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Publication Number
US-11389206-B2
Publication Date
2022-07-19
Expiration Date
Abstract
A pedicle screw includes a tulip head, a rod seat, a screw shank, and a retainer collar. The tulip head has an upper opening disposed in a top end of the tulip head and a lower opening disposed in a bottom end of the tulip head opposite the upper opening. The upper and lower openings form a single cavity extending through the tulip head from a top end to the bottom end. The rod seat is disposed within the cavity of the tulip head and engages a stop extending inwardly from an interior wall of the cavity. The screw shank has a thread disposed along a length of the screw shank and a connector positioned at an upper end. The retainer collar has a pass through aperture, an expansion slit, and is disposed about the connector of the screw shank. Other embodiments are described and claimed.
Core Innovation
The disclosed pedicle screw comprises a tulip head with upper and lower openings forming a single cavity, an interior stop, a rod seat, a threaded screw shank, and a retainer collar disposed about the shank connector. An anti-rotation tab on the retainer collar engages an anti-rotation socket in the tulip-head cavity. The assembly is configured for bottom loading through the lower opening.
Bottom loading permits a common tulip head to accommodate shanks with different thread diameters or pitches and supports a lower-profile head design. Additionally, rod-seat ledges engage tulip-head arms to prevent rotation of the rod seat relative to the tulip head. Because background disclosures are not provided, the specific problem being solved is not explicitly described in the patent.
Claims Coverage
The patent includes two independent claims defining five inventive features directed to a pedicle screw with a through-cavity tulip head, rod seat, threaded shank, and anti-rotation retainer collar. Dependent claims further recite retention arrangements and rotation-resisting geometry.
Tulip-head cavity and stop
Both independent claims recite upper and lower openings forming a single cavity through the tulip head, internal threads adjacent to the upper opening, and a stop separate from the threads. One claim specifies that the stop extends substantially at right angles inwardly from the interior wall, whereas the other specifies that it extends inwardly.
Rod seat engageable with the stop
Both independent claims recite a rod seat disposed within the cavity and engageable with the stop. The rod seat includes a rod mating face, an opposite shank mating face, and a hole through both faces.
Threaded screw shank and retainer collar
Both independent claims recite a screw shank with a thread along its length and a connector at its upper end. A retainer collar is disposed about the connector and comprises a collar body, a pass-through aperture, an anti-rotation tab, and a collar expansion split.
Engagement of the anti-rotation tab and socket
Both independent claims recite an anti-rotation socket in the tulip-head cavity constructed to receive and engage the anti-rotation tab of the retainer collar.
Locking ring and rod-seat retention refinements
Dependent claims add retention grooves in the collar and tulip head, a locking ring disposed in the grooves with wire-ring and compression-state features, and rod-seat retention ledges that engage tulip-head arms to prevent rotation of the rod seat relative to the tulip head.
The two independent claims cover the same principal pedicle-screw arrangement, differing primarily in the geometric description of the stop's inward extension. Dependent claims add locking-ring retention structures and ledge-and-arm anti-rotation features.
Stated Advantages
Bottom loading permits a common tulip head to accommodate shanks with different thread diameters or pitches.
Bottom loading supports a lower-profile head.
Engagement of the rod-seat ledges with the tulip-head arms prevents rotation of the rod seat relative to the tulip head.
Documented Applications
Not explicitly described in patent.
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