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US 8,444,681 B2Granted
Polyaxial bone anchor with pop-on shank, friction fit retainer and winged insert
OwnerRoger P. Jackson, James L. Surberinventors
Life of this patent
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Abstract
A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A down-loadable compression insert with tool receiving arm extensions, a down-loadable friction fit split retaining ring and an up-loadable shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled.
Claims21
In a bone anchor, the improvement comprising:
- a) a shank having a body for fixation to a bone and an integral upper substantially spherical head;
- b) a receiver having a top portion and a base and an outer surface, the receiver top portion defining an open channel, the base defining a chamber and a lower opening, the chamber communicating with both the channel and the lower opening, the top portion having a pair of opposed through apertures formed therein;
- c) at least one insert disposed within the receiver, the insert having a curved surface sized and shaped for frictional mating cooperation with the shank head, the insert further having a pair of outwardly extending arm portions, each arm portion partially extending through one of the apertures of the receiver, the arm portions being engageable by manipulation tools located at the receiver outer surface for movement of the insert both downwardly into contact with the shank head and upwardly away from the shank head;
- and
- d) a resilient open retainer having a base, the retainer captured within the chamber and expandable about at least a portion of the shank head and wherein expansion-only locking engagement occurs between the shank upper portion and the retainer base and between the retainer base and the receiver.
2 more elements
In a bone anchor, the improvement comprising:
- a) a shank having a body for fixation to a bone and an integral upper substantially spherical head having a first radius;
- b) a receiver having a base, a first pair of upright arms and an outer surface, the receiver upright arms defining an open channel, the base defining a chamber and a lower opening, the chamber communicating with both the channel and the lower opening, each arm having a through aperture formed therein;
- c) at least one insert disposed within the receiver chamber, the insert having a surface sized and shaped for frictional mating cooperation with the shank head, the insert further having a second pair of upright arms, each arm having an outwardly extending wing, each wing extending through one of the apertures of the receiver, the wings being engageable by tooling placed adjacent to the receiver outer surface for movement of the insert both toward and away from the shank head;
- and
- d) a resilient open retainer having a base, the retainer captured within the chamber and expandable about at least a portion of the shank head and wherein expansion-only locking engagement occurs between the shank upper portion and the retainer base and between the retainer base and the receiver, the retainer having a concave second substantially spherical surface with a radius smaller than the radius of the shank head, the second surface terminating at upper and lower edges, the edges temporarily frictionally mating with the shank head, providing a friction fit between the retainer and the shank head during non-locking angular manipulation of the shank with respect to the receiver.
2 more elements
In a bone anchor, the improvement comprising:
- a) a shank having a body for fixation to a bone and an integral upper portion having a convex substantially spherical first surface with a first radius;
- b) a receiver having a base and a pair of upright arms forming an open channel, the base defining a chamber and having a lower opening, the channel communicating with the chamber;
- c) at least one insert disposed within the receiver chamber having structure that directly engages lock and release tools;
- d) a resilient open retainer captured within the chamber and expandable about at least a portion of the shank upper portion, the retainer having a concave surface with a radius smaller than the radius of the shank upper portion first surface, the retainer concave surface terminating at upper and lower edges, the edges frictionally mating with the shank first spherical surface, providing a friction fit between the retainer and the shank during non-locking angular manipulation of the shank with respect to the receiver;
- and
- e) wherein expansion-only locking engagement occurs between the shank upper portion and the retainer and between the retainer and the receiver.
3 more elements
Dependencies are inferred from the claim text.