U.S. patent application number 13/429246 was filed with the patent office on 2012-08-16 for methods and systems for repairing an intervertebral disc using a transcorporal approach.
This patent application is currently assigned to TransCorp, Inc.. Invention is credited to David Lowry, Desmond O'Farrell, Scott Tuinstra, Roger Veldman.
Application Number | 20120209387 13/429246 |
Document ID | / |
Family ID | 40383589 |
Filed Date | 2012-08-16 |
United States Patent
Application |
20120209387 |
Kind Code |
A1 |
Lowry; David ; et
al. |
August 16, 2012 |
Methods and Systems for Repairing an Intervertebral Disc Using a
Transcorporal Approach
Abstract
The invention includes a system and methods for performing
surgery on a spinal disc. The system includes an implantable bone
plate with an access port to accommodate a bone cutting device, a
spinal repair device insertable through the access port of the bone
plate configured to occupy a surgically-formed vertebral channel
from an anterior surface of the host vertebral body to a site
central to an end plate of the host vertebral body, a trajectory
control sleeve engageable to the bone plate to direct the
trajectory of a cutting device, and a cutting device engageable
within the trajectory control sleeve. Methods are directed to
forming a vertebral channel and restoring the vertebral body and
disc with devices that both repair the bone and the disc.
Inventors: |
Lowry; David; (Holland,
MI) ; O'Farrell; Desmond; (Grand Rapids, MI) ;
Tuinstra; Scott; (Holland, MI) ; Veldman; Roger;
(Hudsonville, MI) |
Assignee: |
TransCorp, Inc.
Ada
MI
|
Family ID: |
40383589 |
Appl. No.: |
13/429246 |
Filed: |
March 23, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12323361 |
Nov 25, 2008 |
8163021 |
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13429246 |
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60990587 |
Nov 27, 2007 |
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Current U.S.
Class: |
623/17.16 |
Current CPC
Class: |
A61F 2/28 20130101; A61F
2002/3085 20130101; A61B 17/1757 20130101; A61F 2002/30574
20130101; A61F 2002/30583 20130101; A61F 2002/2835 20130101; A61F
2002/4685 20130101; A61F 2002/2817 20130101; A61F 2002/444
20130101; A61B 2017/00544 20130101; A61F 2/442 20130101; A61B
17/8827 20130101; A61F 2002/30576 20130101; A61F 2002/30563
20130101; A61B 17/7059 20130101; A61F 2/4611 20130101; A61B 17/1728
20130101; A61B 2017/564 20130101; A61F 2002/30601 20130101; A61F
2210/0085 20130101; A61F 2002/30693 20130101; A61F 2/44
20130101 |
Class at
Publication: |
623/17.16 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. A spinal repair device comprising at least one lumen
communicating between a proximal end of the device and a distal end
of the device, the device sized and configured to occupy at least a
portion of a surgically-formed transcorporal channel in a vertebral
body that extends on a trajectory from a non end-plate surface to
an end plate where an opening of the channel communicates into an
intervertebral space, the at least one lumen sized and configured
to (selectively) permit the flow therethrough of a disc replacement
material.
2. The spinal repair device of claim 1 wherein the at least one
lumen comprises a flow path for a liquid state disc repair
material.
3. The spinal repair device of claim 1 wherein the at least one
lumen comprises a flow prevention element that prevents egress of a
liquid state disc repair material from the intervertebral
space.
4. The spinal repair device of claim 1 wherein the at least one
lumen comprises two channels, a first channel configured for liquid
flow into the intervertebral space, and a second channel configured
to allow liquid or gas egress from the intervertebral space.
5. The spinal repair device of claim 1 wherein the device comprises
a surface portion sufficiently porous to allow in-growth of
bone.
6. The spinal repair device of claim 1 comprising a biologically
compatible material.
7. The spinal repair device of claim 6 comprising any of a polymer,
a metal, a ceramic, or a combination thereof.
8. The spinal repair device of claim 1 comprising an osteogenic
agent.
9. The spinal repair device of claim 1 comprising a porous
cage.
10. The spinal repair device of claim 9 wherein a bone cell
preparation is included within the porous cage.
11. The spinal repair device of claim 1 comprising a biologically
absorbable material.
12. The spinal repair device of claim 1 wherein the device is
linear in form, such linear form configured to occupy a linear
transcorporal channel.
13. The spinal repair device of claim 1 wherein the device is
arcuate in form, such arcuate form configured to occupy an arcuate
transcorporal channel.
14. A system for spinal disc surgery comprising: a spinal repair
device according to claim 1; and a trajectory control apparatus
adapted to attach to the non-end plate surface of the vertebral
body and comprising a portion configured to hold at least a portion
of a bone cutting tool such that when the apparatus is engaged to
the vertebral body, the bone cutting tool is positioned to form the
transcorporal channel.
15. The system of claim 14 wherein the trajectory control apparatus
comprises a cutting tool holder portion and an implantable bone
plate portion, the cutting tool holding portion detachably
engageable to the implantable bone plate portion.
16. The system of claim 15 wherein the cutting tool holder portion
comprises a sleeve that receives at least a portion of a cutting
tool.
17. The system of claim 15 wherein the cutting tool holder has a
bone plate engagement feature and the bone plate has a cutting tool
holder engagement feature, the respective engagement features
configured such that when the bone plate is attached to the
vertebral body, and the cutting tool holder and the bone plate are
mutually engaged, the cutting tool holder is oriented to direct a
cutting tool on the trajectory.
18. The system of claim 15 wherein the bone plate portion comprises
an access port configured to accommodate a cutting portion of a
bone cutting tool and to accommodate through passage of the spinal
repair device.
19. The system of claim 14 further comprising a bone cutting tool
adapted to form the transcorporal channel, at least a portion of
the bone cutting tool configured to be movably held by the
trajectory control apparatus.
20. The system of claim 19, wherein the cutting tool comprises a
mechanical stop configured to limit the penetration of the cutting
tool into the vertebral body.
21. The system of claim 14 further comprising an injector
configured to deliver a disc replacement material through the
internal cannula of the spinal repair device and into an
intradiscal void.
22. The system of claim 21 further comprising a valve device
coupled with the injector, the valve device having at least two
input ports and at least one output port, the output port being in
fluid communication with the injector; a vacuum delivery device in
fluid communication with one of the two input ports of the valve
device; and a reservoir device containing the disc replacement
material in communication with the second of the two input ports of
the valve device.
23. The system of claim 21 wherein the injector comprises a channel
configured to allow liquid or gas egress from the intervertebral
space.
24. The system of claim 21 wherein the disc replacement material
comprises a flowable substance.
25. The system of claim 24 wherein the flowable substance comprises
any of a liquid, a settable liquid, a liquid-to-solid phase
changing material, a gel, a suspension, or a slurry.
26. A spinal repair device sized and configured to occupy at least
a portion of a surgically-formed transcorporal channel in a host
vertebral body and at least a portion of an intervertebral space
adjacent to the host vertebral body, the device comprising: a
proximal portion sized to occupy at least a portion of the
transcorporal channel, the channel having a trajectory that extends
from a non-end plate surface to an end plate where a channel
opening communicates into the intervertebral space; and a distal
portion sized to extend from the end plate of the host vertebral
body into the intervertebral space.
27. The spinal repair device of claim 26 wherein the distal portion
extends to a point where it comes into intimate contact with an
endplate of an adjacent vertebral body.
28. The spinal repair device of claim 26 wherein the proximal
portion is adapted to replace at least a portion of bone and the
distal portion is adapted to replace at least a portion of an
intervertebral disc.
29. The spinal repair device of claim 26 wherein the proximal
portion and the distal portion of the spinal repair device are of
different composition.
30. The spinal repair device of claim 26 wherein at least a portion
of the external surface of the proximal portion of the device is
sufficiently porous to allow in-growth of bone.
31. The spinal repair device of claim 26 wherein the proximal
portion of the device comprises an osteogenic agent.
32. The spinal repair device of claim 26 wherein the proximal
portion of the device comprises a porous cage.
33. The spinal repair device of claim 32 wherein a bone cell
preparation is included within the porous cage.
34. The spinal repair device of claim 26 wherein the distal portion
of the spinal repair device comprises a resilient composition.
35. The spinal repair device of claim 26 wherein the distal portion
of the spinal repair device comprises a distal surface adapted to
articulatingly engage the end plate of the adjacent vertebral
body.
36. The spinal repair device of claim 26 wherein the device is
linear in form, such linear form configured to occupy a linear
transcorporal channel.
37. The spinal repair device of claim 26 wherein the device is
arcuate in form, such arcuate form configured to occupy an arcuate
transcorporal channel.
38. The spinal repair device of claim 26 further comprising at
least one lumen communicating between an opening on the proximal
end of the device and an opening on the distal end of the device,
the channel comprising a flow path for a flowable disc replacement
material.
39. A system for spinal disc surgery comprising: a spinal repair
according to claim 26; and a trajectory control apparatus adapted
to attach to the non-end plate surface of the vertebral body and
comprising a portion configured to hold at least a portion of a
bone cutting tool such that when the apparatus is engaged to the
vertebral body, the bone cutting tool is positioned to form the
transcorporal channel.
40. The system of claim 39 wherein the trajectory control apparatus
comprises a cutting tool holder and an implantable bone plate
portion, the cutting tool holding portion detachably engageable to
the implantable bone plate portion.
41. The system of claim 40 wherein the cutting tool holding portion
comprises a sleeve that receives at least a portion of a cutting
tool.
42. The system of claim 40 wherein the cutting tool holder has a
bone plate engagement feature and the bone plate has a cutting tool
holder engagement feature, the respective engagement features
configured such that when the bone plate is attached to the
vertebral body, and the cutting tool holder and the bone plate are
mutually engaged, the cutting tool holder is oriented to direct a
cutting tool on the trajectory.
43. The system of claim 40 wherein the bone plate portion comprises
at least one access port configured to accommodate a cutting
portion of a bone cutting tool and to accommodate through passage
of the spinal repair device.
44. The system of claim 39 comprising two spinal repair devices,
the devices configured to occupy dual surgically-formed
transcorporal channels.
45. The system of claim 39 further comprising a bone cutting tool
adapted to form the transcorporal channel, at least a portion of
the bone cutting tool configured to be accommodated by the
trajectory control apparatus.
46. The system of claim 45, wherein the cutting tool comprises a
mechanical stop configured to limit the penetration of the cutting
tool into the host vertebral body.
47. The system of claim 39 further comprising a disc replacement
material comprising any of a liquid, a liquid that can solidify, a
liquid-to-solid phase changing material, a fabric, or a solid, or
any combination of these materials.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional patent application which
claims priority to U.S. patent application Ser. No. 12/323,361, of
Lowry et al., entitled "Methods and Systems for Repairing an
Intervertebral Disc Using a Transcorporal Approach", as filed on
Nov. 25, 2008 (pending); which claims priority to U.S. Provisional
Patent Application No. 60/990,587 of Lowry et al., entitled
"Methods and Systems for Repairing an Intervertebral Disc Using a
Transcorporal Approach", as filed on Nov. 27, 2007 (expired).
FIELD OF INVENTION
[0002] The invention relates to a system and methods of spinal
surgery. More particularly, the invention provides a system,
devices, and methods to create a surgical access channel between a
surgically-exposed surface of a vertebra and the end plate bone
tissue of the vertebra adjacent the degenerated disc.
INCORPORATION BY REFERENCE
[0003] All publications, patents and patent applications mentioned
in this specification, either by inventors common to this
application or other inventors, are herein incorporated by
reference to the same extent as if each individual publication,
patent or patent application was specifically and individually
indicated to be incorporated by reference.
[0004] In particular, the following U.S. patent applications
include related subject matter, and are incorporated in their
entirety by this reference: U.S. patent application Ser. No.
11/855,124 of Lowry et al. (filed on Sep. 13, 2007, and entitled
"Implantable bone plate system and related method for spinal
repair"), U.S. patent application Ser. No. 12/210,109 of Lowry et
al. (filed on Sep. 12, 2008, entitled "Device and method for tissue
refraction in spinal surgery"), U.S. patent application Ser. No.
12/210,089 of Lowry et al. (filed on Sep. 12, 2008, entitled
"Transcorporeal spinal decompression and repair system and related
method"), and U.S. patent application Ser. No. 12/239,431 of Lowry
et al. (filed on Sep. 26, 2008, entitled "Vertebrally mounted
tissue retractor and method for use in spinal surgery").
BACKGROUND OF THE INVENTION
[0005] Intervertebral discs provide articulating means and
mechanical stress absorption in the spine and further serve to
permit controlled motion across vertebral segments. Vertebral discs
degenerate progressively as a result of the natural aging process,
and injury or disease, and with physical degeneration comes a loss
in thickness or height of the disc, and a loss in their capacity to
support a load and to absorb shock. Physically, disc degeneration
can present in the form of the disc bulging material beyond its
normal anatomical space or with collapse of the disc, both
conditions being associated with spinal stenosis. Degenerative disc
disease is variously associated with axial neck or back pain, a
loss of normal spinal motion or increased abnormal motion, back
pain, numbness, tingling, or weakness in one or more limbs.
[0006] In other instances a sudden physical stress on the spine can
cause a defect to occur on the fibrous outer ring of the disc, the
annulus fibrosis. In these cases the inner disc material, the
nucleus pulposus, can rupture or protrude beyond the outer surface
of the annulus, or shift outward a portion of the ring of the
annulus fibrosis, resulting in an impingement on an adjacent neural
structure. This is commonly referred to as a disc herniation,
protrusion, or rupture, and typically causes symptoms similar to
those of degenerative disc disease.
[0007] Nerve root impingements related to disc degeneration can
occur throughout the spine but are most common in the lumbar and
cervical regions. Most symptomatic disc degenerations occur
posteriorly, and are thus particularly problematic as they are
immediately adjacent to the spinal cord and nerve roots, and
thereby prone to inducing neural impingement.
[0008] There are various treatment options for degenerative disc
disease and disc herniations. Mild degenerative disc disease is
often treated non-surgically, but more severe cases often require
surgical treatment. These treatments may include the removal of the
disc (discectomy), a reconditioning of the disc using a synthetic
substance added to the nucleus (nucleoplasty), artificial total
disc replacement (arthroplasty), or a spinal fusion procedure
(arthrodesis). Recent trends in spine surgical development have
focused on the replacement or repair of damaged discs with various
biocompatible implants or repair devices. While a total disc
arthroplasty in the cervical spine is presently done from an
anterior surgical approach to the spine, a reconditioning of any
disc may be achieved injecting an artificial nucleus pulposus
material through a defect surgically created in the annulus
fibrosis in the course of resecting compressing disc material.
[0009] Presently, current techniques for reconditioning the nucleus
pulposus with a synthetic material or performing a total disc
arthroplasty (disc replacement) require that a defect be made in
the outer rim of the disc, the annulus fibrosis. The annulus defect
may be several millimeters wide, as when injecting a nucleus
reconditioning substance such as NuCore (Spine Wave, Inc., Shelton,
Conn.), or it may be as large as several centimeters, as when doing
a disc arthroplasty. Any defect in the annulus, however, can
initiate a post-operative herniation or migration of the implanted
reconditioning substance out of the normal interior space of the
disc. This undesirable result can induce a compression of an
adjacent neural structure and/or induce a collapse of the
intervertebral disc.
[0010] Some improvements have been made in surgical approaches to
disc damage or disease, as exemplified by U.S. Pat. Publ. No.
2006/0271198 of McAfee, U.S. Pat. Publ. No. 2005/0149046 of
Friedman, and U.S. Pat. Publ. No. 2006/0074424 of Alleyne. There
remains a need, however, specifically for approaches by which the
inner portion, the nucleus pulposus, of the vertebral discs,
particularly cervical discs, can be accessed and repaired,
restored, or replaced without violating the annulus fibrosis of the
disc.
SUMMARY OF THE INVENTION
[0011] The invention provides a system with devices and methods by
which to utilize the system and devices to form and repair an
intervertebral channel useful in surgical procedures involving
repair or replacement of at least a portion of the intervertebral
disc, such portion typically involving the central portion of the
disc, the nucleus pulposis. The channel is transcorporal in nature,
i.e., it traverses through a vertebral body and approaches the disc
from a central aspect that preserves the integrity of the
peripheral portion of the disc, the annulus fibrosis. Embodiments
of the invention also include repair devices that fill the channel
once the channel has fulfilled its function as well as substitute
disc materials that functionally replace a damaged or excised
portion of a disc. Embodiments of these bone repair devices include
ones that have a lumen communicating between the proximal and
distal ends of the device for the delivery of a flowable substitute
disc material into the intervertebral space. Other bone repair
device embodiments have a portion that occupies the transcorporal
channel, but also another portion that extends into the
intervertebral space to functionally replace a disc. Some of these
latter embodiments may also include a lumen for the delivery of
flowable substitute disc material that may augment support provided
by the bone repair device itself, or help to support the integrity
of the intervertebral space.
[0012] An embodiment of a spinal repair device, according to this
invention, includes at least one lumen communicating between a
proximal end of the device and a distal end of the device. The
device embodiment is sized and configured to occupy at least a
portion of a surgically-formed transcorporal channel in a vertebral
body that extends on a trajectory from a non end-plate surface to
an end plate where an opening of the channel communicates into an
intervertebral space, the at least one lumen sized and configured
to permit the flow therethrough of a disc replacement material. The
trajectory of the channel, and by extension, the trajectory of a
spinal repair device may be understood as a prescribed trajectory
inasmuch as the optimal course of the channel and device are
precisely planned by a surgeon prior to operating, such
prescription based on the medical aspects and spinal dimensions of
the patient.
[0013] With regard to the lumen or internal channel feature of the
spinal repair device, in some embodiments, the at least one lumen
provides a flow path for a liquid state disc repair material. In
some embodiments, the lumen includes a flow prevention element that
prevents egress of a liquid state disc repair material from the
intervertebral space. And in some embodiments, the lumen includes
two channels, a first channel configured for liquid flow into the
intervertebral space, and a second channel configured to allow
liquid or gas egress from the intervertebral space.
[0014] Some aspects and features of the implantable spinal repair
device relate to the biocompatibility of the device and to its
ability to integrate into the bone of the host vertebral body.
Thus, in some embodiments, the device includes a surface portion
that is sufficiently porous to allow in-growth of host bone. Some
embodiments of the device include a biologically compatible
material, which may include any of a polymer, a metal, a ceramic,
or a combination thereof. In some embodiments, the device may
include biologically absorbable material. Some embodiments of the
device include an osteogenic agent incorporated into the device
composition. In some embodiments, the device is formed in whole or
in part from a porous cage, which permits passage of biological
fluid and cells. In some of these embodiments, a bone cell
preparation is included within the porous cage; these cells may be
derived as an autograft preparation from the patient, from a
compatible donor individual, and further, bone cells from any
source may be cultured in an in vitro system prior to
implantation.
[0015] With regard to the form and dimensions of the implantable
bone repair device, some embodiments of the device are linear in
form, such linear form configured to occupy a linear transcorporal
channel. Other embodiments may be arcuate in form, such arcuate
form configured to occupy an arcuate transcorporal channel.
Embodiments of the device typically have a length that ranges from
about 8 mm to about 20 mm and a diameter that ranges from about 3
mm and about 7 mm.
[0016] An embodiment of a system for spinal disc surgery, according
to this invention, includes the above-summarized spinal repair
device which includes the lumen, as well as a trajectory control
apparatus adapted to attach to the non-end plate surface of the
vertebral body and comprising a portion configured to hold at least
a portion of a bone cutting tool such that when the apparatus is
engaged to the vertebral body, the bone cutting tool is positioned
to form the transcorporal channel. In these embodiments of a
system, the trajectory control apparatus includes a cutting tool
holder portion and an implantable bone plate portion; the cutting
tool holding portion is detachably engageable to the implantable
bone plate portion. Some embodiments of the cutting tool holder
include a sleeve that receives at least a portion of a cutting
tool. In some of these trajectory control apparatus embodiments,
the cutting tool holder has a bone plate engagement feature and the
bone plate has a cutting tool holder engagement feature; the
respective engagement features are configured such that when the
bone plate is attached to the vertebral body, and the cutting tool
holder and the bone plate are mutually engaged, the cutting tool
holder is oriented to direct a cutting tool on the trajectory. In
some of these trajectory control apparatus embodiments, the bone
plate portion includes an access port configured to accommodate a
cutting portion of a bone cutting tool and to accommodate through
passage of the spinal repair device.
[0017] Some embodiments of the system for spinal surgery include a
bone cutting tool that is adapted to form the transcorporal
channel; at least a portion of the bone cutting tool is configured
to be movably held by the trajectory control apparatus. In some of
these embodiments, the cutting tool includes a mechanical stop
configured to limit the penetration of the cutting tool into the
vertebral body.
[0018] Some embodiments of the system for spinal surgery include an
injector that is configured to deliver a disc replacement material
through the internal cannula of the spinal repair device and into
an intradiscal void. These injector-including system embodiments
may further include a valve device coupled with the injector, the
valve device having at least two input ports and at least one
output port (the output port being in fluid communication with the
injector), a vacuum delivery device in fluid communication with one
of the two input ports of the valve device, and a reservoir device
containing the disc replacement material in communication with the
second of the two input ports of the valve device. In some of these
embodiments, the injector includes a channel that is configured to
allow liquid or gas egress from the intervertebral space. In these
injector-including embodiments, the disc replacement material is
typically a flowable substance, which may include, for example, any
of a liquid, a settable liquid, a liquid-to-solid phase changing
material, a gel, a suspension, or a slurry.
[0019] An embodiment of a method for accessing and repairing an
intervertebral disc in the spine, according to this invention,
makes use of the above-summarized device which includes a lumen,
and the summarized system that includes such a device. The method
embodiment includes engaging a trajectory control apparatus to a
non-endplate surface of a vertebral body; forming a transcorporal
channel in a vertebral body with a trajectory that extends from a
non end-plate surface to an end plate where a channel opening
communicates into an intervertebral space; implanting into the
transcorporal channel a spinal repair device sized and configured
to occupy at least a portion of the channel; and injecting a disc
replacement material through the spinal repair device and into a
void within a space formerly occupied by at least a portion of the
intervertebral disc. In some embodiments of this method, forming a
transcorporal channel that extends from a non end-plate surface
includes forming the channel from any of an anterior surface, a
lateral surface, a posterior aspect of a pedicle, or a posterior,
or posterolateral surface.
[0020] In some embodiments of the method, the engaging step
includes implanting a bone plate portion of the trajectory control
apparatus on the non-endplate surface of the vertebral body and
then engaging a bone cutting tool holder portion of the trajectory
control apparatus to the bone plate. In some of these embodiments,
implanting a bone plate on the non-endplate surface of the
vertebral body includes securing it to the surface with one or more
fastening elements. And in some embodiments, the method may further
include removing the bone plate after implanting it.
[0021] Some embodiments of method may also include removing at
least a portion of the intervertebral disc through the
transcorporal channel before injecting the disc replacement
material, and in some of these particular embodiments, removing at
least a portion of the intervertebral disc includes removing the
nucleus pulposis and leaving the annulus fibrosis intact.
[0022] Some embodiments of the method may further include allowing
gas from within the intervertebral space to escape through the
spinal repair device during the injecting step. In some embodiments
of the method, forming the transcorporal channel includes cutting
bone with a bone-cutting tool. In some embodiments of the method,
implanting the spinal repair device comprises compressively
engaging an external surface of the spinal repair device with
cancellous bone of the host vertebral body.
[0023] Another embodiment of a spinal repair device, according to
this invention, includes a spinal repair device sized and
configured to occupy at least a portion of a surgically-formed
transcorporal channel in a host vertebral body and at least a
portion of an intervertebral space adjacent to the host vertebral
body. This embodiment of the device has a proximal portion sized to
occupy at least a portion of the transcorporal channel, the channel
having a trajectory that extends from a non-end plate surface to an
end plate where a channel opening communicates into the
intervertebral space, and a distal portion sized to extend from the
end plate of the host vertebral body into the intervertebral space.
In some embodiments of this latter device, the distal portion
extends to a point where it comes into intimate contact with an
endplate of an adjacent vertebral body.
[0024] The proximal and distal portions various embodiments of the
device may differ in composition, features, and function. For
example, the proximal portion may be adapted to replace at least a
portion of bone and the distal portion may be adapted to replace at
least a portion of an intervertebral disc. In being adapted to
generally replace bone or a portion of bone, at least the external
surface of the proximal portion may be sufficiently porous to allow
in-growth of bone. In some embodiments, the proximal portion of the
device may include an osteogenic agent within its composition. Some
embodiments of the proximal portion of the spinal repair device may
include a porous cage, and some of these embodiments, a bone cell
preparation may be included within that porous cage.
[0025] With regard to the distal portion of the spinal repair
device, some embodiments may include a resilient composition that
provides a shock-absorbing functionality similar to that of a
healthy and intact disc. Some embodiments of the distal portion may
include a distal surface adapted to articulatingly engage the end
plate of the adjacent vertebral body, which can replicate the
smooth low-friction slidable engagement that exists between a disc
surface and vertebral end plates.
[0026] Some embodiments of the device are linear in form, such
linear form configured to occupy a linear transcorporal channel.
Other embodiments of the device are arcuate in form, such arcuate
form configured to occupy an arcuate transcorporal channel. Some
embodiments of this repair device, with distinct proximal and
distal portions, may also include a lumen that communicates between
an opening on the proximal end of the device and an opening distal
end of the device, the channel comprising a flow path for a
flowable disc replacement material.
[0027] With regard to the form and dimensions of the implantable
bone repair device, some embodiments of the device are linear in
form, such linear form configured to occupy a linear transcorporal
channel. Other embodiments may be arcuate in form, such arcuate
form configured to occupy an arcuate transcorporal channel.
Embodiments of the device typically have a length that ranges from
about 12 mm to about 25 mm and a diameter that ranges from about 3
mm to about 7 mm.
[0028] An embodiment of a system for spinal disc surgery, according
to this invention, includes the above-summarized spinal repair
device which includes a proximal portion within the transcorporal
channel and a distal portion that extends into the intervertebral
space, and further includes a trajectory control apparatus adapted
to attach to the non-end plate surface of the vertebral body and
comprising a portion configured to hold at least a portion of a
bone cutting tool such that when the apparatus is engaged to the
vertebral body, the bone cutting tool is positioned to form the
transcorporal channel.
[0029] In some embodiments of this system, the trajectory control
apparatus includes a cutting tool holder and an implantable bone
plate portion, the cutting tool holding portion detachably
engageable to the implantable bone plate portion. In various of
these embodiments, the cutting tool holding portion includes a
sleeve that receives at least a portion of a cutting tool. In some
embodiments, the cutting tool holder has a bone plate engagement
feature and the bone plate has a cutting tool holder engagement
feature. These respective engagement features are configured such
that when the bone plate is attached to the vertebral body, and the
cutting tool holder and the bone plate are mutually engaged, the
cutting tool holder is oriented to direct a cutting tool on the
trajectory. In some embodiments of this system, the bone plate
portion includes at least one access port configured to accommodate
a cutting portion of a bone cutting tool and to accommodate through
passage of the spinal repair device.
[0030] Some embodiments of the system of claim may include two
spinal repair devices, the devices being configured to occupy dual
surgically-formed transcorporal channels. These channels are
typically parallel, and may be advantageous to the patient by
providing bilateral support within a vertebral body.
[0031] Some embodiments of the system may further include a bone
cutting tool that is adapted to form the transcorporal channel, and
at least a portion of the bone cutting tool is configured to be
accommodated by the trajectory control apparatus. In some
embodiments, the cutting tool includes a mechanical stop configured
to limit the penetration of the cutting tool into the host
vertebral body.
[0032] Embodiments of the system may further include a disc
replacement material which may be any of a liquid, a liquid that
can solidify, a liquid-to-solid phase changing material, a fabric,
or a solid, or any combination of these materials.
[0033] An embodiment of a method for accessing and repairing an
intervertebral disc in the spine, according to this invention,
makes use of the above-summarized spinal repair device which
includes a proximal portion within the transcorporal channel and a
distal portion that extends into the intervertebral space and the
system that further includes the trajectory control apparatus that
is adapted to attach to the non-end plate surface of a vertebral
body and has a portion configured to hold at least a portion of a
bone cutting tool. This method embodiment includes engaging a
trajectory control apparatus to a surface of a host vertebral body;
forming a transcorporal channel within a host vertebral body, the
channel extending from a surface of the host vertebral body on a
trajectory toward an intervertebral disc between the host vertebral
body and an adjacent vertebral body, and extending at least as far
as the end plate of the host vertebral body; replacing at least a
portion of the disc; and implanting a spinal repair device
configured to fit into the channel and extending into the
intervertebral space.
[0034] In some embodiments of the method, forming a transcorporal
channel that extends from a non end-plate surface includes forming
the channel from any of an anterior surface, a lateral surface, a
posterior aspect of a pedicle, or a posterior, or posterolateral
surface. In some embodiments of the method, forming the
transcorporal channel includes cutting bone with a bone-cutting
tool.
[0035] In some embodiments of the method, implanting a spinal
repair device includes placing a distal portion of the device in
intimate contact with the end plate tissue of the vertebral body
and a proximal portion in intimate contact with cancellous bone
tissue within the transcorporal channel. In some embodiments of the
method, implanting the spinal repair device comprises includes
engaging an external surface of the spinal repair device with an
internal surface of the transcorporal channel.
[0036] In some embodiments of the method, the engaging step may
include implanting a bone plate portion of the trajectory control
apparatus on the non-endplate surface of the vertebral body and
then engaging a bone cutting tool holder portion of the trajectory
control apparatus to the bone plate. In various of these
embodiments, implanting a bone plate on the non-endplate surface of
the vertebral body includes securing it to the surface with one or
more fastening elements. And some embodiments of the method may
further include removing the bone plate after implanting it. Such
removal may occur at various points, such as after forming the
transcorporal channel, after replacing a portion of the disc, or
after implanting the spinal repair device.
[0037] Some embodiments of the method may further include removing
at least a portion of the intervertebral disc through the
transcorporal channel before implanting the spinal repair device.
In particular embodiments of the method, removing a portion of a
disc includes removing a nucleus pulposis and leaving an annulus
fibrosis intact.
[0038] In some embodiments of the method, replacing at least a
portion of the disc comprises replacing the portion of the disc
with any of a any of a liquid, a liquid that can solidify, a
liquid-to-solid phase changing material, a fabric, or a solid, or
any combination of these materials. Some embodiments of the method
may further include injecting a flowable disc material through a
lumen in the spinal repair device into the intervertebral
space.
[0039] Another embodiment of a system for spinal disc surgery
includes a spinal repair device sized and configured to occupy at
least a portion of a surgically-formed transcorporal channel in a
vertebral body that extends on a trajectory from a non end-plate
surface to an end plate where an opening communicates into an
intervertebral space, a bone plate sized and configured to be
implantable on a surface of the host vertebral body and configured
to be engageable to a cutting tool holder, and a cutting tool
holder configured to detachably engage the bone plate and
configured to receive at least a portion of a bone cutting tool,
the cutting tool holder, when engaged to the bone plate, positioned
to guide the bone cutting tool to form the transcorporal channel
with the trajectory. These system embodiments may further include a
bone plate cover that is engageable to the bone plate and
configured to cover an opening of the transcorporal channel on the
non-endplate surface.
[0040] An embodiment of a method for accessing and repairing an
intervertebral disc in the spine, according to this invention,
makes use of the above-summarized system for spinal disc surgery
which includes spinal repair device, a bone plate, and a cutting
tool holder. This method embodiment includes engaging an
implantable bone plate to a non-endplate surface of a vertebral
body; detachably engaging a cutting tool holder to the implanted
bone plate; forming a transcorporal channel in a vertebral body
with a trajectory that extends from a non end-plate surface to an
end plate where an opening communicates into an intervertebral
space; implanting into the transcorporal channel a spinal repair
device sized and configured to occupy at least a portion of the
channel; and injecting a disc replacement material through the
spinal repair device and into a void within a space formerly
occupied by at least a portion of the intervertebral disc. Some of
the embodiments of this method further include installing a bone
plate cover on the bone plate and sealing an opening of the
transcorporal channel on the non-endplate surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIGS. 1A-1F are schematic cross-sectional views that
storyboard a method for creating an transcorporal access channel
within a vertebral body for accessing, repairing, replacing and/or
restoring intervertebral disc tissue and thereafter repairing the
intravertebral or transcorporal access channel with a bone repair
material, and affixing an implantable bone plate to the surface of
the vertebral bone tissue to prevent migration of the bone repair
implant out of the intravertebral access channel.
[0042] FIG. 1B shows the transcorporal access channel expanded so
as to include the central portion of an intervertebral disc.
[0043] FIG. 1C shows an injector penetrating the transcorporal
access channel and delivering a disc repair material into the void
within the disc, as in Figure B.
[0044] FIG. 1D shows the injector (FIG. 1B) having been withdrawn,
and the injected disc repair material having coalesced into a solid
form.
[0045] FIG. 1E shows a bone repair implant being inserted into the
transcorporal access channel.
[0046] FIG. 1F shows the bone repair implant completely in place,
and its proximal end covered and secured by a bone plate that is
attached to the vertebral body.
[0047] FIG. 2 is a perspective view of a vertebral body
illustrating a transcorporal access channel from an anterior
perspective.
[0048] FIG. 3 is a perspective view of a vertebral body showing the
exit point of the transcorporal access channel of FIG. 2 through
the vertebral end plate.
[0049] FIG. 4 is a cut away perspective view through a vertebral
bone segment along the centerline of the transcorporal access
channel, showing the access to nucleus pulposus of the
intervertebral disc through the access channel.
[0050] FIG. 5 is a perspective view that includes a cut away view
through a vertebral bone segment along the centerline of the
transcorporal access channel and illustrating the remaining annulus
fibrosis of the intervertebral disc after the nucleus pulposus has
been excised.
[0051] FIG. 6 is a lateral perspective view of adjacent vertebral
bodies and the annulus fibrosis of the intervertebral disc after
the nucleus pulposus has been excised.
[0052] FIG. 7 is a perspective view of adjacent vertebral bodies
with a cut away central focus on showing the nucleus pulposus
volume of the intervertebral disc filled with a substitute disc
material and the transcorporal access channel bone repair implant
in the pre-installation position.
[0053] FIG. 8 is a perspective view of adjacent vertebral bodies
showing the nucleus pulposus volume of the intervertebral disc
filled with a substitute disc material and the transcorporal access
channel bone repair implant in the installed position.
[0054] FIG. 9 is an anterior perspective of a vertebral body
showing a bone plate in the installed position, covering the
proximal end of the transcorporal repair implant device (not
visible).
[0055] FIG. 10 is a cross-section side view of two adjacent
vertebral bodies showing the completed disc repair, illustrating
the intact annulus fibrosis of the intervertebral disc, the
substitute disc material contained therein, the access channel bone
repair implant in the fully installed position and the bone plate
installed on the vertebral body.
[0056] FIG. 11 is an anterior view of a vertebral body with a bone
plate implanted on its anterior surface, with two integral tissue
access ports visible on the bone plate.
[0057] FIG. 12A is a side view of a vertebral body with a bone
plate implanted on its anterior surface, and a trajectory control
sleeve temporarily installed on the bone plate.
[0058] FIG. 12B is a side view of a vertebral body with a bone
plate and a trajectory control sleeve as in FIG. 12A, with a bone
cutting device engaged into the trajectory control sleeve,
positioned to form a transcorporal access channel into the host
vertebral body.
[0059] FIG. 13 is an anterior view of a vertebral body with a bone
plate implanted on its surface, and with integral tissue access
ports that have been used to provide access to a cutting tool
guided by a trajectory control sleeve to form transcorporal access
channels.
[0060] FIG. 14 shows a pair of interbody disc implant devices
schematically suspended in air aligned and aligned for entry into
prepared access channels through an implanted bone plate.
[0061] FIG. 15 is an illustration of two interbody repair devices
in their fully installed position with the distal ends protruding
past the end plate into the interdiscal space within the annulus
fibrosis.
[0062] FIG. 16 is a cross section view of two adjacent vertebrae,
showing the intact annulus fibrosis of the intervertebral disc and
a unitary interbody repair device in the fully installed
position.
[0063] FIG. 17 is a cross section view of two adjacent vertebrae,
showing the intact annulus fibrosis of the intervertebral disc and
a composite interbody repair device in its fully installed position
with the pliant disc substitute material being in intimate contact
with the end plate of the adjacent vertebra and the bone repair
material in intimate contact with the cancellous bone tissue within
the transcorporal access channel.
[0064] FIG. 18 is a cross section view of an interbody repair
device the device having a central filling channel therethrough and
a fluid backflow prevention device within the channel.
[0065] FIG. 19 is a cross section view of an interbody repair
device with a fluid injection device within the central filling
channel and penetrating through the backflow prevention device.
[0066] FIG. 20 is a cross section view of an interbody repair
device having a fluid egress path located radially around distal
end of the repair device.
[0067] FIG. 21A is a perspective view of an interbody repair device
having a fluid egress path located radially around distal end of
the repair device.
[0068] FIG. 21B is a perspective view of the channels within the
device shown in FIG. 21A, the channels rendered as pipes.
[0069] FIG. 22 is a cutaway view through a vertebral body, showing
an interbody repair device in situ within the vertebral body and a
fluid injection device located entering the central access
channel.
[0070] FIG. 23 is a cutaway view through a vertebral body, showing
an interbody repair device in situ within the vertebral body and a
fluid injection device located within the central access channel,
the injection device having penetrated the fluid backflow element
and entered the nucleus pulposus volume within the intervertebral
disc.
[0071] FIGS. 24 and 25 are lateral cutaway views showing disc
repair material being injected into the nucleus pulposus volume
within the intervertebral disc. FIG. 24 shows the injection in
progress, with a relatively small amount of disc material in the
host site. FIG. 25 shows the host site nearly filled with
substitute disc material.
[0072] FIG. 26 is a cross section view of the intervertebral disc
after it has been filled with a disc repair material and after the
injection device has been extracted through the fluid backflow
element.
[0073] FIG. 27 is a schematic illustration of an embodiment of a
vacuum fill system.
DETAILED DESCRIPTION OF THE INVENTION
[0074] The present invention provides a system, various devices,
and methods to create and repair a transcorporal or intravertebral
surgical access channel between a (1) surgically-exposed host
vertebral body surface and (2) the end plate of the vertebral body
that is adjacent to a disc in need of a surgical intervention, such
as a degenerated disc. In some embodiments of the invention, the
channel may be considered to extend beyond the vertebral body and
into the intervertebral space, where a void has been created by
removal or excision of at least a portion (the nucleus pulposus,
for example) of the intervertebral disc. Accordingly, such a
channel may be generally referred to as a vertebral repair channel,
such channel also broadly including channels that are fully
included within a single vertebral body, such as a transcorporal or
intravertebral channel. These channels, formed by embodiments of
devices and methods of the invention, may be used to provide
surgical access to an intervertebral space, including access to a
disc residing in the space, as well as to provide a host site for
the implantation of a bone repair device, as per embodiments of
devices provided by the invention.
[0075] An optimal surgical outcome, as provided by the invention,
is one in which symptoms are relieved and the stability of the
spine is improved. The physical bases of the functional or
mechanical improvement provided by surgical procedures and devices
provided herein includes the repairing, restoring, or replacing
degenerated disc tissue, and restoring intervertebral height. In
some embodiments, the procedure includes maintaining the integrity
of annulus fibrosis of the disc, i.e., not disrupting the annulus
fibrosis while replacing the nucleus pulposis within the annulus
fibrosis with a substitute or replacement material or structure. In
typical embodiments of the method, the repair of the transcorporal
channel, used for surgical access to the intervertebral space or
the disc therein, is filled in and restored to a state such that
the former site of the channel poses no vulnerability. Devices
included in a system that can implement the inventive method
include various embodiments of an implantable bone repair device,
an implantable bone plate, and a trajectory control sleeve, and a
bone cutting tool, as described further below. In various
embodiments of the invention, a trajectory control sleeve may also
be referred to as a cutting tool holder; and in various embodiments
of the invention, a cutting tool holder and a bone plate,
particularly when joined together, may be understood to be portions
of a single conjoined trajectory control apparatus. And these
component portions, although identified separately, may also be
referred to singularly in the conjoinable form as a trajectory
control apparatus. Typical embodiments of a cutting tool holder do
include a sleeve-like portion that holds at least a portion of a
cutting tool during an aspect of the method when a transcorporal
channel is being formed.
[0076] A transcorporal channel, as formed by method and device
embodiments of the invention, allows direct access to the internal
volume of the disc, more particularly to the nucleus pulposis of
the disc, so that a disc repair, restoration or replacement
procedure may be performed without penetrating or compromising the
peripheral annulus fibrosis of the disc. Repair and restoration
procedures may include the removal and replacement of nucleus
pulposus tissue; the replacement materials may include solids,
liquids, or phase-changing materials. The invention restores disc
height, thus alleviating symptoms associated with degenerative disc
disease. The method further and advantageously preserves a
substantial amount of healthy disc tissue, more particularly, the
method preserves the integrity of the annulus fibrosis and
preserves healthy bone tissue, by virtue of the use of a
transcorporal access pathway to the center of the disc, rather than
a disruptive transdiscal approach. In terms of another benefit, the
transcorporal approach contributes the net preservation or
conservation of native bone and disc tissue compared to presently
conventional surgical approaches.
[0077] In some embodiments, after completion of a disc repair
procedure, a bone repair implant formed from natural bone material
or a biocompatible bone substitute material (or a combination
thereof) may be compressively engaged within the access channel to
prevent the outflow, extrusion, or expulsion of the disc repair
material, and to restore the mechanical integrity of the vertebral
body. As described further below, a variation of the bone repair
implant embodiment is one where the implanted bone repair includes
a distal portion that serves as an intradiscal or intervertebral
repair implant that functionally replaces the disc.
[0078] In some embodiments of the invention, a vertebral bone plate
may be applied and fastened to the exposed surface of the host
vertebral body, thereby covering the proximal end of the implanted
bone repair device. The bone plate stabilizes the bone repair
device in its host site, the former access channel, and supports
the integrity of the host vertebral body. The bone plate, in an
implementation of the method, is applied to the bone prior to the
formation of an access channel, where it provides a base for a
trajectory control sleeve which establishes an anatomically
appropriate or prescribed path for a bone cutting device to form
the channel. A prescribed path of trajectory of the transcorporal
channel refers to a path that is planned by the surgical physician
that is based on measurements or images of the vertebral site of
the operation, and which are the basis for determining the precise
angle which the channel needs to follow from the anterior surface
to the target site within the endplate.
[0079] Embodiments of a trajectory control sleeve, one of the
devices included in the inventive system, may be attached directly
to an anterior vertebral surface, but are typically attached
indirectly to the vertebral surface by way of temporary engagement
to an implanted bone plate during the aspect of the procedure when
the transcorporal channel is being formed by a bone cutting tool.
The bone plate, thus is adapted to be compatible both with a
trajectory control sleeve, when the channel is being formed with a
prescribed trajectory, and also compatible with a bone repair
device in that the repair device passes through the primary
aperture of the bone plate.
[0080] The channel through a host vertebral body, as provided by
embodiments of the invention, is oriented obliquely with respect to
the plane of the targeted disc; it starts on the anterior surface
of the host vertebral body and terminates at or near the end plate
bone tissue of the vertebral body in the locale of the nucleus
pulposus of the targeted disc. The formed channel then becomes the
route through which the targeted disc is accessed for a procedure
to remove or repair damaged tissue, and through which artificial
disc substitute material can be introduced. On completion of such a
procedure, the access channel may be filled with an embodiment of a
bone repair device.
[0081] In some embodiments of the invention, the bone cutting tool
that forms a transcorporal channel is a drill or a trephine, as
exemplified by the embodiment depicted in FIG. 12B, which forms a
straight channel. Bone repair devices appropriate for these
channels are straight, as are embodiments depicted herein as
examples of the invention. However, in other embodiments of this
invention, a channel may be formed by a cutting tool affixed to a
flexible shaft, or a cutting tool guided by a jig, as performed
freehand, or by other methods known in the art, which form an
arcuate channel. Methods may be applied, for example, as described
in the U.S. patent application Ser. No. 10/968,867 of Carl et al.
(Publication No. 2005/0267481, published Dec. 1, 2005). Aspects of
the present invention, accordingly, include bone repair devices and
systems that are arcuate or curvilinear, as are appropriate and
complementary to arcuate transcorporal channels. Straight
transcorporal channels and arcuate transcorporal channels each may
have particular benefits or advantages, depending on particulars of
the patient's spine, the vertebral body location within the spine,
the elected site of transcorporal channel entry, and the
instruments that are used in the procedure.
[0082] Some embodiments of the inventive method include creating a
channel within a vertebral body and thereafter through the space of
the nucleus pulposus of the adjacent disc, terminating at the end
plate bone tissue of the vertebral body adjacent to the nucleus
pulposus. The method may continue with the insertion of an
intervertebral implant device through the channel, the distal end
of the implant engaging the end plate bone tissue of the adjacent
vertebral body to provide a load bearing and articulating surface
that engages the adjacent vertebra so as to restore normal motion
to the vertebral joint. Some embodiments of the intervertebral
implant device are formed as a unitary device that includes a
biocompatible material such as polyethylene, polyetheretherketone
(PEEK), tantalum, or a titanium alloy. Other embodiments of the
intervertebral implant device may be formed as device that includes
two regions of at least partially distinct composition, the distal
end of the device including a pliant or resilient material
appropriate and compatible with disc tissue and the proximal
portion of the device being appropriate and compatible with
bone.
[0083] In some embodiments of the invention, some intervertebral
void space resulting from the creation of the access channel may
remain even after implantation of a bone repair device. Such void
space may be filled with a bone substitute implant of synthetic or
natural composition that prevents leakage of the artificial disc
substance out of the normal confines of the disc space and further
supports the structural integrity of the host vertebral body.
[0084] Some embodiments of the invention include a surgical system
and related method for accessing and repairing, restoring or
replacing degenerative disc tissue within the annulus fibrosis of
an intervertebral disc. In this method, an access channel of a
prescribed size and trajectory is created in a vertebral body, the
channel having a prescribed point of entry on an exposed vertebral
surface and having an exit on the end plate of the same vertebral
body, the exit being located within the inner perimeter of the
annulus fibrosis of the intervertebral disc. In some embodiments,
the internal disc material is excised through the access channel, a
substitute disc material is inserted into the intra-discal void and
the access channel is repaired by the insertion of a bone repair
implant, having a complimentary size, within the access
channel.
[0085] Some embodiments of the invention include an implantable
bone repair device having a lumen or internal channel connecting
the proximal and distal ends of the implant, the lumen having a
unidirectional valve. The lumen is configured to receive a filling
element inserted there through for the purpose of conveying an
injectable liquid phase disc replacement material into an internal
disc volume, the volume being contained within the annulus fibrosis
of the disc. The unidirectional valve is configured to allow the
passage or penetration of the injection element therethrough and to
provide a sealing means upon the removal of the injection device.
This device is used in a method that includes creating an open
channel in a vertebral body which starts on an exposed surface and
is obliquely directed to a termination at the end plate, the
terminus in the locale of the nucleus pulposus of the adjacent
disc. The method continues with inserting a bone repair device with
the internal channel or lumen into the transcorporal access
channel, inserting a needle through the lumen of the bone repair
device into the internal disc volume, and injecting a liquid or
phase-changing disc substitute into the disc volume.
[0086] Alternative embodiments of the invention vary with respect
to the site of entry of a channel into a vertebral body. For
example, an alternative embodiment of the inventive method includes
creating an open channel within or through a vertebral body from a
trans-pedicular approach, the channel originating at the posterior
aspect of a vertebral pedicle and terminating at or near the end
plate of the vertebral body adjacent to the nucleus pulposus.
Another alternative embodiment of the inventive method includes
creating an open channel within or through a vertebral body from a
posterior, lateral or posterolateral extra-pedicular approach, with
the channel originating at the posterior-lateral aspect of a
vertebral body and terminating at or near the end plate bone tissue
adjacent to the nucleus pulposus.
[0087] Aspects and exemplary embodiments of the invention, as
generally described above, are described further in the context of
FIGS. 1-27, as follows below.
[0088] FIGS. 1A-1F are schematic cross-sectional views that
storyboard a method for creating a transcorporal access channel
within a vertebral body for accessing, repairing, replacing and/or
restoring intervertebral disc tissue. The method continues with a
repairing of the intervertebral access channel with a bone repair
material, and affixing an implantable bone plate to the surface of
the vertebral bone tissue to prevent migration of the bone repair
implant out of the intervertebral access channel.
[0089] FIG. 1A show two adjacent vertebral bodies, a device-hosting
vertebral body 100 and an adjacent vertebral body 102, and an
intervertebral disc 103. A generally cylindrical intervertebral
access channel 101 has been created within a vertebral body
adjacent the disc to be repaired. The access channel has a point or
site of entry 104 on the exposed surface of the vertebral body 100,
and then penetrates the vertebral bone and exits through the
vertebral end plate 105 at a site near the center of an
intervertebral disc 103.
[0090] FIG. 1B shows a vacant internal volume 107 created within
the central nucleus pulposus region of the intervertebral disc 103
that has been formed by surgically displacing or excising the
nucleus pulposus tissue through the transcorporal access channel
101.
[0091] FIG. 1C shows an injection device introducing disc repair
material 108 into the vacant internal disc volume 107 through the
transcorporal access channel 101.
[0092] FIG. 1D shows the formerly vacant (FIG. 1C) internal disc
volume now filled with the disc repair material 108.
[0093] FIG. 1E shows the entry of a bone repair implant or device
115 into the transcorporal access channel 101.
[0094] FIG. 1F shows a completed post surgical result of having
repaired the intervertebral disc by implanting therein a disc
repair material 108, having repaired the transcorporal access
channel by inserting into it a bone repair device 115, and having
secured the device 115 in the installed location by affixing a bone
plate 110 to the exposed surface of the vertebral bone.
[0095] FIGS. 2-5 show an embodiment of a transcorporal access
channel 101 from various perspectives, and at various points in a
surgical repair procedure. The channel 101 is generally cylindrical
in form and has a point of entry 104 on the anterior surface of
vertebral body 100 and a point of exit 106 on the vertebral end
plate thereby providing unrestricted access to the internal nucleus
pulposus portion 103np of the intervertebral disc 103 through the
access channel. FIG. 2 is a perspective view of a vertebral body
100 showing a transcorporal access channel 101 from an anterior
perspective. FIG. 3 is a perspective view of a vertebral body
showing the exit point 106 of the transcorporal access channel of
FIG. 2 through the vertebral end plate 105. FIG. 4 is a perspective
view that includes a cut away view through a vertebral body 100
segment along the centerline of the transcorporal access channel
101, showing the access to nucleus pulposus 103np of the
intervertebral disc through the access channel.
[0096] FIG. 5 is similar to FIG. 4, but focuses attention on an
internal void 112 created within an intervertebral disc by a
surgical procedure operated within the space provided by the access
channel 101, in which the nucleus pulposus of the disc has been
displaced or excised. The confinement of the procedure within the
access channel has precluded the penetration or compromise the
annulus fibrosis 113 of the intervertebral disc 103.
[0097] FIG. 6 is a lateral perspective view of adjacent vertebral
bodies (a device hosting vertebral body 100, shown transparently by
dotted outline, and an adjacent vertebral body 102) and the annulus
fibrosis 113 of an intervertebral disc remnant after its nucleus
pulposus has been excised. An internal void 112 has been created
and is confined within an intact annulus fibrosis 113af of the
intervertebral disc.
[0098] FIG. 7 is a perspective view of adjacent vertebral bodies
100 and 102 on either side of a repaired disc 103. The central
portion of the figure includes a cut away of a portion of a
vertebral body that allows a view of the repaired intervertebral
disc, wherein the internal void 112 (FIG. 6) within the annulus
fibrosis 113 of a disc has been replaced with a substitute disc
material 108. FIG. 7 further shows a vertebral bone repair implant
115 embodiment suspended in space, but directed toward its host or
installation site. Bone repair device 115 has a distal end 117
disposed to be generally meet the plane of the vertebral end plate
105 when implanted in its host site, and a proximal end 116
disposed to be generally proximal to the anterior surface of the
vertebral body 100 when in the final installed position. The
proximal end of bone repair device 115 may have an abutment 118
disposed to engage the anterior surface of the host vertebral body
so as to prevent its insertion beyond the prescribed depth within
the host vertebral body.
[0099] In various embodiments of the invention, the bone repair
implant may include particular osteointegrative features such as
those provided in U.S. Patent Application No. 60/972,192 of Lowry
et al., as filed on Sep. 13, 2008. Examples of osteointegrative
features include the external surface of the devises having at
least a portion of which is porous enough for native bone ingrowth,
and incorporating osteogenic agents into the matrix of the bone
repair device. Inclusion of a bone cell preparation within the
device, as described further below, is also a major
osteointegrative feature, as such bone cells can migrate into the
host site, and knit together host and grafted bone.
[0100] FIG. 8 is a perspective view of adjacent vertebral bodies
100 and 102 with a cutaway central portion of the superior and host
vertebral body 100 that has been operated on, showing the nucleus
pulposus volume of the intervertebral disc 103 filled with a
substitute disc material 108 and the formally open transcorporal
access channel now occupied by the installed bone repair implant
115 embodiment. Below the now repaired disc 100 is an adjacent and
intact vertebral body 100. The abutment 118 of the bone repair
implant 115 can be seen flush against the surface of the host
vertebral body. The distal end of bone repair implant 115 (not
visible) can be understood to meet the end plate 105 of the host
vertebral body. An intact disc 103 can be seen on the superior
aspect of the host vertebral body.
[0101] FIG. 9 shows a bone plate 110 embodiment permanently affixed
to the anterior surface of a host vertebral body 100 by one or more
bone screws 120, the bone plate engaging the proximal end of the
bone implant 118 (not visible here, but shown in FIG. 8) so as to
prevent migration of the implant out of the access channel. Discs
103 lie above and below the superior host vertebral body; an
adjacent intact vertebral body 100 lies inferior to the host
vertebral body.
[0102] FIG. 10 is a cross sectional side view of adjacent vertebral
bodies 100 and 102, a repaired intervertebral disc 103, the disc
having an intact annulus fibrosis 113 and a substitute disc
material 108 contained therein. The formerly open transcorporal
access channel has been repaired with an implanted bone repair
device 115 and a bone plate 110 fastened to the vertebral body over
the bone repair device to prevent its migration, and to assure the
optimal mechanical integrity of the post-operative vertebral
body.
[0103] Some embodiments of the invention are directed toward the
implantation of devices through a host vertebral body that include
a disc-replacing portion with a distal surface that is
articulatable against the end plate of the adjacent vertebral body.
Such articulatable surfaces are hard and smooth. In some
embodiments, these devices are implanted singly in a host vertebral
body, and in other embodiments, these devices are implanted as a
side-by-side dual set, hosted by dual channels within a vertebral
body. The dual channel (dual devices) approach differs from the
typical embodiment used when surgical access to a disc is the
primary purpose of a procedure; these embodiments typically make
use of a single channel with the implantation of a single repair
device. In embodiments of the invention that include the
implantation of an articulating disc replacement, dual channels
(and dual implanted devices) may provide particular benefit with
regard to maintaining posture and symmetrical load bearing within
the spine.
[0104] FIG. 11 is a perspective view of adjacent vertebral bodies
100 and 102, and intervertebral discs 103 lying above and below the
superior vertebral body 100 that is now host to an embodiment of an
implanted bone plate 110. The bone plate 130 is attached to the
exposed surface of a host vertebral 100 by one or more bone screws
131 in a manner so as to symmetrically locate the bone access ports
132 relative to the medial centerline of the vertebra, thereby
establishing a point of entry for a tool such as bone cutting
device at the bone surface.
[0105] FIG. 12A is a side view of a spinal section having an
embodiment of a bone plate 110 affixed to the anterior surface of a
vertebral body 100 and an embodiment trajectory control sleeve or
cutting tool holder 134 positively engaging the bone plate 110.
Bone plate 100 and trajectory control sleeve 134 have complimentary
orientation control features 135 (on the bone plate) and 136 (on
the trajectory control sleeve). These features are configured to
establish a desired angle 138 of penetration for a bone cutting
device such as a drill from a point of entry 137 (in FIG. 11) and
into the vertebral bone so as to assure that the point of exit of
the drill at the vertebral end plate is adjacent to the annulus
fibrosis of the intervertebral disc. These complementary features,
while generally fixed on any given device (bone plate or trajectory
control sleeve), may be varied from device-to-device, either on one
or both of the complementary devices, in order to form a desired
angle. Further, in some embodiments, one or both of the features of
the complementary devices may be configured such that the angle of
engagement is adjustable. FIG. 12B is a side view of a vertebral
body with a bone plate and a trajectory control sleeve (as in FIG.
12A) with a bone cutting device 400 engaged into the trajectory
control sleeve, positioned to form a transcorporal access channel
into the host vertebral body.
[0106] FIG. 13 is an anterior perspective view of a vertebral body
100 that shows two substantially parallel transcorporal access
channels 139 through the vertebral body. A nucleus pulposus 103NP
portion of an intervertebral disc 103 is exposed through the access
channels that are framed by bone plate 110. The channels 139 have
been formed with a cutting device whose path was directed by a
trajectory control sleeve or cutting tool holder 134 (see FIG. 12)
which has since been removed.
[0107] FIG. 14 shows a pair of intra-discal implant 140 embodiments
schematically positioned in an alignment directed toward the
anterior openings of the transcorporal access channels 139 within
the bone plate 110 implanted in vertebral body 100. Intra-discal
implants or repair device embodiments are similar to bone repair
device (generally labeled 115) embodiments as described above and
as depicted in FIGS. 7 and 8, however the intra-discal implants
(generally labeled 140) have further structure and function such
that, when implanted, they extend beyond the bone plate and occupy
space that replaces an excised nucleus pulposus portion of an
intervertebral disc. As will be described below and as
comparatively depicted in FIGS. 16 and 17, intra-discal implants or
repair devices may be of a unitary construction and composition
140A or they may be of a composite construction 140B, including at
least two different portions.
[0108] FIG. 15 shows embodiments of two intra-discal implants 140A
in their fully inserted position in a host vertebral body 100. The
implants have a proximal end 141 that engages the bone plate 110 in
a manner that controls the depth of penetration of the distal end
142 into the intervertebral disc space. FIG. 15 further illustrates
that the intra-discal implants 140A are contained within an intact
annulus fibrosis 113 of the remnant disc.
[0109] A function of embodiments of intradisc repair implant 140
(FIGS. 16 and 17) is to replace degenerated native disc material,
to restore articulating motion between the adjacent vertebral
segments, and to restore disc height while preserving the annulus
fibrosis of the disc and substantially all of the native vertebral
end plate tissue. Further, the mechanical integrity of the
vertebral body transgressed by the access channel is restored by
the insertion of the bone repair implant, the implant device 140
thus facilitates its own osteointegration with the native bone
tissue of the host vertebral body 100 during the healing
process.
[0110] FIG. 16 is a cross sectional view of two adjacent vertebrae
100 and 102 with an embodiment of a unitary intra-disc repair
implant 140A inserted through a transcorporal access channel within
a host vertebral body 100. The device 140A is implanted in such a
manner so as to assure intimate or abutting contact between the
distal end 142 of the device and the end plate bone tissue 105 of
the adjacent (non-hosting) vertebral body 102. The site of contact
occurs within bounds of the intact annulus fibrosis of the
intervertebral disc 113, the nucleus pulposus having been removed.
The proximal end 147 of the intra-disc repair implant 140A device
may lockably engage the bone plate 110 or may be retained in place
by the attachment of a complimentary bone plate device. FIG. 17
shows an alternate embodiment of a repair implant, this embodiment
being an intra-disc repair device 140B used as described in
conjunction with FIG. 16. This embodiment of the implantable device
is formed as a construct of two materials; the proximal portion 145
includes a biocompatible bone repair material so as to promote bone
in-growth therein and the distal portion 146 includes a pliant
material with characteristics comparable to those of natural disc
tissue so as to improve shock absorption and enhance relative
motion between the adjacent vertebral bodies 100 and 102. As
described further below, embodiments of the proximal portion 145 of
the device may also include bone cell preparations.
[0111] In various embodiments of the invention, the bone repair
implant may include particular osteointegrative features such as
those provided in U.S. Patent Application No. 60/972,192 of Lowry
et al., as filed on Sep. 13, 2008, which is incorporated into the
present application in its entirety by this reference. That
application described in detail the use of a preparation of the
patient's own bone within a porous cage like device that ultimately
integrates into the host vertebral body. These use of a trephine to
form a channel is shown in Figure of 30 of application 60/972,192,
and various views of embodiments of the porous cage device and the
method of implanting it are shown in FIGS. 31-37.
[0112] Embodiments of the porous cage device, or the porous cage
proximal portion of the device and aspects of its preparation and
implantation will now be described briefly.
[0113] Implantation of the patient's own bone tissue (an autologous
graft) is a generally advantageous approach to repairing bone, as
autologous grafting typically yields high success rates and a low
rate of surgical complications. Accordingly, some embodiments of
the invention include using core bone tissue harvested from the
forming of the vertebral access channel, and implanting the plug,
intact, in the form of bone repair graft. An advantage to
recovering and making use of bone derived from the channel includes
the absence of a need to harvest bone from a second site.
Embodiments of the invention, however, do include harvesting bone
from secondary sites on the patient, such as the iliac crest, as
may be appropriate in the practice of the invention under some
circumstances. In some embodiments, for example, it may be
advantageous to supplement bone derived from the access channel
with bone from other sites. In still other embodiments, under
various clinical circumstances, it may be appropriate to make use
of bone from donor individuals. Bone from other autologous sites or
other donor individuals may be used as a repair device in the form
of an appropriately formed plug, or bone may be fragmented or
morselized, and packaged as a solid plug, or bone may be included
as a preparation provided in a porous cage, as described further
below.
[0114] Some embodiments of methods provided make use of a trephine
type bone cutting system, as noted above. With a trephine bone
cutting system, the external diameter of the bone tissue core is
about equal to the internal diameter of the trephine device, while
the internal diameter of the access channel is about equal to the
external diameter of the device. Thus, a trephine-derived bone plug
from forming the access channel provides an appropriately-sized
piece to be inserted into the channel for repair and healing, but
does not necessarily make intimate contact with the inside surface
of the channel due to the width of the kerf created by the
trephine.
[0115] Optimal healing and recovery from implantation of bone
material into an access channel occurs when there is an intimate or
compressive engagement of the graft material with the vertebral
bone tissue (substantially cancellous bone), as this intimate
association provides for rapid blood profusion and bone healing
while providing mechanical support during healing. Accordingly, an
embodiment of the bone repair device provided herein includes a
device with bone tissue inside a porous cage, as described in
detail below.
[0116] The porosity of the cage is a particularly advantageous
feature for allowing cell to cell contact through the boundary of
the device. To some degree, it may also allow cell migration,
however the most advantageous factor in promoting rapid healing is
cell to cell contact that initiates sites of tissue unification,
which can then spread, stabilize a healing zone around the graft or
bone repair device, and ultimately lead to effective fusion and
integration of the graft within the host vertebral body.
[0117] A porous cage, as provided by this invention, also has a
compressibility, such that when the contents of the cage are
subject to a compressive force, however transient and minimal,
blood or plasma and bone cells that are present in the harvested
cancellous bone are forced outward into the environment within and
around the access channel site. Extrusion of biological fluid in
this manner, advantageously packs bone tissue closer together
within the cage, and bathes the periphery of the graft and the
host-graft intersectional zone with a medium that is optimal for
exchange of dissolved gas and nutrients that are critical in the
initial stages of healing. Some embodiments of the invention
include bathing the bone tissue preparation in a supportive liquid
medium before implantation. Such bathing may occur prior to placing
the bone tissue preparation in the porous cage and/or after placing
the preparation in the cage. The liquid medium may be any
appropriate cell culture medium, and may be further supplemented
with biological agents, such as osteogenic agents or other growth
factors.
[0118] Embodiments of the implantable porous cage bone repair
device, as provided herein, encapsulate the bone tissue contained
therein, and provide mechanical stability to the access channel
during healing. These embodiments compensate for the volumetric
loss associated with the bone cutting process of the trephine and
promote contact between the bone volume within the device and the
surrounding vertebral bone tissue. The device, as a whole, and like
other bone repair embodiments provided, cooperates with the
implanted bone plate so that the orientation and penetration depth
of the implant device within the access channel may be controlled.
These forms of control assure that the device does not
over-penetrate through the channel, thereby compressing the dura
mater or neural elements within the vertebra, and assuring that the
implanted device cannot migrate in an anterior direction out of the
access channel.
[0119] In various alternate embodiments of the invention, a bone
repair implant or an intradisc repair device may be held in place
with bone cement, by a press-fit with the bone and/or by screwing
the implant into the bone. These methods may be used independently
or in conjunction with a bone plate 110 described above.
Embodiments of the bone plate may be constructed from a
biocompatible polymer, a biocompatible metal, a biocompatible
ceramic and/or a bioabsorbable material. A biologically-absorbable
or partially-absorbable bone plate is particularly compatible in
the context of embodiments of the method in which the bone repair
device is osteointegrative, as for example, when it includes bone
tissue that ultimately fuses and/or integrates with bone of the
host site. In these instances, once integrated, a bone plate may
serve no substantially beneficial purpose, and restoration of the
surgical site to a near-native configuration may be beneficially
served by the absorption of bone plate material. In some
embodiments of the inventive system and methods of operating the
system, the bone plate may be temporarily in place during a spinal
procedure, and it may be removed, for example, after an
intervertebral channel has been formed, or after a spinal repair
device has been implanted.
[0120] An alternate embodiment of the invention will now described
in which disc repair is not performed by implantation of a
preformed solid implant such the exemplary devices 140A or 140B as
described above, but rather, repair is effected by injection of a
flowable material that solidifies into a supporting structure. As
previously described and as FIGS. 2, 3, and 4 show, an
transcorporal access channel 101 created through a vertebral body
between an exposed surface on the vertebral body and the end plate
bone tissue of the vertebra and FIGS. 5 and 6 show the formation of
an intra-disc void. In the present alternative embodiment of the
invention (FIGS. 18-27), thereafter a bone repair implant having an
internal filling channel or lumen is inserted into the
transcorporal access channel and the intra-disc void is filled with
a fluidic or flowable material, such as, by way of example, a
liquid, a liquid-to-solid phase-changing material, a settable
liquid, a gel, a suspension, or a slurry by means of a fluid
injection device such as a syringe needle, the injection device
being inserted into the intra-disc void through a filling channel
within the bone repair implant device.
[0121] A cross-sectional view of a bone repair implant 200
embodiment, shown in FIGS. 18 and 19, has a proximal end 201, a
distal end 202, and an internal filling channel or lumen 203. The
internal filling lumen may have a unidirectional flow control
element 204 to allow the passage of the injection device 205 and
injected flowable disc-substitute material 108 into a prepared
internal disc volume and thereafter restrict the backflow of the
material. The back flow control element may be, for example, a plug
that is sufficiently compliant that it permits the passage of an
injection needle, and is sufficiently resilient that it closes and
seals the injection passage after the needle has been withdrawn.
FIGS. 20, 21A, and 21B show an alternate embodiment of an
implantable bone repair device 200. In this embodiment, the fluid
injection does not directly enter the internal disc void, but
rather courses through internal access channel or lumen 203 and
intersecting one or more diffusion channels 206, distributing
around the distal end of the implant device so as to assure a more
complete filling of the intra-disc void. FIG. 21B is a perspective
view of the lumens within the device shown in FIG. 21A, the lumens
rendered as pipes within the solid piece. This embodiment may be
particularly suited to use in conjunction with the implantation of
a solid intra-disc repair device (FIGS. 16 and 17), where void
spaces may remain in the annulus fibrosis of the disc after the
disc repair implants are inserted and where supplemental disc
substitute material is beneficial to the long term outcome of the
procedure.
[0122] As described above in general, and in some particularity
with regard to the spinal repair device embodiment of FIG. 17, a
portion or the substantial entirety of a device may be formed by a
porous cage that includes a bone cell preparation. Embodiments such
as those depicted in FIGS. 18-27 that include an internal lumen may
also be formed from porous cages, or the devices may include forms
with portions having walls of mixed composition, some wall portions
solid and some wall portions porous. In some embodiments, for
example, an internal lumen may be formed from a solid wall, while
the external walls are porous.
[0123] FIG. 22 shows a bone repair implant 200 with an internal
fill lumen inserted within the transcorporal access channel within
a host vertebral body 100. FIG. 22 further shows an internal disc
void 112 contained within the intact annulus fibrosis 113 of the
intervertebral disc. Such an internal void is generally the result
of a surgical procedure in which the void has been formed by
removal of at least a portion of the nucleus pulposis of the disc.
The fluid injection device 205 is shown entering the proximal end
201 of implant device 200. FIG. 23 shows the fluid injection device
having penetrated the back flow prevention element 204 and entered
the intra-disc void 112.
[0124] FIGS. 24 and 25 show the progressive injection of a flowable
disc substitute material 108 into the internal disc void, the
material being constrained by the annulus fibrosis 113 and by the
end plate bone tissue of the adjacent vertebral body 102. FIG. 24
shows the injection in an early stage; FIG. 25 shows the injection
at stage where the host site is nearly filled with the substitute
disc material. The injection process may be regulated by the
introduction of a prescribed volume of substitute material, by
monitoring back pressure at the injection device, or by other
volumetric, pressure or displacement means. FIG. 26 shows the
repaired spine section; the fluid injection device has been removed
through the backflow prevention element 204, leaving within the
annulus fibrosis a restored disc structure, with solidified disc
substitute material 108 filling the formerly void space within the
disc. In a final step, a bone plate 130 may be fixed to the
vertebral body by conventional bone screws so as to resist the
expulsion of the bone repair implant 200 and to resist movement so
as to promote bone growth of new bone into the device.
[0125] In various embodiments of the methods described herein, the
vertebral segments may be distracted using currently available
methods and tools such as vertebral distractor pins prior to or
during the performance of a transcorporal disc repair or
replacement procedure.
[0126] In various embodiments described herein where a liquid or
phase changing material is implanted within the intra-disc volume,
it may be advantageous to evacuate gas or fluid from the volume so
as to assure optimal filling of the void space with substitute
material, and the formation of an appropriate level of substitute
material density within the space. The trapping of air within the
intervertebral space or within liquid disc substitute material is
not a trivial consequence as air is compressible, and for the
repaired, restored or substituted disc to function in its normal
capacity, the disc volume needs to be resilient, but the total
volume is desirably non-compressible. In embodiments of the
invention, this gas evacuation may be achieved variously by means
of a vent channel integral to the injection device, by means of a
vent channel within the bone repair implant device, or by means of
a vacuum filling process wherein the gaseous volume is evacuated by
a vacuum and a liquid disc material is introduced thereafter into
the evacuated volume to relieve the negative pressure within the
void, thereby assuring a more complete filling of the complete
volume of the void. More generally, the internal cannula or the
injector itself may include two channels, one configured for
proximal-to-distal flow of liquid disc substitute material, and a
second channel configured for distal-to-proximal escape of air that
would otherwise remain entrapped. In some embodiments of the
method, there may also be egress of liquid disc substitute material
through this out-channel as well. This does no particular harm and
indeed provides an indication to the operating physician that the
intervertebral space (or intradiscal space) is filled. In still
other gas-ventable embodiments, the spinal repair device may
include longitudinally running folds on the external surface that
would allow gas to escape. Some embodiments including these various
features may include a cap to be applied to the proximal, external
facing surface of the device after injection of the disc substitute
material to prevent escape of disc substitute fluid.
[0127] FIG. 27 shows a schematic view of an embodiment of a vacuum
fill system 300 that may be used in conjunction with a bone repair
implant device 200, and as an adjunct to the basic method of using
device 200 as described above. In a method making use of the vacuum
system 300, a fluid injection device 205 is inserted into the
intradiscal void 112. A bi-directional control valve device 301 has
two inlet ports 310 and 320 and one outlet port 330, with the
outlet port 330 being connected to a fluid injection device 205. A
vacuum source 303 is attached to the first inlet port 310 and a
fluid reservoir 302 containing the disc repair fluid is attached to
the second inlet port 320.
[0128] The valve position is set to open an access channel between
the vacuum inlet port 310 and the fill device port 330 and a vacuum
is created within the intra-disc volume 112. Thereafter the valve
device 300 is switched to close the vacuum port 310 and
simultaneously open the fluid port 320. The pressure differential
between the fluid reservoir 302 and the intra-disc void 113 causes
the fluid in the reservoir 302 to flow into the intra-disc void
112, completely filling the internal volume with fluid and avoiding
gaseous voids in the disc.
[0129] While the exemplary embodiments provided herein all involve
an access channel being formed from an anterior surface of the
vertebral body towards the nucleus pulposus of the intervertebral
disc, such an access channel may alternatively be formed using a
lateral or posterior approach. Similarly, while all of the
embodiments shown herein involve approaching the nucleus pulposus
from a cephalad direction, a caudal approach may be preferable in
some instances. Further details of methods and systems for forming
a transcorporal access channel into a vertebral body may be found
in U.S. Provisional Application No. 60/972,192, filed Sep. 13,
2007, and entitled "Transcorporal Spinal Decompression and Repair
System and Related Method," incorporated herein by reference.
* * * * *