The present invention relates generally to a uniplanar pedicle fastener for attachment to a vertebrae as part of a spinal stabilization apparatus. In particular, the present invention relates to a uniplanar pedicle fastener that can be bottom-loaded and hinges via a complementary arrangement of the housing and fastener.
Typical pedicle fasteners anchor to a surgical patient's bone, such as a spinal vertebrae. Such fasteners receive additional equipment or implants, such as a stabilization rod, either before or after being anchored to the bone. The positioning and alignment of the fastener dictates the location and orientation of the additional equipment. In a spinal stabilization procedure, a plurality of pedicle fasteners are mounted to vertebrae and one or more rods extend between the fasteners so as to immobilize a portion of the spine.
In accordance with a preferred embodiment, the present invention provides a uniplanar pedicle fastener comprising a bone fastener and a housing. The bone fastener includes a stem and a head having a protrusion. The housing includes a cavity with sidewalls and a bottom portion. The bottom portion has an elongated opening and a recess for articulating with the protrusion of the head.
In accordance with another preferred embodiment, the present invention provides a uniplanar pedicle fastener comprising a fastener that includes a head and a shaft, and a housing. The head includes a protrusion therefrom. The housing receives the fastener and includes an inner cavity having a bottom wall, sidewalls and an open top end. The bottom wall of the housing includes an opening therethrough and a depression for engaging the fastener protrusion as a ball and socket-like joint.
In accordance with yet another preferred embodiment, the present invention provides a uniplanar pedicle system comprising a bone fastener, a housing, a seating element, a rod, and a fastener. The bone fastener includes a shaft and a head with a textured upper surface and a protrusion. The housing is for receiving the fastener and includes an inner cavity, an open top end, sidewalls, and a bottom. The bottom of the housing has an elongate opening configured to receive the head therethrough and a depression configured to articulate with the protrusion. The seating element is for engaging the textured upper surface of the fastener. The rod is received within the housing. The fastener is to affix together the fastener, housing, rod, and seating element.
The foregoing summary, as well as the following detailed description of the preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
In the drawings:
Reference will now be made in detail to the preferred embodiments of the invention illustrated in the accompanying drawings. Wherever possible, the same or like reference numbers will be used throughout the drawings to refer to the same or like features. It should be noted that the drawings are in simplified form and are not drawn to precise scale. In reference to the disclosure herein, for purposes of convenience and clarity only, directional terms such as top, bottom, above, below and diagonal, are used with respect to the accompanying drawings. Such directional terms used in conjunction with the following description of the drawings should not be construed to limit the scope of the invention in any manner not explicitly set forth. Additionally, the term “a,” as used in the specification, means “at least one.” The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import.
“About” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, and ±0.1% from the specified value, as such variations are appropriate.
Ranges throughout this disclosure and various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range.
In accordance with a preferred embodiment, the present invention provides a uniplanar pedicle system 10, as shown in
As best shown in
The head 20 of bone fastener 12 is generally elongated or oblong in cross-section as shown in
The protrusion 24 is preferably integrally formed with the bone fastener head so as to be a unitary piece, however multi-part constructions can be configured. As shown in
A top surface 28 of the bone fastener head 20 is preferably curved convexly and includes grooves 30. As best shown in
The stem 22 of the head 20 of bone fastener 12 is configured as shown in
Referring now to
The housing also includes a slot 58, and preferably a pair of slots diametrically opposed for receiving the rod 62. The sidewalls may additionally include a counterbore 56.
The bottom portion 44 of housing 14, which may be considered a bottom wall or bottom, preferably extends substantially transversely from the sidewalls toward the central vertical major axis 48 of the housing and includes an elongate opening 50 and a recess 52. The bottom portion is generally planar and preferably substantially planar, although other shapes are contemplated such as concave, convex, or sloped.
The elongate opening 50 of the bottom portion 44 of the housing 14, as shown in
The socket or recess 52 of the housing 14, as shown in
The recess 52 is preferably spaced radially inwardly from the sidewalls 42, however other locations may be configured such as extending to abut the sidewall or being partially defined in both the bottom and the sidewalls. The recess 52 is also preferably coextensive with the elongate opening 50 as shown in
The stabilization system 16 includes seating element 60, a rod 62, and a fastener 64. Referring to
The seating element 60 top surface 68 defines, by its concave shape, a first longitudinal axis that extends parallel with rod 62 when assembled. Moreover, the seating element 60 bottom surface defines, by its concave shape, a second longitudinal axis that extends generally or substantially transverse to the first longitudinal axis.
Referring to
Referring again to
In use, the bone fastener 12 and housing 14 are complementarily sized and shaped. In particular, complementary shapes and sizes are provided among the head 20 and protrusion 24 of the bone fastener 12 along with the elongate opening 50 and recess 52 of the housing 14. In particular, the lower periphery 24A of the protrusion 24 is sized and shaped to fit and pivot within the recess 52. The shapes discussed below are exemplary; other shapes are possible so long as they are generally complementary such that uniplanar pedicle screw 10 functions similarly.
For initiating assembly as best shown in
To complete assembly of the uniplanar pedicle system 10, one of the head 20 or housing 14 is rotated about a respective major axis 26 or 48 to a retention orientation, as best shown in
Referring again to
Additionally when assembled within the housing recess 52, the protrusion 24 functions with the recess similar to a hinge joint. More preferably, the protrusion 24 functions with recess 52 similarly to a ball of a typical ball-and-socket joint, due to the complementary shapes of the protrusion and recess. The present embodiment allows smooth pivoting between protrusion 24 and recess 52, although they may alternatively be configured with retention elements such as complementary grooves.
As shown in
In use, a surgeon can easily connect the bone fastener 12 and housing 14 by aligning the bone fastener head 20 at the insertion orientation relative to the elongate opening 50 of housing 14, sliding the head through the opening, turning either the housing or the bone fastener head approximately 90 degrees to the retention orientation, providing a slight tensile load such that the fastener head protrusion 24 positively engages and sits in the housing recess 52, pivoting the bone fastener relative to the housing to a desired angle, engaging the seating element grooves 66 with the bone fastener grooves 30 to hold the fastener at the angle, inserting the rod 62 above the seating element 60, and tightening the set screw 64 down onto the rod. Once the set screw 64 is tightened, the complementary grooves 66 and 30 cannot be disengaged, and thus the relative angle between the housing and bone fastener is set. In other words, the relative longitudinal pivot angle between the housing major axis 48 and the bone fastener major axis 26 is thereby set. Additional pedicle fastener assemblies may be attached to the rod 62.
It will be appreciated by those skilled in the art that changes could be made to the preferred embodiments described above without departing from the broad inventive concept thereof. For example, auxiliary components can be added to the various portions of the pedicle system, and the components described above may be divided into multi-part constructions. Further, any known material with suitable properties, such as strength, corrosion resistance, and biocompatibility, may be implemented for each component. For example, components may be formed from titanium-based alloys, pure titanium, stainless steel, aluminum, vanadium, other metals and alloys, cobalt-chrome, graphite, polymers, and combinations of the above. The set screw top surface and bone fastener head may be dimensioned in various ways so as to be capable of being grabbed and manipulated by various desired tools, such as a Phillips head screwdriver, flat-head screwdriver, Allen wrench, open-ended wrenches, ratchet wrenches, and the like. It is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.
This application claims the benefit of U.S. Provisional Application No. 62/201,929, filed Aug. 6, 2015, the entire disclosure of which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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62201929 | Aug 2015 | US |