WO2007011407A1 - Universal link bone screw system - Google Patents

Universal link bone screw system Download PDF

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Publication number
WO2007011407A1
WO2007011407A1 PCT/US2005/039283 US2005039283W WO2007011407A1 WO 2007011407 A1 WO2007011407 A1 WO 2007011407A1 US 2005039283 W US2005039283 W US 2005039283W WO 2007011407 A1 WO2007011407 A1 WO 2007011407A1
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WO
WIPO (PCT)
Prior art keywords
bone
receiver
head
bone anchor
assembly
Prior art date
Application number
PCT/US2005/039283
Other languages
French (fr)
Inventor
Dong Myung Jeon
Patrick Dennis Moore
Original Assignee
Dong Myung Jeon
Patrick Dennis Moore
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dong Myung Jeon, Patrick Dennis Moore filed Critical Dong Myung Jeon
Publication of WO2007011407A1 publication Critical patent/WO2007011407A1/en

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7001Screws or hooks combined with longitudinal elements which do not contact vertebrae
    • A61B17/7035Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other
    • A61B17/7038Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other to a different extent in different directions, e.g. within one plane only
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7001Screws or hooks combined with longitudinal elements which do not contact vertebrae
    • A61B17/7035Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other
    • A61B17/7037Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other wherein pivoting is blocked when the rod is clamped
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7001Screws or hooks combined with longitudinal elements which do not contact vertebrae
    • A61B17/7032Screws or hooks with U-shaped head or back through which longitudinal rods pass

Definitions

  • the present invention relates to devices and implants used in osteosynthesis and other orthopedic surgical procedures such as devices for use in spinal surgery, and, in particular, to an posterior pedicle screw, connector/rod assembly which is implantable within a patient for stabilization of the spine.
  • the present invention contemplates a top loading bone anchor assembly capable of achieving multiple angular, as well as multiple spherical axial orientations with respect to an elongated member extending along bone tissue.
  • an elongated member such as a bendable rod is disposed longitudinally along a length of the bone(s).
  • the rod is preferably bent to correspond to the normal curvature of the spine in the particular region being instrumented.
  • the rod can be bent to form a normal kyphotic curvature for the thoracic region of the spine, or a lordotic curvature for the lumbar region.
  • the rod is engaged to various vertebrae along a length of the spinal column by way of a number of fixation elements.
  • fixation elements can be provided which are configured to engage specific portions of the vertebra and other bones.
  • one such fixation element is a hook that is configured to engage the laminae of the vertebra.
  • Another very prevalent fixation element is a screw that can be threaded into various parts of the vertebrae or other bones.
  • the rod is situated on opposite sides of the spine or spinous processes.
  • a plurality of bone screws are threaded into a portion of several vertebral bodies, very frequently into the pedicles of these vertebrae.
  • the rods are affixed to these plurality of bone screws to apply corrective and stabilizing forces to the spine.
  • a rod-type spinal fixation system includes elongated rods and a variety of hooks, screws and bolts all configured to create a segmental construct throughout the spine.
  • the spinal rod is connected to the various vertebral fixation elements by way of an eyebolt.
  • the fixation elements are engaged to the spinal rod laterally adjacent to the rod.
  • a variable angle screw is engaged to the spinal rod by way of an eyebolt. The variable angle screw allows pivoting of the bone screw in a single plane parallel to the plane of the spinal rod. Details of this variable angle screw can be found hi U.S. Pat. No. 5,261,909 to Sutterlin et al.
  • One goal achieved by the system is that the surgeon can apply vertebral fixation elements, such as a spinal hook or a bone screw, to the spine in appropriate anatomic positions.
  • the system also allows the surgeon to easily engage a bent spinal rod to each of the fixation elements for final tightening.
  • fixation elements for engagement between an elongated rod and the spine.
  • the fixation elements themselves include a body that defines a slot within which the spinal rod is received.
  • the slot includes a threaded bore into which a threaded plug is engaged to clamp the rod within the body of the fixation element.
  • the system includes hooks and bone screws with this "open-back" configuration. Details of this technology can be found in U.S. Pat. No. 5,005,562.
  • fixation elements of the system are capable only of pivoting about the spinal rod to achieve variable angular positions relative to the rod. While this limited range of relative angular positioning is acceptable for many spinal pathologies, many other cases require more creative orientation of a bone screw, for instance, relative to a spinal rod. Certain aspects of this problem are addressed by the variable angle screw of the system, as discussed in the '909 Patent. However, there is a need for a bone screw that is capable of angular orientation in multiple planes relative to the spinal rod as well as multiple spherical head orientations.
  • the bone screw axis is capable of various three dimensional orientations with respect to the spinal rod as well as three dimensional spherical axis orientation to the receiving (head) element of the devices axial orientation of the bone engaging screw member.
  • Screws of this type of angular orientation in multiple planes relative to the spinal rod have been referred to as poly-axial or multi-axial bone screws.
  • no screw systems have employed both angular orientation in multiple planes relative to the spinal rod and three dimensional spherical axis orientation to the receiving (head) element of the devices axial orientation of the bone engaging screw member.
  • a bone screw which includes a spherical projection on the top of the bone screw.
  • An externally threaded receiver member supports the bone screw and a spinal rod on top of the spherical projection.
  • An outer nut is tightened onto the receiver member to press the spinal rod against the spherical projection to accommodate various angular orientations of the bone screw relative to the rod. While this particular approach utilizes a minimum of components, the security of the fixation of the bone screw to the rod is lacking. In other words, the engagement or fixation between the small spherical projection on the bone screw and the spinal rod is readily disrupted when the instrumentation is subjected to the high loads of the spine, particularly in the lumbar region.
  • a spherical headed bone screw is supported within separate halves of a receiver member. The bottom of the halves are held together by a retaining ring. The top of the receiver halves are compressed about the bone screw by nuts threaded onto a threaded spinal rod.
  • Harms et al. in U.S. Pat. No., 5,207,678, a receiver member is flexibly connected about a partially spherical head of a bone screw. Conical nuts on opposite sides of the receiver member are threaded onto a threaded rod passing through the receiver.
  • the receiver member flexibly compresses around the head of the bone screw to clamp the bone screw in its variable angular position.
  • the spinal rod must be threaded in order to accept the compression nuts. It is known that threading rods can tend to weaken the rods in the face of severe spinal loads.
  • the design of the bone screws in the '458 and '678 Patents require a multiplicity of parts and are fairly complicated to achieve complete fixation of the bone screw.
  • a further approach illustrated in U.S. Pat. No. 5,797,911 to Sherman et al. is to provide a U-shaped holder through the top of which a bone fastener topped with a crown member is loaded.
  • the holder accommodates a rod in a channel above the crown member and a compression member above the rod.
  • the compression member presses on the rod and crown member to lock the fastener against the holder in any of a number of angles in three dimensions with respect to the rod.
  • This approach has proven to be quite effective in addressing the above-identified problems. However, it does not permit bottom-loading of the fastener. Additionally, the holder is somewhat bulky in order to accommodate the other structural components.
  • a bone fixation assembly in one embodiment, includes a receiver member defining an upper opening portion and a lower shaft portion creating an "U-shape" geometry, a channel configured to receive the elongated member (rod) and communicating with said upper opening portion and said lower shaft portion, and internal threaded portion located at the top outside surface of the posts; and
  • a bone-engaging anchor having a lower portion configured to engage a bone and a head having a width, said width of said head fashioned in the shape of an upside/down "U” creating a closed loop, said head being movably disposed over and around said one upper receiver posts and located at the bottom of the "U" shape;
  • a compression retaining member defining an aperture smaller than said outside width of said receiving member posts, said retaining member at least partially housed in said top portion of said receiver member and positioned over said elongated member and tightened during utilization. Forces transmitted during tightening are imparted on the bone anchor member, and the lower surface ' of the receiving member to anchor all said components in any angular and/or axial configuration within design parameters.
  • FIG. 1 is a side elevational view of one embodiment of the multi-axial bone screw anchor assembly of the present invention.
  • FIG. 2 is an exploded view of the embodiment of the invention depicted in FIG. 1.
  • FIG. 3 a is a side elevational view of an embodiment of the receiver member of the embodiment of the invention illustrated in FIG. 2.
  • FIG. 3 b is a front elevational view of the embodiment of the receiver member illustrated in FIG. 3a.
  • FIG. 3c is a sectional view, taken along the lines 3c-3c in FIG. 3a, and viewed in the direction of the arrows, of the embodiment of the receiver member illustrated in FIG. 3a.
  • FIG. 3d is a sectional view, taken along the lines 3d— 3d of FIG. 3b and viewed in the direction of the arrows, of the embodiment of the receiver member illustrated in FIG. 3 a.
  • FIG. 4a is a side elevational view of an embodiment of a bone anchor used in the embodiment of the invention illustrated in FIG. 2.
  • FIG. 4b is a sectional view, taken along the lines 4b ⁇ 4b of FIG. 4a and viewed in the direction of the arrows, of the embodiment of the bone anchor illustrated in FIG. 4a.
  • FIG. 4c is a magnified view of one embodiment of the head of the embodiment of the bone anchor illustrated in FIG. 4a.
  • FIG. 5a is a top view of the retaining member.
  • FIG. 5b is a side elevational view of the retaining member.
  • FIG. 6 is an enlarged sectional view of the embodiment of the present invention illustrated in FIG. 1.
  • assembly 20 includes a receiver member 30, a bone anchor 50.
  • the assembly 20 of the present invention is designed for use with an elongated member R (FIG. 6) such as a spinal rod, bar or other orthopedic construct, as further described below.
  • Receiver member 30 defines an upper opening portion 31a and a lower shaft portion 31b, which in the illustrated embodiment form a single opening 32 extending through receiver member 30 from an upper aperture 33 in top end 34 to a lower closed loop 35 in bottom end 36. Lower closed loop portion 31b of opening 32.
  • upper and lower closed loop portions 3 Ia, 3 Ib can have a variety of configurations, such as each having one or more sections of differing diameter.
  • Opening 32 is partially surrounded by a chamfered or rounded edge 40a at top end 34 of receiver member 30.
  • Receiver member 30 in the illustrated embodiment includes a pair of upright branches 42, 43 through which opening 32 extends. Branches 42, 43 further define a U-shaped channel 45 transverse to opening 32 that communicates with upper portion 31a and lower portion 3 Ib of opening 32, and that accommodates an elongated member R (FIG. 6).
  • internal threads 44 are formed in branches 42, 43, internal thread 44 in a specific embodiment is a modified acme buttress thread.
  • FIGS. 4a-4c an embodiment of a bone anchor 50 used in the present invention is shown.
  • the illustrated bone anchor 50 is a bone screw.
  • Bone anchor 50 includes an anchorage portion 52 and a head portion 54.
  • Anchorage portion 52 includes at least one thread 56, which may be a cancellous self-tapping thread.
  • Head portion 54 forms part of a sphere/loop in the illustrated embodiment, though alternative curvate and other configurations may be employed.
  • Head 54 in one particular embodiment includes a series of ridges/lines 58 for improving purchase with the interface of receiver member 30 (described below).
  • Head 54 may have alternative friction- increasing surface configuration(s) such as roughening or knurling.
  • bone anchor 50 could be a bone-engaging hook rather than a screw.
  • anchorage portion 52 would be configured with a hook rather than an elongated section with thread 56.
  • Head 54 of bone anchor 50 is shaped and sized to fit over and around either post of the receiver member 30. Specifically, head 54 has a "U-shaped” geometry that being movably disposed over and around said one upper receiver posts and located at the bottom of the "U" shape portion 70.
  • assembly 20 is assembled as follows: bone anchor 50, is inserted over and around either post of the receiver member 30 substantially in one step as shown in (Fig. 2).
  • Bone anchor member 50 remains slideably and rotatably positioned in lower shaft 3 Ib of opening 32 and retained in that location of receiving member 30, and bone anchor 50 remains multi-axially moveable with respect to receiving member 30.
  • assembly 20 is assembled (as described above) prior to use in a surgical procedure.
  • bone anchor 50 of assembly 20 is threaded into an appropriately prepared hole in a bone (not shown). It will be understood that in alternative embodiments of the invention, for example where bone anchor 50 is a bone hook, drilling a hole in bone and threading the anchor therein may not be necessary.
  • an appropriate screwing tool is threaded onto the external threads of the receiving member 30, thus locking the assembly co-axially into one solid assembly, and is used to "drive" the bone anchor 50 therefore, threaded into the bone.
  • the appropriate screwing tool is then removed.
  • receiver member 30 is positioned so that opening 32 forms a desired angle with bone anchor 50, as depicted in FIG. 1.
  • the angle theta. between bone anchor 50 and opening 32 can be any value up to 90 degrees in any direction (180 degrees total angulation) .
  • the maximum angle of bone anchor 50 relative to opening 32 can be changed in two ways, for example by angling bone anchor 50 to its maximum off axis in association with maximum rotation of the receiver member 30 component.
  • receiver member 30 may be angled as the surgeon desires with respect to bone anchor 50.
  • An elongated member R such as a spinal rod, connector, or other orthopedic surgical implant is coupled with assembly 20. Elongated member R is placed in channel 45 of receiver member 30, and contacts outer surface 50 of bone anchor member 70.
  • a compression member 120 such as a skirted nut, skirted set-screw or similar device, is threaded into/onto threads 44 of receiver member 30 and down onto elongated member R.
  • Compression member 120 in one embodiment, is a skirted set- screw having external threads and a "skirt" to slide over the receiver member 30 and a print 124 for applying torque.
  • compression member 120 could be an internally- threaded nut.
  • assembly 20 can be assembled during the surgical procedure.
  • Preferred materials for the present invention include stainless steel and titanium. It will be recognized that any sturdy biocompatible material may be used to accomplish the osteosynthesis and other orthopedic surgical goals of the present invention.

Abstract

A top-loading Universal link bone anchor apparatus is disclosed. The apparatus includes a “U-Shaped” upper receiver member, a bone anchor and a compression retaining member. The “U-Shaped” upper receiver member defines two upper posts and a lower shaft, which may form part of the “U-Shape”, a channel, and internal threaded portion located at the top, on the posts. The bone anchor is loaded over and around either of the upper posts of the “U-Shaped” upper receiver member and being movably disposed and located at the bottom of the “U” shaped” upper receiver member. creating a “link” between the bone anchor member and the “U-Shaped” upper receiver member.

Description

UNIVERSAL LINK BONE SCREW SYSTEM
Inventors: Jeon; Dong M. (Salt Lake City, UT); Moore; Patrick D. (Salt Lake City, UT)
Assignee: Jeon; Dong M. (Salt Lake City, UT); Moore; Patrick D. (Salt Lake City, UT)
Appl. No.:
Filed:
Current U.S. Class: 606/60; 606/61 tntern'l Class: A61B 017/68; A61B 017/70
Field of Search: 606/60,61 ,69,72,73
References Cited [Referenced BvI
U.S. Patent Documents
4763644 Aug., 1988 Webb.
4805602 Feb., 1989 Puno et al.
4946458 Aug., 1990 Harms et al.
5005562 Apr., 1991 Cotrel.
5176678 Jan., 1993 Tsou 606/61.
5207678 May., 1993 Harms et al.
5217497 Jun., 1993 Mehdian 623/17.
5261909 Nov., 1993 Sutterlin et al.
5360431 Nov., 1994 Puno et al.
5443467 Aug., 1995 Biedermann et al.
5466237 Nov., 1995 Byrd III, et al.
5474555 Dec, 1995 Puno et al.
Metz-Stavenhagen et
5476464 Dec, 1995 al.
5501684 Mar., 1996 Schlapfer et al.
5520690 May., 1996 Errico et al.
5531746 JuI., 1996 Errico et al.
5549608 Aug., 1996 Errico et al.
5554157 Sep., 1996 Errico et al.
5562661 Oct., 1996 Yoshimi et al.
5575792 Nov., 1996 Errico et al.
5578033 Nov., 1996 Errico et al.
5584834 Dec, 1996 Errico et al.
5586984 Dec, 1996 Errico et al. 5607426 Mar., 1997 Ralph et al.
5609593 Mar., 1997 Errico et al.
5609594 Mar., 1997 Errico et al.
5647873 JuL, 1997 Errico et al.
5669911 Sep., 1997 Errico et al.
5672176 Sep., 1997 Biedermann et al.
5688273 Nov., 1997 Errico et al.
5690630 Nov., 1997 Errico et al.
5733286 Mar., 1998 Errico et al.
5782833 M, 1998 Haider 606/61.
5797911 Aug., 1998 Sherman et al. 606/61.
5817094 Oct., 1998 Errico et al.
5879350 Mar., 1999 Sherman et al. 606/61.
5882350 Mar., 1999 Ralph et al. 606/61.
5885286 Mar., 1999 Sherman et al. 606/61.
5891145 Apr., 1999 Morrison et al. 606/61.
6053917 Apr., 2000 Sherman et al. 606/61.
6063090 Feb., 2000 Schlapfer 606/61.
Foreign Patent Documents
3711013 Sep., 1988 DE.
195 09 332 Aug., 1996 DE.
2 173 104 Oct., 1996 GB. ~
Other References
Primary Examiner* Assistant Examiner: Attorney, Agent or Firm:
Description
FIELD OF THE INVENTION
The present invention relates to devices and implants used in osteosynthesis and other orthopedic surgical procedures such as devices for use in spinal surgery, and, in particular, to an posterior pedicle screw, connector/rod assembly which is implantable within a patient for stabilization of the spine. Specifically, the present invention contemplates a top loading bone anchor assembly capable of achieving multiple angular, as well as multiple spherical axial orientations with respect to an elongated member extending along bone tissue.
BACKGROUND OF THE INVENTION
Several techniques and systems have been developed for correcting and stabilizing damage or malformation of bones, especially the long bones and the spine. In one type of system, an elongated member such as a bendable rod is disposed longitudinally along a length of the bone(s). In spinal applications, the rod is preferably bent to correspond to the normal curvature of the spine in the particular region being instrumented. For example, the rod can be bent to form a normal kyphotic curvature for the thoracic region of the spine, or a lordotic curvature for the lumbar region. In accordance with such a system, the rod is engaged to various vertebrae along a length of the spinal column by way of a number of fixation elements. A variety of fixation elements can be provided which are configured to engage specific portions of the vertebra and other bones. For instance, one such fixation element is a hook that is configured to engage the laminae of the vertebra. Another very prevalent fixation element is a screw that can be threaded into various parts of the vertebrae or other bones.
In one typical spinal procedure utilizing a bendable rod, the rod is situated on opposite sides of the spine or spinous processes. A plurality of bone screws are threaded into a portion of several vertebral bodies, very frequently into the pedicles of these vertebrae. The rods are affixed to these plurality of bone screws to apply corrective and stabilizing forces to the spine.
One example of a rod-type spinal fixation system includes elongated rods and a variety of hooks, screws and bolts all configured to create a segmental construct throughout the spine. In one aspect of the system, the spinal rod is connected to the various vertebral fixation elements by way of an eyebolt. In this configuration, the fixation elements are engaged to the spinal rod laterally adjacent to the rod. In another aspect of the system, a variable angle screw is engaged to the spinal rod by way of an eyebolt. The variable angle screw allows pivoting of the bone screw in a single plane parallel to the plane of the spinal rod. Details of this variable angle screw can be found hi U.S. Pat. No. 5,261,909 to Sutterlin et al. One goal achieved by the system is that the surgeon can apply vertebral fixation elements, such as a spinal hook or a bone screw, to the spine in appropriate anatomic positions. The system also allows the surgeon to easily engage a bent spinal rod to each of the fixation elements for final tightening.
Another rod-type fixation system provides a variety of fixation elements for engagement between an elongated rod and the spine. In one aspect of the system, the fixation elements themselves include a body that defines a slot within which the spinal rod is received. The slot includes a threaded bore into which a threaded plug is engaged to clamp the rod within the body of the fixation element. The system includes hooks and bone screws with this "open-back" configuration. Details of this technology can be found in U.S. Pat. No. 5,005,562.
On the other hand, these fixation elements of the system are capable only of pivoting about the spinal rod to achieve variable angular positions relative to the rod. While this limited range of relative angular positioning is acceptable for many spinal pathologies, many other cases require more creative orientation of a bone screw, for instance, relative to a spinal rod. Certain aspects of this problem are addressed by the variable angle screw of the system, as discussed in the '909 Patent. However, there is a need for a bone screw that is capable of angular orientation in multiple planes relative to the spinal rod as well as multiple spherical head orientations. Preferably, the bone screw axis is capable of various three dimensional orientations with respect to the spinal rod as well as three dimensional spherical axis orientation to the receiving (head) element of the devices axial orientation of the bone engaging screw member. Screws of this type of angular orientation in multiple planes relative to the spinal rod have been referred to as poly-axial or multi-axial bone screws. One should note, as of yet, no screw systems have employed both angular orientation in multiple planes relative to the spinal rod and three dimensional spherical axis orientation to the receiving (head) element of the devices axial orientation of the bone engaging screw member. The use of both angular orientation in multiple planes relative to the spinal rod and three dimensional spherical axis orientation to the receiving (head) element of the devices axial orientation of the bone engaging screw member technology allows for virtually unlimited axial angulations of the bone engaging screw member as well as an ultra-low profile of the said device utlizating a minimum of components without sacrificing the security of the interfaces of the invention components.
Others have approached the solution to this problem with various poly-axial screw designs. For example, in U.S. Pat. No. 5,466,237 to Byrd et al., a bone screw is described which includes a spherical projection on the top of the bone screw. An externally threaded receiver member supports the bone screw and a spinal rod on top of the spherical projection. An outer nut is tightened onto the receiver member to press the spinal rod against the spherical projection to accommodate various angular orientations of the bone screw relative to the rod. While this particular approach utilizes a minimum of components, the security of the fixation of the bone screw to the rod is lacking. In other words, the engagement or fixation between the small spherical projection on the bone screw and the spinal rod is readily disrupted when the instrumentation is subjected to the high loads of the spine, particularly in the lumbar region.
In another approach shown in U.S. Pat. No. 4,946,458 to Harms et al., a spherical headed bone screw is supported within separate halves of a receiver member. The bottom of the halves are held together by a retaining ring. The top of the receiver halves are compressed about the bone screw by nuts threaded onto a threaded spinal rod. In another approach taken by Harms et al., in U.S. Pat. No., 5,207,678, a receiver member is flexibly connected about a partially spherical head of a bone screw. Conical nuts on opposite sides of the receiver member are threaded onto a threaded rod passing through the receiver. As the conical nuts are threaded toward each other, the receiver member flexibly compresses around the head of the bone screw to clamp the bone screw in its variable angular position. One detriment of the systems in the two Harms et al. patents is that the spinal rod must be threaded in order to accept the compression nuts. It is known that threading rods can tend to weaken the rods in the face of severe spinal loads. Moreover, the design of the bone screws in the '458 and '678 Patents require a multiplicity of parts and are fairly complicated to achieve complete fixation of the bone screw.
A further approach illustrated in U.S. Pat. No. 5,797,911 to Sherman et al., is to provide a U-shaped holder through the top of which a bone fastener topped with a crown member is loaded. The holder accommodates a rod in a channel above the crown member and a compression member above the rod. The compression member presses on the rod and crown member to lock the fastener against the holder in any of a number of angles in three dimensions with respect to the rod. This approach has proven to be quite effective in addressing the above-identified problems. However, it does not permit bottom-loading of the fastener. Additionally, the holder is somewhat bulky in order to accommodate the other structural components.
Yet a further approach is shown in U.S. Pat. No. 5,733,285 to Errico et al., in which a holder is provided with a tapered and colletted portion at the bottom into which a bone fastener head is inserted. A sleeve is provided that slides down around the colletted portion to crush lock the colletted portion around the head of the bone fastener. This apparatus is believed to be relatively bulky and difficult to manipulate given the external sliding locking mechanism. It is further dependent on the fit of the external sleeve and the relative strength of the collet and its bending and crushing portions for secure locking of the bone fastener head.
There is therefore a need remaining in the industry for a ultra-low profile, multi-axial bone anchor that can be readily and securely engaged to an elongated member of any configuration—i.e., smooth, roughened, knurled or even threaded— which achieves greatly improved angulations of the bone anchor, improved strength, and reduced size, including profile and bulk, of the components used to engage the bone anchor to the elongated member in any of a variety of angular orientations as well and a simplified construct in regards to quantity and complexity if its components .
SUMMARY OF THE INVENTION
In one embodiment of the invention, a bone fixation assembly is provided that includes a receiver member defining an upper opening portion and a lower shaft portion creating an "U-shape" geometry, a channel configured to receive the elongated member (rod) and communicating with said upper opening portion and said lower shaft portion, and internal threaded portion located at the top outside surface of the posts; and
a bone-engaging anchor having a lower portion configured to engage a bone and a head having a width, said width of said head fashioned in the shape of an upside/down "U" creating a closed loop, said head being movably disposed over and around said one upper receiver posts and located at the bottom of the "U" shape; and
a compression retaining member defining an aperture smaller than said outside width of said receiving member posts, said retaining member at least partially housed in said top portion of said receiver member and positioned over said elongated member and tightened during utilization. Forces transmitted during tightening are imparted on the bone anchor member, and the lower surface'of the receiving member to anchor all said components in any angular and/or axial configuration within design parameters.
Additional embodiments, examples, advantages, and objects of the present invention will be apparent to those of ordinary skill in this art from the following specification.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of one embodiment of the multi-axial bone screw anchor assembly of the present invention.
FIG. 2 is an exploded view of the embodiment of the invention depicted in FIG. 1.
FIG. 3 a is a side elevational view of an embodiment of the receiver member of the embodiment of the invention illustrated in FIG. 2.
FIG. 3 b is a front elevational view of the embodiment of the receiver member illustrated in FIG. 3a.
FIG. 3c is a sectional view, taken along the lines 3c-3c in FIG. 3a, and viewed in the direction of the arrows, of the embodiment of the receiver member illustrated in FIG. 3a.
FIG. 3d is a sectional view, taken along the lines 3d— 3d of FIG. 3b and viewed in the direction of the arrows, of the embodiment of the receiver member illustrated in FIG. 3 a.
FIG. 4a is a side elevational view of an embodiment of a bone anchor used in the embodiment of the invention illustrated in FIG. 2.
FIG. 4b is a sectional view, taken along the lines 4b~4b of FIG. 4a and viewed in the direction of the arrows, of the embodiment of the bone anchor illustrated in FIG. 4a.
FIG. 4c is a magnified view of one embodiment of the head of the embodiment of the bone anchor illustrated in FIG. 4a.
FIG. 5a is a top view of the retaining member.
FIG. 5b is a side elevational view of the retaining member.
FIG. 6 is an enlarged sectional view of the embodiment of the present invention illustrated in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein, being contemplated as would normally occur to one skilled in the art to which the invention relates.
Referring generally to FIGS. 1 and 2, there is shown one embodiment of a multi-axial bone anchor assembly 20 of the present invention. In the illustrated embodiment, assembly 20 includes a receiver member 30, a bone anchor 50. The assembly 20 of the present invention is designed for use with an elongated member R (FIG. 6) such as a spinal rod, bar or other orthopedic construct, as further described below.
Referring now generally to FIGS. 3a-3d, one embodiment of the receiver member 30 of the present invention is shown. Receiver member 30 defines an upper opening portion 31a and a lower shaft portion 31b, which in the illustrated embodiment form a single opening 32 extending through receiver member 30 from an upper aperture 33 in top end 34 to a lower closed loop 35 in bottom end 36. Lower closed loop portion 31b of opening 32.
Alternatively, upper and lower closed loop portions 3 Ia, 3 Ib can have a variety of configurations, such as each having one or more sections of differing diameter.
Opening 32 is partially surrounded by a chamfered or rounded edge 40a at top end 34 of receiver member 30.
Receiver member 30 in the illustrated embodiment includes a pair of upright branches 42, 43 through which opening 32 extends. Branches 42, 43 further define a U-shaped channel 45 transverse to opening 32 that communicates with upper portion 31a and lower portion 3 Ib of opening 32, and that accommodates an elongated member R (FIG. 6). In a specific embodiment, internal threads 44 are formed in branches 42, 43, internal thread 44 in a specific embodiment is a modified acme buttress thread. Referring now generally to FIGS. 4a-4c, an embodiment of a bone anchor 50 used in the present invention is shown. The illustrated bone anchor 50 is a bone screw. Bone anchor 50 includes an anchorage portion 52 and a head portion 54. Anchorage portion 52 includes at least one thread 56, which may be a cancellous self-tapping thread. Head portion 54 forms part of a sphere/loop in the illustrated embodiment, though alternative curvate and other configurations may be employed. Head 54 in one particular embodiment includes a series of ridges/lines 58 for improving purchase with the interface of receiver member 30 (described below). Head 54 may have alternative friction- increasing surface configuration(s) such as roughening or knurling.
Other embodiments of bone anchor 50 are contemplated as being within the scope of the present invention. For example, bone anchor 50 could be a bone-engaging hook rather than a screw. In that embodiment, anchorage portion 52 would be configured with a hook rather than an elongated section with thread 56.
Head 54 of bone anchor 50 is shaped and sized to fit over and around either post of the receiver member 30. Specifically, head 54 has a "U-shaped" geometry that being movably disposed over and around said one upper receiver posts and located at the bottom of the "U" shape portion 70.
Generally referring to FIGS. 1, 2 and 6, assembly 20 is assembled as follows: bone anchor 50, is inserted over and around either post of the receiver member 30 substantially in one step as shown in (Fig. 2).
Bone anchor member 50 remains slideably and rotatably positioned in lower shaft 3 Ib of opening 32 and retained in that location of receiving member 30, and bone anchor 50 remains multi-axially moveable with respect to receiving member 30.
Preferably, assembly 20 is assembled (as described above) prior to use in a surgical procedure. In using the illustrated embodiment of assembly 20, bone anchor 50 of assembly 20 is threaded into an appropriately prepared hole in a bone (not shown). It will be understood that in alternative embodiments of the invention, for example where bone anchor 50 is a bone hook, drilling a hole in bone and threading the anchor therein may not be necessary.
An appropriate screwing tool is threaded onto the external threads of the receiving member 30, thus locking the assembly co-axially into one solid assembly, and is used to "drive" the bone anchor 50 therefore, threaded into the bone. The appropriate screwing tool is then removed. When bone anchor 50 has been threaded into the bone to the desired depth, receiver member 30 is positioned so that opening 32 forms a desired angle with bone anchor 50, as depicted in FIG. 1. In the illustrated embodiment, the angle theta. between bone anchor 50 and opening 32 can be any value up to 90 degrees in any direction (180 degrees total angulation) . It will be seen that the maximum angle of bone anchor 50 relative to opening 32 can be changed in two ways, for example by angling bone anchor 50 to its maximum off axis in association with maximum rotation of the receiver member 30 component.
As described above, receiver member 30 may be angled as the surgeon desires with respect to bone anchor 50. An elongated member R such as a spinal rod, connector, or other orthopedic surgical implant is coupled with assembly 20. Elongated member R is placed in channel 45 of receiver member 30, and contacts outer surface 50 of bone anchor member 70. A compression member 120, such as a skirted nut, skirted set-screw or similar device, is threaded into/onto threads 44 of receiver member 30 and down onto elongated member R. Compression member 120, in one embodiment, is a skirted set- screw having external threads and a "skirt" to slide over the receiver member 30 and a print 124 for applying torque. In a further embodiment, alternatively, where receiver member 30 is externally threaded, compression member 120 could be an internally- threaded nut.
As compression member 120 is tightened, elongated member R is forced downward against bone anchor 50. Head 54 is thereby clamped between internal compression memoer izυ ana receiving member Ji>. in the embodiment or the invention in which head 54 includes ridges 58, ridges 58 are pressed into surface of receiving member 30. In this way, bone anchor 50 is locked into the desired angular position with respect to elongated member R and the remainder of assembly 20.
Alternatively, assembly 20 can be assembled during the surgical procedure.
Preferred materials for the present invention include stainless steel and titanium. It will be recognized that any sturdy biocompatible material may be used to accomplish the osteosynthesis and other orthopedic surgical goals of the present invention.
While the present invention has been shown and described in terms pf preferred embodiments thereof, it will be understood that this invention is not limited to any particular embodiment, and that changes and modifications may be made without departing from the true spirit and scope of the invention as defined and desired to be protected.

Claims

ClaimsWhat is claimed is:
1. A bone anchor assembly for engagement to an elongated member, comprising of:
a "U-Shaped" upper receiver member, a bone anchor and a compression retaining member. The "U-Shaped" upper receiver member defines two upper posts and a lower shaft which may form part of the "U-Shape", a channel configured to receive the elongated member (rod), and internal threaded portion located at the top outside surface of the posts. The bone anchor is loaded over and around either of the upper posts of the "U-Shaped" upper receiver member and being movably disposed and located at the bottom of the "U" shaped" upper receiver member creating a "link" between the bone anchor member and the "U-Shaped" upper receiver member.; and
a bone-engaging anchor having a lower portion configured to engage a bone and a head having a width, said width of said head fashioned in the shape of an upside/down "U" creating a closed loop, said head being movably disposed over and around said one upper receiver posts and located at the bottom of the "U" shape; and
a compression retaining member defining an aperture smaller than said inside width of said receiving member posts, said retaining member at least partially housed in said top portion of said receiver member and positioned over said elongated member and tightened during utilization. Forces transmitted during tightening are imparted on the bone anchor member, and the lower surface of the receiving member to anchor all said components in any angular and/or axial configuration within design parameters.
2. The assembly of claim 1, wherein said upper opening portion and said lower shaft portion form at least part of a single opening through said receiver member.
3. The assembly of claim 2, wherein said receiver member includes two branches which define said upper opening portion and said channel.
4. The assembly of claim 3, wherein said branches include internal threads.
5. The assembly of claim 4 further including a compression retaining member threadedly connected to said internal threads.
6. The assembly of claim 2, wherein said receiver member defines a "U" shape that forms at least a part of said upper opening portion, and said bone anchor member being movably disposed around said lower shaft.
7. The assembly of claim 6, wherein said anchor is a bone screw with a head to be located and retained around the lower shaft of the said receiver member.
8. The assembly of claim 7, wherein said head of said bone screw is at least partially spherical. ~
9. The assembly of claim 8, wherein said head of said bone screw includes ridges or spherical/lateral grooves or general rough finish.
10. The assembly of claim 1, wherein said compression retaining member is a cylinder- shaped member with external threads and a "skirt".
11. The assembly of claim 10, wherein said compression retaining member has an unloaded outer threaded diameter, said receiver member has a threaded internal diameter, and said unloaded outer threaded diameter of said retaining member is lesser than said threaded diameter of said receiver member per the requirements for mating thread forms.
12. The assembly of claim 2, wherein said compression retaining member is a cylindered- shaped member.
13. The assembly of claim 12, wherein said compression retaining member has a body width, said groove has a groove depth, and said body width and said elongated member width is equal to, or less than said groove depth.
14. A bone fixation apparatus comprising:
an elongated member configured for placement adjacent and along a length of at least one bone;
a receiver member defining an opening there through from a top end to a bottom end, said opening having a lower shaft at said bottom end creating a "U" shape, said receiver member further including a channel communicating with said opening and said upper aperture, said channel being configured to receive said elongated member therein;
a bone anchor having a lower portion configured for engaging a bone and a head having a width dimension, said head being insertable over and around said posts of the receiving member locating at the bottom around said lower shaft of said receiver member;
Once the bone anchor member is restrained over the lower shaft of the receiving member, the bone anchor member is capable of multi-axial positioning with respect to the receiver member;
A compression retaining member defining an aperture smaller than said width of said head, said retaining member at least partially housed in said groove of said receiver member and positioned over said elongated member and tightened during utilization. Forces transmitted during tightening are imparted on the bone anchor member, and the lower surface of the receiving member to anchor all said components in any angular and/or axial configuration within design parameters.
15. The apparatus of claim 14, wherein said elongated member is a spinal rod.
16. The apparatus of claim 15, wherein said compression retaining member is a cylinder- shaped member.
17. The apparatus of claim 16, wherein said compression retaining member has an unloaded outer threaded diameter, said receiver member has an internal threaded diameter, and said unloaded outer threaded diameter of said retaining member is lesser than said internal threaded diameter of said receiver member.
18. The apparatus of claim 17, wherein said compression retaining member has a body width, said groove has a groove depth, and said body width and said elongated member width is equal to, or less than said groove depth.
19. The apparatus of claim 18, wherein said retaining member includes an internal tool surface for assembly and tightening and a flat lower surface for engaging said elongated member and said head of said bone anchor.
20. The apparatus of claim 19, wherein said internal tool surface does not interfere with the flat geometry.
21. The system of claim 1, wherein refers to the system requirements to include ancillary components. The technology a receiver member defining an upper opening portion and a lower shaft portion each having respective minimum widths, a channel configured to receive the elongated member (rod) and communicating with said upper opening portion and said lower shaft portion; and
said head of the bone-anchor member being movably disposed over and around said lower shaft portion; and
a bone anchor having a lower portion configured for engaging a bone and a head having a width dimension, said head being insertable over and around said posts of the receiving member locating at the bottom around said lower shaft of said receiver member;
Once the bone anchor member is restrained over the lower shaft of the receiving member, the bone anchor member is capable of multi-axial positioning as well as multi-polar positioning with respect to the receiver member; and
A compression retaining member defining an aperture smaller than said width of said head, said retaining member at least partially housed in said groove of said receiver member and positioned over said elongated member and tightened during utilization. Forces transmitted during tightening are imparted on the bone anchor member, and the lower surface of the receiving member to anchor all said components in any angular and/or axial configuration within design parameters, thus utilizing the technology for required ancillary components of this system.
PCT/US2005/039283 2005-07-18 2005-10-31 Universal link bone screw system WO2007011407A1 (en)

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US70046805P 2005-07-18 2005-07-18
US60/700,468 2005-07-18

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Cited By (2)

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US8419778B2 (en) 2010-01-15 2013-04-16 Ebi, Llc Uniplanar bone anchor system
US8647370B2 (en) 2010-01-15 2014-02-11 Ebi, Llc Uniplanar bone anchor system

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US20030149431A1 (en) * 2002-02-01 2003-08-07 Varieur Michael S. Closure system for spinal fixation instrumentation

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US5782833A (en) * 1996-12-20 1998-07-21 Haider; Thomas T. Pedicle screw system for osteosynthesis
US20030149431A1 (en) * 2002-02-01 2003-08-07 Varieur Michael S. Closure system for spinal fixation instrumentation

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Publication number Priority date Publication date Assignee Title
US8419778B2 (en) 2010-01-15 2013-04-16 Ebi, Llc Uniplanar bone anchor system
US8647370B2 (en) 2010-01-15 2014-02-11 Ebi, Llc Uniplanar bone anchor system
US8986356B2 (en) 2010-01-15 2015-03-24 Ebi, Llc Uniplanar bone anchor system
US9211143B2 (en) 2010-01-15 2015-12-15 Ebi, Llc Uniplanar bone anchor system
US9820781B2 (en) 2010-01-15 2017-11-21 Ebi, Llc Uniplanar bone anchor system

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