USRE39035E1 - Universal coupler for spinal fixation - Google Patents

Abstract

A spinal rod coupler assembly providing four degrees of freedom for connecting a spinal rod to a vertebrae of a patient which includes a tubular coupler member, an eyebolt, an insert and a set screw. The coupler member has a longitudinal bore, a central axis, and an end portion that is open ended and internally threaded and a second end portion that is closed. A plurality of openings in the tubular coupler member that includes a first pair of openings intersecting the central axis of the bore at generally right angles and a second pair of openings intersecting the central axis of the bore at generally right angles. The first and second pairs of openings being perpendicular to each other. The first pair of openings are sized and shaped to receive a spinal rod. The eyebolt has a shank portion and an eye portion, with the shank portion being insertable through the second pair of openings of the coupler body. The eye portion has an opening sized and shaped to mate with a selected bone bolt or bone screw. The insert fits within the bore and has opposed, arc-shaped end portions with recesses for engaging the spinal rod and eyebolt member. The set screw threadably engages the internally threaded end portion of the bore and tightens the assembly of the rod, insert, and eyebolt within the coupler member.

Description

FIELD OF THE INVENTION

The present invention relates to spinal fixation devices, and more particularly, relates to an improved spinal fixation connector that allows for adjustment in four axes of movement when attaching a longitudinal rod to a vertebrae of a spinal column.

BACKGROUND OF THE INVENTION

There are a number of surgical procedures that require a fixation of portions of the spine with respect to one another. Typically, bone screws or bolts are employed in the fixation of the spine wherein the bone screws or bolts are implanted in a surgical procedure involving the formation of one or more surgical openings in adjacent portions of the spine, for implanting the threaded bone bolts or screws into the vertebrae. Structures such as longitudinal rods or plates extend between the various spine members and are connected to the implanted bone bolts or screws with connector devices.

Connectors for attaching the rods or plates to vertebrae of a spinal column are known in the art. However, current bolt to rod connectors do not allow for adjustability in multiple planes in order to better conform to the anatomical structure of the patient and to eliminate initial stresses on the spinal fixation construct. In spinal surgery that requires distraction, compression, and rotation of the construct to obtain proper assembly, stresses are put on the component parts of existing spinal fixation systems and on the vertebral column, which are not designed to accommodate stresses much higher than those encountered during normal patient activity. By reducing the initial stresses on the construct and the vertebral column, the connector of the present invention allows the entire strength of the connector to be reserved for stresses encountered during patient activity. This provides a spinal construct for a non-compliant patient with activity limitations that is less likely to fail than one with initial high stresses.

Additionally, some existing fixation systems, such as U.S. Pat. Nos. 5,209,752 and 5,176,697, require lateral or medial approaches to assemble and tighten the construct which causes complicated surgical procedures due to the soft tissues that are lateral to the incision. Potential damage can also occur to neurological elements that are medial to the construct.

Current spinal fixation systems, for example such as those shown in U.S. Pat. Nos. 4,719,905 and 5,296,014, also have many pieces to assemble and lack anatomical adjustability which results in long surgeries that put increased stresses on the surgeon and surgical staff. Long surgical times increases patient morbidity due to blood loss and stresses of anesthesia. The large number of pieces in current fixation systems require hospitals to keep large inventories which is difficult during the present time of medical cost containment.

Accordingly, it is a principal object of the present invention to provide a simple and fast way to attach a spinal rod to the spine. The “single piece” (4 pieces pre-assembled) connector of the present invention facilitates rapid assembly during implantation of the fixation construct. This reduces operating time, blood loss and complications which makes the present invention more appealing to surgeons who will spend less time assembling and adjusting spinal fixation constructs in the operating room.

It is another object of the present invention to provide a spinal fixation connector that has a wide range of adjustability to accommodate a range of anatomical variations and to eliminate the initial stresses on the spinal fixation construct.

It is a further object of the present invention to provide a connector that is secured by means of a single set screw that is accessed from a posterior approach. This provides fewer screws for the surgeon to tighten and makes the securing and tightening of the spinal construct easier to access.

It is a further object of the present invention to provide a connector that allows adjustment in four axes of movement that includes a cephalad/caudal direction, a medial/lateral direction and angulation in a sagittal plane and a transverse plane when the assembly is being implanted in a patient.

SUMMARY OF THE INVENTION

The present invention provides a coupler assembly having four axes of movement for connecting a spinal rod to a vertebrae of a patient with a bone bolt or bone screw. The coupler assembly includes a tubular coupler member having a longitudinal bore surrounded by a wall. The bore has a central axis and first and second end portions with one end being open and internally threaded and the other end portion being closed. A plurality of openings are formed through the wall of the tubular coupler member with each of the openings communicating with the bore.

The plurality of openings include a first pair of openings aligned along a first line that intersects the central axis of the bore at generally right angles, and a second pair of openings aligned along a second line that intersects the central axis of the bore at generally right angles. The first and second pairs of openings are generally perpendicular to each other and are spaced apart so that the periphery of the first pair of openings is spaced longitudinally from the periphery of the second pair of openings. The first pair of openings is sized and shaped to receive a spinal rod with the spinal rod's longitudinal axis aligning with the first line of the first pair of openings of the coupler body.

The coupler assembly also includes an eyebolt having a shank portion with a central axis and an eye portion. The shank portion is insertable through the second pair of openings of the coupler body, with the central axis of the shank aligning with the second line of the second pair of openings. The eye portion of the eyebolt has an opening sized and shaped to mate with a selected bone bolt or bone screw.

An insert having an outer surface that generally conforms to the shape of the bore, fits within the bore. The insert has opposed, arc-shaped end portions with recesses for engaging the spinal rod on one end and the eyebolt on the other end. A set screw threadably engages the internally threaded end portion of the bore so that the set screw tightens the assembly of the rod, insert, and eyebolt within the coupler member when tightened down.

The coupler assembly of the present invention provides for movement along four axes that includes a cephalad/caudad direction, a medial/lateral direction, a sagittal plane and transverse plane when the assembly is being implanted in a patient.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention can be obtained when the detailed description of exemplary embodiments set forth below is reviewed in conjunction with the accompanying drawings, in which:

FIG. 1 is a posterior view of a portion of a vertebral column, showing a spinal fixation device connected to the vertebrae by connectors embodying the present invention;

FIG. 2 is a partial cross-sectional view taken alongsight line2—2 inFIG. 1, illustrating the manor in which the apparatus of the present invention connect the spinal rods to a vertebrae;

FIG. 3 is a perspective view of the preferred embodiment of the apparatus of the present invention with a spinal rod and bone screw inserted in the apparatus;

FIG. 4 is an exploded perspective view of the preferred embodiment of the apparatus of the present invention;

FIG. 4A is a side plan view of an alternate bone fastener;

FIG. 5A is a side perspective view of the coupler member or the present invention;

FIG. 5B is a cross-sectional view taken alongsight line5B—5B inFIG. 5A;

FIG. 5C is a cross-sectional view taken alongsight line5C—5C inFIG. 5A;

FIG. 5D is a side plan view of the coupler member of the present invention;

FIG. 6A is a side perspective view of the set screw of the apparatus of the present invention;

FIG. 6B is a cross-sectional view of the set screw inFIG. 6A;

FIG. 7A is a side perspective view of the insert of the present invention;

FIG. 7B is a cross-sectional view taken alongsight line7B—7B inFIG. 7A;

FIG. 7C is a cross-sectional view taken alongsight line7C—7C inFIG. 7A;

FIG. 8A is a side perspective view of the eyebolt of the present invention;

FIG. 8B is an end plan view taken alongsight line8B—8B inFIG. 8a;

FIG. 8C is a lower plan view of the eyebolt of the present invention; and

FIG. 8D is a cross-sectional view taken along sight line8D—8D in FIG.8A.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

FIGS. 1 and 2 show the preferred embodiment of the coupler assembly of the present invention, designated generally by the numeral10 implanted in a spinal column.Coupler assembly10 includes a coupler body ormember30, aneyebolt member50, aninsert70 and aset screw80, and is used to attachlongitudinal rods12 to avertebral column14 comprising a plurality ofvertebrae16. Thecoupler assembly10 is shown attached to threevertebrae16 as part of a spinal implant system that is used to hold and stabilizevertebrae16. Although the attachment of only threevertebrae16 is shown, it should be understood that the number ofassemblies10 used can vary such that any number of vertebrae can be held in place.

Each of theassemblies10 is connected to arespective vertebrae16 by afastener18 which may be either a bone bolt (FIGS. 2,3,4) or abone screw18A (FIG.4A). Thefastener18 is shown inFIGS. 2,3 and4 asbone bolt18 having a first threadedend portion22 for threaded engagement with an opening formed in apedicle20 of thevertebrae16.Bolt18 includes ashoulder portion24 which establishes how far the first threadedend portion22 can extend into thevertebrae16 and spaces theassembly10 away from thevertebrae16.Bolt18 has a second threadedend portion26 extending past thepedicle20 for engaging theeyebolt50 of theassembly10. Thebone bolt18 also includes anut28 that can be threaded upon the threadedend portion26 of thebolt18 to secureeyebolt50 ofassembly10 against thebolt shoulder24.Bone screw18A includes a first threadedend portion22A and ahead portion28A having a spherically shaped lower portion.

Afterbone bolt18 has been implanted inpedicle20 of thevertebrae16,assembly10 is placed over the threaded end portion of26 of thebolt18. Thenut28 is threaded over theend portion26 in order to securely fasten thebone bolt18 to theassembly10. Thelongitudinal rod12, having a longitudinal axis A1—A1 (FIG. 4) is placed through an opening in theassembly10 and theset screw80 secures the entire assembly10A together (FIGS. 3,4). The coupler assembly10A includes thecoupler assembly10, thespinal rod12 and thebone fastener18.

In the embodiment of the present invention shown inFIG. 4, theassembly10 includes the cylindrical coupler body ormember30, theeyebolt member50, insert70, and theset screw80 that when assembled forms the singlepiece coupler assembly10. In a preferred embodiment, thecoupler body30 is tubular in shape and has alongitudinal bore32 surrounded by awall34. Thebore32 has a central axis C1 and a first ortop portion36 and a second orbottom portion38. Thetop portion36 is open-ended and includesinternal threading40. The second orbottom end portion38 is closed. Thecoupler body30 also has anupper portion36A and alower portion38A. In a preferred embodiment, theupper portion36A of thecoupler body30 has a larger diameter in relation to thelower portion38A.

Coupler body30 includes at least two through openings. In a preferred embodiment,coupler body30 includes a first pair of openings throughwall34 aligned along a first line L1—L1 that intersects the central axis C1 ofbore32 at generally right angles (FIGS. 5A,5B).Coupler body30 also includes a second pair ofopenings44 aligned along a second line L2—L2 that intersects the central axis C1 ofbore32 at generally right angles (FIGS. 5A,5C).Openings42 and44 are generally perpendicular to each other and spaced apart from each other such that the periphery of the first pair ofopenings42 is spaced longitudinally from the periphery of the second pair ofopenings44 as shown inFIGS. 3,4 and5A. In a preferred embodiment,openings42 are placed in theupper portion36A ofcoupler body30 andopenings44 are placed in thelower portion38A ofcoupler body30.

Openings42 are sized and shaped to receive thespinal rod12 with the longitudinal axis A1 of therod12 aligning with the line L1—L1 of theopenings42 when therod12 is placed throughopenings42 of coupler body30 (FIG.3).Openings44 have alower wall portion46 which is concave in shape in order to accommodate the cylindrical shank portion of the eyebolt50 (FIG.5B).

In a preferred embodiment, a pair ofnotches48 are positioned on the outside surface ofwall34 at the open-endedportion36 of coupler body30 (FIGS. 5A,5D). Thenotches48 are sized and shaped to accommodate a tool such as a wrench which is used to stabilize thecoupler body30 while theset screw80 is being tightened into place.

Eyebolt member50 includes ashank portion52 and an eye portion54 (FIG.8A).Shank portion52 has a central axis C2—C2 and an outer surface56 (FIG.8C). In a preferred embodiment,shank portion52 is cylindrical in shape withknurling58 on a portion of the outer surface56 (FIGS. 8A,8C).Shank portion52 includes ashank end64 with arecess66 so as to allow slight flanging ofshank end64 after theshank portion52 is inserted throughopenings44 of coupler body30 (FIGS. 8B,8D). The flanging prevents theshank portion52 from sliding out of theopenings44 after thecoupler assembly10 has been assembled. Whenshank portion52 ofeyebolt50 is inserted throughopenings44 ofcoupler body30, the shank portion's52 central axis C2—C2 is aligned along line L2—L2 of openings44 (FIG.3).

Eye portion54 ofeyebolt50 includes anopening60, an upper surface61, and alower surface62.Opening60 has a spherically shapedsurface63 on the upper andlower surfaces61,62 ofeye portion54 and is sized and shaped to mate with thefastener18. When implanted in a patient, the spherically shapednut28 mates with the spherically shapedsurface63 on the upper surface61 of the eye portion opening60 and the spherically shapedshoulder portion24 mates with the spherically shapedsurface63 on thelower surface62 of the eye portion opening60. If thebone screw18A is used as the bone fastener instead, the spherically shaped surface of the bonescrew head portion28A mates with the spherically shapedsurface63 on the upper surface61 of the eye portion opening.

Insert70 is cylindrical in shape and has opposed arc-shapedend portions72,76 (FIG.7A).First end portion72 has arecess74 that is sized and shaped to engage the spinal rod12 (FIGS. 7A,7B).Second end portion76 has arecess78 sized and shaped to engage theshank portion52 of eyebolt50 (FIGS. 7A,7C).Insert70 has an outer surface71 that generally conforms to the shape ofbore32 ofcoupler body30.

During assembly of thecoupler assembly10, insert70 is placed inbore32 after theshank portion52 ofeyebolt50 has been placed throughopenings44 ofcoupler body30.Insert70 is placed inbore32 such thatrecess78 contacts theouter surface56 ofshank portion52 ofeyebolt50. When thespinal rod12 is placed through theopenings42,recess74 ofinsert70 contacts the surface of thespinal rod12. Thus, insert70 provides greater surface to surface contact between therod12 andshank portion72 then would be possible if thecoupler assembly10 was used withoutinsert70. In acoupler assembly10 withoutinsert70, there would only be a single point of surface contact between the insertedrod12 andshank portion52 when they are in the perpendicular alignment allowed by theopenings42 and44 of thecoupler body30.

Setscrew80 has anupper surface82, alower surface84, and a threadedbody portion86 that engages and cooperates with the internally threadedend portion36 ofcoupler body30.Upper surface82 is generally flat with a toolreceptive socket88 sized and shaped for receiving a tool designed to thread and tighten theset screw80 into the threadedportion40 ofbore32 ofcoupler body30. In a preferred embodiment,lower surface84 has a smooth outer surface and is generally conical in shape. Theset screw80 provides means for tightening therod12, insert70, andeyebolt50 within thecoupler body30.

In alternate embodiments, the coupler body can include a U-shaped top opening, sized and shaped to receive thespinal rod12, instead of the pair ofopenings42. A cap or a cross-bar with at least one set screw can be used to tighten theassembly10 together instead of theset screw80.

Coupler assembly10 is assembled by placingshank portion52 ofeyebolt50 throughopenings44 ofcoupler body30.Insert70 is inserted in thebore32 so as to allowrecess78 to engage the outer surface ofshank portion52. Setscrew80 is partially threaded intobore32 which provides thesingle piece assembly10 as shown in FIG.3. After thefastener18 has been implanted inpedicle20 ofvertebrae16, the threadedend26 ofbone bolt18 is inserted through the eyebolt opening60 ofcoupler assembly10.Spinal rod12 is inserted throughopenings42 such that thespinal rod12 engagesrecess74 ofinsert70. After thecoupler assembly10 androd12 have been adjusted to conform to the anatomical structure of thevertebral column14, setscrew80 is tightened intobore32 ofcoupler body30, securing the entire assembly10A in place in the selected position.

Thecoupler assembly10 allows for adjustment along four degrees of freedom, as shown in FIG.3.Assembly10 allows for movement along the longitudinal axis A1—A1 ofspinal rod12 which provides adjustment in a cephalad-caudad direction CC—CC.Eyebolt50 can be moved in theopenings44 along the central axis C2 ofshank portion50 allowing for adjustment in a medial-lateral direction ML—ML. The rotation of thespinal rod12 around its longitudinal axis A1—A1 in theopenings42 allows for angulation in a transverse plane TA—TA. The rotation of theeyebolt50 around its central axis C2—C2 inopenings44 allows for angulation in a sagittal plane SA—SA.

Thus, the present invention provides a “single piece” connector for attaching a spinal rod to a vertebrae that facilitates rapid assembly and allows a wide range of adjustability in four axes of movement.

Thecoupler assembly10 is formed of a biocompatible material, and in a preferred embodiment, is formed of stainless steel.

It should be understood that there can be improvements and modifications made to the embodiments of the invention described in detail above without departing from the spirit or scope of the invention, as set forth in the accompanying claims.

Claims (47)

1. A spinal rod coupler assembly providing four degrees of freedom for connecting a spinal rod to a vertebrae of a patient, comprising:

a) a tubular coupler member having a longitudinal bore surrounded by a wall, the bore having a central axis and first and second end portions, the first end portion being open ended and internally threaded, the second end portion being closed;

b) a plurality of openings through the wall of the tubular coupler member, each of the openings communicating with the bore;

c) the plurality of openings including a first pair of openings aligning along a first line that intersects the central axis of the bore at generally right angles, and a second pair of openings aligning along a second line that intersects the central axis of the bore at generally right angles, the first and second lines being generally perpendicular to each other and spaced apart so that the periphery of the first pair of openings is spaced longitudinally from the periphery of the second pair of openings;

d) the first pair of openings sized and shaped for receiving a spinal rod having a longitudinal axis, which can be aligned with the first line of the first pair of openings of the coupler body;

e) an eyebolt having a shank portion with a central axis and an eye portion, the shank portion being insertable through the second pair of openings of the coupler body, aligning the central axis of the shank with the second line of the second pair of openings, the eye portion having an opening sized and shaped to mate with a selected fastener;

f) an insert that fits within the bore, the insert having an outer surface that generally conforms to the shape of the bore, the insert having opposed, arc-shaped end portions with recesses for engaging the spinal rod the eyebolt shank portion;

g) a set screw that threadably engages the internally threaded end portion of the bore so that the set screw tightens the assembly of the rod, insert, and eyebolt within the coupler member;

h) whereby the coupler assembly provides for movement along four degrees of freedom which include a movement along and a rotation about the longitudinal axis of the spinal rod, and a movement along and a rotation about the central axis of the eyebolt shank when the assembly is being implanted in a patient.

2. The coupler assembly ofclaim 1, wherein the eye portion of the eyebolt has an upper and a lower surface with the eye portion opening having a spherically shaped surface on the upper and lower surface of the eye portion.

3. The coupler assembly ofclaim 1, wherein the shank portion of the eyebolt has an outer surface with knurling on a portion of the outer surface.

4. The coupler assembly ofclaim 1, wherein the shank portion of the eyebolt includes a shank end with a recess so as to allow slight flanging of the shank end after the shank portion is inserted through the second pair of openings in the coupler body.

5. The coupler assembly ofclaim 1, wherein the tubular coupler member includes an upper portion and a lower portion with the first pair of openings positioned in the upper portion and the second pair of openings positioned in the lower portion.

6. The coupler assembly ofclaim 5, wherein the upper portion of the tubular coupler member has a larger diameter in relation to the lower portion of the tubular coupler member.

7. The coupler assembly ofclaim 1, wherein the set screw has an upper surface and a lower surface, the lower surface being generally conical in shape and the upper surface being generally flat with a tool receptive socket for receiving a tool designed to thread the set screw into the threaded portion of the bore.

8. A spinal prosthesis providing four degrees of freedom, comprising:

a) an elongated spinal rod having a central longitudinal axis;

b) a tubular coupler member having a longitudinal bore surrounded by a wall, the bore having a central axis and first and second end portions, the first end portion being open ended and internally threaded, the second end portion being closed;

c) a plurality of openings through the wall of the tubular coupler member, each of the openings communicating with the bore;

d) the plurality of openings including a first pair of openings aligning along a first line that intersects the central axis of the bore at generally right angles, and a second pair of openings aligning along a second line that intersects the central axis of the bore at generally right angles, the first and second lines being generally perpendicular to each other and spaced apart so that the periphery of the first pair of openings is spaced longitudinally from the periphery of the second pair of openings;

e) the first pair of openings sized and shaped to receive a spinal rod having a longitudinal axis with the rod being insertable through the first pair of openings, aligning the rod's longitudinal axis with the first line of the first pair of openings of the coupler body;

f) an eyebolt having a shank portion with a central axis and an eye portion, the shank portion being insertable through the second pair of openings of the coupler body, aligning the central axis of the shank with the second line of the second pair of openings, the eye portion having an opening sized and shaped to mate with a selected fastener;

g) an insert that fits within the bore, the insert having an outer surface that generally conforms to the shape of the bore, the insert having opposed, shaped end portions with recesses for engaging the spinal rod and the eyebolt shank portion;

h) a set screw that threadably engages the internally threaded end portion of the bore so that the set screw tightens the assembly of the rod, insert, and eyebolt within the coupler member;

i) the bone fastener for anchoring the coupler assembly to a patient's vertebrae, the bone bolt having a first threaded portion configured to be surgically implantable into a patient's bone tissue and a second portion having surfaces for engaging the eyebolt opening;

j) whereby the assembled spinal prosthesis provides for movement along four degrees of freedom which include a movement along and a rotation about the longitudinal axis of the spinal rod, and a movement along and a rotation about the central axis of the eyebolt shank when implanted in a patient.

9. The coupler assembly ofclaim 8, wherein the eyebolt has an upper and a lower surface with the eyebolt opening having a spherically shaped surface on the upper and lower surface of the eyebolt that cooperates with the surface of the bone fastener.

10. The coupler assembly ofclaim 8, wherein the shank portion of the eyebolt has an outer surface with knurling on a portion of the outer surface.

11. The coupler assembly ofclaim 8, wherein the shank portion of the eyebolt includes a shank end with a recess so as to allow slight flanging of the shank end after the shank portion is inserted through the second pair of openings in the coupler body.

12. The coupler assembly ofclaim 8, wherein the tubular coupler member includes an upper portion and a lower portion with the first pair of openings positioned in the upper portion and the second pair of openings positioned in the lower portion.

13. The coupler assembly ofclaim 12, wherein the upper portion of the tubular coupler member has a larger diameter in relation to the lower portion of the tubular coupler member.

14. The coupler assembly ofclaim 8, wherein the set screw has an upper surface and a lower surface, the lower surface being generally conical in shape and the upper surface being generally flat with a tool receptive socket for receiving a tool designed to thread the set screw into the threaded portion of the bore.

15. The coupler assembly ofclaim 8, wherein the bone fastener further includes a central non-threaded portion having a load transfer surface and an second threaded portion for threadably receiving a nut, the second threaded portion sized to be insertable through the eyebolt opening and able to be locked into place with the nut.

16. A spinal rod coupler assembly providing four degrees of freedom for connecting a spinal rod to a vertebrae of a patient, comprising:

a) a coupler member having a longitudinal bore surrounded by a wall, the bore having a central axis and first and second end portions, the first end portion being open ended and internally threaded, the second end portion being closed;

b) a plurality of openings in the coupler member, each of the openings communicating with the bore;

c) the plurality of openings including a first through opening aligning along a first line that intersects the central axis of the bore at generally right angles, and a second through opening aligning along a second line that intersects the central axis of the bore at generally right angles, the first and second lines being generally perpendicular to each other and spaced apart so that the periphery of the first opening is spaced longitudinally from the periphery of the second opening;

d) the first opening being sized and shaped to receive a spinal rod having a longitudinal axis, the rod's longitudinal axis aligning with the first line of the first opening of the coupler body;

e) an eyebolt member having a shank portion with a central axis and an eye portion, the shank portion being insertable through the second opening of the coupler body, aligning the central axis of the shank with the second line of the second opening, the eye portion having an opening sized and shaped to mate with a selected bone fastener;

f) means for tightening the assembly of the rod and eyebolt in a selected position within the coupler member;

g) whereby the coupler assembly provides for movement along four degrees of freedom which include a movement along and a rotation about the longitudinal axis of the spinal rod, and a movement along and a rotation about the central axis of the eyebolt shank when the assembly is being implanted in a patient.

17. A spinal rod coupler assembly comprising:

a coupler member having first, second, and third openings, the first opening dimensioned to slidably receive a spinal rod and fully surround a portion thereof and the second opening dimensioned to receive a locking fastener to retain the spinal rod within a coupler member; and

a fastener receiving member having an opening to receive a bone fastener, the fastener receiving member rotatably and slidably mounted with respect to the coupler member to adjust the position of the fastener, the fastener receiving member being mountable in the third opening of the coupler member.

18. The coupler assembly ofclaim 17, wherein a longitudinal axis extending through the first opening is transverse to a longitudinal axis extending though the second opening.

19. The coupler assembly ofclaim 17, wherein a longitudinal axis extending through the third opening is transverse to the longitudinal axis of the first opening.

20. The coupler assembly ofclaim 17, wherein the longitudinal axis of the third opening is transverse to the longitudinal axis of the second opening.

21. The coupler assembly of17, wherein the periphery of the second and third openings are spaced apart.

22. The coupler assembly of17, wherein the opening in the fastener receiving member is circular in configuration.

23. The coupler assembly of17, wherein the bone fastener is a bolt.

24. The coupler assembly of17, wherein the bone fastener is a screw.

25. The coupler assembly of17, wherein a potion of the second opening of the coupler member is internally threaded.

26. The coupler assembly of25, further comprising an insert member mountable within the second opening, the insert member having a first recess which conforms to the shape of the spinal rod.

27. The coupler assembly of26, wherein the fastener receiving member has an elongated shank portion extending into the third opening of the coupler member and the insert has a second recess which conforms to the shape of the shank portion.

28. The coupler assembly of17, wherein the locking fastener is a set screw engagable with an internal thread formed adjacent the second opening of the coupler member.

29. The coupler assembly of17, wherein the fastener receiving member has an elongated shank portion extending into the third opening of the coupler member.

30. The coupler assembly of29, wherein at least a portion of the shank portion has a knurled surface.

31. The coupler assembly of29, wherein the shank portion is substantially cylindrical in configuration.

32. The coupler assembly of31, wherein the shank portion has an end portion with a recess formed therein.

33. The coupler assembly of17, wherein a portion of the coupler opposite the second opening is closed.

34. A spinal rod coupler assembly comprising:

a coupler member having first, second, and third openings, the first opening dimensioned to slidably receive a spinal rod, and the second opening dimensioned to receive a locking fastener to retain the spinal rod within the coupler member, a portion of the coupler opposite the second opening being closed;

a fastener receiving member having an opening to receive a bone fastener, the fastener receiving member rotatably and slidably mounted with respect to the coupler member to adjust the position of the fastener, the fastener receiving member being mountable in the third opening of the coupler member,

and an insert interposed between the spinal rod and the fastener receiving member.

35. The coupler assembly of34, further comprising a nut engagable with a threaded portion of the bone fastener.

36. A spinal rod coupler comprising:

a first opening dimensioned to slidably receive and fully surround a portion of a spinal rod and having a first longitudinal axis extending therethrough;

a second opening dimensioned to receive a locking fastener and having a second longitudinal axis extending therethrough transverse to the first longitudinal axis; and

a third opening dimensioned to slidably and rotatably receive an elongated connector to mount a bone fastener, the third opening having a third longitudinal axis extending therethrough transverse to the first longitudinal axis and the second longitudinal axis.

37. The spinal rod coupler ofclaim 36, wherein at least portion of the second opening is threaded.

38. The spinal rod coupler ofclaim 36, wherein the periphery of the first and third openings are longitudinally spaced.

39. The spinal rod coupler ofclaim 37, wherein the coupler is substantially cylindrical in configuration.

40. A spinal rod coupler assembly comprising:

a coupler having a first opening to receive a spinal rod and fully surround a portion thereof;

a connecting member having a longitudinal axis, the connecting member extending from the coupler and rotatable with respect to the coupler;

a bone fastener positioned within the connecting member, wherein movement of the connecting member with respect to the coupler adjusts the position of the bone fastener; and

a locking member for securing the spinal rod the locking member extending at an angle to the longitudinal axis of the connecting member.

41. The spinal rod coupler assemblyclaim 40, wherein the connecting member is slidably movable within a first bore formed in the coupler.

42. The spinal rod coupler assembly ofclaim 41, wherein the connecting member is rotatably mounted with the first bore.

43. The spinal rod coupler assembly ofclaim 40, wherein the coupler is slidably mounted with respect to the spinal rod.

44. The spinal rod coupler assembly ofclaim 40, wherein the coupler is rotatably mounted with respect to the spinal rod.

45. The spinal rod coupler assembly ofclaim 40, wherein the bone fastener is received in a circular opening in the connecting member.

46. A spinal rod coupler assembly comprising:

a coupler having a first opening to receive a spinal rod;

a connecting member extending from the coupler;

a bone fastener positioned within the connecting member, wherein movement of the connecting member with respect to the coupler adjusts the position of the bone fastener; and

an insert mounted within the coupler and interposed between the spinal rod and connecting member.

47. A spinal rod coupler assembly providing four degrees of freedom for connecting a spinal rod to a vertebrae of a patient, comprising:

a)a coupler member having a longitudinal bore surrounded by a wall, the bore having a central axis and first and second end portions, the first end portion being open ended and internally threaded, the second end portion being closed;

b)a plurality of openings in the coupler member, each of the openings communicating with the bore;

c)the plurality of openings including a first through opening aligning along a first line that intersects the central axis of the bore at generally right angles, and a second through opening aligning along a second line that intersects the central axis of the bore at generally right angles;

d)the first opening being sized and shaped to receive a spinal rod having a longitudinal axis, the rod's longitudinal axis aligning with the first line of the first opening of the coupler body;

e)an eyebolt member having a shank portion with a central axis and an eye portion, the shank portion being insertable through the second opening of the coupler body, aligning the central axis of the shank with the second line of the second opening, the eye portion having an opening sized and shaped to mate with a selected bone fastener;

f)whereby the coupler assembly provides for movement along four degrees of freedom which include a movement along and a rotation about the longitudinal axis of the spinal rod, and a movement along a rotation about the central axis of the eyebolt shank when the assembly is being implanted in a patient.

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