The present invention is directed to polyaxial bone screws for use in bone surgery, particularly spinal surgery, and elongate connecting members that are at least somewhat plastically deformable. Such screws have a receiver or head that can swivel about a shank of the bone screw, allowing the receiver to be positioned in any of a number of angular configurations relative to the shank.
Many spinal surgery procedures require securing various implants to bone and especially to vertebrae along the spine. For example, elongate or longitudinal connecting members, such as solid rigid rods are often utilized that extend along the spine to provide support to vertebrae that have been damaged or weakened due to injury or disease. Such elongate members must be supported by certain vertebrae and support other vertebrae.
The most common mechanism for providing vertebral support is to implant bone screws into certain bones which then in turn support the elongate member or are supported by the elongate member. Bone screws of this type may have a fixed head or receiver relative to a shank thereof. In the fixed bone screws, the head cannot be moved relative to the shank and the rod or other elongate member must be favorably positioned in order for it to be placed within the head. This is sometimes very difficult or impossible to do. Therefore, polyaxial bone screws are commonly preferred.
Polyaxial bone screws allow rotation of the receiver about the shank until a desired rotational position of the receiver is achieved relative to the shank. Thereafter, a rod or other elongate connecting member can be inserted into the receiver and eventually the rod and the receiver are locked or fixed in a particular position relative to the shank.
A variety of polyaxial or swivel-head bone screw assemblies are available. One type of bone screw assembly includes an open head or receiver that allows for placement of a rod or other elongate member within the receiver. A closure top or plug is then used to capture the rod in the receiver of the screw. Thus, in such bone screws, the closure top or plug pressing against the rod not only locks the rod in place but also locks the bone screw shank in a desired angular position with respect to the receiver. A draw back to such a system occurs when the rod or other elongate connecting member is made from a material that is more flexible and may be more readily deformed or exhibit creep or viscoelastic behavior. Creep is a term used to describe the tendency of a material to move, flow or to deform permanently to relieve stresses. Material deformation occurs as a result of long term exposure to levels of stress that are below the yield or ultimate strength of the material. Rods and other longitudinal connecting members made from polymers, such as polyetheretherketone (PEEK), have a greater tendency to exhibit creep, than, for example metals or metal alloys. When a rod or other longitudinal connecting member exhibits creep deformation over time, the closure top may no longer tightly engage the connecting member. This in itself is not necessarily problematic. However, such loosening also results in loosening of the frictional engagement between the receiver and the bone screw shank that locks the angular orientation of the shank with respect to the receiver. Body movement and stresses may then result in undesirable pivoting of the shank with respect to the receiver causing mis-alignment, greater stress and further loosening of the various polyaxial bone screw components.
A polyaxial bone screw assembly of the present invention includes a shank having a generally elongate body with an upper end portion and a lower threaded portion for fixation to a bone. The bone screw assembly further includes a receiver having a top portion and a base. The top portion is open and has a channel. The base includes an inner seating surface partially defining a cavity and has a lower aperture or opening. The channel of the top portion communicates with the cavity, which in turn communicates with an opening to an exterior of the base. The shank upper portion is disposed in the receiver cavity and the shank extends through the receiver base opening. The cooperating shapes of the shank upper portion external surface and the receiver inner surface enable selective angular positioning of the shank body with respect to the receiver. The shank upper surface engages a compression insert that in turn engages a longitudinal connecting member being supported within the receiver. In certain embodiments, the compression insert includes a planar bottom seat and spaced planar sides for closely receiving an elongate connecting member that has planar sides. Such a compression insert can also receive a cylindrical or other shaped connecting member. A single-piece closure structure initially engages the connecting member and, after some plastic deformation of such member, then the closure structure engages the compression insert for securing the assembly in a wide range of angular orientations.
Objects of the invention include: providing an implant wherein all of the parts remain together and do not separate; providing a lightweight, low profile polyaxial bone screw that assembles in such a manner that the components cooperate to create an overall structure that prevents unintentional disassembly; providing a polyaxial bone screw that provides substantially independent locking for the bone screw shank and a deformable longitudinal connecting member; providing such an assembly that includes a flexible longitudinal connecting member that may be of non-circular or circular cross-section; providing such an assembly that remains in a locked position even if the flexible longitudinal connecting member undergoes deformation such as creep; providing a polyaxial bone screw with features that provide adequate frictional or gripping surfaces for bone implantation tools and may be readily, securely fastened to each other and to bone; and providing apparatus and methods that are easy to use and especially adapted for the intended use thereof and wherein the apparatus are comparatively inexpensive to make and suitable for use.
Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.
The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. It is also noted that any reference to the words top, bottom, up and down, and the like, in this application refers to the alignment shown in the various drawings, as well as the normal connotations applied to such devices, and is not intended to restrict positioning of bone attachment assemblies of the application and cooperating connecting members in actual use.
With reference to
As will be described in greater detail below, the illustrated shank 4 is top loaded into the receiver 10 and thereafter the substantially spherical upper portion 8 slidingly cooperates with an inner substantially spherical inner surface of the receiver 10 such that the receiver 10 and the shank 4 can be secured at any of a plurality of angles, articulations or rotational alignments relative to one another and within a selected range of angles both from side to side and from front to rear, to enable flexible or articulated engagement of the receiver 10 with the shank 4 until both are locked or fixed relative to each other near the end of an implantation procedure. It is noted that although the drawing figures show a top loaded polyaxial mechanism having a spherical sliding connection between the shank upper portion and the receiver inner surface, other kinds of top loaded and bottom loaded embodiments may be utilized according to the invention. For example, bottom loaded bone screws, such as that disclosed in Applicant's U.S. Pat. Pub. No. 2007/0055244 (U.S. patent application Ser. No. 11/522,503 filed Sep. 14, 2006), the disclosure of which is incorporated by reference herein, having a threaded capture connection between a shank upper portion and a retainer structure disposed within the receiver may be utilized for providing a polyaxial connection between the receiver and the shank for use with the present invention. Specifically, U.S. Pat. Pub. No. 2007/0055244 discloses a bone screw shank that includes an upper portion that further includes an outer helical thread mateable with a retaining structure that includes a mating inner helical thread. The retaining structure has a partially spherical surface that is slidingly mateable with a cooperating inner surface of the receiver, allowing for a wide range of pivotal movement between the shank and the receiver. Bottom or top loaded polyaxial bone screws with other types of capture connections may also be used according to the invention, including but not limited to other types of threaded connections, frictional connections utilizing frusto-conical or polyhedral capture structures, or other integral top or downloadable shanks.
The shank 4, best illustrated in
The neck 26 extends axially upwardly from the shank body 6. The neck 26 may be of reduced radius as compared to an adjacent top 32 of the threaded body 6. Further extending axially upwardly from the neck 26 is the shank upper portion 8 that provides a connective or capture apparatus disposed at a distance from the threaded body top 32 and thus at a distance from the vertebra when the body 6 is implanted in the vertebra.
The shank upper portion 8 is configured for a polyaxial connection between the shank 4 and the receiver 10 and capturing the shank 4 upper portion 8 in the receiver 10. The upper portion 8 generally includes an outer spherical surface 34; a planar annular upper surface 36 and with an internal drive feature or structure 38 formed in the surface 36. A driving tool (not shown) has a driving projection configured to fit within the tool engagement structure 38 for both driving and rotating the shank body 6 into the vertebra. As best shown in
The shank 4 shown in the drawings is cannulated, having a small central bore 40 extending an entire length of the shank 4 along the axis A. The bore 40 is defined by an inner cylindrical wall of the shank 4 and has a circular opening at the shank tip 28 and an upper opening communicating with the internal drive 38. The bore 40 is coaxial with the threaded body 6 and the upper portion 8. The bore 40 provides a passage through the shank 4 interior for a length of wire (not shown) inserted into the vertebra (not shown) prior to the insertion of the shank body 6, the wire providing a guide for insertion of the shank body 6 into the vertebra (not shown).
To provide a biologically active interface with the bone, the threaded shank body 6 may be coated, perforated, made porous or otherwise treated. The treatment may include, but is not limited to a plasma spray coating or other type of coating of a metal or, for example, a calcium phosphate; or a roughening, perforation or indentation in the shank surface, such as by sputtering, sand blasting or acid etching, that allows for bony ingrowth or ongrowth. Certain metal coatings act as a scaffold for bone ingrowth. Bio-ceramic calcium phosphate coatings include, but are not limited to: alpha-tri-calcium phosphate and beta-tri-calcium phosphate (Ca3(PO4)2, tetra-calcium phosphate (Ca4P2O9), amorphous calcium phosphate and hydroxyapatite (Ca10(PO4)6(OH)2). Coating with hydroxyapatite, for example, is desirable as hydroxyapatite is chemically similar to bone with respect to mineral content and has been identified as being bioactive and thus not only supportive of bone ingrowth, but actively taking part in bone bonding.
Referring to
The receiver 10 includes a base 50 integral with a pair of opposed substantially similar or identical upstanding arms 52 forming a squared-off U-shaped cradle and defining a channel 56 between the arms 52 with an upper opening 57 and a lower planar seat 58. The channel 56 is defined in part by planar opposed parallel walls 60 of the receiver arms 52 that run perpendicular to the lower planar seat 58. The walls 60 are spaced to closely receive the bar-shaped connecting member 14 but may also receive a cylindrical rod or oval rod having a diameter or width the same or less than a width of the connecting member 14.
Each of the arms 52 has an interior surface 64 that defines the inner cylindrical profile and includes a partial helically wound guide and advancement structure 66. In the illustrated embodiment, the guide and advancement structure 66 is a partial helically wound interlocking flange form configured to mate under rotation with a similar structure on the closure structure 16, as described more fully below. However, it is foreseen that the guide and advancement structure 66 could alternatively be a square thread, a buttress thread, a reverse angle thread or other thread like or non-thread like helically wound advancement structure for operably guiding under rotation and advancing the closure top downward between the arms 52.
Opposed tool engaging apertures 68 are formed on or through surfaces of the arms 52 that may be used for holding the receiver 10 during assembly with the shank 4 and the retainer structure 12 and also during the implantation of the shank body 6 into a vertebra (not shown). Furthermore, the illustrated embodiment includes upper undercut tool engaging grooves 70 for cooperating with manipulation tools. It is foreseen that tool receiving grooves or apertures may be configured in a variety of shapes and sizes and be disposed at other locations on the receiver arms 52.
A pair of spring tabs 76, each having an upper body portion 78 integral with a respective arm 52, and a lower and inner surface 80 extending below the respective upper body portion 78. The surface 80 is sized and shaped for frictional contact with a portion of the insert 12 as will be described in greater detail below. The tabs 76 are generally directed towards the axis B and downwardly generally toward the base 50. The lower contact surfaces 80 are positioned to engage the compression insert 12 and hold such insert in a desired position, prohibiting rotation of the inert 14 about the axis B. The tabs 76 are typically initially disposed parallel to the axis B and then a tool (not shown) is inserted into the aperture 68 from outside of the receiver 10 to engage and push the respective tab 76, thereby bending the tab 76 inwardly in a direction toward the axis B until the tab 76 is at a desired angular position, such as is illustrated in
With further reference to
The base 50 further includes a restrictive neck 88 defining a bore, generally 90, communicating with the spherical surface 84 of the cavity 82 and also communicating with a lower exterior 92 of the base 50. The bore 90 is coaxially aligned with respect to the rotational axis B of the receiver 10. The neck 88 and associated bore 90 are sized and shaped to be smaller than an outer radial dimension of the shank upper portion 8, so as to form a restriction at the location of the neck 88 relative to the shank upper portion 8 to prohibit the upper portion 8 from passing through the cavity 82 and out to the lower exterior 92 of the receiver 10.
With particular reference to
The compression insert 12 further includes a bottom annular surface 130 and a substantially cylindrical outer surface 132. An inner cylindrical surface 134 partially defines a central through-bore extending along a central axis of the compression insert 12. The surface 134 is located between the seating surface 116 and a concave substantially spherical surface 136. The compression insert through-bore is sized and shaped to receive a driving tool (not shown) therethrough that engages the shank drive feature 38 when the shank body 6 is driven into bone. The surface 136 extends between the inner cylindrical surface 134 and the bottom surface 130. The surface 136 is sized and shaped to slidingly and pivotally mate with and ultimately frictionally engage the outer convex spherical surface 34 of the shank upper portion 8. The surface 136 may include a roughening or surface finish to aid in frictional contact between the surface 136 and the surface 34, once a desired angle of articulation of the shank 4 with respect to the receiver 10 is reached. A pair of recesses 138 or flat surfaces are formed in the insert cylindrical surface 132 and located spaced from the flanged portions 120. With reference to
The cylindrical surface 132 has an outer diameter slightly smaller than a diameter between crests of the guide and advancement structure 66 of the receiver 10 allowing for top loading of the compression insert 12 with the flanged portions 120 being located between the planar walls 60 during insertion of the insert 12 into the receiver 10 as shown in
The compression or pressure insert 12 ultimately seats on the shank upper portion 8 and is disposed substantially in the upper cylindrical portion 86 of the cavity 82, with the tabs 76 engaging the insert 12 at the grooves 128, thereby holding the insert 12 in desired alignment with respect to the connecting member 14. In operation, the insert 12 extends at least partially into the channel 56 such that the seating surface 116 substantially contacts and engages the adjacent planar surface of the connecting member 14 when such member 14 is placed in the receiver 10 and the closure structure or top 18 is tightened therein. The connecting member 14 is held in spaced relation with the lower seat 58 of the receiver 10.
With reference to
With reference to
The closure top 16 may further include a cannulation through bore extending along a central axis thereof and through a surface of the drive 156 and the bottom surface 158. Such a through bore provides a passage through the closure 16 interior for a length of wire (not shown) inserted therein to provide a guide for insertion of the closure top into the receiver arms 52.
With particular reference to
In use, the bone screw 3 is typically screwed into a bone, such as a vertebra (not shown), by rotation of the shank 4 using a driving tool (not shown) that operably drives and rotates the shank 4 by engagement thereof with the tool engagement structure 38. The vertebra (not shown) may be pre-drilled to minimize stressing the bone and have a guide wire (not shown) that is shaped for the cannula 40 inserted to provide a guide for the placement and angle of the shank 4 with respect to the vertebra. A further tap hole may be made using a tap with the guide wire as a guide. Then, the bone screw 3 is threaded onto the guide wire utilizing the cannulation bore 40 by first threading the wire into the bottom opening 28 and then out of the top at the internal drive 38. The shank 4 is then driven into the vertebra, using the wire as a placement guide.
With reference to
If removal of the connecting member 14 from any of the bone screws 3 is necessary, or if it is desired to release the connecting member 14 at a particular location, disassembly is accomplished by using the driving tool (not shown) that mates with the internal drive 156 on the closure structure 16 to rotate and remove the closure structure 16 from the cooperating receiver 10. Disassembly is then accomplished in reverse order to the procedure described previously herein for assembly.
With reference to
With reference to
With reference to
With reference to
With reference to
With reference to
It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.
This application is a continuation of U.S. application Ser. No. 16/745,994, filed Jan. 17, 2020, which is a continuation of U.S. application Ser. No. 16/411,826, filed May 14, 2019, now U.S. Pat. No. 10,561,444, which is a continuation of U.S. application Ser. No. 15/940,343 filed Mar. 29, 2018, now U.S. Pat. No. 10,335,200, which is a continuation-in-part of U.S. application Ser. No. 15/389,296, filed Dec. 22, 2016, now abandoned, which is a continuation of U.S. application Ser. No. 12/661,042 filed Mar. 10, 2010, now abandoned, which claims the benefit of U.S. Provisional Application No. 61/210,058 filed Mar. 13, 2009, each of which is incorporated by reference in its entirely herein, and for all purposes. U.S. application Ser. No. 12/661,042 is also a continuation-in-part of U.S. application Ser. No. 12/229,207, filed Aug. 20, 2008, now U.S. Pat. No. 8,353,932, which claims the benefit of U.S. Provisional Application No. 60/994,083, filed Sep. 17, 2007, each of which is incorporated by reference in its entirely herein, and for all purposes.
Number | Name | Date | Kind |
---|---|---|---|
5669911 | Errico et al. | Sep 1997 | A |
5672176 | Biedermann et al. | Sep 1997 | A |
5690630 | Errico et al. | Nov 1997 | A |
5733286 | Errico et al. | Mar 1998 | A |
5782833 | Haider | Jul 1998 | A |
5797911 | Sherman et al. | Aug 1998 | A |
5885286 | Sherman et al. | Mar 1999 | A |
6010503 | Richelsoph et al. | Jan 2000 | A |
6063090 | Schläpfer | May 2000 | A |
6074391 | Metz-Stavenhagen et al. | Jun 2000 | A |
6090111 | Nichols | Jul 2000 | A |
6187005 | Brace et al. | Feb 2001 | B1 |
6254602 | Justis | Jul 2001 | B1 |
6280442 | Barker et al. | Aug 2001 | B1 |
6355040 | Richelsoph et al. | Mar 2002 | B1 |
6471705 | Biedermann et al. | Oct 2002 | B1 |
6485491 | Farris et al. | Nov 2002 | B1 |
6485494 | Haider | Nov 2002 | B1 |
6530929 | Justis et al. | Mar 2003 | B1 |
6540748 | Lombardo | Apr 2003 | B2 |
6554834 | Crozet et al. | Apr 2003 | B1 |
6565565 | Yuan et al. | May 2003 | B1 |
6626908 | Cooper et al. | Sep 2003 | B2 |
6648888 | Shluzas | Nov 2003 | B1 |
6723100 | Biedermann et al. | Apr 2004 | B2 |
6740086 | Richelsoph | May 2004 | B2 |
6835093 | Biedermann et al. | Dec 2004 | B1 |
6835196 | Biedermann et al. | Dec 2004 | B2 |
6837889 | Shluzas | Jan 2005 | B2 |
6905500 | Jeon et al. | Jun 2005 | B2 |
6945975 | Dalton | Sep 2005 | B2 |
7066937 | Shluzas | Jun 2006 | B2 |
7087057 | Konieczynski et al. | Aug 2006 | B2 |
7141051 | Janowski et al. | Nov 2006 | B2 |
7144396 | Shluzas | Dec 2006 | B2 |
7163539 | Abdelgany et al. | Jan 2007 | B2 |
7179261 | Sicvol et al. | Feb 2007 | B2 |
7264621 | Coates et al. | Sep 2007 | B2 |
7306606 | Sasing | Dec 2007 | B2 |
7311712 | Dalton | Dec 2007 | B2 |
7377923 | Purcell et al. | May 2008 | B2 |
7445627 | Hawkes et al. | Nov 2008 | B2 |
7479156 | Lourdel et al. | Jan 2009 | B2 |
7604655 | Warnick | Oct 2009 | B2 |
7618444 | Shluzas | Nov 2009 | B2 |
7686834 | Saint Martin | Mar 2010 | B2 |
7686835 | Warnick | Mar 2010 | B2 |
7695497 | Cordaro et al. | Apr 2010 | B2 |
7699876 | Barry et al. | Apr 2010 | B2 |
7722654 | Taylor et al. | May 2010 | B2 |
7766915 | Jackson | Aug 2010 | B2 |
7766945 | Nilsson et al. | Aug 2010 | B2 |
7776067 | Jackson | Aug 2010 | B2 |
7789896 | Jackson | Sep 2010 | B2 |
7789900 | Levy et al. | Sep 2010 | B2 |
7811310 | Baker et al. | Oct 2010 | B2 |
7833251 | Ahlgren et al. | Nov 2010 | B1 |
7842073 | Richelsoph et al. | Nov 2010 | B2 |
7901436 | Baccelli | Mar 2011 | B2 |
7905907 | Spitler et al. | Mar 2011 | B2 |
7909830 | Frigg et al. | Mar 2011 | B2 |
7914536 | MacDonald et al. | Mar 2011 | B2 |
7935135 | Mujwid | May 2011 | B2 |
7947065 | Hammill, Sr. et al. | May 2011 | B2 |
7951172 | Chao et al. | May 2011 | B2 |
7955359 | Matthis et al. | Jun 2011 | B2 |
7967850 | Jackson | Jun 2011 | B2 |
7972364 | Biedermann et al. | Jul 2011 | B2 |
7988694 | Barrus et al. | Aug 2011 | B2 |
8021397 | Farris et al. | Sep 2011 | B2 |
8048112 | Suzuki et al. | Nov 2011 | B2 |
8066744 | Justis et al. | Nov 2011 | B2 |
8083776 | Alvarez | Dec 2011 | B2 |
8162985 | Kim | Apr 2012 | B2 |
8197517 | Lab et al. | Jun 2012 | B1 |
8221472 | Peterson et al. | Jul 2012 | B2 |
8328817 | Strauss | Dec 2012 | B2 |
8353932 | Jackson | Jan 2013 | B2 |
8398683 | Berrevoets et al. | Mar 2013 | B2 |
8439922 | Arnold et al. | May 2013 | B1 |
8562652 | Biedermann et al. | Oct 2013 | B2 |
8628558 | Harvey et al. | Jan 2014 | B2 |
8663298 | Keyer et al. | Mar 2014 | B2 |
8696712 | Biedermann et al. | Apr 2014 | B2 |
9119674 | Matthis et al. | Sep 2015 | B2 |
9445847 | Biedermann et al. | Sep 2016 | B2 |
9655652 | Biedermann et al. | May 2017 | B2 |
20030149431 | Varieur | Aug 2003 | A1 |
20040102781 | Jeon | May 2004 | A1 |
20040186473 | Cournoyer et al. | Sep 2004 | A1 |
20040260283 | Wu et al. | Dec 2004 | A1 |
20050203516 | Biedermann et al. | Sep 2005 | A1 |
20060058788 | Hammer et al. | Mar 2006 | A1 |
20060161152 | Ensign et al. | Jul 2006 | A1 |
20060161153 | Hawkes et al. | Jul 2006 | A1 |
20060217716 | Baker et al. | Sep 2006 | A1 |
20070118123 | Strausbaugh et al. | May 2007 | A1 |
20070270813 | Garamszegi | Nov 2007 | A1 |
20100152787 | Walsh et al. | Jun 2010 | A1 |
Number | Date | Country |
---|---|---|
1857064 | Nov 2007 | EP |
WO 2009055747 | Apr 2009 | WO |
Number | Date | Country | |
---|---|---|---|
20230181223 A1 | Jun 2023 | US |
Number | Date | Country | |
---|---|---|---|
61210058 | Mar 2009 | US | |
60994083 | Sep 2007 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 16745994 | Jan 2020 | US |
Child | 18162647 | US | |
Parent | 16411826 | May 2019 | US |
Child | 16745994 | US | |
Parent | 15940343 | Mar 2018 | US |
Child | 16411826 | US | |
Parent | 12661042 | Mar 2010 | US |
Child | 15389296 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 15389296 | Dec 2016 | US |
Child | 15940343 | US | |
Parent | 12229207 | Aug 2008 | US |
Child | 12661042 | US |