Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR SPINE JOINT REPLACEMENT
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Field Of The Invention
This invention relates to surgical devices and
methods in general, and more particularly to surgical
devices and methods for replacing a damaged, diseased,
or otherwise painful spinal joint.
Background Of The Invention
Traumatic, inflammatory, metabolic, synovial,
neoplastic and degenerative disorders of the spine can
produce debilitating pain that can have severe
socioeconomic and psychological effects.
One of the most common surgical interventions today
is arthrodesis, or spine fusion, in which two or more
adjacent vertebral bodies are fused together in order to
alleviate pain associated with the disc(s) located
between those vertebral bodies. Approximately 300,000
such procedures are performed annually in the United
States alone. Clinical success varies considerably,
depending upon technique and indications, and
consideration must be given to the concomitant risks and
complications.
For example, while spine fusion generally helps to
eliminate certain types of pain, it has also been shown
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to decrease function by limiting the range of motion for
patients in flexion, extension, rotation and lateral
bending. Furthermore, it is believed that spine fusion
creates increased stresses on (and, therefore,
accelerated degeneration of) adjacent non-fused motion
segments. Additionally, pseudoarthrosis, resulting from
an incomplete or ineffective fusion, may reduce or even
totally eliminate the desired pain relief for the
patient. Also, the fusion device(s) used to effect
fusion, whether artificial or biological, may migrate
out of the fusion site, thereby creating significant new
problems for the patient.
Recently, attempts have been made to recreate the
natural biomechanics of the spine through the use of an
artificial disc. Artificial discs are intended to
restore articulation between vertebral bodies so as to
recreate the full range of motion normally allowed by
the elastic properties of the natural disc, which
directly connects two opposing vertebral bodies.
Various artificial discs are described by Stefee et al.
in U.S. Pat. No.5,071,437; Gill et al.in U.S. Pat. No.
6,113,637; Bryan et al. in U.S. Pat. No. 6,001,130;
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Hedman et al. in U.S. Patent No. 4,759,769; Ray in U.S.
Patent No. 5,527,312; Ray et al. in U.S. Pat.
5,824,093; Buttner-Janz in U.S. Patent No. 5,401,269;
and Serhan et al. in U.S. Patent No. 5,824,094.
Still other artificial discs are known in the art.
Unfortunately, however, artificial discs alone do
not adequately address all of the mechanics of the
motion of the spinal column.
In addition to the intervertebral disc, posterior
elements called the facet joints help to support axial,
torsional and shear loads that act on the spinal
column. Furthermore, the facet joints are diarthroidal
joints that provide both sliding articulation and load
transmission features. However, the facet joints can
also be a significant source of spinal disorders and,
in many cases, debilitating pain. For example, a
patient may suffer from arthritic facet joints, severe
facet joint tropism or otherwise deformed facet joints,
facet joint injuries, etc. There is currently a lack
of good interventions for facet joint disorders.
Facetectomy, or the removal of the facet joints, may
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provide some relief, but it is also believed to produce
significant decreases in the stiffness of the spinal
column (i.e., hypermobility) in all planes of motion:
flexion and extension, lateral bending, and rotation.
Furthermore, problems with the facet joints can also
complicate treatments associated with other portions of
the spine. By way of example, contraindications for
artificial discs include arthritic facet joints, absent
facet joints, severe facet joint tropism or otherwise
deformed facet joints.
A superior vertebra with its inferior facets, an
inferior vertebra with its superior facets, the
intervertebral disc, and seven spinal ligaments together
comprise a spinal motion segment or functional is spine
unit. The spinal motion segment provides complex motion
along three orthogonal axis, both in rotation (lateral
bending, flexion and extension, and axial rotation) and
in translation (anterior-posterior, medial-lateral, and
cranial-caudal). Furthermore, the spinal motion segment
provides physiological limits and stiffnesses in each
rotational and translational direction to create a
stable and strong column structure to support
physiological loads.
_ , .~. ~ . . _
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As mentioned above, compromised facet joints are a
contraindication for disc replacement, due to the
inability of the artificial disc (when used with
compromised facet joints, or when used with missing
facet joints) to properly restore the natural
biomechanics of the spinal motion segment. It would
therefore be an improvement in the art to provide a
spine implant system that facilitates concurrent
replacement of the intervertebral disc and facet joints
where both have been compromised due to disease or
trauma.
U.S. Pat. No. Re. 36,758 (Fitz) discloses an
artificial facet joint where the inferior facet, the
mating superior facet, or both, are covered with a cap.
This cap requires no preparation of the bone or
articular surfaces; it covers and, therefore, preserves
the bony and articular structure. The capping of the
facet has several potential disadvantages, however.
If the facet joint is osteoarthritic, a cap will not
remove the source of the pain. Additionally, at least in
the case of surface replacements for osteoarthritic
femoralheads, the capping of articular bone ends has
proven to lead to clinical failure by means of
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mechanical loosening. This clinical failure is
hypothesized to be a sequela of disrupting the
periosteum and ligamentum teres femoris, both serving a
nutrition delivery role to the femoral head, thereby
leading to avascular necrosis of the bony support
structure for the surface replacement. It is possible
that corresponding problems could develop from capping
the facet. Another potential disadvantage of facet
capping is that in order to accommodate the wide
variability in anatomical morphology of the facets, not
only between individuals but also between levels within
the spinal column, a very wide range of cap sizes and
shapes is required.
U.S. Pat. No. 6,132,464 (Martin) discloses a spinal
facet joint prosthesis that is supported on the lamina
(which is sometimes also referred to as the posterior
arch). Extending from this support structure are
inferior and/or superior blades that replace the
cartilage at the facet joint. Like the design of the
aforementioned U.S. Pat. No. Re. 36,758, the prosthesis
of U.S. Pat. No. 6,132,464 generally preserves existing
bony structures and therefore does not address
pathologies which affect the bone of the
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facets in addition to affecting the associated
cartilage. Furthermore, the prosthesis of U.S. Pat. No.
6,132,464 requires a secure mating between the
prosthesis and the lamina. However, the lamina is a very
complex and highly variable anatomical surface. As a
result, in practice, it is very difficult to design a
prosthesis that provides reproducible positioning
against the lamina so as to correctly locate the
cartilage-replacing blades for the facet joints.
Another approach to surgical intervention for
spinal facets is disclosed in International Patent
Publication No. WO9848717A1 (Villaret et al.). While
this publication teaches the replacement of spinal
facets, the replacement is interlocked in a manner so as
to immobilize the joint.
Thus it will be seen that previous attempts to
provide facet joint replacement have proven inadequate.
In some circumstances, additional structures of a
vertebra beside the facets may have been compromised by
disease or trauma. For example, the lamina, the spinous
process and/or the two transverse processes may have
been compromised by disease or trauma. In such a
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circumstance, it would be useful to have a prosthesis
which would allow the replacement of the same.
Summary Of The Invention
One object of the present invention is to provide
a spine joint reconstruction assembly that replaces the
intervertebral disc and one or more of the facet joints
in order to restore the natural biomechanics of a spinal
motion segment.
Another object of the present invention is to
provide a method for reconstructing the spine joint by
replacing the intervertebral disc and one or more of
the facet joints in order to restore the natural
biomechanics of a spinal motion segment.
Still another object of the present invention is to
provide a kit for the reconstruction of multiple spine
joints to replace intervertebral discs and facet joints
in order to restore the natural biomechanics of a spinal
joint motion segment.
In accordance with the present invention, the
preferred embodiment, the intervertebral disc is excised
and replaced with an artificial disc. This artificial
disc may be a device such as is described by
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Stefee et al. in U.S. Pat. No. 5,071,437; Gill et al. in
U.S. Pat. No. 6,113,637; Bryan et al. in U.S. Pat. No.
6,001,130; Hedman et al. in U.S. Patent No. 4,759,769;
Ray in U.S. Patent No. 5,527,312; Ray et al. in U.S.
Pat. No. 5,824,093; Buttner-Janz in U.S. Patent No.
5,824,094; and Serhan et al. in U.S. Patent No.
5,824,099. Alternatively, the artificial disc may be
some other artificial disc of the sort known in the art.
In addition to replacing the intervertebral disc,
at least one of the facet joints is replaced in
accordance with the apparatus and methods described
hereinafter. Alternatively, the facet joints may be
replaced as described by Fitz in U,S. Pat. No. Re.
36,758; Martin in U.S. Pat. No. 6,132,464; and/or
Villaret et al. in International Patent Publication No.
WO 9848717A1. Or one or more of the facet joints may be
replaced by other apparatus and methods known in the
art.
The present invention has several advantages over
the prior art. For one thing, the present invention
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can provide a complete replacement of all of the
articulation surfaces of a spine motion segment: the
intervertebral disc and the facet joints. Proper disc
height is restored while degenerated facet joints and
the underlying painful bone is replaced. The prosthetic
disc and prosthetic facet joints work together to
reproduce the desired physiological range of motion and
to provide low friction articulations, so that adjacent
motion segments are returned to physiological levels of
stress and strain. Furthermore, osteophytic growth can
be concurrently removed, and the artificial disc and
facet joint prosthesis together reestablish
intervertebral and central foraminal spaces to ensure
decompression of any nerve structure. Thus, all sources
of pain, such as pain associated with osteoarthritis,
instability, and nerve compression, are removed while
restoring full function of the spine motion segment.
Brief Description Of The Drawings
These and other objects and features of the present
invention will be more fully disclosed or rendered
obvious by the following detailed description
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of the preferred embodiments of the invention, which is
to be considered together with the accompanying drawings
wherein like numbers refer to like parts and further
wherein:
FIG. 1 is a perspective view of a portion of the
spine;
FIG. 2 is a dorsal view of the portion of the spine
shown in FIG. 1;
FIG. 3 is a lateral view of a spine joint
reconstructed in accordance with one aspect of the
present invention;
FIG. 4 is a dorsal view of the facet joint shown in
FIG. 3;
FIG. 5 is a perspective view of the implanted left
inferior facet prosthesis shown in FIGS. 3 and 4;
FIG. 6 is a perspective view of the left inferior
facet prosthesis shown in FIGS. 3 and 4;
FIG. 7 is a cranial view of the implanted left
superior facet prosthesis shown in FIGS. 3 and 4;
FIG. 8 is a perspective view of the left superior
facet prosthesis shown in FIGS. 3 and 4;
FIG. 9 is a perspective view of an alternate
implanted left superior facet prosthesis;
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FIG. 10 is a perspective view of an alternate left
superior facet prosthesis;
FIG. 11 is a lateral view of an alternative
reconstructed spine joint;
FIG. 12 is a dorsal view of an alternative
reconstructed spine joint;
FIG. 13 is a perspective view of the implanted left
inferior facet prosthesis shown in FIGS. 11 and 12;
FIG. 14 is a perspective view of the alternative
left inferior facet prosthesis shown in FIGS. 11 and 12;
FIG. 15 is a cranial view of the alternative
implanted left superior facet prosthesis shown in FIGS.
11 and 12;
FIG. 16 is a perspective view of the alternative
left superior facet prosthesis shown in FIGS. 11 and 12;
FIG. 17 is a perspective view of an alternate
bearing surface for the superior facet prosthesis shown
in FIG. 16;
FIG. 18 is a perspective view of a spine motion
segment;
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FIG. 19 is a dorsal view of a bilateral facet joint
reconstructed in accordance with the present invention;
FIG. 20 is a lateral view of the bilateral facet
joint prosthesis shown in FIG. 19;
FIG. 21 is a dorsal view of the implanted inferior
bilateral facet prosthesis shown in FIGS. 19 and 20;
FIG. 22 is an inferior view of the implanted
inferior bilateral facet prosthesis shown in FIGS. 19
and 20;
FIG. 23 is a ventral view of the inferior bilateral
facet prosthesis shown in FIGS. 21 and 22;
FIG. 24 is a dorsal view of the implanted superior
bilateral facet prosthesis shown in FIGS. 19 and 20;
FIG. 25 is a superior view of the implanted
superior bilateral facet prosthesis shown in FIGS. 19
and 20
FIG. 26 is a ventral view of the superior bilateral
facet prosthesis shown in FIGS. 24 and 25;
FIG. 27 is a perspective view of an alternative
embodiment of the superior bilateral facet prosthesis
shown in FIGS. 24 and 25;
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FIG. 28 is a dorsal view of a two level facet joint
replacement;
FIG. 29 is a lateral view of the two level facet
joint replacement of FIG. 28;
FIG. 30 is a dorsal view of the implanted four
facet prosthesis shown in FIGS. 28 and 29;
FIG. 31 is a perspective view of the four facet
prosthesis shown in FIG. 30;
FIG. 32 is a perspective view of an alternative
form of inferior bilateral facet prosthesis;
FIG. 33 is a perspective view of an implanted
superior and inferior unilateral facet prosthesis;
FIG. 34 is a perspective view of the unilateral
facet prosthesis shown in FIG. 33;
FIG. 35 is a perspective view of a lumbar vertebra;
FIG. 36 is a perspective view of a novel prosthesis
that replaces the lamina, the four facets, the spinous
process and the two transverse processes of a vertebra;
FIG. 37 is an anterior view of the prosthesis shown
in FIG. 36;
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FIG. 38 is a perspective view of a vertebra which
has been resected to receive the prosthesis shown in
FIG. 36
FIG. 39 is a perspective view of the prosthesis
shown in FIG. 36 mounted to the resected vertebra shown
in FIG. 38;
FIG. 40 is a dorsal view of the prosthesis shown in
FIG. 36 mounted to the resected vertebra shown in FIG.
38;
FIG. 41 is a lateral view of the prosthesis shown
in FIG. 36 mounted to the resected vertebra shown in
FIG. 38;
FIG. 42 is a perspective view of a novel prosthesis
that replaces the lamina, the four facets and the
spinous process of a vertebra;
FIG. 43 is a perspective view of a novel prosthesis
that replaces the lamina, the four facets and the two
transverse processes of a vertebra;
FIG. 44 is a perspective view of a novel prosthesis
that replaces the lamina and the four facets of a
vertebra;
FIG. 45 is a perspective view of a novel prosthesis
that replaces the two pedicles, the lamina,
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the four facets, the spinous process and the two
transverse processes of a vertebra;
FIG. 46 is a lateral view of the prosthesis shown
in FIG. 45;
FIG. 47 is an anterior view of the prosthesis shown
in FIG. 45;
FIG. 48 is a perspective view of a vertebra which
has been resected to receive the prosthesis shown in
FIG. 45;
FIG. 49 is a perspective view showing the
prosthesis of FIG. 45 mounted to the resected vertebra
shown in FIG. 48;
FIG. 50 is a perspective view of a novel prosthesis
that replaces the two pedicles, the lamina, the four
facets and the spinous process of a vertebra;
FIG. 51 is a perspective view of a novel prosthesis
that replaces the two pedicles, the lamina, the four
facets and the two transverse processes of a vertebra;
FIG. 52 is a perspective view of a novel prosthesis
that replaces the two pedicles, the lamina and the four
facets of a vertebra; and
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FIG. 53 is a perspective view showing an alternative
arrangement for mounting the prosthesis of FIG. 45 to a
vertebra.
Detailed Description of the Preferred Embodiments
Disc Prosthesis and Single Facet Prosthesis
Referring now to FIGS. 1 and 2, there is shown a
superior vertebra 1 and an inferior vertebra 3, with an
intervertebral disc 2 located in between. Vertebra 1 has
superior facets 43, inferior facets 6, posterior arch 35
and spinous process 46. Vertebra 3 has superior facets
7, inferior facets 44, posterior arch 36 and spinous
process 45.
Referring now to FIG. 3, in accordance with one
aspect of the present invention, the intervertebral disc
2 has been replaced by an artificial disc AD. This
artificial disc AD may be a device such as is described
by Stefee et al. in U.S. Pat. No. 5,071,437; Gill et al.
in U.S. Pat. No. 6,113,637; Bryan et al. in U.S. Pat.
No. 6,001,130; Hedman et al. in U.S. Pat. No. 4,759,769;
Ray in U.S. Pat. No. 5,527,312; Ray et al. in U.S. Pat.
No. 5,824,093; Buttner-Janz in U.S. Patent
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No. 5,401,269; and Serhan et al. in U.S. Pat. No.
5,824,094. Alternatively, the artificial disc may be
some other artificial disc of the sort known in the art.
In addition to the foregoing, the left inferior
facet 6 of vertebra 1 has been resected and an inferior
facet prosthesis 4 has been attached to vertebra 1.
Similarly, the left superior facet of vertebra 3 has
been resected and a superior facet prosthesis 5 has been
attached to vertebra 3.
FIG. 4 illustrates a dorsal view of the elements
shown in FIG. 3. It can be appreciated that inferior
facet prosthesis 4 replicates the natural anatomy when
compared to the contralateral inferior facet 6 of
vertebra 1. Similarly, it can be appreciated that
superior facet prosthesis 5 replicates the natural
anatomy when compared to the contralateral superior
facet 7 of vertebra 3.
Turning now to FIG. 5, a perspective view of
vertebra 1 with implanted inferior facet prosthesis 4 is
provided. Resection at 31 has removed the natural
inferior facet 6 at the bony junction between the
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,....:.... .. ...... ...._.... ..__..__ , _..._. ..,., .__.._..._....
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facet 6 and the posterior arch 35. In this manner, bone
pain associated with a disease, such as osteoarthritis,
or trauma may be eliminated as the involved bony tissue
has been osteotomized.
FIG. 6 illustrates a perspective view of inferior
facet prosthesis 4. Surface 8 replicates the natural
articular surface of the replaced inferior facet 6. Post
9 provides a means to affix inferior facet prosthesis 4
to vertebra 1. Post 9 is implanted into the interior
bone space of the left pedicle P (FIG. 7) on vertebra 1
and may or may not extend into the vertebral body of
vertebra 1 to provide additional stability.
FIG. 7 illustrates a cranial view of vertebra 3
with implanted superior facet prosthesis 5. Resection
surface 32 represents the bony junction between the
natural superior facet and the posterior arch 35.
FIG. 8 illustrates a perspective view of superior
facet prosthesis 5. Surface 36 replicates the natural
articular surface of the replaced superior facet 7. Post
37 provides a means for affixing superior facet
prosthesis 5 to vertebra 3. Post 37 is implanted into
the interior bone space of the left pedicle P (FIG. 7)
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on vertebra 3 and may or may not extend into the
vertebral body of vertebra 3 to provide additional
stability.
When the total facet joint is replaced, as shown in
FIGS. 3 and 4, then surface 8 (FIG. 6) articulates with
surface 36 (FIG. 8) to recreate the natural biomechanics
of the spine motion segment made up of vertebra 1,
vertebra 3, and intervertebral disc 2.
FIG. 9 illustrates an alternative inferior facet
prosthesis 10 which is implanted into the interior bone
space of posterior arch 35. The interior bone space is
accessed from the resection 31.
FIG. 10 shows details of alternative inferior facet
prosthesis 10, including the fin 13 that extends into
the interior bone space of posterior arch 35. Surface 12
replicates the natural articular surface of the replaced
facet.
If desired, a corresponding fin construction can be
used to form a prosthetic superior facet.
The surfaces of post 9 (FIG. 6), post 37 (FIG. 8)
and fin 13 (FIG. 10) may or may not include porous
coatings to facilitate bone ingrowth to enhance the long
term fixation of the implant. Furthermore, such
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porous coatings may or may not include osteoinductive or
osteoconductive substances to further enhance the bone
remodeling into the porous coating.
Referring now to FIG. 11, there is shown a lateral
view of a superior vertebra 14 and an inferior vertebra
16, with an intervertebral disc 15 located in between is
shown. The left inferior facet of vertebra 14 has been
resected and an inferior facet prosthesis 18 has been
attached to vertebra 14 by means of a screw fastener 17.
Similarly, the left superior facet of vertebra 16 has
been resected and a superior facet prosthesis 19 has
been attached to vertebra 16 by means of a screw
fastener 17.
FIG. 12 illustrates a dorsal view of the elements
of FIG. 11. It can be appreciated that inferior facet
prosthesis 18 replicates the natural anatomy when
compared to the contralateral inferior facet 22 of
vertebra 14. Similarly, it can be appreciated that
superior facet prosthesis 19 replicates the natural
anatomy when compared to the contralateral superior
facet 21 of vertebra 16.
Turning now to FIG. 13, there is provided a
perspective view of vertebra 14 with implanted inferior
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facet prosthesis 18. Resection 34 has removed the
natural inferior facet at the bony junction between the
inferior facet and the posterior arch 37. In this
manner, bone pain associated with a disease, such as
osteoarthritis, or trauma may be eliminated inasmuch as
the involved bony tissue has been osteotomized.
FIG. 14 illustrates a perspective view of inferior
facet prosthesis 18. Surface 23 replicates the natural
articular surface of the replaced facet. Flange 25
contacts the pedicle and hole 24 receives a fastener to
attach inferior facet prosthesis 18 to vertebra 14.
FIG. 15 illustrates a cranial view of vertebra 16
with implanted superior facet prosthesis 19. Resection
surface 35 represents the bony junction between the
natural superior facet and the posterior arch 38.
FIG. 16 illustrates a perspective view of superior
facet prosthesis 19. Surface 27 replicates the natural
articular surface of the replaced facet. Flange 39
contacts the pedicle and hole 26 receives a fastener to
attach inferior facet prosthesis 19 to vertebra 16.
FIG. 17 illustrates an alternative superior facet
prosthesis 40 with an bearing surface 41 that mounts to
substrate 42. The bearing surface 41 is a
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biocompatible polymeric material, such as ultra high
molecular weight polyethylene. Alternately, the bearing
surface can be ceramic, such as zirconia or alumina, or
metal. The substrate is a biocompatible metal alloy,
such as an alloy of titanium, cobalt, or iron.
Disc Prosthesis and Double Facet Prosthesis
Referring next to FIG. 18, there is shown a
superior vertebra 1005 and an inferior vertebra 1010,
with an intervertebral disc 1015 located in between.
Vertebra 1005 has superior facets 1020, inferior facets
1025, a lamina (also sometimes referred to as a
posterior arch) 1030, a spinous process 1035, and
pedicles 1040. Vertebra 1010 has superior facets 1045,
inferior facets 1050, a posterior arch 1055, a spinous
process 1060, and pedicles 1065 (only one of which is
seen in FIG. 18).
Referring now to FIGS. 19 and 20, in accordance
with another aspect of the invention, intervertebral
disc 1015 has been replaced by an artificial disc AD.
This artificial disc AD may be a device such as is
described by Stefee et al. in U.S. Pat. No. 5,071,437;
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Gill et al. in U.S. Patent No. 6,113,637; Bryan et al.
in U.S. Pat. No. 6,001,130; Hedman et al. in U.S. Patent
No. 4,759,769; Ray in U.S. Patent No. 5,527,312; Ray et
al. in U.S. Pat. 5,824,093; Buttner-Janz in U.S. Patent
No. 5,401,269; and Serhan et al. in U.S. Patent No.
5,824,094. Alternatively, the artificial disc may be
some other artificial disc of the sort known in the art.
In addition to the foregoing, the left and right
inferior facets 1025 of vertebra 1005 have been
resected at 1070 and a bilateral inferior facet
prosthesis 1075 has been attached to vertebra 1005
using screw fasteners 1080. Similarly, the left and
right superior facets 1045 of vertebra 1010 have been
resected at 1082 (Fig. 24) and a bilateral superior
facet prosthesis 1085 has been attached to vertebra
1010 using screw fasteners 1090.
In Fig. 20 it can be appreciated that bilateral
inferior facet prosthesis 1075 replicates the natural
anatomy when compared to the intact inferior facet 1025
of vertebra 1005. Furthermore, bilateral facet
prosthesis 1075 extends from its attachment point in a
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manner that does not require contact with, or mating to,
the complex geometry of the lamina (or posterior arch)
1030. Resection surfaces 1070 provide adequate clearance
for bilateral inferior facet prosthesis 1075 and provide
complete removal of the diseased or traumatized natural
inferior facets 1025.
FIGS. 21 and 22 illustrate how the geometry of the
bridge 1095 of bilateral inferior facet prosthesis 1075
matches that of the posterior arch 1030 of vertebra 1005
in order to provide adequate clearance for the central
foramen 1100. Articular surfaces 1105 articulate with
the opposing superior facets 1045 (or their prosthetic
replacements) of the vertebra 1010.
FIG. 23 illustrates the bilateral inferior facet
prosthesis 1075 with flanges 1110 that abut against the
pedicles 1040 of vertebra 1005. Bridge 1095 connects the
articular surfaces 1105. Holes 1115 allow the attachment
of bilateral inferior facet prosthesis 1075 to vertebra
1005 by means of screw fasteners 1080. Alternatively,
screw fasteners 1080 could be replaced with staples,
pins, tacks, anchors, modular fixation posts, or the
like. These alternative fasteners could further include
porous coatings to further enhance bony
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fixation, and could also include osteoconductive or
osteoinductive substances.
In FIG. 24 it can be appreciated that bilateral
superior facet prosthesis 1085 replicates the natural
anatomy when compared to the intact superior facets 1045
of vertebra 1010. Furthermore, bilateral facet
prosthesis 1085 extends from its attachment point in a
manner that does not require contact with, or mating to,
the complex geometry of the lamina (or posterior arch)
1055. Resection surfaces 1082 provide adequate clearance
for bilateral superior facet prosthesis 1085 and provide
complete removal of the diseased or traumatized natural
superior facets 1045.
FIG. 25 illustrates how the geometry of the bridge
1120 of bilateral superior facet prosthesis 1085 matches
that of the posterior arch 1055 of vertebra 1010 in
order to provide adequate clearance for the central
foramen 1125. Articular surfaces 1130 articulate with
the opposing inferior facets of the vertebra 1005.
FIG. 26 illustrates the bilateral superior facet
prosthesis 1085 with flanges 1135 that abut against the
pedicles 1065 of vertebra 1010. Bridge 1120 connects
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the articular surfaces 1130 (seen in FIG. 25 but not
seen in FIG. 26). Holes 1140 allow the attachment of
bilateral superior facet prosthesis 1085 to vertebra
1010 by means of screw fasteners 1090.
FIG. 27 illustrates an alternative superior facet
prosthesis 1085A with a bearing surface 1130A that
mounts to substrate 1131A. The bearing surface 1130A is
preferably a biocompatible polymeric material, such as
ultra high molecular weight polyethylene. Alternately,
the bearing surface 1130A can be ceramic, such as
zirconia or alumina. The substrate 1131A is preferably a
biocompatible metal alloy, such as an alloy of titanium,
cobalt, or iron.
FIG. 28 illustrates a superior vertebra 1145, a
middle vertebra 1150, and an inferior vertebra 1155.
Superior facet prosthesis 1085 articulates with
quad-facet prosthesis 1160 to recreate the natural
biomechanics of the replaced facet joints. Inferior
facet prosthesis 1075 articulates with quad-facet
prosthesis 1160 to recreate the natural biomechanics of
the replaced facet joints at the next upper level. Thus,
FIG. 28 illustrates a two level reconstruction of facet
joints. Superior facet prosthesis 1085,
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quad-facet prosthesis 1160, and inferior facet
prosthesis 1075 are each attached to bone by means of
screw fasteners 1165.
In the lateral view of FIG. 29, it can be
appreciated that superior facet prosthesis 1085,
quad-facet prosthesis 1160, and inferior facet
prosthesis 1075 do not encroach into the intervertebral
foraminal spaces 1167 where nerve roots extend laterally
from the spinal cord.
Referring next to FIG. 30, it should be appreciated
that superior bridge 1170 and inferior bridge 1175 of
quad-facet prosthesis 1160 do not contact any portion of
vertebra 1150. Mounting holes 1180 (shown in FIG. 31)
are used to secure the flanges 1185 against the pedicles
of vertebra 1150.
In FIG. 32, an alternative inferior bilateral facet
prosthesis 1190 is presented. To further stabilize the
implant and to counter moments that act upon the two
points of fixation into the pedicles, a set of parallel
flanges 1195 extend posteriorly such that the two
flanges straddle the spinous process 1035. A bolt 1200
is used to fasten the parallel flanges to the spinous
process. Alternatively, other adjunctive
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structural features could be added to further stabilize
the prosthesis. For example, a strut that extends, and
attaches, to the transverse process could be used to
further stabilize the prosthesis.
Looking next at FIGS. 33 and 34, there is shown a
superior and inferior unilateral facet prosthesis 1300.
Unilateral facet prosthesis 1300 comprises a body 1305
and a stem 1310 extending out of body 1305. A superior
element 1315 extends vertically upward from body 1305,
and an inferior element 1310 extends vertically downward
from body 1305. Unilateral facet prosthesis 1300 is
configured so that when its stem 1310 extends into the
pedicle of vertebra 1325, superior element 1315 will
replace a resected superior facet, and inferior element
1320 will replace a resected inferior facet. If desired,
stem 1310 could be replaced with a screw extending
through a hole in body 1305 and into the pedicle.
Disc Prosthesis and Quadruple Facet Prosthesis
Referring next to FIG. 35, there is shown a natural
lumbar vertebra 2005 comprising a natural vertebral body
2010, a pair of natural pedicles 2015
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extending from natural vertebral body 2010, a natural
lamina 2020 extending from natural pedicles 2015, a
pair of natural superior facets 2025 extending from
natural pedicles 2015 and natural lamina 2020, a pair
of natural inferior facets 2030 extending from natural
lamina 2020, a natural spinous process 2035 extending
from natural lamina 2020, and a pair of natural
transverse processes 2040 extending from natural
pedicles 2015.
In accordance with another aspect of the
invention, the intervertebral disc on one side or the
other of vertebral body 2010 is replaced by an
artificial disc. This artificial disc may be a device
such as is described by Stefee et al. in U.S. Pat. No.
5,071,437; Gill et al. in U.S. Pat. No. 6,113,637;
Bryan et al. in U.S. Patent No. 6,001,130; Hedman et al.
in U.S. Patent No. 4,759,769; Ray in U.S. Patent No.
5,527,312; Ray et al. in U.S. Pat. 5,824,093; Buttner-
Janz in U.S. Patent No. 5,401,269; and Serhan et al. in
U.S. Patent No. 5,824,094. Alternatively, the
artificial disc may be some other artificial disc of the
sort known in the art.
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In addition to the foregoing, and looking next at
FIGS. 36 and 37, there is shown a novel prosthesis 2100
which is adapted to replace the natural lamina 2020, the
two natural superior facets 2025, the two natural
inferior facets 2030, the natural spinous process 2035,
and the two natural transverse processes 2040. To this
end, prosthesis 2100 comprises a pair of prosthetic
mounts 2115, a prosthetic lamina 2120 extending from
prosthetic mounts 2115, a pair of prosthetic superior
facets 2125 extending from prosthetic mounts 2115 and
prosthetic lamina 2120, a pair of prosthetic inferior
facets 2130 extending from prosthetic lamina 2120, a
prosthetic spinous process 2135 extending from
prosthetic lamina 2120, and a pair of prosthetic
transverse processes 2140 extending from prosthetic
mounts 2115.
In the use of prosthesis 2100, natural lumbar
vertebra 2005 is resected at its natural pedicles 2015
so as to remove the natural lamina 2020, the two natural
superior facets 2025, the two natural inferior facets
2030, the natural spinous process 2035, and the two
natural transverse processes 2040, leaving a pair of
pedicle end surfaces 2041 (FIG. 38). Then the
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prosthesis 2100 may be attached to the natural pedicles
2015, e.g., by placing prosthetic mounts 2115 against
pedicle surfaces 2041 and then passing screws 2145
through screw holes 2147 and into natural pedicles 2015,
as shown in FIGS. 39-41. As seen in the drawings, the
relative size, shape and positioning of the prosthetic
lamina 2120, the two prosthetic superior facets 2125,
the two prosthetic inferior facets 2130, the prosthetic
spinous process 2135, and the two prosthetic transverse
processes 2140 essentially mimic the relative size,
shape and positioning of the natural lamina 2020, the
two natural superior facets 2025, the two natural
inferior facets 2030, the natural spinous process 2035,
and the two natural transverse processes 2040, whereby
to effectively restore the vertebra. If desired, holes
2150 may be provided in the prosthetic spinous process
2135 and/or the two prosthetic transverse processes 2140
so as to facilitate re-attaching soft tissue to these
structures.
Looking next at FIG. 42, there is shown a novel
prosthesis 2200 which is adapted to replace natural
lamina 2020, the two natural superior facets 2025, the
two natural inferior facets 2030, and natural spinous
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process 2035. To this end, prosthesis 2200 comprises a
pair of prosthetic mounts 2215, a prosthetic lamina 2220
extending from prosthetic mounts 2215, a pair of
prosthetic superior facets 2225 extending from
prosthetic mounts 2215 and prosthetic lamina 2220, a
pair of prosthetic inferior facets 2230 extending from
prosthetic lamina 2220, and a prosthetic spinous process
2235 extending from prosthetic lamina 2220.
In the use of prosthesis 2200, natural lumbar
vertebra 2005 is resected at its natural pedicles 2015
so as to remove the natural lamina 2020, the two natural
superior facets 2025, the two natural inferior facets
2030, the spinous process 2035 and the two natural
transverse processes 2040, leaving a pair of pedicle
surfaces 2041 (FIG. 38). Then the prosthesis 2200 may be
attached to the natural pedicles 2015, e.g., by placing
prosthetic mounts 2215 against pedicle surfaces 2041 and
then passing screws 2145 through holes 2247 and into
natural pedicles 2015. As seen in the drawing, the
relative size, shape and positioning of prosthetic
lamina 2220, the two prosthetic superior facets 2225,
the two prosthetic inferior facets 2230, and the
prosthetic spinous process 2235 essentially
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mimic the relative size, shape and positioning of the
natural lamina 2020, the two natural superior facets
2025, the two natural inferior facets 2030, and the
natural spinous process 2035, whereby to effectively
restore the vertebra. If desired, holes 2150 may be
provided in the prosthetic spinous process 2235 so as to
facilitate re-attaching soft tissue to this structure.
Looking next at FIG. 43, there is shown a novel
prosthesis 2300 which is adapted to replace the natural
lamina 2020, the two natural superior facets 2025, the
two natural inferior facets 2030, and the two natural
transverse processes 2040. To this end, prosthesis 2300
comprises a pair of prosthetic mounts 2315, a prosthetic
lamina 2320 extending from prosthetic mounts 2315, a
pair of prosthetic superior facets 2325 extending from
prosthetic mounts 2315 and prosthetic lamina 2320, a
pair of prosthetic inferior facets 2330 extending from
prosthetic lamina 2320, and a pair of prosthetic
transverse processes 2340 extending from prosthetic
mounts 2315.
In the use of prosthesis 2300, natural lumbar
vertebra 2005 is resected at natural pedicles 2015 so
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as to remove natural lamina 2020, the two natural
superior facets 2025, the two natural inferior facets
2030, the natural spinous process 2035 and the two
natural transverse processes 2040, leaving a pair of
pedicle surfaces 2041 (FIG. 38). Then the prosthesis
2300 may be attached to the natural pedicles 2015, e.g.,
by placing prosthetic mounts 2315 against pedicle
surfaces 2041 and then passing screws 2145 through holes
2347 and into natural pedicles 2015. As seen in the
drawing, the relative size, shape and positioning of the
prosthetic lamina 2320, the two prosthetic superior
facets 2325, the two prosthetic inferior facets 2330,
and the two prosthetic transverse processes 2340
essentially mimic the relative size, shape and
positioning of the natural lamina 2020, the two natural
superior facets 2025, the two natural inferior facets
2030, and the two natural transverse processes 2040,
whereby to effectively restore the vertebra. If desired,
holes 2150 may be provided in the two prosthetic
transverse processes 2340 so as to facilitate
re-attaching soft tissue to these structures.
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Looking next at FIG. 44, there is shown a novel
prosthesis 2400 which is adapted to replace the natural
lamina 2020, the two natural superior facets 2025, and
the two natural inferior facets 2030. To this end,
prosthesis 2400 comprises a pair of prosthetic mounts
2415, a prosthetic lamina 2420 extending from prosthetic
mounts 2415, a pair of prosthetic superior facets 2425
extending from prosthetic mounts 2415 and prosthetic
lamina 2420, and a pair of prosthetic inferior facets
2430 extending from prosthetic lamina 2420.
In the use of prosthesis 2400, natural lumbar
vertebra 2005 is resected at pedicles 2015 so as to
remove the natural lamina 2020, the two natural superior
facets 2025, the two natural inferior facets 2030, the
natural spinous process 2035, and the two natural
transverse processes 2040, leaving a pair of pedicle
surfaces 2041 (FIG. 38). Then the prosthesis 2400 may be
attached to the natural pedicles 2015, e.g., by placing
prosthetic mounts 2415 against pedicle surfaces 2041 and
then passing screws 2145 through holes 2447 and into
natural pedicles 2015. As seen in the drawing, the
relative size, shape and positioning
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of prosthetic lamina 2420, the two prosthetic superior
facets 2425, and the two prosthetic inferior facets 2430
essentially mimic the relative size, shape and
positioning of the natural lamina 2020, the two natural
superior facets 2025 and the two natural inferior facets
2030, whereby to effectively restore the vertebra.
Looking next at FIGS. 45-47, there is shown a novel
prosthesis 2500 which is adapted to replace a pair of
natural pedicles 2015, the natural lamina 2020, the two
natural superior facets 2025, the two natural inferior
facets 2030, the natural spinous process 2035, and the
two natural transverse processes 2040. To this end,
prosthesis 2500 comprises a pair of prosthetic pedicles
2515, a prosthetic lamina 2520 extending from prosthetic
pedicles 2515, a pair of prosthetic superior facets 2525
extending from prosthetic pedicles 2515 and prosthetic
lamina 2520, a pair of prosthetic inferior facets 2530
extending from prosthetic lamina 2520, a prosthetic
spinous process 2535 extending from prosthetic lamina
2520, and a pair of prosthetic transverse processes 2540
extending from prosthetic pedicles 2515.
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In the use of prosthesis 2500, natural lumbar
vertebra 2005 is resected at the bases of natural
pedicles 2015 so as to remove to two natural pedicles
2015, the natural lumina 2020, the two natural superior
facets 2025, the two natural inferior facets 2030, the
natural spinous process 2035, and the two natural
transverse processes 2040, leaving a vertebral body end
face 2042 (FIG. 48). Then the prosthesis 2500 may be
attached to the natural vertebral body 2010, e.g., by
placing prosthetic pedicles 2515 against vertebral body
end face 2042 and then passing screws 2145 through holes
2547 and into natural vertebral body 2010, as shown in
FIG. 49. As seen in the drawings, the relative size,
shape and positioning of the two prosthetic pedicles
2515, the prosthetic lamina 2520, the two prosthetic
superior facets 2525, the two prosthetic inferior facets
2530, the prosthetic spinous process 2535, and the two
prosthetic transverse processes 2540 essentially mimic
the relative size, shape and positioning of the two
natural pedicles 2015, the natural lamina 2020, the two
natural superior facets 2025, the two natural inferior
facets 2030, the natural spinous process 2035, and the
two natural
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transverse processes 2040, whereby to effectively
restore the vertebra. If desired, holes 2150 may be
provided in prosthetic spinous process 2535 and the two
prosthetic transverse processes 2540 so as to facilitate
re-attaching soft tissue to these structures.
Looking next at FIG. 50, there is shown a novel
prosthesis 2600 which is adapted to replace the two
natural pedicles 2015, the natural lamina 2020, the two
natural superior facets 2025, the two natural inferior
facets 2030, and the natural spinous process 2035. To
this end, prosthesis 2600 comprises a pair of prosthetic
pedicles 2615, a prosthetic lamina 2620 extending from
prosthetic pedicles 2615, a pair of prosthetic superior
facets 2625 extending from prosthetic pedicles 2615 and
prosthetic lamina 2620, a pair of prosthetic inferior
facets 2630 extending from prosthetic lamina 2620, and a
prosthetic spinous process 2635 extending from
prosthetic lamina 2620.
In the use of prosthesis 2600, natural lumbar
vertebra 2005 is resected at the bases of natural
pedicles 2015 so as to remove the two natural pedicles
2015, the natural lamina 2020, the two natural superior
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facets 2025, the two natural inferior facets 2030, the
natural spinous process 2035 and the two natural
transverse processes 2040, leaving a vertebral body end
face 2042 (FIG. 48). Then the prosthesis 2600 may be
attached to the natural vertebral body 2010, e.g., by
placing prosthetic pedicles 2615 against vertebral body
end face 2042 and then passing screws 2145 through holes
2647 and into natural vertebral body 2010. As seen in
the drawing, the relative size, shape and positioning of
the two prosthetic pedicles 2615, the prosthetic lamina
2620, the two prosthetic superior facets 2625, the two
prosthetic inferior facets 2630, and the prosthetic
spinous process 2635 essentially mimic the relative
size, shape and positioning of the two natural pedicles
2015, the natural lamina 2020, the two natural superior
facets 2025, the two natural inferior facets 2030, and
the natural spinous process 2035, whereby to effectively
restore the vertebra. If desired, holes 2150 may be
provided in prosthetic spinous process 2635 so as to
facilitate re-attaching soft tissue to this structure.
Looking next at FIG. 51, there is shown a novel
prosthesis 2700 which is adapted to replace the two
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natural pedicles 2015, the natural lamina 2020, the two
natural superior facets 2025, the two natural inferior
facets 2030, and the two natural transverse processes
2040. To this end, prosthesis 2700 comprises a pair of
prosthetic pedicles 2715, a prosthetic lamina 2720
extending from prosthetic pedicles 2715, a pair of
prosthetic superior facets 2725 extending from
prosthetic pedicles 2715 and prosthetic lamina 2720, a
pair of prosthetic inferior facets 2730 extending from
prosthetic lamina 2720, and a pair of prosthetic
transverse processes 2740 extending from prosthetic
pedicles 2715.
In the use of prosthesis 2700, natural lumbar
vertebra 2005 is resected at the bases of natural
pedicles 2015 so as to remove the two natural pedicles
2015, the natural lamina 2020, the two natural superior
facets 2025, the two natural inferior facets 2030, the
natural spinous process 2035, and the two natural
transverse processes 2040, leaving a vertebral body end
face 2042 (FIG. 48). Then the prosthesis 2700 may be
attached to the natural vertebral body 2010, e.g., by
placing prosthetic pedicles 2715 against vertebral body
end face 2042 and then passing screws 2145 through
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holes 2747 and into vertebral body 2010. As seen in the
drawing, the relative size, shape and positioning of the
two prosthetic pedicles 2715, the prosthetic lamina
2720, the two prosthetic superior facets 2725, the two
prosthetic inferior facets 2730, and the two prosthetic
transverse processes 2740 essentially mimic the relative
size, shape and positioning of the two natural pedicles
2015, the natural lamina 2020, the two natural superior
facets 2025, the two natural inferior facets 2030, and
the two natural transverse processes 2040, whereby to
effectively restore the vertebra. If desired, holes 2150
may be provided in the two prosthetic transverse
processes 2740 so as to facilitate re-attaching soft
tissue to these structures.
Looking next at FIG. 52, there is shown a novel
prosthesis 2800 which is adapted to replace the two
natural pedicles 2015, the natural lamina 2020, the two
natural superior facets 2025, and the two natural
inferior facets 2030. To this end, prosthesis 2800
comprises a pair of prosthetic pedicles 2815, a
prosthetic lamina 2820 extending from prosthetic
pedicles 2815, a pair of prosthetic superior facets
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2825 extending from prosthetic pedicles 2815 and
prosthetic lamina 2820, and a pair of prosthetic
inferior facets 2830 extending from prosthetic lamina
2820.
In the use of prosthesis 2800, natural lumbar
vertebra 2005 is resected at the bases of natural
pedicles 2015 so as to remove the two natural pedicles
2015, the natural lamina 2020, the two natural superior
facets 2025, the two natural inferior facets 2030, the
natural spinous process 2035, and the two natural
transverse processes 2040, leaving a vertebral body end
face 2042 (FIG. 48). Then the prosthesis 2800 may be
attached to natural vertebral body 2010, e.g., by
placing prosthetic pedicles 2715 against vertebral body
end face 2042 and then passing screws 2145 through holes
2847 and into natural vertebral body 2010. As seen in
the drawing, the relative size, shape and positioning of
the two prosthetic pedicles 2815, the prosthetic lamina
2820, the two prosthetic superior facets 2825, and the
two prosthetic inferior facets 2830 essentially mimic
the relative size, shape and positioning of the two
natural pedicles 2015, the natural lamina 2020, the two
natural superior facets
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2025, and the two natural inferior facets 2030, whereby
to effectively restore the vertebra.
It should also be appreciated that prostheses 2100,
2200, 2300, 2400, 2500, 2600, 2700 and 2800 may be
attached to natural vertebra 2005 with apparatus other
than the screws 2145 discussed above. Thus, for example,
prostheses 2100, 2200, 2300, 2400, 2500, 2600, 2700 and
2800 may be attached to natural vertebra 2005 with rods
or posts, etc. See, for example, FIG. 53, where
prosthesis 2500 is shown attached to natural vertebra
2005 with rods 2146 which pass through, and snap into
engagement with, prosthetic pedicles 2515.
Having thus described preferred embodiments of the
invention with reference to the accompanying drawings,
it is to be understood that the embodiments shown herein
are provided by way of example only, and that various
changes and modifications may be effected by one skilled
in the art without departing from the scope or spirit of
the invention as defined in the claims.
