U.S. patent application number 12/624946 was filed with the patent office on 2010-07-01 for method, implant & instruments for percutaneous expansion of the spinal canal.
Invention is credited to D. Greg Anderson, Wayne Beams, Barry Turner.
Application Number | 20100168751 12/624946 |
Document ID | / |
Family ID | 42243030 |
Filed Date | 2010-07-01 |
United States Patent
Application |
20100168751 |
Kind Code |
A1 |
Anderson; D. Greg ; et
al. |
July 1, 2010 |
Method, Implant & Instruments for Percutaneous Expansion of the
Spinal Canal
Abstract
A method for correcting spinal stenosis involves cannulating a
passage in a vertebra, and placing a distal portion of an implant
therein. Then, a circumferential vertebral cut is performed from
within the passage, using a proximal end of the distal portion of
the implant to align the vertebral cut. Then, a proximal portion of
the implant is placed into the passage, positioned against the
distal portion at the vertebral cut. Operation of the distal and
the proximal portions of the implant relative to one another widens
the vertebral cut and expands the spinal canal. The proximal
portion can then be secured to the distal portion to stabilize the
vertebral cut, allowing vertebral healing with the spinal canal
expanded. Flanges may exist that radially extend outward from the
implant and into the vertebral cut, or into the passage walls, to
assist vertebral cut widening and stabilization.
Inventors: |
Anderson; D. Greg;
(Moorestown, NJ) ; Turner; Barry; (Columbus,
IN) ; Beams; Wayne; (Bloomington, IN) |
Correspondence
Address: |
BLANK ROME LLP
ONE LOGAN SQUARE
PHILADELPHIA
PA
19103
US
|
Family ID: |
42243030 |
Appl. No.: |
12/624946 |
Filed: |
November 24, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11656790 |
Jan 22, 2007 |
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12624946 |
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10102525 |
Mar 19, 2002 |
7166107 |
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11656790 |
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61117726 |
Nov 25, 2008 |
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Current U.S.
Class: |
606/82 ; 606/191;
606/86A |
Current CPC
Class: |
A61B 2017/22038
20130101; A61B 17/7071 20130101; A61B 17/8685 20130101; A61B
17/1631 20130101; A61B 17/142 20161101; A61B 17/1617 20130101; A61B
17/1671 20130101; A61B 17/1637 20130101; A61B 17/8004 20130101 |
Class at
Publication: |
606/82 ;
606/86.A; 606/191 |
International
Class: |
A61B 17/00 20060101
A61B017/00; A61B 17/56 20060101 A61B017/56; A61M 29/00 20060101
A61M029/00 |
Claims
1. A method for expanding a spinal canal, comprising the steps of
creating at least one passage into a vertebra; placing a distal
portion of an implant into the passage; performing a
circumferential vertebral cut from within the passage, through to
the spinal canal and through to an outside of the vertebra, using a
proximal end of the distal portion of the implant to align the
vertebral cut; placing a proximal portion of the implant into the
passage, positioning a distal end of the proximal portion of the
implant against the proximal end of the distal portion of the
implant at the vertebral cut; and operating the distal and the
proximal portions of the implant relative to one another to widen
the vertebral cut and expand the spinal canal.
2. The method of claim 1, further comprising the step of: securing
the proximal portion of the implant to the distal portion of the
implant to stabilize the vertebral cut, whereby the vertebra heals
with the spinal canal expanded.
3. The method of claim 1, wherein the at least one passage and the
vertebral cut extend through a pedicle of the vertebra, and where
widening the vertebral cut elongates the pedicle, thereby
increasing an area of the spinal canal.
4. The method of claim 1, wherein the vertebral cut is located in a
lumbar vertebra.
5. The method of claim 1, further comprising a preliminary step of
introducing a guide wire into the vertebra to guide a drilling of
the at least one passage into the vertebra.
6. The method of claim 5, wherein a cannulated drill is positioned
over the guide wire to drill the at least one passage into the
vertebra.
7. The method of claim 1, wherein the at least one passage into the
vertebra is located in the pedicle of the vertebra, the passage
forming a hollow, cylindrical column within the pedicle.
8. The method of claim 1, wherein, during operation of the distal
and the proximal portions of the implant, at least one flange
radially extends outward from the implant and into the vertebral
cut, assisting the widening of the vertebral cut and a
stabilization of the vertebral cut.
9. The method of claim 1, wherein, during operation of the distal
and the proximal portions of the implant, at least one flange
radially extends outward from the implant and into the passage to
engage side walls of the passage, thereby facilitating
stabilization of the implant within the passage.
10. The method of claim 1, wherein the distal and the proximal
portions of the implant include external threads, and are
threadably introduced into the passage to engage side walls of the
passage.
11. The method of claim 1, wherein: the proximal portion further
includes a threaded device and an expanding device; and the implant
further includes a screw communicating with the threaded device and
the expanding device, wherein operation of the screw moves the
expanding device relative to the threaded device to increase a
length of the proximal portion, the increasing length of the
proximal portion, bearing against the distal portion, acts to widen
a vertebral cut to expand the spinal canal.
12. The method of claim 1, wherein the screw threadably engages an
inner channel of the threaded device, and abuts a base of the
expanding device, to translate the expanding device away from the
threaded device, upon operation of the screw, to widen the
vertebral cut.
13. The method of claim 1, wherein the implant further includes a
locking bolt configured for insertion through the proximal portion
and into the distal portion, wherein engagement of the locking bolt
with the proximal and the distal portions fastens the implant about
the vertebral cut, whereby the vertebral cut is stabilized,
allowing vertebral healing with the spinal canal expanded.
14. The method of claim 1, wherein: the distal portion has inner
threads; the proximal portion has inner threads, wherein the inner
threads of the distal portion are of a substantially different
pitch than the inner threads of the proximal portion, creating a
dual pitch configuration; and wherein: the implant further includes
a screw capable of communication with the distal and the proximal
portions, the screw having: outer threads at a distal end
substantially similar in pitch to the inner threads of the distal
portion; and outer threads at a proximal end substantially similar
in pitch to the inner threads of the proximal portion; wherein
operation of the screw within the distal and the proximal portions
translates the proximal portion relative to the distal portion, due
to the dual pitch configuration, about a vertebral cut, to widen
the vertebral cut and expand the spinal canal.
15. An implant for expanding a spinal canal, comprising: a distal
portion; a proximal portion including a threaded device and an
expanding device; and a screw communicating with the threaded
device and the expanding device, wherein operation of the screw
moves the expanding device relative to the threaded device to
increase a length of the proximal portion, the increasing length of
the proximal portion, bearing against the distal portion, acts to
widen a vertebral cut to expand the spinal canal.
16. The implant of claim 15, further comprising a locking bolt
configured for insertion through the proximal portion and into the
distal portion, wherein engagement of the locking bolt with the
proximal and the distal portions fastens the implant about the
vertebral cut, whereby the vertebral cut is stabilized, allowing
vertebral healing with the spinal canal expanded.
17. The implant of claim 16, wherein the distal portion further
comprises a floating nut movably housed therein, whereby the
movable configuration of the floating nut within the distal portion
facilitates acceptance of the locking bolt within the distal
portion, after insertion through the proximal portion, even if a
longitudinal central axis of the proximal and the distal portions
becomes translationally malaligned during vertebral widening.
18. The implant of claim 15, wherein the distal portion and the
threaded device include external threads to engage a vertebra about
each side of the vertebral cut, the distal portion engaging one
side of the vertebral cut and the threaded device engaging another
side of the vertebral cut.
19. The implant of claim 15, wherein the screw threadably engages
an inner channel of the threaded device, and abuts a base of the
expanding device, to translate the expanding device away from the
threaded device, upon operation of the screw, to widen the
vertebral cut.
20. The implant of claim 15, wherein the threaded device further
comprises at least one flange configured to project radially from
the proximal portion, into the vertebral cut, during operation of
the screw.
21. The implant of claim 20, wherein the at least one flange is
movably attached to the threaded device, wherein operation of the
screw causes the at least one flange to project radially from the
proximal portion, into the vertebral cut, prior to a lengthening of
the proximal portion to widen the vertebral cut.
22. The implant of claim 21, wherein the at least one flange
movably attached to the threaded device, upon radial projection
into the vertebral cut, bears against a proximal side of the
vertebral cut during vertebral widening.
23. The implant of claim 15, wherein the expanding device further
comprises at least one flange configured to project radially from
the proximal portion, into the vertebral cut, during operation of
the screw.
24. The implant of claim 23, wherein the at least one flange is
movably attached to the expanding device, wherein operation of the
screw causes the at least one flange to project radially from the
proximal portion, into the vertebral cut, prior to a lengthening of
the proximal portion to widen the vertebral cut.
25. The implant of claim 24, wherein the at least one flange
movably attached to the expanding device, upon radial projection
into the vertebral cut, bears against a distal side of the
vertebral cut during vertebral widening.
26. The implant of claim 15, further comprising: two flanges
movably attached to the threaded device; and two flanges movably
attached to the expanding device, wherein; the flanges are
configured to project radially from the proximal portion, into the
vertebral cut, during operation of the screw, prior to a
lengthening of the proximal portion to widen the vertebral cut;
operation of the screw causes a distal end of the screw to bear
against a respective distal end of each flange to radially extend
each flange radially outward beyond an exterior of the proximal
portion and into the vertebral cut, the two flanges movably
attached to the threaded device bear against a proximal side of the
vertebral cut during the lengthening of the proximal portion; and
the two flanges movably attached to the expanding device bear
against a distal side of the vertebral cut during the lengthening
of the proximal portion.
27. The implant of claim 26, wherein the flanges include
osteoconductive, osteoinductive or osteogenic material to assist
with healing of the vertebral cut.
28. An implant for expanding a spinal canal, comprising: a distal
portion having inner threads; a proximal portion having inner
threads, wherein the inner threads of the distal portion are of a
substantially different pitch than the inner threads of the
proximal portion, creating a dual pitch configuration; and a screw
capable of communication with the distal and the proximal portions,
the screw having: outer threads at a distal end substantially
similar in pitch to the inner threads of the distal portion; and
outer threads at a proximal end substantially similar in pitch to
the inner threads of the proximal portion; wherein operation of the
screw within the distal and the proximal portions translates the
proximal portion relative to the distal portion, due to the dual
pitch configuration, about a vertebral cut, to widen the vertebral
cut and expand the spinal canal.
29. The implant of claim 28, wherein the distal portion and the
proximal portions each further comprise external threads to engage
an interior of a passage within a vertebra, the outer threads of
the distal portion engaging the interior of the passage on one side
of the vertebral cut and the outer threads of the proximal portion
engaging the interior of the passage on another side of the
vertebral cut.
30. The implant of claim 28, wherein the distal portion further
comprises at least one flange movably attached thereto, configured
to project radially from the distal portion, into an interior of a
passage within a vertebra, to facilitate stabilization of the
distal portion within the passage during operation of the screw and
widening of the vertebral cut.
31. The implant of claim 30, wherein insertion of the screw within
the distal portion causes the at least one flange to project
radially from the distal portion into the interior of the
passage.
32. The implant of claim 28, wherein the proximal portion further
comprises at least one flange movably attached thereto, configured
to project radially from the proximal portion, into an interior of
a passage within a vertebra, to facilitate stabilization of the
proximal portion within the passage during operation of the screw
and widening of the vertebral cut.
33. The implant of claim 32, wherein insertion of the screw within
the proximal portion causes the at least one flange to project
radially from the proximal portion into the interior of the
passage.
34. A bone saw, comprising: a flexible saw blade, rectangular in
shape, having a central longitudinal axis and a cutting edge at a
distal tip; a shaft having: a central longitudinal axis; a blade
passage within the shaft that houses the saw blade, wherein the
central longitudinal axis of the saw blade, of the shaft, and of
the blade passage, are parallel; a blade opening located at and
through a distal end of the shaft and of the blade passage, the
blade opening being essentially perpendicular to the longitudinal
axis of the shaft; a curved abutment within the blade passage,
aligning the saw blade with the blade opening, wherein distally
translating the saw blade within the blade passage causes the saw
blade to conform to the curved abutment and exit the blade opening
with the cutting edge essentially perpendicular to the longitudinal
axis of the shaft.
35. The bone saw of claim 34, further comprising a trunion at a
distal tip of the shaft, the trunion located distal of the blade
opening, the trunion facilitating placement of the distal tip of
the shaft to precisely locate a desired blade opening location.
36. The bone saw of claim 34, wherein: the saw blade further
comprises a longitudinal groove along a side thereof; the blade
opening further comprises an indentor penetrating therein, the
indentor positioned to align with the groove of the saw blade as
the saw blade exits the blade opening, thereby facilitating desired
perpendicular blade alignment upon exiting the blade opening.
37. The bone saw of claim 34, further comprising an indentor
penetrating into the blade opening, the indentor configured to
introduce a crimp or counter bend to the flexible saw blade,
thereby counteracting a curling of the saw blade during a passing
of the saw blade through the curved abutment of the blade
passage.
38. The bone saw of claim 34, further comprising a threaded drive
mechanism located at a proximal end of the shaft and communicating
with the saw blade, wherein distally advancing the threaded drive
mechanism distally translates the saw blade within the blade
passage, causing the cutting edge to exit the blade opening, and
proximally retracting the threaded drive mechanism proximally
translates the saw blade within the blade passage, causing the
cutting edge to retract into the blade opening.
39. The bone saw of claim 38, further comprising a depth indicator
located a proximal end of the shaft and communicating with the
threaded drive mechanism, wherein a distance of advancing or
retracting of the drive mechanism, associated with a length of
advancing or retracting the cutting edge is indicated on the depth
indicator.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part (CIP) of U.S.
Ser. No. 11/656,790, filed Jan. 22, 2007; which application is a
continuation of U.S. Ser. No. 10/102,525, filed Mar. 19, 2002 (now
U.S. Pat. No. 7,166,107). This application also claims benefit of
U.S. Provisional Application Ser. No. 61/117,726, filed Nov. 25,
2008, entitled "Method, Implant & Instruments for Percutaneous
Expansion of the Spinal Canal." The above-identified related
applications are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to spinal surgery,
and more particularly to instruments and a device for cutting and
lengthening the spinal pedicles to correct spinal canal narrowing
or spinal stenosis and to relieve pressure on spinal nerves.
BACKGROUND OF THE INVENTION
[0003] Spinal stenosis is a condition or disease causing narrowing
of the spinal canal and compression of the spinal nerves. Spinal
stenosis affects millions of people world wide and leads to
symptoms of back and leg pain, weakness, numbness and trouble
walking Spinal stenosis is a particularly common problem among
older individuals and can result in severe disability and lack of
normal mobility. Spinal stenosis is one of the most common
conditions requiring spinal surgery. Surgery for spinal stenosis is
required to alleviate compression of the spinal nerves and improve
the symptoms of back and leg pain, weakness, numbness and trouble
walking.
[0004] The traditional surgical operation for spinal stenosis is a
called a laminectomy. This procedure involves cutting away the
spinal lamina or posterior bony covering of the spinal canal,
followed by trimming of the medial portions of the facet joints to
expand the room available to the spinal nerves. Some surgeons
prefer to use similar procedure called a laminotomy which removes
only a portion of the spinal lamina followed by trimming of the
facet joints to expand the room available for the spinal
nerves.
[0005] More recently, implantable medical devices called
intraspinous spacers have been used to treat spinal stenosis. These
devices are designed to wedge between the spinous processes of two
adjacent vertebrae, blocking the vertebral joint from extending or
bending backward. Because the spinal canal becomes most narrow in
the extended position, intraspinous devices can help a subset of
spinal stenosis patients that only experience pain while
standing.
[0006] Although laminectomy, laminotomy and intraspinous spacer
devices may all be successful for patients with spinal stenosis,
each of these approaches has significant limitations in a
significant proportion of patients with spinal stenosis. For
instance, laminectomy generally is a major spinal operation
requiring general anesthesia which can lead to complications
especially in older patients. Several important disadvantages have
been identified with the use of laminectomy to treat spinal
stenosis such as damage to back muscles, destabilization of the
spine and scarring around the nerve roots. In some cases,
destabilization of the spine may cause a serious forward slippage
of one vertebra on the adjacent vertebra requiring a major revision
surgery called spinal fusion. Also, laminectomy requires a large
surgical incision, leading to the risk of major bleeding and the
need for general anesthesia. Because most patients with spinal
stenosis are elderly, major surgery such as laminectomy may lead to
medical complications, making this approach suboptimal for the
older, medically fragile patient. In addition, laminectomy may not
provide a permanent cure for spinal stenosis, which recur causing
the need for further major surgery in the future.
[0007] Laminotomy is quite similar to laminectomy but does not
require removal of the entire bony lamina. Like laminectomy,
laminotomy is normally performed under general anesthesia and
involves trimming away portions of the spinal lamina and facet
joints to decompress the spinal nerves. Advocates of laminotomy
believe that the laminotomy approach may lessen the risks of spinal
destabilization and nerve scarring compared to laminectomy.
However, laminotomy still requires major open spinal surgery and
general anesthesia. It also is more technically difficult to
perform compared to laminectomy and may not adequately relieve the
pressure on the spinal nerves. In addition, there is a risk that
with time, the spinal stenosis may recur, leading to the need for
additional surgery.
[0008] Recently, intraspinous process spacers, such as the device
described by Zucherman, et. al. (U.S. Pat. No. 5,836,948) have been
described for the treatment of spinal stenosis. These devices are
designed to be wedged between the spinous processes, and block the
vertebral joint from assuming an extended position. Because the
extended position causes the spinal canal to be smaller, the
avoidance of this position may alleviate the symptoms of spinal
stenosis in a subset of patients with symptoms only while standing
(or bending backward; i.e., extending) that are relieved with
sitting (or bending forward; i.e., flexing). This subset of
patients generally have less severe narrowing of the spinal canal
and may achieve relief of pain by blocking the position of the
vertebral joint leading to the worst narrowing of the spinal
canal.
[0009] Unfortunately, intraspinous devices only provide a slight
expansion of the spinal canal compared to laminectomy and
laminotomy. Thus, intraspinous spacers are only useful in the
subset of spinal stenosis patients with relatively mild stenosis.
Also, because the narrowed spinal canal is not significantly
enlarged, and because the narrowing of the spinal canal worsens
with time, intraspinous process device may only provide temporary
relief of the symptoms of spinal stenosis. Thus, many patients
treated with laminectomy may ultimately require a laminectomy as
their condition worsens. Also, intraspinous process spacers are not
able to be used in patients whose spinous processes are weakened by
osteoporosis or absent due to a prior laminectomy procedure.
[0010] For all these reasons, a better treatment approach to spinal
stenosis is needed. In U.S. Pat. No. 6,358,254, issued Mar. 19,
2002, entitled "A Method and Implant for Expanding a Spinal Canal,"
and in U.S. Pat. No. 7,166,107, issued Jan. 23, 2007, entitled
"Percutaneous Technique and Implant for Expanding the Spinal
Canal", novel inventions are disclosed whereby the spinal canal can
be expanded by cutting and lengthening the spinal pedicles. The
present invention describes further, novel instruments, devices,
spinal implants and methods pertaining to the art of pedicle
lengthening that can be used to expand the spinal canal for the
correction of spinal stenosis. The present invention provides
significant advantages compared to the prior art methods and
devices for treating spinal stenosis.
[0011] In U.S. patent application Ser. No. 10/386,357 (US
2003/0212400) to Bloemer et al., a method for expansion of the
spinal canal is disclosed. In Bloemer, spinal stenosis is treated
by cutting, distracting and holding spinal pedicles with implanted
devices. However, the approach of Bloemer has certain limitations
and disadvantages that severely limit its usefulness for treating
spinal stenosis. First, no cutting method or tools disclosed by
Bloemer allow the bone cuts to be performed. The work of the
present invention has demonstrated that safe and accurate cutting
of the spinal pedicles is highly complex given the dense bone of
the spinal pedicles and the close proximity of the bone cuts to the
delicate nerve tissue and fluid filled dural sac. In addition, the
shape of the spinal pedicles is not regular but rather the bone of
the pedicle forms an irregular shape in cross section that
resembles an oval. In addition, the bone of the pedicle has thick
and thin regions which make the cutting task a substantial
challenge for which no instruments or tools have been previously
known to the art of spine and bone surgery.
[0012] Second, the implants disclosed by Bloomer fail to gain
purchase within the pedicle bone cut, but rather rely on bony
purchase within the pedicle bore. Research surrounding the present
invention has shown that due to the soft or poor quality bone
within the upper region of the pedicle, an implant as disclosed by
Bloemer would not gain adequate bony purchase to achieve the
distraction force necessary to create a gap within the pedicle
sufficient in size to expand the spinal canal.
[0013] Third, the device of Bloemer does not provide for the
geometric offset that tends to occur during pedicle lengthening.
Because of the lateral to medial angulation of the pedicles, there
is the potential for the pedicle lengthening maneuver of the
pedicles to produce a malalignment between the upper (proximal) and
lower (distal) portion of the implant. This potential problem was
not anticipated by Bloemer, and thus no mechanism to contend with
geometric offset was disclosed by Bloemer.
[0014] Fourth, the disclosure of Bloemer provides no means to
precisely align the pedicle cut with the portion of the implant
that performs the pedicle lengthening maneuver. Proper alignment of
the implant with the pedicle cut is crucial for the pedicle
lengthening device to work correctly and yet no means to achieve
this alignment was disclosed.
[0015] For all these reasons, Bloemer fails to provide a workable
concept to achieve pedicle lengthening for the correction of spinal
stenosis. Not surprisingly, the work of Bloemer has not been
reduced to practice within the field of spine surgery, nor has
research on the technique been disclosed in the public domain.
Therefore, additional novel inventions are required to overcome
these limitations and provide a functional means for achieving a
correction of spinal stenosis through pedicle lengthening.
[0016] In view of the foregoing, a new, less invasive method to
correct spinal stenosis without the limitations of current methods
is needed to address the disabling symptoms suffered by millions of
individuals with spinal stenosis. The optimal treatment method must
be safe, reproducible, effective in eliminating nerve pressure and
minimally invasive so that older patients or those with health
problems could be treated without the need for major, risky
surgery. The present invention achieves these goals.
SUMMARY OF THE INVENTION
[0017] The present invention comprises novel instruments for
cutting the spinal pedicles in precise and reproducible location
without injury to the surrounding delicate nerve tissue or fluid
filled nerve sac. Also disclosed are novel spinal implants and
devices capable of aligning the pedicle cut precisely to the spinal
implant, performing the distraction of the pedicle cut and fixating
the cut in the expanded state to allow bony healing to occur, thus
permanently expanding the spinal canal. Further provided are spinal
implants capable of gaining bony purchase at the site of the
pedicle cuts to provide adequate grip of bony structure to allow
pedicle distraction to be achieved.
[0018] In addition, a novel mechanism is provided, allowing for
connection between the upper (proximal) and lower (distal) portions
of the implant, even in the setting of misalignment which may occur
during the pedicle lengthening process. Also disclosed is a simple,
reproducible means of performing the pedicle lengthening procedure
in the human spine through a percutaneous technique to relieve
pressure on the spinal nerves.
[0019] Embodiments of the present invention will be shown variously
to:
[0020] maintain the integrity of the spinal canal while expanding
the space available for nerve tissue; avoid surgical scarring
around the spinal nerves such as would be expected with a
laminectomy or laminotomy procedure;
[0021] avoid creating of spinal instability while expanding the
area available to the nerve tissue;
[0022] decompress spinal nerves with a quick, safe and minimally
invasive approach;
[0023] provide a long term solution to spinal stenosis with minimal
risk of recurrent stenosis;
[0024] expand the spinal canal using only small, percutaneous skin
incisions;
[0025] allow the pedicle lengthening procedure to be performed
under local anesthesia;
[0026] reliably and safely cut the spinal pedicle from within a
bore or passage within the pedicle;
[0027] provide a means to precisely align the spinal implant with
the bone cut so reliable lengthening of the pedicles is
achieved;
[0028] provide a means to mechanically purchase the stronger
cortical bone at the site of the bone cut during pedicle
lengthening;
[0029] provide a reliable means to ensure that the bone cut is
performed in precisely the correct location within the spinal
pedicle;
[0030] provide a means of lengthening the pedicle a set distance
during the lengthening procedure;
[0031] provide a means to accommodate a change in the position or
alignment between the upper and lower portions of the implant (a
proximal and distal portion) during the lengthening procedure;
[0032] provide a means of locking the proximal and distal portions
of the implant together after the lengthening maneuver;
[0033] provide a means to gain mechanical purchase of the bone on
both the proximal and distal portions of the osteotomy, to provide
resistance to multidirectional biomechanical forces during healing
of the bone cut;
[0034] provide a means to perform the pedicle lengthening procedure
over a guide wire to ensure ease of the operative steps;
[0035] provide bone threads on the implant optimized for purchase
of the spinal bone;
[0036] provide resistance to excessive bone stress during the
pedicle lengthening procedure;
[0037] provide a means to lengthen the pedicle osteotomy using a
controlled, threaded mechanism; and
[0038] provide a means to secure the pedicle lengthening implant in
place to allow for bone healing at the site of the bone cut.
[0039] In one aspect of the present invention, a method for
correcting spinal stenosis is disclosed whereby the spinal canal is
substantially enlarged. First, at least one passage is created, or
cannulated, into a vertebra. The passage can be created through the
long axis of the spinal pedicles at one or more vertebral levels.
Here, an enlarged bone bore can be prepared along the axis of the
pedicle on each side of the spine to create a hollow column of bone
with intact bony cortical walls.
[0040] Next, a distal portion of an implant is placed into the
passage. A proper depth of the implant can be visualized with
radiographic imaging. Next, a circumferential vertebral cut is
performed, using one or more bone saws, from within the passage,
through to the spinal canal and through to an outside of the
vertebra, using a proximal end of the distal portion of the implant
to align the vertebral cut.
[0041] After the cut, a proximal portion of the implant is placed
into the passage. A distal end of the proximal portion of the
implant is positioned against the proximal end of the distal
portion of the implant at the vertebral cut. Then, operation of the
distal and the proximal portions of the implant relative to one
another widens the vertebral cut and expands the spinal canal.
[0042] Prior to vertebral cut widening, internal implant components
can be manipulated to deploy fins into the bone cut, or into the
passage side walls, resulting in good bony purchase of the proximal
and distal portion of the vertebral cut. Then, internal implant
components can again be used to elongate the distance between the
proximal and distal portions of the implant to widen or expand the
gap, at the site of the bone cut. Next, an internal connecting
means can be used to secure the proximal and distal portions of the
implant together to secure the bone cut in the elongated position.
Finally, a locking means can be used to secure the implant so that
the component are locked into position to allow for healing of the
pedicle cuts in the expanded position thus correcting the narrowing
of the spinal canal.
[0043] In one preferred embodiment, the at least one passage and
the vertebral cut extend through a pedicle of the vertebra, and
where widening the vertebral cut elongates the pedicle, thereby
increasing an area of the spinal canal. The vertebral cut can be
located in a lumbar vertebra.
[0044] Further, a preliminary step might introduce a guide wire
into the vertebra to guide a drilling of the at least one passage
into the vertebra. In this preliminary step, a cannulated drill is
positioned over the guide wire to drill the at least one passage
into the vertebra.
[0045] As introduced above, in one preferred embodiment, during
operation of the distal and the proximal portions of the implant,
at least one flange radially extends outward from the implant and
into the vertebral cut, assisting the widening of the vertebral cut
and a stabilization of the vertebral cut. Alternatively, or in
addition to, at least one flange can radially extend outward from
the implant and into the passage to engage side walls of the
passage, thereby facilitating stabilization of the implant within
the passage.
[0046] In another aspect of the present invention, an implant for
expanding a spinal canal is provided, and includes a distal
portion, a proximal portion including a threaded device and an
expanding device, and a screw communicating with the threaded
device and the expanding device. Herein, operation of the screw can
move the expanding device relative to the threaded device to
increase a length of the proximal portion. The increasing length of
the proximal portion, bearing against the distal portion, acts to
widen a vertebral cut to expand the spinal canal. Moving the
expanding device relative to the threaded device might involve a
screw, threadably engaging an inner channel of the threaded device,
and abutting a base of the expanding device, to translate the
expanding device away from the threaded device, upon operation of
the screw, to widen the vertebral cut.
[0047] The implant can further include a locking bolt configured
for insertion through the proximal portion and into the distal
portion. Engagement of the locking bolt with the proximal and the
distal portions fastens the implant about the vertebral cut. The
vertebral cut is then stabilized, allowing vertebral healing with
the spinal canal expanded.
[0048] In this aspect, the distal portion might further include a
floating nut movably housed therein. The movable configuration of
the floating nut within the distal portion can assist acceptance of
the locking bolt within the distal portion, after insertion through
the proximal portion, even if a longitudinal central axis of the
proximal and the distal portions becomes translationally malaligned
during vertebral widening.
[0049] Concerning the radial flange aspect of the invention, the
one or more flanges might be movably attached to the threaded
device. Here, operation of the screw causes the at least one flange
to project radially from the proximal portion, into the vertebral
cut, prior to a lengthening of the proximal portion to widen the
vertebral cut. Upon radial projection of the at least one flange
into the vertebral cut, the one or more threaded device flanges
might bear against a proximal side of the vertebral cut during and
assisting vertebral widening.
[0050] Further, the expanding device might also include one or more
flanges configured to project radially from the proximal portion,
into the vertebral cut, during operation of the screw. Still
further, the at least one expanding device flange, upon radial
projection into the vertebral cut, might bear against a distal side
of the vertebral cut during and assisting vertebral widening. The
flanges can include osteoconductive, osteoinductive or osteogenic
material to assist with healing of the vertebral cut.
[0051] In another aspect of the invention, an implant for expanding
a spinal canal includes a distal portion having inner threads, a
proximal portion having inner threads, and a screw. In this aspect,
the inner threads of the distal portion are of a substantially
different pitch than the inner threads of the proximal portion,
creating a dual pitch configuration. The screw is capable of
communication with the distal and the proximal portions, and has
outer threads at a distal end substantially similar in pitch to the
inner threads of the distal portion, and outer threads at a
proximal end substantially similar in pitch to the inner threads of
the proximal portion. In this aspect, operation of the screw within
the distal and the proximal portions translates the proximal
portion relative to the distal portion, due to the dual pitch
configuration, about a vertebral cut, to widen the vertebral cut
and expand the spinal canal.
[0052] In one embodiment, the distal portion and the proximal
portions each further include external threads to engage an
interior of a passage within a vertebra, the outer threads of the
distal portion engaging the interior of the passage on one side of
the vertebral cut and the outer threads of the proximal portion
engaging the interior of the passage on another side of the
vertebral cut.
[0053] Fins or flanges can be employed in the dual pitch implant as
well. In one aspect, the distal portion and/or the proximal portion
further comprise at least one flange movably attached thereto,
configured to project radially from the distal portion, into an
interior of a passage within a vertebra, to facilitate
stabilization of the distal portion within the passage during
operation of the screw and widening of the vertebral cut. In this
aspect, insertion of the screw within the distal portion causes the
at least one flange to project radially from the distal and/or the
proximal portions into the interior of the passage.
[0054] In a further aspect of the invention, a bone saw is
provided, that includes a flexible saw blade and a shaft. The saw
blade is rectangular in shape, has a central longitudinal axis and
a cutting edge at its distal tip. The shaft has a central
longitudinal axis, and a blade passage within the shaft that houses
the saw blade. The blade passage also has a central longitudinal
axis, where the central longitudinal axis of the saw blade, of the
shaft, and of the blade passage, are parallel.
[0055] The bone saw includes a blade opening located at and through
a distal end of the shaft and of the blade passage, the blade
opening being essentially perpendicular to the longitudinal axis of
the shaft. Within the blade passage is a curved abutment that
aligns the saw blade with the blade opening. Distal translation of
the saw blade within the blade passage causes the saw blade to
conform to the curved abutment and exit the blade opening with the
cutting edge essentially perpendicular to the longitudinal axis of
the shaft.
[0056] The bone saw can also include a trunion at a distal tip of
the shaft. The trunion would be located distal of the blade
opening, to facilitate placement of the distal tip of the shaft, to
precisely locate a desired blade opening location. The saw blade
might further include a longitudinal groove along a side thereof,
and the blade opening could further include an indentor penetrating
therein. Here, the indentor would be positioned to align with the
groove of the saw blade, or would create a groove or indent in the
saw blade, as the saw blade exits the blade opening, to facilitate
a desired perpendicular blade alignment upon blade exiting of the
blade opening.
[0057] In one bone saw embodiment, a threaded drive mechanism is
included and located at a proximal end of the shaft. The drive
mechanism communicates with the saw blade, so that distal
advancement of the threaded drive mechanism distally translates the
saw blade within the blade passage, causing the cutting edge to
exit the blade opening. Additionally, proximally retracting the
threaded drive mechanism proximally translates the saw blade within
the blade passage, causing the cutting edge to retract into the
blade opening. A depth indicator could also be included in one or
more embodiments, located at a proximal end of the shaft and
communicating with the threaded drive mechanism. The depth
indicator would indicate a distance of advancement or retraction of
the drive mechanism, the distance being associated with a length of
advancing or retracting the cutting edge.
[0058] The present invention has the following advantages over
currently known methods for treating spinal stenosis:
[0059] (1) Normal spine anatomical structures are not
disturbed;
[0060] (2) Normal muscle attachments to the spine are
maintained;
[0061] (3) There is diminished chance of unwanted spinal
instability;
[0062] (4) Less disturbance of the nerves is incurred;
[0063] (5) Less scaring around the spinal nerves is incurred;
[0064] (6) Spinal decompression is achieved in a more permanent
fashion;
[0065] (7) The corrective procedure is achieved in a more rapid
fashion;
[0066] (8) The corrective procedure is achieved with minimal blood
loss;
[0067] (9) The corrective procedure is achieved with small,
percutaneous incisions; and
[0068] (10) The corrective procedure is achieved using under local
anesthesia.
BRIEF DESCRIPTION OF THE DRAWINGS
[0069] The drawings herein are included for the purpose of
illustrating preferred embodiments of the present inventions;
however, it should be realized that the invention is not limited to
the precise arrangements and/or sequence of steps shown.
[0070] FIGS. 1A-1C illustrate a lower or distal shell portion of a
pedicle lengthening implant, in accordance with one preferred
embodiment of the invention;
[0071] FIGS. 2A1-2D2 illustrate components of the distal or lower
shell, in top and cross-sectional views, including the shell with
inner channels, a floating nut and a retaining washer;
[0072] FIGS. 3A-3B illustrate the components of the lower shell of
the implant in exploded and assembled perspective views;
[0073] FIGS. 4A-4D illustrate an expanding portion of an upper or
proximal portion of the pedicle lengthening implant in multiple
perspective views, in accordance with one preferred embodiment of
the invention;
[0074] FIGS. 5A-5C illustrate a threaded portion of the upper or
proximal portion of the implant in top, side and cross-sectional
views, in accordance with one preferred embodiment of the
invention;
[0075] FIGS. 6A-6D illustrate the threaded portion of the upper
portion in a multiplicity of perspective views;
[0076] FIGS. 7A1-7D illustrate components and assembly of the upper
portion of the implant;
[0077] FIGS. 8A1-8D2 illustrate the upper or proximal portion in a
multiplicity of top and cross-sectional views;
[0078] FIGS. 9A-9C illustrate the upper implant portion in a
multiplicity of perspective views;
[0079] FIGS. 10A1-10D2 illustrate the function of the floating nut
within the lower implant portion to accommodate offset between the
upper and the lower portions of the implant;
[0080] FIGS. 11A-11C illustrate the entire pedicle lengthening
implant (distal and proximal portions, along with jack screw and
locking bolt) in a multiplicity of exploded and cross-sectional
views;
[0081] FIG. 12 illustrates the entire implant (distal and proximal
portions) in an exploded, perspective view;
[0082] FIGS. 13A-13E illustrate a linear saw in cross-section, with
accompanying front views, in accordance with one preferred
embodiment of the invention;
[0083] FIGS. 14A-14B illustrate a cutting end of a saw blade of the
linear saw;
[0084] FIGS. 15A-15E illustrate a radial saw in cross-section and a
multiplicity of working end views, in accordance with another
preferred embodiment of the invention;
[0085] FIGS. 16A-16B illustrate a cutting end of the radial
saw;
[0086] FIGS. 17A-17E illustrate lower (distal) and upper (proximal)
portions of a dual pitch pedicle lengthening implant, in accordance
with another preferred embodiment of the invention;
[0087] FIGS. 18A-18C illustrate cross-sectional views of the dual
pitch implant in various working states;
[0088] FIG. 19 illustrates a cross-sectional view of a vertebrae
undergoing drilling of a pedicle bore along a long axis of one
pedicle;
[0089] FIG. 20 illustrates a cross-sectional view of a vertebrae
undergoing insertion of the distal or lower portion of the pedicle
lengthening implant into the pedicle passage or bore, in accordance
with one preferred embodiment of the invention;
[0090] FIG. 21A-21B illustrate a cross-sectional view of a
vertebrae undergoing the final seating of the lower implant into
the pedicle bore using an insertion tool;
[0091] FIG. 22 illustrates a cross-sectional view of a vertebrae
following seating of the lower implant into the bottom of the
pedicle bore;
[0092] FIGS. 23A-23B illustrate a cross-sectional view of a
vertebrae undergoing cutting of a lateral portion of the pedicle
wall using a linear pedicle saw, in accordance with one preferred
embodiment of the invention;
[0093] FIG. 24 illustrates a cross-sectional view of a vertebrae
undergoing cutting of a medial portion of the pedicle wall using
the linear pedicle saw;
[0094] FIG. 25 illustrates a cross-sectional view of a vertebrae
undergoing initial insertion of an upper portion of the pedicle
lengthening implant, in accordance with one preferred embodiment of
the invention;
[0095] FIG. 26 illustrates a cross-sectional view of a vertebrae
undergoing final seating of the upper or proximal portion of the
implant into the pedicle bore;
[0096] FIG. 27 illustrates a cross-sectional view of a vertebrae
following deployment of expandable flanges from the upper portion
of the implant;
[0097] FIG. 28 illustrates a cross-sectional view of a vertebrae
following placement of the upper and lower implant portions, and
with deployment of expandable flanges from the upper portion of the
implant, in accordance with one preferred embodiment of the
invention;
[0098] FIG. 29 illustrates a cross-sectional view of a vertebrae
following linear expansion of a gap between the cut edges of the
pedicle, on both sides of the vertebrae;
[0099] FIGS. 30A-30C illustrate a cross-sectional view of a
vertebrae undergoing insertion of a locking bolt to lock or fasten
the upper and lower portions of the implant together, and to secure
the lengthened state of the pedicle and the expanded state of the
spinal canal:
[0100] FIG. 31 illustrates a cross-sectional view of a vertebrae in
a final lengthened state, with all components of one embodiment of
the pedicle lengthening implant inserted to secure the construct
and spinal canal in the expanded state.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0101] Referring now to the drawings, where like numerals indicate
like elements, there is shown in FIGS. 1A-1C, a top view 1A, side
view 1B, and cross-sectional view 1C, of a lower or distal shell
portion 10 of a pedicle lengthening implant of the present
invention. The lower implant shell 10 has outer threads 2 and
hollow inner spaces 8, 12, along with side wall slots 4 and a
cannulation hole 6.
[0102] FIGS. 2A1-2D2 comprises lower implant components, including
the lower implant shell 10, a floating nut 20 and a locking ring
30. The locking ring 30 is shown in cross-section, and by top view,
in FIGS. 2A1 and 2A2, respectively. The locking ring 30 comprises a
substantially circular shape and has a central passage 22. The
floating nut 20 is shown in cross-section and by top view in FIGS.
2B1 and 2B2, respectively. The floating nut 20 contains a plurality
of flanges 18 on its' outer surface, and a tapered entrance 16 to
an inner threaded portion 14.
[0103] An assembled lower implant portion 40 is shown in cross
section and by top view in FIGS. 2D1 and 2D2, respectively. When
assembled, the floating nut 20 fits loosely into the space 8 of the
outer shell 10, while the locking ring 30 is substantially press
fit, or otherwise secured into the space 12 of the lower implant
shell 10. Notice that the locking ring 30 secures the floating nut
20 within the outer shell 10, but allows the floating nut 20 to
move in a substantially side to side direction (perpendicular to
the long axis of the lower implant shell 10) within the space 8,
while the outer flanges 18 of the floating nut 20 are loosely
confined within the side wall slots 4 of the outer implant shell 10
to prevent rotation of floating nut 20 during the threadable
insertion of a locking bolt (described later).
[0104] FIGS. 3A-3B illustrate the assembled lower or distal implant
portion 40 in perspective exploded view, FIG. 3A, and perspective
assembled view FIG. 3B. The exploded view FIG. 3A shows the
relationship of the locking ring 30, the floating nut 20 and the
lower implant shell 10 in one preferred embodiment, while FIG. 3B
shows a perspective view of the assembled lower implant 40.
[0105] FIGS. 4A-4D illustrate an expanding portion 50 of upper or
proximal implant 60 in a plurality of perspective views. The
expanding portion 50 is substantially cylindrical in shape and
comprises a plurality of slots 32 in its' side walls that divide
the cylindrical walls into flange-like projections 24. The base 34
of the expanding portion 50 of the upper implant 60 contains an
opening 38 for the passage of a locking bolt (described later).
[0106] In this embodiment, the side wall flanges 24 are shown to
have a bore 26 for the secure attachment of a plurality of guide
pins 54 (shown in FIG. 12) that connect and guide the expanding
portion 50 and the threaded portion 70 (shown in FIGS. 5A-5C) of
the upper implant 60 (shown in FIG. 8) together. In addition, the
expanding portion 50 of upper implant 60 contains holes 28 for
hinge pins 110 (shown in FIGS. 7 and 9) used to moveably connect
the hinged flanges 100 (FIGS. 7 and 9) to the expanding portion 50
of the upper implant 60.
[0107] FIGS. 5A-5C illustrate a threaded portion 70 of the upper or
proximal portion 60 of the implant, as shown in side view in FIG.
5A, cross-sectional view in FIG. 5B, and top view in FIG. 5C. In
the presently shown embodiment, the threaded portion 70 of the
upper implant portion 60 has outer threads 42, side slots 52, and a
threaded inner passage 58. A gliding hole 56, shown at the base of
each slot 52, allows for the slidable passage of guide pins 54
therein (shown in FIG. 12), to slidably connect the threaded
portion 70 to the expanding portion 50 (FIG. 4) of the upper or
distal implant 50 (FIGS. 7-9 and 11, 12).
[0108] FIGS. 6A-6D illustrate a threaded portion 70 of the upper
implant 60 in perspective view in FIGS. 6A and 6C, a bottom view in
FIG. 6B, and a top view FIG. 6C. A threaded outer surface 42 can be
appreciated on the threaded portion 70 of the upper implant 60, for
threadable introduction into a bone bore or passage in the pedicle.
The threaded portion 70 of the upper or proximal implant 60
contains an inner threaded passage 58 with threads 44 on its side
walls threadable insertion of a jack screw 80 (FIG. 7). The
threaded upper portion 70 further contains side wall slots 52, with
gliding holes 56 at the base of each slot 52, wherein guide pins 54
(FIG. 12) are passed for slidable attachment of the threadable 70
and expanding 50 portions of the upper or proximal implant 60. The
threaded portion 70 of the upper implant 60 is also shown to
contain holes for hinge pins 48, used to connect hinged flanges 90
(FIGS. 7 and 9) that can fit partially into slots 46 on the bottom
surface of the threaded portion 70 of the upper implant 60.
[0109] FIGS. 7A1-7D illustrate multiple cross-sectional views of
upper implant 60. The upper implant 60 is comprised of the threaded
portion 70 and the expanding portion 50, along with jack screw 80,
guide pins 54 (FIG. 12), and expandable flanges 90, 100. In FIG.
7A1-7A2, the plane of the cross-section is designated by line A-A
76 shown in FIG. 7E. The expandable flanges 90 in this plane are
shown to hinge on the expanding portion 50 of the upper implant
60.
[0110] In FIG. 7B1-7D, the plane of cross-section is designated by
line B-B 77 in FIG. 7F, which is substantially at a right angle to
line A-A 76 in FIG. 7E. The expandable flanges 100 in this plane
are hinged on the threaded portion 70 of the upper implant 60.
[0111] When assembled in the unlengthened state, the threaded
portion 70 of the upper implant 60 is positioned just above the
expanding portion 50 of the upper implant 60, leaving an inner
passage 58 through which the jack screw 80 can be threaded.
Further, note that the jack screw 80 can be partially threaded into
the inner threaded passage 58 of the threaded portion 70 of the
upper implant 60, with both sets of expanding flanges 90, 100
remaining hinged into the confines of the expanding portion 50 of
the upper implant 60. However, from this state, further threadable
insertion of the jack screw 80 (as shown in FIG. 7C) causes the
expandable flanges 90 to hinge outward, so that the flange
projections 66 extend substantially outside the confines of the
expanding portion 50 of the upper implant 60. Note that the length
of the upper implant 60, with flanges radially extended as shown in
FIG. 7C, remains unchanged from the length of the upper implant
portion 60 shown in FIGS. 7A and 7B.
[0112] With further threadable insertion of the jack screw 80, as
shown in FIG. 7D, the overall length of the upper implant 60
increases (lengthened state of the upper implant 60) as the jack
screw 80 contacts the base 34 of the expanding portion 50 of the
upper implant 60, and pushes the expandable portion 50 away from
the threaded portion 70, causing an overall lengthening of the
upper or proximal implant portion 60. It should be apparent to one
skilled in the art that the overall length of the upper implant 60
is greater in FIG. 7D, compared to the length of the upper implant
60 in FIGS. 7A, 7B and 7C.
[0113] FIGS. 8A1-8D2 illustrate an upper implant 60 in its
unlengthened (FIGS. 8A2, 8B2 and 8C2) and lengthened (FIG. 8D2)
states. FIGS. 8A1, 8B1, 8C1 and 8D1 show top views of the threaded
portion 70 of the upper implant 60 with various planes of
cross-section, demarcated by lines A-A 76, B-B 77 and C-D 79, used
to illustrate the planes of cross-section shown in corresponding
FIGS. 8A2, 8B2, 8C2 and 8D2 directly below.
[0114] FIGS. 8A1 and 8A2 show a top view and a cross-sectional
view, respectively, of the upper implant 60 along line A-A 76. In
FIG. 8A2, the hinged flanges 90 are shown to hinge on the threaded
upper portion 70, while the jack screw 80 is shown threadably
inserted to a level of contact with the base 34, but without
substantially pushing the base 34 of the expanding portion 50 of
the upper implant 60 away from the threaded portion 70 of the upper
implant 60.
[0115] FIGS. 8B1 and 8B2 show a top view and a cross-sectional
view, respectively, of the upper implant 60 along line B-B 77. In
FIG. 8B2, the hinged flanges 100 are shown to hinge on the slidable
portion 50, allowing the hinged flanges 100 to move with the
expanding portion 50 as the jack screw 80 pushes the expanding
portion 50 away from the upper threaded portion 70.
[0116] FIGS. 8C1 and 8C2 show the upper implant 60 in a top view
and cross-sectional view, respectively, along line C-D 79. In this
view, the hinged flanges 90, 100 are respectively attached to the
threaded upper portion 70 and the expanding portion 50 of the upper
implant 60, although in the unlengthened state, the flange
projections 66 are at substantially the same level.
[0117] FIGS. 8D1 and 8D2 show a top view and a cross-sectional
view, respectively, of the upper implant 60 in the lengthened
state, with the plane of cross section illustrated by line C-D 79.
In this view, the jack screw 80 has been threadably inserted
further into the threaded portion 70 of the upper implant 60, and
has pushed against the base 34 of the expanding portion 50 of the
upper implant 60, resulting in an overall lengthening of the upper
implant portion 60. In the lengthened state, as shown in FIG. 8D2,
it should be apparent that the flange projections 66 lie at
different levels, with a vertical gap 74 between the levels of
respective flange projections 66.
[0118] FIGS. 9A-9C illustrate one preferred embodiment of the
invention, showing the upper implant 60 in three different
perspective views (all in the unlengthened state). The threaded
portion 70 has exterior threads 42, and is shown substantially in
contact with the expanding portion 50 of the upper implant portion
60. The flange projections 66 are shown to project outside a
diameter of the expanding portion 50, as a result of the jack screw
80 being threadably inserted into the threaded portion 70 of the
upper implant 60.
[0119] FIGS. 10A1-10D2 illustrate a novel mechanism for
accommodating lateral offset (translational malalignment) between
the upper 60 and lower 40 portions of the pedicle lengthening
implant or device 150 that may occur during the lengthening
process. In FIGS. 10A1, 10B1, 10C1 and 10D1, the upper 60 and lower
40 implant portions are represented in cross-section with the
central axis of the upper implant portion 60 shown as line 68 and
the central axis of the lower implant portion 40 shown as line 72.
A space 74, between the upper 60 and lower 40 implant portions,
represents a gap created by lengthening of the upper implant
portion 60, as would be done during a pedicle lengthening
procedure.
[0120] In the event the central axis of the upper 60 and lower 40
implant portions should be offset (translationally malaligned), the
floating nut 20 (FIGS. 10A2, 10B2, 10C2 and 10D2) is able to shift
in position, so that locking bolt 120 (FIGS. 11 and 12) is able to
secure the upper portion 60 to the lower portion 40 in the offset
position. FIGS. 10A-10D illustrate progressive amounts of offset
between the central axis of the upper 60 and the lower 40 implants,
and progressive lateral shift of the floating nut 20, within the
space 8 of the lower implant shell 10, to accommodate the
offset.
[0121] FIGS. 11A-11C illustrate cross-sectional views of a
preferred embodiment of the pedicle lengthening device 150 (in an
exploded cross-sectional view in FIG. 11A, and an assembled
cross-sectional view in FIGS. 11B and 11C). The planes of the
cross-section are illustrated by lines A-A 76 and B-B 77,
respectively. FIG. 11A shows the lower implant portion 40, the
upper implant portion 60 (in the lengthened state), and the locking
bolt 120.
[0122] The lower implant portion 40 is shown to contain the
floating nut 20 and the retaining washer 30. The upper implant
portion 60 has a threaded portion 70, an expanding portion 50, and
incorporates an internal jack screw 80 shown threaded into the
upper implant portion 60 such that the base 34 of the expanding
portion 50 is pushed away from the threaded portion 70, resulting
in an overall lengthening of the upper implant portion 60
(lengthened state).
[0123] The locking bolt 120 comprises a threaded tip 78, shaft 84
and drive mechanism 82. FIG. 11B shows an assembled pedicle
lengthening device 150 in cross-section along a plane illustrated
by line A-A 76. The pedicle lengthening device 150 is shown to
contain a jack screw 80 threaded inward to cause a lengthening of
the upper implant portion 60 by a distance 74. The locking bolt 120
is shown to pass through a central region of the jack screw 80, and
to threadably attach to the floating nut 20, to fasten the upper 60
and the lower 40 portions of the implant 150 securely together.
[0124] FIG. 11C shows the pedicle lengthening device 150, in
cross-section along line B-B 77. In this cross-sectional plane, the
expandable flanges 100 are shown to hinge on the expanding portion
50 of the upper implant 60. As this view illustrates, the
lengthened state of the implant 150 presents a gap 75 between the
threaded 70 and the expanding 50 portions of the upper implant 60
due to the action of the jack screw 80 pushing the expanding
portion 50 of the upper implant 60 away from the threaded portion
70 of the upper implant 60.
[0125] FIG. 12 illustrates an exploded perspective view of the
pedicle lengthening device 150. In this illustration, the
relationship of the various components of this preferred embodiment
can be appreciated. The lower implant shell 10 is shown to contain
the floating nut 20 and the locking ring or retaining washer 30.
The expanding portion 50 of the upper implant 60 is shown to have a
pair of attached expandable flanges 100. The threaded portion 70 of
the upper implant 60 also has a pair of expandable flanges 90 which
are oriented at substantially different positions than the
expandable flanges 100 of the expanding portion 50 of the upper
implant 60. The expanding 50 and the threaded 70 portions of the
upper implant 60 are attached by guide pins 54 which allow the
threaded 70 and the expanding 50 portions of the upper implant 60
to move apart from one another (resulting in a lengthening of the
upper implant 60) in a direction substantially parallel to the
longitudinal axis of the pedicle lengthening implant or device 150,
but to remain in alignment along the longitudinal axis. The jack
screw 80 is shown to have a hollow interior, allowing the locking
bolt 120 to pass there through, and thread into the floating nut 20
to secure or lock the entire implant 150 together following
implantation.
[0126] FIGS. 13A-13E illustrate a preferred embodiment of a novel
linear bone saw. FIG. 13A illustrates a saw blade 94 manufactured
from a flexible material, such as stainless steel, titanium,
nitinol, cobalt chromium alloy, tantalum, or a polymeric or
composite material. The saw blade 94 includes a cutting edge or tip
108 and attachment holes 111, or other attachment means, to allow
fastening to the saw 140.
[0127] FIG. 13B shows a cross-sectional view of the linear saw 140,
including a shaft 107, a body 105, and a handle 123. The body 105
of the saw 140 contains a blade holding mechanism 115, securing the
saw blade 94 via the attachment holes 111. The blade 94 is shown to
pass down a blade passage 101 within the shaft 107. The blade
passage 101 is substantially parallel to the longitudinal axis of
the saw 140, until reaching a curved region 97 within the blade
passage 101, and exiting the shaft 107 at a blade opening 99
located on the side of a distal end of the shaft 107.
[0128] The blade 94 is attached to a threaded drive mechanism 121,
which can be threadably advanced or withdrawn within the body 105
of the saw 140 by turning a knob 127. The saw 140 includes a depth
indicator 125 that indicates a distance the cutting edge or tip 108
protrudes from blade opening 99. The shaft 107 of the saw 140
includes a trunion 128 on the cutting or distal end of the shaft
107 for engagement with the lower implant portion 40 (FIGS. 1-3)
during cutting.
[0129] FIG. 13C shows an end view of the cutting or distal end of
the saw 140, illustrating the shaft 107 and trunion 128. FIG. 13D
shows a cross-sectional view of the saw 140, with the blade 94
extending from the blade opening 99. Note that in comparison to
FIG. 13B, the blade 94 has been advanced so that it protrudes from
the side of the shaft 107, and that the threaded drive mechanism
121 has been threaded distally deeper into the body 105 of the saw
140. Also, note that the depth indicator 125 protrudes above the
knob 127, to reveal the distance the cutting edge 108 of the blade
94 protrudes from the blade opening 99.
[0130] FIG. 13E illustrates an end view of the cutting end of saw
140 with the blade 94 protruding, as in FIG. 13D. The shaft 107 and
trunion 128 are shown, and blade 94 is shown protruding from the
side of the shaft 107, with the cutting edge or tip 108 pointed
away, or perpendicular, from the central, longitudinal axis of the
saw 140.
[0131] FIGS. 14A-14B illustrate the cutting or distal end of the
linear bone saw 140 in two perspective views. As shown in FIGS. 13B
and 13D, the saw 140 includes a shaft 107 with a trunion 106 at the
distal end of the shaft 107, designed to engage the lower implant
portion 40 (FIGS. 1-3). A blade opening 99 is located at a
substantially perpendicular angle to the longitudinal axis of the
linear saw 140. The flexible blade 94 is shown having the cutting
edge 108 protruding from the blade opening 99. Blade opening 99
includes an indentor 98, which is a raised portion designed to
introduce a crimp or counter bend to the flexible saw blade 94,
which serves to counteract a curling of the blade 94 possibly
produced by a passing of the flexible blade 94 through the curved
portion 97 of the blade passage 101 (FIGS. 13A and 13C).
Alternatively, a groove could be pre-manufactured into the flexible
saw blade 94, with the indentor 98 positioned to align with the
groove of the saw blade 94 as the saw blade exits the blade opening
99, thereby facilitating desired perpendicular blade 94 alignment
upon exiting the blade opening 99.
[0132] FIGS. 15A-15E illustrate a preferred embodiment of a radial
bone saw 130. The radial saw 130 includes a handle 132 and a shaft
113. Internally, the radial saw 130 has a drive shaft 116 attached
to a saw blade 96 on a cutting or distal end of the saw 130. The
drive shaft 116 is also attached to an offset rotation knob 118 on
the non-cutting or proximal end of the saw 130. A trunion 128, for
alignment with the lower implant portion 40 (FIGS. 1-3), is also
located on the cutting end of the saw 130. A cannulation passage
114 is shown to pass through a central region of the longitudinal
axis of the saw 130, so that the saw 130 can be placed over a guide
wire.
[0133] FIGS. 15B, 15C and 15D illustrate the cutting or distal end
of the saw 130 in an end, cross-sectional view at the level (or
location) of the blade opening 102. In FIG. 15B, the saw blade 96
is shown attached to the drive shaft 116. Note that the drive shaft
116 is located towards a periphery of the cross-section of the
shaft 113. In FIG. 15B, the blade 96 is shown contained within the
shaft 113, and a central cannulation hole 114 is shown along a
central axis of the shaft 113 so that the saw 130 can be placed
over a guide wire. FIG. 15C illustrates the blade 96 partially
protruding from the shaft 113 due to the rotational movement of the
drive shaft 116. FIG. 15D shows the blade 96 fully protruding from
the shaft 113. The blade 96 has a cutting surface 112 oriented away
from a central axis of the shaft 113, and has a cut away region 119
so that the blade does not cover the cannulation hole 114 when the
blade is contained within the shaft 113. FIG. 15E shows an end view
of the non-cutting or proximal end of the radial saw 130. The
rotation knob 118 has a central axis substantially offset from the
handle 132. The rotation knob 118 also has a semicircular slot 117
to allow passage of a guide wire in all rotational positions of
rotation knob 118. The rotation knob 118 also attaches to the drive
shaft 116 and deploys the blade 96 by its rotation relative to the
saw handle 132.
[0134] FIGS. 16A and 16B illustrate the cutting or distal end of
the radial saw 130 in two perspective views. The saw 130 has a
shaft 113 with an opening 102 for the blade 96 to protrude or
deploy outward from within the shaft 113. The blade 96 is shown to
comprise a cutting surface 112 and a cut away region 119 for the
passage of a guide wire.
[0135] FIGS. 17 and 18 illustrate an alternate preferred embodiment
of a pedicle lengthening device or implant 160. FIGS. 17A-17E
illustrate components of the alternate preferred embodiment. FIG.
17A shows a base section or proximal portion 170 of the alternate
device in a side view and FIG. 17D illustrates the proximal portion
or base section 170 in a cross-sectional view. The base section 170
has outer threads 224 and an inner threaded passage 226 having
inner threads 227. A distal end of the base section 170 contains an
optional cannulation hole 234, allowing the device to be placed
over a guide wire.
[0136] The base section 170 also includes a plurality of hinged
flanges 222 attached through a hinge mechanism 236 to the base
section 170. These optional hinged flanges 222 on the base section
170 are designed to improve the bony purchase of the base section
170 to the vertebral bone from within the passage. In addition, the
base section 170 is shown to contain a close tolerance bore 232 for
the passage of the inner bolt (FIG. 17C).
[0137] FIGS. 17B and 17E illustrate a side view and cross-sectional
view, respectively, of the upper section or proximal portion 180 of
the alternate preferred embodiment of the pedicle lengthening
device or implant 160. The upper section 180 has outer threads 224
and an inner threaded passage 228 comprising inner threads 229. The
upper section or proximal portion 180 can also include a plurality
of flanges 222 hinged on the upper section through a hinge
mechanism 236. The purpose of the hinged flanges 222 on the upper
section 222 is to grip the bone at the site of the pedicle cut.
[0138] FIG. 17C illustrates an inner bolt 190 comprising a shaft
248, a distal tip 242, and a drive mechanism 243 at a proximal end
providing threadable insertion of the inner bolt 190. The inner
bolt 190 also includes a plurality of threaded sections 244, 246
for engagement with the base section or distal portion 170 and the
upper section or proximal portion 180, respectively, of the pedicle
lengthening device. It should be appreciated by one skilled in the
art that the pitch of the threads 244 on the distal portion of the
inner bolt 190 are substantially smaller than the pitch of the
threads 246 on the proximal end of the inner bolt 190. The smaller
pitch distal threads 244 are substantially similar to the pitch of
the inner threads 227 of the base section 170, while the larger
pitch proximal threads 246 of the inner bolt 190 are substantially
similar to the threads 228 of the upper section 180.
[0139] FIGS. 18A, 18B and 18C illustrate the function of the
alternate preferred embodiment of the pedicle lengthening device or
implant 160. In FIG. 18A, the base section 170 and upper section
180 are in substantial contact, and the inner bolt 190 is partially
threaded into the inner threaded passage 226 of the base section
170. In FIG. 18A, the inner bolt 190 is shown to have caused the
hinged flanges 222 on both the base section 170 and the upper
section 180 to be pushed outward (compared to FIG. 17), such that a
portion of the hinged flanges 222 projects beyond the outer thread
224 of the base 170 and of the upper section 180.
[0140] FIG. 18B illustrates the effect of deeper threaded insertion
of the inner bolt 190 into the upper section 180 and the base
section 170. The inward threading of the inner bolt 190 has caused
the upper section 180 to be drawn away from the base section 170 as
a result of the larger pitch threads 246 within the upper section
180 relative to the smaller pitch threads 244 of the base section
170. The further inward threading of the inner bolt 190 has
resulted in the formation of a gap 252 between the base 170 and the
upper 180 sections.
[0141] FIG. 18C illustrates the effect of further threaded
insertion of the inner bolt 190. Deeper, more distal, insertion of
the inner bolt 190 results in a further widening of the gap 252
between the upper 180 and the base sections 170 of the pedicle
lengthening device 160.
[0142] FIGS. 19-31 illustrate a preferred sequence of steps for
performing pedicle lengthening in accordance with the present
invention. FIG. 19 illustrates a cross-sectional view of a vertebra
214 having a vertebral body 212, a pedicle 206, a transverse
process 204, a spinous process 202, and a spinal canal 208. A
cannulated drill 124 is shown forming a pedicle bore 126 through a
central region of the pedicle 206.
[0143] FIG. 20 shows a vertebra 214 after the pedicle bore 126 is
formed. The lower implant portion 40 is shown undergoing threadable
insertion into the pedicle bore 126 using an insertion tool 86.
[0144] FIGS. 21A-21B again show a vertebra 214 with the lower
implant portion 40 seated at the base of the pedicle bore 126 (FIG.
20). Note that the top of the lower implant portion 40 is
positioned substantially at a junction between the pedicle 206 and
the vertebral body 212.
[0145] FIG. 22 illustrates the vertebra 214 after insertion of the
lower implant portion 40 at the base of the pedicle bore 126.
Again, the upper surface, or proximal end, of the lower implant
portion 40 is shown positioned at the junction of the pedicle 206
and the vertebral body 212.
[0146] FIGS. 23A and 23B illustrate a vertebra 214 undergoing
cutting of the pedicle 206 with a pedicle saw 140. The saw 140 is
shown cutting the bone of the lateral wall of the pedicle 206 from
inside the pedicle passage or bore 126. Note that the pedicle saw
140 is positioned substantially in contact with the lower implant
40 to properly align the pedicle cut with the pedicle lengthening
device.
[0147] FIG. 24 illustrates a vertebra 214 undergoing the completion
of cutting of the pedicle 206. The saw 140 is shown cutting the
bone of the medial wall of the pedicle 206 to complete a
circumferential transection of the pedicle 206, leaving bone cut 92
at the junction of the pedicle 206 and the vertebral body 212.
[0148] FIG. 25 illustrates a vertebrae 214 following completion of
the pedicle cut 92. An upper implant portion 60 is shown at a
beginning of threadable insertion into the pedicle bore 126.
[0149] FIG. 26 illustrates a vertebra 214 with the upper implant 60
seated within the pedicle bore 126 to the point where it comes into
substantial contact with the lower implant 40.
[0150] FIG. 27 illustrates a vertebra 214 following deployment of
the expandable flanges 90 which have projected (hinged) outward by
the threadable insertion of the jack screw 80 so that the flange
projections 66 are deployed into the pedicle cut 92.
[0151] FIG. 28 illustrates a vertebra 214 after the sequence of
pedicle preparation and implant insertion as shown in FIGS. 17-25
have been repeated on the opposite pedicle 206 of the vertebra
214.
[0152] FIG. 29 illustrates a vertebra 214 after lengthening of the
pedicles 206 bilaterally. Note that further insertion of the jack
screws 80 has caused further widening of the pedicle cut 92,
thereby forming a gap 256. The pedicle lengthening devices 150 are
in place within each pedicle 206, maintaining the lengthened state
of the pedicles 206. Notice that the lengthening of the pedicles
206 has resulted in enlargement of the spinal canal 208.
[0153] FIGS. 30A-30C illustrate a locking bolt 120 threadably
inserted into each upper 60 and each lower 40 implant portion to
secure the pedicle lengthening devices 150 securely together and
preserve the spinal canal 208 in the expanded state.
[0154] FIG. 31 illustrates a final appearance of a preferred
embodiment of the pedicle lengthening procedure. Both pedicles 206
have been lengthened and secured by the pedicle lengthening devices
150. The spinal canal 208 has been enlarged. The upper 60 and the
lower 40 implant portions are fastened together and held by the
locking bolt 120 so that bone healing of the pedicle gap 256 can
occur.
Summary of Operation of Example Embodiments
[0155] A non-limiting summary of certain invention embodiments is
provided as follows: First, a central pedicle bore 126 is drilled
through a long axis of pedicles 206 using a drill 124 or related
device (FIG. 19). The pedicle bore 126 is then created in such a
way as to leave intact outer walls 129 of the pedicle 206 intact
(FIG. 19). The drilling of the pedicle bore may be performed over a
guide wire. The guide wire could be placed or the drilling could be
performed using the guidance of x-ray, fluoroscopy, CAT scan or by
image guided means, all techniques well known in the art of spinal
surgery.
[0156] Next, a lower or distal implant portion 40 is placed into
the pedicle bore 126 to a depth whereby the upper or proximal
surface of the lower implant portion 40 is substantially localized
at a junction between the pedicle 206 and a vertebral body 212
(FIGS. 20-22). Next, one or more bone saws 130, 140 are used to
circumferentially cut or divide the pedicle 206 such that the
pedicle wall 129 is completely sectioned with a circumferential
bone cut 92 (FIGS. 23-24).
[0157] The radial bone saw 130, as illustrated in FIG. 15, works by
placing the shaft of the saw 113 into the pedicle bore 126 (FIG.
22) until the trunion 128 engages the lower implant portion 40. The
radial saw blade 96 is deployed by turning the offset knob 118. The
bone of the pedicle wall 129 is cut by rotating the saw handle 132
with sequentially increasing saw blade 96 deployment until an
adequate depth of cut is achieved.
[0158] The linear saw 140, as shown is FIG. 13, works by placing
the shaft of the saw 107 into the pedicle bore 126 (FIG. 22) until
the trunion 128 engages the lower implant portion 40. The flexible
saw blade 94 is then deployed by turning the knob 127, causing the
blade 94 to project from the side of the shaft 107. The linear saw
140 is turned in either a circumferential or "back-and-forth"
motion to cut the bone of the pedicle wall 129 while sequentially
increasing the length of flexible blade 94 deployment until the
pedicle cut 92 (FIG. 24) is completed.
[0159] After the pedicle has been cut, the upper implant portion 60
is threadably inserted into the pedicle bore 126 until the upper
implant 60 comes into contact with the lower implant portion 40
(FIGS. 25-26). Next, expanding flanges 90, 100 (FIG. 11) are
deployed so that the flange projections 66 engage the pedicle cut
92 (FIG. 27). The deployment of the expandable flanges 90, 100 is
achieved by the threadable advancement of the jack screw 80 (FIG.
27). Next, similar steps are repeated for the opposite pedicle
(FIG. 28).
[0160] To achieve pedicle lengthening, the pedicle cuts 92 on both
sides are then expanded to create gaps 256 by the further
threadable advancement of the jack screw 80 on both sides of the
vertebrae 214 (FIG. 29). By creating a gap 256 in the pedicles 206,
the spinal canal 208 is enlarged (FIG. 29).
[0161] After the pedicles 206 have been lengthened, a locking bolt
120 is threadably inserted through the central regions of the
pedicle lengthening device so that the upper 60 and the lower 40
portions of the pedicle lengthening device are securely locked
together, thus securing the spinal canal 208 in the expanded state
(FIGS. 30 and 31). With the pedicles 206 locked in the lengthened
state, the pedicle gap 256 will heal, thus reconstituting the
vertebrae 214 so that the spinal canal 208 would remain in a
permanently enlarged state (FIG. 31).
[0162] To assist the vertebral healing process, portions of the
pedicle lengthening device (such as the expandable flanges 90, 100)
could be packed with an osteoconductive, osteoinductive or
osteogenic material, to deliver the material to the pedicle bone
cut 92 to promote the healing of bone across the site of the
pedicle gap 256.
[0163] These and other advantages of the present invention will be
apparent to those skilled in the art from the foregoing
specification. Accordingly, it will be recognized by those skilled
in the art that changes or modifications may be made to the
above-described embodiments without departing from the broad
inventive concepts of the invention. It should therefore be
understood that this invention is not limited to the particular
embodiments described herein, but is intended to include all
changes and modifications that are within the scope and spirit of
the invention.
* * * * *