(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2012/00783.74 A1
`Villiers et al.
`(43) Pub. Date:
`Mar. 29, 2012
`
`US 20120078374A1
`
`(54) SPINAL MIDLINE INDICATOR
`
`(30)
`
`Foreign Application Priority Data
`
`Jan. 31, 2003 (ZA) ................................... 2003/0874
`Publication Classification
`
`(75) Inventors:
`
`(73) Assignee:
`
`Malan De Villiers, Wapadrand
`(ZA); Ulrich Reinhard Hähnle,
`Saxonwold (ZA)
`SpinalMotion, Inc., Mountain
`View, CA (US)
`
`(21) Appl. No.:
`
`13/310,514
`
`(22) Filed:
`
`Dec. 2, 2011
`9
`O
`O
`Related U.S. Application Data
`(63) Continuation of application No. 12/616,697, filed on
`Nov. 11, 2009, now Pat. No. 8,090,428, which is a
`continuation of application No. 1 1/187,733, filed on
`Jul. 21, 2005, now Pat. No. 7,637,913, which is a
`continuation of application No. PCT/IB2004/000170,
`filed on Jan. 26, 2004.
`
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`-
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`-
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`-
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`- -
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`-
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`(51) Int. Cl.
`(2006.01)
`A6IF 2/44
`(52) U.S. Cl. ..................................................... 623/1716
`(57)
`ABSTRACT
`A spinal midline indicator (10) has a body (14) of radiolucent
`material for insertion between adjacent vertebrae (18, 20) and
`a radiographic marker (12) located centrally with the body to
`indicate the position of the spinal midline (22) in anterior
`posterior images when the body is centrally located between
`the vertebrae. The radiographic marker is typically an elon
`gate metal handle. The body may carry secondary radio
`graphic markers (16) on opposite sides of and equidistant
`from the handle so that the handle indicates the position of the
`spinal midline when the body is placed centrally between the
`vertebrae.
`
`NUVASIVE - EXHIBIT 2008
`Alphatec Holdings Inc. et al. v. NuVasive, Inc.
`IPR2019-00362
`
`

`

`Patent Application Publication
`
`Mar. 29, 2012 Sheet 1 of 2
`
`US 2012/00783.74 A1
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`Patent Application Publication
`
`Mar. 29, 2012 Sheet 2 of 2
`
`US 2012/00783.74 A1
`
`
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`Fig.6
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`

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`US 2012/00783.74 A1
`
`Mar. 29, 2012
`
`SPINAL MDLINE INDICATOR
`
`CROSS-REFERENCES TO RELATED
`APPLICATIONS
`0001. This application is a continuation of U.S. patent
`application Ser. No. 12/616,697 (Attorney Docket No.
`298.50-705.302), filed Nov. 11, 2009, which is a continuation
`of U.S. patent application Ser. No. 1 1/187,733 (Attorney
`Docket No. 298.50-705.301), filed Jul. 21, 2005, which is a
`continuation of International Application PCT/IB2004/
`000170 (Attorney Docket No. 29850-705.601), filed Jan. 26,
`2004, which claims the benefit of South African Application
`No. 2003/0874 (Attorney Docket No. 298.50-705.841), filed
`Jan. 31, 2003, the full disclosures of which are incorporated
`herein by reference.
`
`BACKGROUND OF THE INVENTION
`0002 This invention relates to a spinal midline indicator.
`0003. It is important for a surgeon performing an ALIF
`(anterior lumbar interbody fusion) or ACIF (anterior cervical
`interbody fusion) cage or spinal disc replacement procedure
`to be able accurately to establish the centre- or midline of the
`spine. It is only once the Surgeon has correctly established the
`position of the spinal midline that he is able to place the cage
`or spinal disc accurately on that midline. ff-centre placement
`will result in eccentric loading and possible early failure or
`accelerated wear.
`0004 At present, surgeons attempt to establish the spinal
`midline by visual inspection of an A-P (anterior-posterior)
`image. However this is often inaccurate, and can lead to
`Subsequent off-centre placement of the cage or disc with
`potential disadvantages as described above.
`0005. The present invention seeks to provide an instru
`ment which will facilitate accurate establishment of the spinal
`midline.
`
`BRIEF SUMMARY OF THE INVENTION
`0006. According to the present invention there is provided
`a spinal midline indicator comprising a body of radiolucent
`material for insertion between adjacent vertebrae and a radio
`graphic marker associated centrally with the body to indicate,
`in an anterior-posterior radiographic image, the position of
`the spinal midline when the body is appropriately located
`between the vertebrae. Conveniently the radiographic marker
`is an elongate handle which is connected to the body to
`facilitate placement of the body between the vertebrae and
`which is made of a radiographic material, i.e., a material
`which is substantially opaque to radiographic (fluoroscopic)
`imaging.
`0007. In the preferred embodiment, the body carries, in
`addition to the handle which serves as a first radiographic
`marker, two or more secondary radiographic markers on
`opposite sides of and equidistant from the first marker,
`whereby the first marker indicates the position of the spinal
`midline when the body is placed centrally between the verte
`brae and the secondary markers are seen in the radiographic
`image to be equidistant from lateral edges of the vertebrae.
`0008 Further according to the invention there is provided
`a method of identifying a spinal midline which comprises the
`steps of inserting the body of a spinal midline indicator as
`Summarized above between adjacent spinal vertebrae,
`manipulating the body so that the radiographic marker is seen
`in a radiographic image to be on the spinal midline, and, using
`
`the position of the radiographic marker as a guide, applying a
`marking, eg. a pin, to a vertebra to indicate the midline.
`0009. Other features of the invention are set forth in the
`appended claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0010. The invention will now be described in more detail,
`by way of example only, with reference to the accompanying
`drawings.
`0011
`FIG. 1 shows a perspective view of a spinal midline
`indicator according to the invention;
`0012 FIG. 2 shows a side view of the indicator in the
`direction of the arrow 2 in FIG. 1;
`0013 FIG. 3 shows a side view of the indicator in the
`direction of the arrow 3 in FIG. 1;
`0014 FIG. 4 shows an end view of the indicator in the
`direction of the arrow 4 in FIG. 1;
`0015 FIG. 5 diagrammatically illustrates the indicator in
`use; and
`0016 FIG. 6 shows a diagrammatic cross-section at the
`line 6-6 in FIG. 5.
`
`DETAILED DESCRIPTION OF THE INVENTION
`(0017. The spinal midline indicator 10 seen in FIGS. 1 to 4
`includes an elongate handle 12 and abody 14 carried centrally
`at one end of the handle. The handle is made of a radiographic
`material, i.e. one which is opaque to radiation in the radio
`wave part of the spectrum, including X-radiation. The handle
`may, for instance, be made of stainless steel or titanium. The
`handle 12 extends substantially through the body 14. The
`body 14 is made of a radiolucent material, i.e. one which is at
`least to some degree transparent to the radiation. The body
`may, for instance, be made of PEEK (polyetheretherketone)
`or UHMWPE (ultra-high molecular weight polyethylene).
`00.18 Embedded in the body 14 are two elongate markers
`16, also of radiographic material Such as stainless steel or
`titanium. The markers 16 are aligned parallel to the handle 12
`and are located on opposite sides of, and equidistant from the
`handle.
`0019 FIG. 5 diagrammatically illustrates, in an anterior
`view, adjacent upper and lower vertebrae 18 and 20 respec
`tively. As explained above it is important, during an ALIF or
`ACIF cage or spinal disc replacement procedure carried out
`anteriorly, for the surgeon to be able accurately to establish
`the spinal midline, indicated by the line 22, since it is centrally
`on this line that the replacement disc or cage must be placed.
`The procedure is typically carried out, with the patient lying
`prone and flat on his back, through a frontal incision.
`0020. In order to establish the midline 22, the surgeon
`aligns the handle 12 at a vertical orientation and uses it to
`insert the body 14 between the vertebrae 18 and 20. It will be
`understood that a separate instrument 100 is used to hold the
`Vertebrae apart for this insertion to take place. An attempt is
`made to orientate the body centrally with the handle 12 ver
`tical, thereby to ensure that the handle correctly indicates the
`midline 22.
`0021. An X-ray photograph or radiographic image is taken
`in the vertical anterior-posterior direction. In this radio
`graphic image the handle 12, markers 16 and vertebrae 18.20
`will be visible. By ensuring that the markers 16 are equidis
`tantly laterally spaced from the osseous edges 23 of the ver
`tebrae, i.e. that the distance 25 is the same on both sides, the
`Surgeon can ensure that the body 14 and handle 12 are cen
`
`

`

`US 2012/00783.74 A1
`
`Mar. 29, 2012
`
`trally positioned. It will be understood that during this proce
`dure, the handle 12 itself operates as a radiographic marker
`indicating a central position.
`0022. It will also be understood that if the handle 12 and
`markers 16 are aligned with the anterior-posterior direction in
`which the radiographic image is taken, they will appear in the
`radiographic image merely as dots of small lateral dimension.
`However if the handle is not perfectly aligned in the anterior
`posterior, i.e. vertical direction, parallax effects will result in
`the handle and markers being seen as lines rather than dots.
`0023 This is illustrated in FIG. 6 in which the full lines
`show the handle 10 at the correctanterior-posterior or vertical
`orientation and the broken lines show it at orientations in
`which it is misaligned by an angle 9. It will be understood that
`in a radiographic image in the anterior-posterior direction
`indicated by the arrow 24, the handle 12 and markers 16 will
`appear as dots at the full line orientation but as short lines at
`the broken line orientations.
`0024. By consulting radiographic images and manipulat
`ing the indicator 10 as necessary in response to the informa
`tion derived therefrom, the Surgeon can ensure that the indi
`cator is at the correct position and orientation. When the
`
`indicator is in the correct position and at the correct orienta
`tion, the handle 12 will lie in a vertical plane containing the
`midline 22. The Surgeon can now use the handle as a positive
`indicator of that midline. The position of the radiographic
`marker can be used as a guide to apply a marking to a vertebra
`to indicate the midline. He can accurately mark the midline,
`for instance by knocking a pin 26 into one of the vertebrae.
`0025. Once the midline has been marked on one or both of
`the vertebrae, the indicator 10 is no longer required and can be
`removed for later re-use. The marker(s) then serve to indicate
`the midline 22 to enable Subsequent, accurate positioning of
`the relevant prosthesis to take place.
`What is claimed is:
`1. A spinal midline indicator comprising:
`a body of radiolucent material sized and shaped to fit into
`an intervertebral space between two adjacent vertebrae;
`and
`a radiographic marker formed as an elongated handle
`attached to and extending from the body along a central
`axis of the body in an anterior-posterior direction,
`wherein the handle is embedded in the body.
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