U.S. patent application number 11/469791 was filed with the patent office on 2007-01-18 for instrument system for preparing a disc space between adjacent vertebral bodies to receive a repair device.
This patent application is currently assigned to Zimmer Inc.. Invention is credited to Felix Blouin, Bruce Robie, John Wilhelmy, Rafael Zubok.
Application Number | 20070016213 11/469791 |
Document ID | / |
Family ID | 26712567 |
Filed Date | 2007-01-18 |
United States Patent
Application |
20070016213 |
Kind Code |
A1 |
Robie; Bruce ; et
al. |
January 18, 2007 |
INSTRUMENT SYSTEM FOR PREPARING A DISC SPACE BETWEEN ADJACENT
VERTEBRAL BODIES TO RECEIVE A REPAIR DEVICE
Abstract
An instrument system for preparing a disc space between adjacent
vertebral bodies to receive a repair device includes a series of
distractors for distracting the vertebral bodies in a manner that
restores natural lordosis of the lumbar and cervical spine, a
vertebrae immobilizing template to fix the positions of the bodies,
a handle for employing the distractor and the template, and a
reamer for cutting tissue from endplates of the vertebral
bodies.
Inventors: |
Robie; Bruce; (Glen Rock,
NJ) ; Blouin; Felix; (Sterling Forest, NY) ;
Zubok; Rafael; (Midland Park, NJ) ; Wilhelmy;
John; (Danville, CA) |
Correspondence
Address: |
Todd Dawson;VP of Legal Affairs, Zimmer Inc.
P.O. Box 708
Warsaw
IN
46581
US
|
Assignee: |
Zimmer Inc.
Warsaw
IN
|
Family ID: |
26712567 |
Appl. No.: |
11/469791 |
Filed: |
September 1, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10035863 |
Dec 31, 2001 |
|
|
|
11469791 |
Sep 1, 2006 |
|
|
|
60259262 |
Dec 29, 2000 |
|
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|
Current U.S.
Class: |
606/87 |
Current CPC
Class: |
A61B 2090/033 20160201;
A61B 17/1757 20130101; Y10S 606/914 20130101; A61B 2017/00464
20130101; A61B 2017/0256 20130101 |
Class at
Publication: |
606/087 |
International
Class: |
A61F 5/00 20060101
A61F005/00 |
Claims
1. A vertebrae immobilizing template for use in a system that
prepares a disc space between adjacent vertebral bodies to receive
a repair device, the template comprising a sleeve member for fixing
the positions of the vertebral bodies, the sleeve member being
placeable about a distractor inserted into the disc space.
2. The template according to claim 18, further comprising opposing
prongs extending from the sleeve member for fixing the positions of
the vertebral bodies when the prongs are impacted into the
bodies.
3. The template according to claim 18, further comprising a detent
element disposed in a side surface of the sleeve member for
coupling a handle to the template,
Description
[0001] This application is a divisional of application Ser. No.
10/035,863, filed Dec. 31, 2001, which claims the benefit of U.S.
Provisional Application No. 60/259,262 filed Dec. 29, 2000, the
entire disclosures of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to instruments and instrument
systems for preparing a disc space between adjacent vertebral
bodies in a manner that restores the natural lordosis of the lumbar
and cervical spine, so that a repair device can be inserted
therein.
BACKGROUND OF THE INVENTION
[0003] A large segment of the population have chronic back problems
which cause pain and disability. The cause of back pain is often
the result of diseased disc material between opposing vertebrae.
The diseased disc material usually causes pain because the disc
material inadequately supports the opposing vertebrae, thereby
allowing the space between the vertebrae to collapse and irritate
or damage spinal nerves.
[0004] Surgical techniques have been developed to eliminate the
persistent pain resulting from diseased disc material. In such
techniques, the diseased disc material is removed and the joint
between opposing vertebral bodies is fused. Fusion specifically
involves removing the diseased disc, preparing a bore for receiving
an implant, and inserting the implant between the opposing
vertebral bodies.
[0005] Spinal fusion implants and the surgical instruments used for
implanting these fusion implants are well known in the art. The
surgical instruments required for preparing the disc space
typically include one or more distractors, drills, reamers, and
other instruments.
[0006] These prior art instrument sets typically prepare a
cylindrical contact area for the fusion implant or artificial disc.
Such an instrument set is described in U.S. Pat. No. 5,505,732, to
Michelson. The use of a cylindrical shape within the disc space
does not restore the natural lordosis of the lumbar and cervical
spine, but instead, undesirably establishes a relative
kyphosis.
[0007] Accordingly, an instrument system is needed for preparing a
disc space between adjacent vertebral bodies in a manner that
restores the natural lordosis of the lumbar and cervical spine, so
that a repair device can be inserted therein.
SUMMARY OF THE INVENTION
[0008] An instrument system is described herein for preparing a
disc space between adjacent vertebral bodies to receive an implant.
The instrument system comprises at least one distractor including a
tapered body section for distracting the vertebral bodies in a
manner that restores natural lordosis of the lumbar and cervical
spines.
[0009] One exemplary embodiment of the present invention further
comprises a vertebrae immobilizing template. The template is
constructed as a sleeve member that can be placed about the
distractor when the distractor is inserted into the disc space, to
fix the positions of the bodies.
[0010] In another exemplary embodiment of the invention, the
instrument system further comprises a handle including a coupling
member for coupling the handle to the distractor or the template.
The handle is useable with the distractor for distracting the disc
space and is further useable for placing the template about the
distractor after it has been used to distract the vertebral bodies.
The handle may include an impaction member for impacting prongs of
the template into the distracted vertebral bodies.
[0011] In still another exemplary embodiment of the invention, the
instrument system further comprises a reamer having a surface with
cutting elements for cutting tissue from endplates of the vertebral
bodies, and preferably a surface that defines a tapered profile
wherein the cutting elements simultaneously cut tissue from
opposing endplates of the adjacent vertebral bodies.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The advantages, nature, and various additional features of
the invention will appear more fully upon consideration of the
illustrative embodiments now to be described in detail in
connection with accompanying drawings where like numerals are used
to identify like elements and wherein:
[0013] FIG. 1A is a plan view of a distractor made according an
exemplary embodiment of the present invention;
[0014] FIG. 1B is an elevational view of the distractor of FIG.
1A;
[0015] FIG. 1C is an anterior end view of the distractor of FIG.
1A;
[0016] FIG. 1D is a side view of the distractor inserted in the
disc space after distraction and a vertebrae immobilizing template
fixing the positions of the distracted vertebral bodies;
[0017] FIG. 2A is an anterior end view of the vertebrae
immobilizing template made according an exemplary embodiment of the
present invention;
[0018] FIG. 2B is a plan view of the template of FIG. 2A;
[0019] FIG. 2C is an elevational view of the template of FIG.
2A;
[0020] FIG. 3A is a side view of a distractor/template handle made
according to an exemplary embodiment of the present invention;
[0021] FIG. 3B is a distal end view of the handle of FIG. 3A;
[0022] FIG. 4A is an exploded view a reamer assembly made according
to an exemplary embodiment of the present invention;
[0023] FIG. 4B is a distal end view of a reamer sleeve of the
reamer assembly of FIG. 4A;
[0024] FIG. 4C is a side view of the reamer assembly depicting its
use with the vertebrae immobilizing template, wherein the reamer
sleeve is shown engaged with the vertebrae immobilizing template,
and a reamer of the reamer assembly is shown disposed in the disc
space and cutting the endplates of the vertebral bodies; and
[0025] FIGS. 5-12 depict an exemplary method of using the
instrument system of the present invention.
[0026] It should be understood that the drawings are for purposes
of illustrating the concepts of the invention and are not
necessarily to scale.
DETAILED DESCRIPTION OF THE INVENTION
[0027] The present invention is an instrument system for preparing
a disc space between adjacent vertebral bodies to restore the
natural lordosis of the lumbar and cervical spine, so that a repair
device of the type which prevents motion between the two adjacent
vertebrae (commonly referred to as a fusion implant), or which
permits motion between the two adjacent vertebral bodies (sometimes
referred to as an artificial disc or artificial motion segment) can
be inserted therein. The instrument system may comprise the
following instruments: a series of distractors, one of which is
shown in FIGS. 1A-1C (denoted by reference character 10), a
vertebrae immobilizing template 50 as shown in FIGS. 2A-2C, a
distractor/template handle 70 as shown in FIGS. 3A and 3B, and a
reamer assembly as shown in FIG. 4.
[0028] The series of distractors are used for determining the
appropriate size of the repair device to be finally inserted in the
disc space, as the distractors are each dimensioned to
approximately match a correspondingly dimensioned repair device.
Once a distractor has been selected, it is placed into the subject
disc space between two adjacent vertebral bodies to distract the
bodies. As one of ordinary skill in the art will appreciate, each
of the distractors in the series is constructed to provide a
certain amount of interdiscal distraction that restores the natural
lordosis of the lumbar and cervical spine.
[0029] Referring collectively to FIGS. 1A-1C, each distractor 10
generally comprises a body section 11 forming an posterior end 12
of the distractor 10 and a connector section 13 forming an anterior
end 14 of the distractor 10. The body section 11 includes a base
portion 15 and a tapered portion 16. The base portion 15 is formed
by parallel superior and inferior wall portions 17, 18 separated by
parallel side wall portions 19, 20. The tapered portion 16 defines
posterior converging superior and inferior wall portions 21, 22
that respectively extend from the parallel superior and inferior
wall portions 17, 18, and posterior converging side wall portions
23, 24 that respectively extend from the parallel side wall
portions 19, 20. The posterior converging superior, inferior, and
side wall portions 21, 22, 23, 24 meet at a posterior wall 25. The
edges 26 where the posterior converging superior, inferior, and
side wall portions 21, 22, 23, 24 meet the posterior wall 25 may be
radiused.
[0030] The posterior converging superior and/or inferior wall
portions 21, 22 of the tapered body portion 16, adjacent the base
body portion 15, may include one or more groove-like elements 27.
The groove-like elements 27 may extend across the posterior
converging superior and/or inferior wall portions 21, 22 in a
direction which is generally perpendicular to the longitudinal axis
AL of the distractor 10. The posterior converging superior and/or
inferior wall portions 21, 22 may also include indicia 41 to
indicate height, and/or cross-sectional size.
[0031] The posterior converging superior and inferior wall portions
21, 22 define a taper angle .theta. which matches the tapered
portion 16 of the body section 11 to the implant lordosis. In one
exemplary embodiment, the taper angle .theta. defined by the
posterior converging superior and inferior wall portions 21, 22,
may be about 7 degrees. It should be understood, however, that
other taper angles .theta. may be utilized, depending upon the
implant lordosis and the natural lordosis of the disc space being
operated on. Lordosis requires that the anterior height of the disc
space be greater than the posterior height. As shown in FIG. 1D,
the tapered body portion 16 of the distractor 10 reestablishes such
a disc space, and prepares a broad contact area for the repair
device. The contact area provided by the distractors 10 of the
present invention is unlike the disc space resulting from prior art
distractors.
[0032] Referring still to FIGS. 1A-1C, the connector section 13 of
the distractor 10 detachably couples the distractor/template handle
70 to the distractor 10 in a secure manner and aligns the template
50 with the distractor 10. By way of example but not limitation,
the connector section 13, when viewed from its anterior end 14 as
shown in FIG. 1 C, has an elongated configuration formed by
superior and inferior wall portions 28, 29 that merge into curved
side wall portions 30, 31. The superior, inferior, and side wall
portions 28, 29, 30, 31 extend between a posterior flange wall 32
and a generally planar anterior wall 33. The connector section
further includes a female coupling member formed by a T-shape slot
34. The T-shaped slot 34 defines inwardly facing locking flanges
35, 36 which cooperate with a correspondingly shaped male coupling
member 73 disposed at the marginal distal end of
distractor/template handle 70 to provide a bayonet coupling of the
handle 70 to the distractor 10. A chamfered pilot pin receiving
bore 37extends from surface 38 of the slot 34 and terminates in the
body section 11 of the distractor 10. The pilot pin receiving bore
37 is dimensioned to removably receive a pilot pin 78 formed at a
distal-most end of the distractor/template handle 70. The pilot pin
78/pilot pin bore 37 arrangement aids in aligning the male coupling
member 73 of the handle 70 with the anterior opening of connector
section slot 34 of the distractor 10. Once properly aligned, the
coupling member 73 can then be inserted into the slot 34 and
rotated (about 90 degrees) to engage the locking flanges 35, 36. To
prevent inadvertent relative rotation between the handle 70 and the
distractor 10, which would uncouple the handle 70 from the
distractor 10, one or more detent elements 40 are provided on
surface(s) 39 of the slot 34. The detent elements 40 coact with a
corresponding detent element(s) 77 formed on the male coupling
member 73 of the handle 70. In one exemplary embodiment, the detent
element(s) 40 provided in the slot 34 may be spring-biased ball
detent assemblies and the detent element(s) 77 formed on the male
coupling member 73 may be indents.
[0033] Referring collectively to FIGS, 2A-2C, the vertebrae
immobilizing template 50 comprises an elongated sleeve member 51,
which defines a reamer sleeve abutment surface 62 and an elongated
opening 52 that generally corresponds to the elongated
configuration of the connector sections 13 of the distractors 10.
The sleeve member opening 52 is dimensioned and configured so that
the template 50 can be placed about any of the distractors 10 and
is typically sized according to the cross-sectional size of the
repair device to be used as will be explained further on. The
sleeve member opening 52 defines opposing inner superior/inferior
surfaces 59 and opposing side inner surfaces 61. Prong mounting
ears 53 are formed on opposing sides of the sleeve member 51. Each
mounting ear 53 includes an posterior surface 54 and an anterior
surface 55. Spaced-apart prongs 56 extend from the posterior
surface 54 of the mounting ears 53. The anterior surface 55 of each
prong mounting ear 53 includes a handle impaction recess 57. The
inner surfaces 59 of the sleeve member opening 52 include recesses
60 that receive the opposing arms 75 of the male coupling member 73
of the handle 70. One or more detent elements 58 are disposed on
the inner surface(s) 59 of the sleeve member opening 52. The detent
elements 40 coact with the earlier described detent element(s) 77
of the male coupling member 73 of the handle, to couple the handle
70 to the template 50. In one exemplary embodiment, the detent
element(s) 58 may be spring-biased ball detent assemblies.
[0034] The vertebrae immobilizing template 50 is placed about the
distractor 10 after distraction without removing the distractor 10
from the disc space, and the prongs 56 thereof are impacted into
the distracted adjacent vertebral bodies to fix the positions. The
prongs 56 of the template 50 are impacted such that the mounting
ear posterior surfaces 54 of the template 50 are approximately
aligned in the same plane with the posterior flange wall 32 of the
distractor 10 as shown in FIG. 1D. This positions the chuck stop
106 provided on a proximal end 97 of a reamer sleeve 92 of the
reamer assembly 90 (FIG. 4A) to be described further on, at a fixed
distance from where the posterior wall 25 of the distractor 10 was
located in the disc space, prior to removal of the distractor 10
from the disc space. With an appropriate length reamer 94 of the
reamer assembly 90, this ensures that the reamer 94 will not cut
posterior of the position of the posterior wall 25 of the
distractor 10. The appropriate length reamer 94 can be determined
from the following mathematical relationship: RL-SL=DL+TL where RL
is the length of the reamer 94 (not including the chuck-shaft 99),
SL is the length of the reamer sleeve 92, DL is the length of the
distractor 10 between the posterior wall 25 and the posterior
flange wall 32, and TL is the length of the template 50 between the
reamer sleeve abutment surface 62 and the mounting ear posterior
surfaces 54. Accordingly, the template 50 advantageously enables
the reamer assembly 90 to be oriented to the final position of the
distractor 10. This is valuable in that fluoroscopic assessment is
only required for positioniinig the distractor 10, thus, minimizing
time and x-ray exposures in the operating room. This can be
advantageously accomplished without removing the distractor 10 from
the disc space. The template 50 is then used for guiding the reamer
assembly.
[0035] As collectively shown in FIGS. 3A and 3B, the handle 70 is
used for inserting a distractor 10 between the vertebral bodies and
tapping the distractor 10 into the disc space to distract the
bodies. The handle 70 is also used for removing the distractor 10
from the disc space. Additionally, the handle 70 is used for
placing the template 50 about the distractor 10 while it is
disposed in the disc space, and impacting the prongs 56 of the
vertebrae immobilizing template 50 into the distracted adjacent
vertebral bodies. The handle 70 typically includes an elongated
driver shaft 71 and a handle grip 72 having a diameter D.sub.H
which may be greater than the diameter D.sub.S of the shaft 71.
Disposed at the distal end of the shaft 71 is the earlier described
male coupling member 73, The male coupling member 73 may be a
T-shape element formed by a cylindrical body 74 and the earlier
described opposing arms 75, the ends of which define arcuate end
surfaces 76. The end surfaces 76 include the corresponding detent
elements 77 which may be indents as described earlier, that are
capable of coacting with the detent elements 40, 58 of the
distractors 10 and the template 50. The pilot pin 78 described
earlier extends from the male coupling member 73 to define the
distal-most end of the handle 70. The edge of the pilot pin 78 may
be beveled to aid insertion into the pilot pin receiving bore 37 of
the distractor 10. An annular impaction member 79 is disposed at
the base of the male coupling member body 74 and is attached
thereto by spokes 80. The impaction member 79 engages the handle
impaction recesses 57 in the anterior surface 55 of each prong
mounting ear 53 of the vertebrae immobilizing template 50.
[0036] The handle grip 70 may be provided with a knurled surface 81
or other means for facilitating secure manual gripping of the
handle 70. A proximal end 82 of the handle grip 81 is typically
provided with a convex surface 83 against which a mallet or other
like device may be used to tap the handle 70.
[0037] The reamer assembly 90 shown in FIG. 4A, comprises an
elongated reamer sleeve 92 and a series of differently dimensioned
or sized reamers 94 (only one is shown). Each reamer 94 includes a
shaft-like body 95 having a frustoconical end-mill 98 defined at a
distal end 96 thereof and a chuck-shaft 99 defined at a proximal
end 97 thereof. A cylindrical stop member 100 is disposed
proximally to the end-mill 98 on the body 95. The chuck-shaft 99
enables the reamer 94 to be mounted in a chuck 110 of a reamer
rotating device 109, such as a drill. The frustoconical end-mill 98
has a tapered profile that approximately matches the taper angle
.theta. of the distractors 10. The exterior surface of the
frustoconical end-mill 98 typically includes a plurality of bone
cutting elements 101 for cutting tissue from the opposing endplates
of the distracted vertebral bodies. The bone cutting elements 101
may be configured, in one exemplary embodiment, as longitudinal
flutes. This construction enables the reamer 94 to simultaneously
prepare the opposing endplates of the distracted adjacent vertebral
bodies as it is passed across the endplates. The end-mills 98 of
the reamers 94 are each sized so as to controllably remove a
specified amount of tissue off of the opposing endplates of the
vertebral bodies. The size of each reamer end-mill 98 corresponds
to the size of a corresponding distractor 10. Thus, the particular
reamer 94 selected for preparing the endplates is based on the
distractor 10 selected for distraction. Nonlinear geometries can be
accommodated through modifications to the shape of template 50 and
reamer end-mill 98.
[0038] The sleeve 92 includes a cylindrical body 102 that is
dimensioned to rotatively receive the reamers 94. The cylindrical
body 102 includes an enlarged cylindrical section 104 at a distal
end 103 thereof and a chuck stop 106 at a proximal end 105
thereof.
[0039] As best shown in FIG. 4B, the enlarged cylindrical section
104 includes a distal edge surface 107 for engaging the reamer
sleeve abutment surface 62 of the template 50. The distal edge
surface 107 includes reliefs 108 for clearing the mounting ears 53
of the template 50.
[0040] As shown in FIG. 4C, the sleeve 92 operates to limit the
depth of the reamer 94 travel into the disc space as the chuck 110
of the reamer rotating device 109 contacts the chuck stop 106 of
the reamer sleeve 92. Side-to-side travel of the reamer 94 is
limited by the cylindrical stop 100 on the reamer 94, which engages
the opposing side lumer surfaces 61 of the template 50.
[0041] The instruments 10, 50, 70, 90 of the system are typically
made from stainless steel. One of ordinary skill in the art will of
course appreciate that one or more of the instruments 10, 50, 70,
90 may be made from any other suitable bio-compatible material.
[0042] The following surgical technique, known in the art as an
anterior interbody fusion, illustrates the interaction of the
instruments 10, 50, 70, 90 of the instrument system of the present
invention as used in the implantation of an exemplary fusion
device, such as an alif device constructed from HEDROCEL.RTM.,
which is available from Implex Corporation.
[0043] Preoperatively, the surgeon must decide which intervertebral
levels to fuse. This may be done using a variety of diagnostic
techniques, such as radiographs, MRT, discography, patient history,
and physical examination.
[0044] For the L5/S1 level, the patient is positioned in the supine
position, with a pad under the lumbar spine to maintain lordosis.
For higher levels, the surgeon may choose either a supine position
or a lateral decubitus position. In either case, a table should be
used that accommodates both lateral and anterior-posterior
radiographs.
[0045] A vascular or general surgeon usually provides the exposure
while the spine surgeon assists and then performs the fusion. To
access the L5/S1 level, the lumbar spine is exposed through a low
transverse or paramedian incision while a retroperitoneal plane is
developed. For higher levels, it may be more appropriate to use a
midaxillary incision aligned over the level to be treated.
[0046] The device(s) are implanted in an anterior-posterior
direction so that the retroperitoneal plane must be developed from
the anterior direction.
[0047] Standard general and/or vascular surgical instruments are
used to perform the exposure down to the level(s) of the fusion.
They are also used to maintain the exposure via the appropriate
retractors.
[0048] The exposure is completed when the anterior surface of the
spine is exposed.
[0049] To identify the correct disc level(s) and that the approach
is in the appropriate place, needle(s) are inserted into the
intervertebral disc as markers, and the location(s) determined by
means of a C-arm anterior-posterior radiograph. If the needle is
not along the midline, it should be repositioned and an additional
radiograph taken to assure its proper location.
[0050] Iliac crest autograft is harvested from the iliac crest.
This can be done using standard techniques. Depending on the size
and height of the device used, approximately 0.5 to 1.5 cc.sup.3 of
bone is required at each fusion level, The bone graft does not
provide structural support but instead is used for its biological
properties to stimulate bone formation.
[0051] An annulotomy is performed using a scalpel to make a window
in the annulus. It should be centered about the midline. It should
be as long as the space to be occupied by the implant(s).
[0052] Pituitary rongeurs and small curettes can be used to perform
the discectomy.
[0053] Based on radiographic evaluation, an initial distractor 10
is selected. It is assembled to the handle 70. The pilot pin 78 on
the handle 70 fits within a receiving bore 37 on the anterior
surface 38 of the distractor 10. The handle 70 is rotated to align
the male coupling member 73 of the handle 70 with the slot 34 in
the connector section 13 of the distractor 10, The handle 70 is
advanced until the pilot pin 78 is fully engaged. The handle 70 is
rotated 90 degrees to engage the ball detents 40 that help hold the
handle 70 in place relative to the distractor 10.
[0054] As shown in FIG. 5, the distractor 10 is placed into the
interdiscal space, using the handle 70 to manipulate it. The
distractor 10 is inserted under intermittent lateral
fluoroscopic/radiographic evaluation until the distractor 10 is
appropriately seated posteriorly, a few millimeters anterior of the
posterior border of the body.
[0055] The distractors 10 are changed until the appropriate height
of the distractor 10 is determined The height of the distractor 10
is appropriate when the annulus is fully tensioned. Tensioning is
checked by fully seating a distractor 10 and then pulling on the
handle 70 to remove it. When the distractor 10 disengages easily, a
larger distractor 10 should be placed. When the appropriate
distractor 10 is determined and in place, the handle 70 is removed
as shown in FIG. 6.
[0056] Once the distractor 10 is fully seated in the disc space and
the handle 70 is removed, the cross sectional size of the device is
determined from the grooves 27. on the superior and inferior
surfaces 21, 22 of the distractor 10. These grooves 27 are visible
from lateral fluoroscopy/radiograph. Each groove 27 corresponds to
an implant cross section and to a template 50 size as well.
[0057] After the appropriate distractor 10 has been placed into the
interdiscal space, the handle 70 is assembled to the appropriately
sized template 50. Ball detents 58 of the template 50 indicate the
appropriate orientation of the handle 70 with respect to the
template 50. This assembly is then placed over the distractor 10
and slid into place. As shown in FIG. 7, a mallet is used with the
handle 70 to impact the template 50 into the two vertebral bodies.
The prongs 56 on the template 50 engage the adjacent vertebral
bodies and hold the template 50 in place. Impaction continues until
the template 50 bottoms out on the distractor 10. This fixes the
position of the template 50 relative to the posterior edge of the
distractor 10. The handle 70 is then rotated 90 degrees. The ball
detents 40 from the distractor 10 engage the handle 70, indicating
the appropriate position. The distractor 10 is then withdrawn,
leaving the template 50.
[0058] As shown in FIG. 8, the endplates are then prepared using
the reamer assembly 90 having an appropriately sized one of the
reamers 94 installed in the reamer sleeve 92. The reamer assembly
90 is used to remove a fixed amount of bone off of the endplates,
based on the fit of the initial distractor 10. The reamer sleeve 92
prevents the rotation of the reamer 94 from catching adjacent
tissue. The sleeve 92 also limits the penetration of the reamer 94
into the disc space as mentioned earlier. The reamer assembly 90
mates with the template 50. The template 50 limits the lateral
motion of the reamer assembly 90. The template 50 and reamer
assembly 90 result in removal of approximately 1.5 mm from each
endplate. The reamer assembly 90 is then removed as shown in FIG.
9.
[0059] One Hedrocel ALIF device is used at a single level. The
proper implant size is determined by the insertion depth of the
distractor 10 and the distractor height used.
[0060] The following steps describe the insertion of a single
implant 110. Placement of the implant 120 is typically along the
midline. On a sterile table, the hole(s) of the appropriately sized
implant 120 is stuffed with the already harvested autologous bone.
The implant 120 is then placed on an inserter 121. As shown in FIG.
10, the implant 120 is passed through the template 50, into the
space and the inserter 121 removed. The implant 120 is fully seated
using a tamp 122 as shown in FIG. 11.
[0061] The implant's height is sized so that it will further
distract the vertebral bodies by approximately 1/2 mm beyond the
distraction of the initial device.
[0062] Following final implant insertion, lateral and AMP
radiographs may be taken to assure proper implant placement. Once
proper placement is assured, the template 50 is removed as shown in
FIG. 12, using the handle 70 (not shown).
[0063] While the foregoing invention has been described with
reference to the above embodiments, various modifications and
changes can be made without departing from the spirit of the
invention. Accordingly, all such modifications and changes are
considered to be within the scope of the appended claims.
* * * * *