion and a lower portion, the upper portion including one or more tabs extending outwardly from an outer cylindrical surface, and the lower portion including multiple flanges separated by multiple slits, each flange of the multiple flanges having an external surface having a partially spherical convex surface and a conical surface, and an internal surface having at least one partially spherical concave surface, a cylindrical surface, and a conical surface,
- wherein the internal surface of at least one flange comprises a first partially spherical concave surface with a first radius and a second partially spherical concave surface with a second radius, wherein the second radius is smaller than the first radius.
8 more elements
Dependencies are inferred from the claim text.