Pivotal bone anchor assemly with twist-in-place friction fit insert
First Claim
1. A bone anchor assembly for securing a longitudinal connecting member to a bone of a patient via a closure, the bone anchor assembly comprising:
- a receiver having a receiver longitudinal axis, a lower portion with a cavity in communication with a bottom surface of the receiver through a lower opening, and an integral upper portion with an open channel configured to receive the longitudinal connecting member and including a discontinuous helically wound guide and advancement structure, the open channel communicating with the cavity to define a central bore centered on the receiver longitudinal axis, the central bore including an integral downward facing surface below the helically wound guide and advancement structure and a first interference surface;
a shank having a head portion with an upper engagement surface and an anchor portion opposite the head portion configured for attachment to the bone, the head portion configured for being positioned within the cavity of the receiver with the shank extending downwardly through the lower opening; and
a compression insert having at least one vertically extending outer alignment groove with an inwardly extending curvate surface and a second protuberant interference surface adjacent the outer alignment groove, the second protuberant interference surface being configured to inhibit as least some rotation between the compression insert and the receiver, the compression insert being configured for top-loading into the central bore in a first position, and then for being moved down within the receiver and rotated about the receiver longitudinal axis into a second position defined by an engagement between the second protuberant interference surface of the compression insert and the first interference surface of the central bore,wherein the compression insert has radially offset upwardly facing surfaces configured for biased engagement with the downward facing surface of the central bore upon rotation of the compression insert into the second position, so as to apply a downward frictional force on the head portion of the shank prior to locking the assembly with the closure, andwherein the receiver has at least one inwardly extending integral non-resilient structure positionable into the at least one outer alignment groove of the compression insert upon completion of the compression insert being rotated into the second position.
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Accused Products
Abstract
A polyaxial bone screw assembly includes, a threaded shank body having an integral upper portion receivable in a receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A retaining member for capturing the shank in the receiver includes a sloping surface for a frictional, press fit, cammed engagement with the shank. A compression insert having a resilient structure provides non-floppy positioning of the shank with respect to the receiver and also independent locking of the shank with respect to the receiver.
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Citations
29 Claims
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1. A bone anchor assembly for securing a longitudinal connecting member to a bone of a patient via a closure, the bone anchor assembly comprising:
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a receiver having a receiver longitudinal axis, a lower portion with a cavity in communication with a bottom surface of the receiver through a lower opening, and an integral upper portion with an open channel configured to receive the longitudinal connecting member and including a discontinuous helically wound guide and advancement structure, the open channel communicating with the cavity to define a central bore centered on the receiver longitudinal axis, the central bore including an integral downward facing surface below the helically wound guide and advancement structure and a first interference surface; a shank having a head portion with an upper engagement surface and an anchor portion opposite the head portion configured for attachment to the bone, the head portion configured for being positioned within the cavity of the receiver with the shank extending downwardly through the lower opening; and a compression insert having at least one vertically extending outer alignment groove with an inwardly extending curvate surface and a second protuberant interference surface adjacent the outer alignment groove, the second protuberant interference surface being configured to inhibit as least some rotation between the compression insert and the receiver, the compression insert being configured for top-loading into the central bore in a first position, and then for being moved down within the receiver and rotated about the receiver longitudinal axis into a second position defined by an engagement between the second protuberant interference surface of the compression insert and the first interference surface of the central bore, wherein the compression insert has radially offset upwardly facing surfaces configured for biased engagement with the downward facing surface of the central bore upon rotation of the compression insert into the second position, so as to apply a downward frictional force on the head portion of the shank prior to locking the assembly with the closure, and wherein the receiver has at least one inwardly extending integral non-resilient structure positionable into the at least one outer alignment groove of the compression insert upon completion of the compression insert being rotated into the second position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A pivotal bone anchor for securing a longitudinal connecting member to a bone of a patient via a closure, the bone anchor comprising:
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a receiver having a through-bore centered on a receiver longitudinal axis, a lower portion with an inner spherical seating surface partially defining a cavity communicating with a bottom surface of the receiver through a lower opening, and an integral upper portion configured to receive the longitudinal connecting member, the through-bore communicating with the cavity and the bottom surface through the lower opening and including at least one first interference surface; a shank having a shank longitudinal axis, a head with a capture structure and a top surface with a central non-slip tool engagement aperture formed therein and centered on the shank longitudinal axis, and an anchor portion opposite the head for configured fixation to the bone; a retainer having an interior engagement surface configured to capture and hold the capture structure of the head of the shank within the cavity of the receiver, the retainer being engageable with the inner spherical seating surface of the cavity; and a compression insert positionable in the receiver and being sized and shaped for first and second positions with respect to the receiver, the compression insert having radially offset upwardly facing surfaces and a central opening centered on the receiver longitudinal axis when the compression insert is positioned within the receiver and configured to receive therethrough a lower end portion of a driving tool having a non-slip drive structure configured for insertion into the central non-slip tool engagement aperture of the head of the shank, the compression insert including diametrically opposite vertically extending outer alignment grooves with inwardly extending concave surfaces and at least one second protuberant interference surface adjacent the outer alignment grooves, the at least one second protuberant interference surface being configured to at least partially restrict rotation between the compression insert and the receiver upon engagement with the at least one first interference surface, wherein the compression insert is configured to be initially loaded in the first position, and upon rotation about the receiver longitudinal axis into the second position defined by an engagement between the at least one first interference surface of the through-bore of the receiver and the at least one second protuberant interference surface of the compression insert, the radially offset upwardly facing surfaces of the compression insert are configured to frictionally engage a downwardly facing surface formed within the through-bore of the receiver to urge the compression insert into frictional engagement with the top surface of the head of the shank and establish non-floppy movable frictional articulation of the shank with respect to the receiver prior to locking the pivotal bone anchor with the closure, and wherein the outer alignment grooves of the compression insert are configured to receive inwardly extending integral non-resilient structures formed in the receiver to inhibit further rotation of the compression insert with the respect to the receiver after the compression insert has been rotated into the second position. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A bone anchor assembly for securing a longitudinal connecting member to a bone of a patient via a closure, the bone anchor assembly comprising:
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a receiver having a receiver longitudinal axis, a lower portion defining a cavity with an inner seating surface and communicating with a bottom surface of the receiver through a lower opening, and an integral upper portion with an open channel configured to receive the longitudinal connecting member, the open channel communicating with the cavity to define a central bore centered on the receiver longitudinal axis, the central bore including a downwardly facing surface and at least one vertically extending first interference surface; a shank having a shank longitudinal axis, a head, and a body extending distally from the head with an anchor portion configured for fixation to the bone, the head including a top surface with a central non-slip tool engagement aperture formed therein and centered on the shank longitudinal axis, the central non-slip tool engagement aperture including a plurality of non-slip tool engagement surfaces; a retainer configured for capturing the head of the shank within the cavity of the receiver with the top surface of the head extending above a top surface of the retainer; and a compression insert configured to be top-loaded into the central bore of the receiver in a first position;
the compression insert having an upper curvate seating surface configured to receive the longitudinal connecting member and a central driving tool receiving opening centered on the receiver longitudinal axis when the compression insert is positioned within the receiver and configured to allow a lower end portion of a driving tool having a non-slip drive structure to pass through and engage the central non-slip tool engagement aperture of the head of the shank to drive the shank into the bone, the compression insert having diametrically opposite vertically extending outer alignment grooves with inwardly extending concave surfaces and at least one vertically extending second protuberant interference surface,wherein the compression insert is further configured to be rotated about the receiver longitudinal axis from the first position to a second position defined by an engagement between the at least one second protuberant interference surface of the compression insert and at the least one first interference surface of the central bore, with at least one upwardly facing surface on the compression insert coming into a biased engagement with the downwardly facing surface of the central bore so as to apply a downward frictional force on the head of the shank prior to locking the bone anchor assembly with the closure, and with the outer alignment grooves of the compression insert coming into engagement with inwardly extending integral non-resilient structures formed in the central bore so as to hold the compression insert in alignment with respect to the receiver. - View Dependent Claims (25, 26, 27, 28, 29)
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Specification