Note: Descriptions are shown in the official language in which they were submitted.
2 ~
-- 1 --
~PINAL ~TEREOTAXIC DEVICE
Bac~ground of the Invention
This invention relates to medical instru-
ments, and in particular to devices for directing
puncturing devices toward a desired target inside the
body of a patient.
A common problem among sufferers of back
pain is prolapsed lumbar intervertebral disc, wherein
a portion of the disc between two vertebrae in the
lower back prolapses outward and causes pressure on a
nerve. In the past, the only successful treatment had
been major surgery. Because of the substantial trauma
caused by such surgery, however, it was not uncommon
for the patient to experience a recovery period of ten
to twelve weeks before he could return to his previous
employment. Recently a new technique has been devel-
oped wherein nucleus material of the prolapsed disc is
excised by percutaneous aspiration. The disc nucleus
is soft and jelly-like in consistency. It can thus be
resected and aspirated by use of a specially designed
cannula. The aspiration cannula is inserted into the
nucleus of the prolapsed disc with the aid of a guide
wire or needle prior to connecting it to the aspirat-
ing machine. The major problem, however, is that ex-
ac~ing placement of the needle is crucial to avoid
` 20~8~0~
nerve damage.
Since the herniation of the disc most fre-
quently occurs between the fourth and fifth lumbar
vertebrae, or between the fifth lumbar and sacral ver-
tebrae, the insertion of the needle is very difficult.
Particularly in the latter case, the needle must be
inserted not only at an angle to the vertical, but
also at an angle relative to the sagittal axis, in
order to avoid the protective iliac crést of the sa-
crum. Preferably the needle is inserted at about
eight centimeters away from the midline, on the coro-
nal plane of the prolapsed disc level, at an angle of
about 45 degrees. In the past, the needle has been
inserted by trial and error, while monitoring its
placement by fluoroscopic examination.
The difficulty resulting from this require-
ment of the compound angle is referred to in Moore, et
al, U.S. Patent No. 4,723,544. The structure dis-
closed in that patent, however, presents other diffi-
j 20 culties relating to structural rigidity and integrity.
l Another structure intended generally or the same pur-
j pose is disclosed in Zanetti, U.S. Patent No.
j 4,750,487. Both the Moore and the Zanetti structures
provide for the attachment o~ the apparatus to one
side of the operating table. A structure is required
which provides more structural rigidity and flexibili-
; ty in placement of the cannula than either of these
i structures, and still facilitates the attainment of
j the required compound angle. In addition, a structure
is required which can provide guidance to the needle
from either side of the patient without requiring the
removal and replacement of the structure to change
sides.
This invention relates to improvements over
the apparatus described above and to solutions to some
2~8~ 3
-- 3 --
of the problems raised thereby.
t3ummary of the Invent~ on
The inventio~ relates to a stereotaxic de-
vice for directing a puncturing tool, and particularly
a guide needle, toward a designated target within a
body cavity of a patient. The invention includes a
tool guide for directing the puncturing tool toward
the designated target, and positioning means for posi-
tioning the tool guide anywhere on a hemispherical
surface from which to direct the puncturing tool to-
ward the designated target. The positioning means
includes arcuate slider means associated with the tool
guide, with the designated target at the center of the
arc of the arcuate slider means. Rotator means are
slidably connected to the arcuate slider means for
permitting the arcuate slider means to slide while
also permitting a full 360 degrees of rotation, thus
maintaining the tool guide at the hemispherical sur-
face. Adjusting means are provided for adjusting the
position of the rotator means along mutually perpen-
dicular X, Y and Z axes with respect to the designated
target, that rotating means being journaled to the
adjusting means for rotation about one of the axes.
Those adjusting means generally include a rectangular
base plate and a pair of parallel guide rails affixed
thereto. A pair of support means are oriented sub-
stantially normal to the base plate, each slidably
connected at one end to a respective one of the guide
rails to permit sliding movement of the support means
along the guide rails in a Z direction. The support
means includes Y-axis control means for changing the
distance between the opposite end of the support means
and the base plate. The opposite end is thus movable
in a Y direction normal to the Z direction. The in-
vention further provides crossing means for connecting
-- 4
60895-1457
together the pair of support means at the opposite ends thereof.
The crossing means are positioned generally over the patient and
orienied substantially parallel to the plane of the base plate and
normal to the support means. The invention also includes targeting
means for positioning the support means, crossing means and transfer
slider means so that the tool guide guides the puncturing tool to
the designated target. The targeting means includes Y-Z targeting
means for positioning the support means and the crossing means with
respect to the base plate, and X-axis targeting means for position-
ing the transfer slider means with respect to the crossing means.
Other objects and advantages of the inven~ion will become
apparent hereinafter.
Description of the Drawing
Fig. 1 is a front elevation view of a stereotaxic device
constructed according to a preferred embodiment of the invention.
Fig. 2 is a side elevation view of the stereotaxic device
shown in Fig. 1, partially in section.
Fig. 3 is a top plan view of the stereotaxic device
shown in Fig. 1.
Fig. 4 is an isometric view of the portion of the stereo-
taxic device shown in Fig. 1 which permits lateral movement and
rotation of the needle support.
Fig. 5 is an isometric view of the device being aligned
in the Y and Z directions according to the invention.
Fig. 6 is an isometric view of the device being aligned
in the X direction according to the invention.
Fig. 7 is an exploded elevational view, on an enlarged
scale, of an end block assembly according to a preferred embodiment
of the invention.
Description of the Preferred Embodiment
In the following description, there will be
2 ~
-- 5 --
referred to three axes or directions, all mutually
perpendicular, a Z-axis, a Y-axis and an X-axis, or
longitudinal, vertical and lateral directions, respec-
tively. Although the inventio~ is not to be limited
by these direction references in the following de-
scription, most commonly, for reference purposes, as-
suming that the patient is lying down when using the
following described apparatus, the Z-axis or longitu-
dinal direction will refer to a horizontal direction
generally parallel to the medial axis of the patient,
the Y-axis or vertical direction will refer to an up-
right direction normal to the Z-axis, and the X-axis
or lateral direction will refer to a horizontal direc-
tion normal to the Z-axis.
Referring now to Fig. 1, there is shown a
stereotaxic device 10 constructed according to a pre-
ferred embodiment of the invention. As there shown,
the device 10 is entirely portable, and is placed upon
an operating table 12 prior to placing the patient on
the table for the operation. The device 10 includes
a base plate 14 which is generally flat and rectangu-
lar in shape. A pair of guide rails 16 and 18 are
each secured by suitable means to the base plate 14,
spaced apart and generally longitudinally, parallel to
each other and to the side edges of the base plate,
one along each respective side edge. The guide rails
16 and 18 need not be identical to each other. As
shown in Fig. 1, however, both guide rails 16 and 18
are dovetailed. That is, each guide rail 16 and 18
has a relatively narrow base portion which then ex-
pands outward to a wider portion at the top.
A pair of base slider blocks 20 and 22 are
slidably mounted, one on each of the guide rails 16
and 18 respectively, for sliding movement along the
guide rails, that is, along the Z-axis, with each of
2 ~ 0 ~
the base slider blocks conforming to its respective
guide rail. That is, each base slider block 20 and 22
has an internal shape that conforms to the dovetail
shape of the respective guide rail 16 and 18. In each
case, the mounting is preferably journaled to permit
smooth and hitch-free sliding. Each of the base slid-
er blocks 20 and 22 also includes means, such as a set
screw 24 which, when tightened, inhibits the sliding
motion of the block along the guide rail 16 or 18, in
lo any position determined by the physician as described
in more detail below. To this end each set screw 24
is threaded into its respective base slider block 20
or 22, and bottoms on the respective guide rail 16 or
18 when in use, thus preventing relative motion be-
tween the respective base slider block 20 or 22 and
guide rail 16 or 18. Both slider blocks 20 and 22 are
slidable entirely off at least one end of each of the
respective guide rails 16 and 18, to permit removal of
the rest of the device 10 from the base plate 14,
thereby facilitating the movement of the patient onto
the base plate for the operation.
Referring now mainly to Fig. 2, projecting
vertically upward from each base slider block 20 and
22 are vertical support means 26, which essentially
includes two parallel vertical slider rods 28, each
anchored in the respective base slider block 20 or 22.
Each pair of slider rods 28 in each slider block 20 or
22 is topped in common by a single stop block 32.
Each support means 26 further includes a separate ver-
tical slider block 34 slidably mounted on each respec-
tive pair of vertical slider rods 28. The invention
includes means 36 for controlling the vertical move-
ment of the slider block 34 along the rods 28. In the
preferred embodiment, means 36 includes a threaded rod
38, oriented parallel to the rods 28. The bottom end
~ ~ ~ 8 ~ O ~
of threaded rod 38 is rotatably anchored in the base
slider block 20 or 22 while a portion near the top end
is rotatably anchored in stop block 32. The threaded
rod 38 is threaded through the slider block 34, so
that turning the rod causes the slider block to slide
vertically along the slider rods 28. Neans 40 are
then provided for turning the threaded rod 38, in turn
causing the slider block 34 to slide vertically. In
one embodiment turning means 40 are knurled knobs 42,
one affixed to the top of each of the threaded rods
38. Thus is provided means for changing the vertical
height of the vertical support means 26. In the pre-
ferred embodiment the vertical support means 26 fur-
ther include pairs of upper rods 44 affixed to and
projecting upwardly from the upper surface of a trans-
verse projection 34a formed in each slider block 34
for that purpose. Each pair of upper rods 44 is
topped by a respective end block 46, which is securely
affixed to the upper rods. Thus the distance between
the respective end block 46 and vertical sIider block
34 is fixed and immovable, for reasons to be set forth
subsequently.
The two end blocks 46 are connected together
by crossing means 48. In one embodiment the crossing
means 48 includes a pair of spaced apart, parallel
horizontal slider rods 50, shown best in a top view in
Fig. 3. Since the rods 50 are connected between the
end blocks 46, the rods are generally parallel to the
plane of the base plate 14.
The two end blocks 46 are each two-piece end
blocks, each having upper portions 46a and lower por-
tions 46b. Each lower portion 46b is securely affixed
to the respective upper vertical rods 44, while each
upper portion 46a is securely affixed to the horizon-
tal slider rods 50. Each upper portion 46a is con-
2 ~
-- 8 --
nected to the respective lower portion 46b by suitable
removable means, such as a nut 47, sized large enough
to be removable by hand, threaded onto a bolt 46c pro-
iecting upwardly from the top surface of lower portion
46b through the upper portion 46a. Thus is provided
another means for partial disassembly of the device 10
to facilitate the movement of the patient onto the
operating table 12 for the operation. That is, it is
important that the patient, presenting himself for the
operation because of back pain which likely already
restricts his freedom of movement, not be required to
crawl into the device, since to so require would al-
most certainly be extremely uncomfortable and would
thus restrict use of the device to those patients al-
ready sufficiently fle~ible to crawl into it. Rather,
by the means disclosed, whether the removal of the up-
per block portion 46a from the lower block portion
46b, or the sliding of the base slider blocks 20 and
22 off the ends of the guide rails 16 and 18, the de-
vice 10 may be ~uickly partially disassembled to fa-
cilitate the movement of the patient onto the operat-
ing table 12 for the operation, and then easily and
accurately reassembled to begin the operation.
Transverse slider means 52 are slidably
mounted on the horizontal slider rods 50, for lateral
slidable movement along the rods. In the preferred
embodiment the transverse slider means 52 includes a
lateral slider block 54 slidably mounted to the hori-
zontal slider rods 50. A third, threaded, lateral rod
56 is also affixed between the end blocks 46, parallel
to the other two upper rods 44. In the embodiment
shown in Figs. 2, 3 and 4, the threaded lateral rod 56
is positioned between the two upper rods 44. Threaded
lateral rod 56 passes through a smooth bore formed in
the lateral slider block 54, and is not threaded
2 ~
therein. As shown best in Figs. 3 and 4, two nuts 58
are threaded onto the threaded lateral rod 56, one on
each side of the lateral slider block 54. Thus is
provided means for affixing the lateral slider block
in a particular lateral position along the horizontal
slider rods 50. This affixing means permits the oper-
ator to turn or rotate the nuts away from the lateral
slider block 54 to permit free movement of the block
and then, when the operator deems the block in the
desired position as will be explained more fully sub-
sequently, the nuts are tightened against the block to
prevent further movement.
Rotator means 60 are connected to the later-
al slider block 54 so as to be rotatable about a ver-
tical axis after being moved to the desired position
as referred to above. In the preferred embodiment,
the rotator means 60 includes an arc holder 62, the
upper part of which is generally cylindrical in shape.
The arc holder 62 includes an annular projection 64
about the entire periphery of the top end of the arc
holder, the cross sectional shape of the projection
being dove-tailed. As shown best in Fig. 2, the lower
surface of the projection 64 fits onto a shelf 66 pro-
vided for that purpose in the front face of lateral
slider block 54.
A clamp plate 68, Figs. 2, 3 and 4, is pro-
vided to secure the annular projection 64 and hence
the arc holder 62 in place. The clamp plate 68 is
secured to the top surface of the lateral slider block
54 by any suitable means which is capable of being
fastened and loosened without complete removal. In
the preferred embodiment, the clamp plate 68 is se-
cured by a pair of finger screws 70 inserted through
respective openings provided for that purpose in the
clamp plate and threaded into the top surface of the
2~8~
-- 10 --
lateral slider block 54. As shown in Fig. 2, the
clamp plate 68 projects beyond the edge of the lateral
slider block 54 on the side toward the arc holder 62,
and includes an arcuate groove 68a in its lower sur-
face for fitting closely with the upper surface of the
annular projection 64 of the arc holder 62. Hence
with the finger screws 70 slightly loose, the arc hold-
er 62 may without limit be rotated smoothly and
slidingly with respect to the lateral slider block 54.
lo Once the arc holder 62 is rotated to the desired posi-
tion, the finger screws 70 are tightened down and the
arc holder is no longer rotatable.
Rotator means 60 further includes a cylin-
drical insert 72 inserted inside the annular projec-
tion 64. The cylindrical insert 72 has flat top and
bottom surfaces which are clear, and which are provid-
ed with X-axis sighting means 73, such as cross-hairs
74 at the top surface and a dot 76 in the bottom sur-
face, to aid in positioning the transverse slider
means 52.
One side of the arc holder 62 includes an
arcuate groove 62a, into which is slidably mounted a
smooth arc member 78. As shown in Fig. 1, the arc
member 78 preferably has a T-shaped cross-section, the
cross bar 78a of the T being positioned toward the arc
holder 62, and fitting into the groove 62a, which has
a similar T-shape to accommodate the arc member.
Also, the radius of the arc member 78 corresponds to
the radius of the groove 62a. A set screw 80 (Fig. 2)
may be provided as means for locking the arc member 78
in place with respect to the arc holder 62.
The invention also calls for a tool guide 82
for guiding a piercing tool 84 such as a cannula when
using the device 10. In the preferred embodiment, the
tool guide 82 is a tube having an inside diameter of
2~58~
-- 11 --
a size to closely accommodate the outside diameter of
the piercing tool 84. The outside of the tool guide
82 includes a collar 86 which acts as a stop when the
tool guide is inserted into a support arm 88. The
support arm 88 is in turn slidably mounted to the arc
member 78 by means of tool guide slider 90. The tool
guide slider 90 is mounted to the side of the arc mem-
ber 78 opposite to the side by which the arc member is
mounted to the arc holder 62. Thus the tool guide
slider 90 may slide in an arcuate path along the en-
tire length of the arc member 78, and at the same time
the arc member 78 may slide its entire length with
respect to the arc holder 62.
The device 10 is designed to be used and
operated only by physicians fully familiar with the
physiology and pathology of the spine. Such physi-
cians should also be properly qualified to perform
spinal surgical procedures.
In operation, a patient 92 requiring a disc-
ectomy is placed upon the base plate 14 and secured
there by any suitable means constructed of X-ray
translucent material, such as fabric straps 94, se-
cured together by suitable removable means such as
hook-and-pile fasteners. As can be seen by comparing
Fig. 5 and Fig. 2, the device 10 is first aligned in
the Y and Z directions by use of Y-Z sighting means 96
attached to the vertical slider blocks 34. The Y-Z
sighting means 96 include flat plates 98 and 100 each
attached to a respective one of the vertical slider
blocks 34. Each of the flat plates 98 and 100 is con-
structed of X-ray translucent material. It may also
be helpful if the flat plates 98 and 100 are construc-
ted of a rugged but transparent material, such as
Lexan or plexiglass, to enhance visual alignment. In
the most preferred embodiment one of the flat plates
2~8~J~
- 12 -
98 includes cross hairs 102 of X-ray opaque material,
while the other of the plates lO0 includes a small
ball or dot 104, also of an X-ray opaque material.
A generally conventional C-arm image inten-
sifier 106 is shown in Figs. 5 and 6, having a C-arm
108, an X-ray projector 110 at one end of the C-arm
and a fluoroscope 112 at the othex end aligned with
the X-ray projector, creating a line-of-sight 114 be-
tween the two. A fluoroscopic display 115 is connect-
ed to the fluoroscope 112 to show the view produced by
the intensifier 106. According to the invention, as
indicated above, the patient 92 is placed on the base
plate 14 on the operating table 12. Before s~curing
the patient 92 by means of straps (Fig. 1) as de-
scribed earlier, the intensifier 106 is activated and
the patient is aligned with the device 10. This
alignment is done by aligning the spinous process of
the patient with a wire 117 (Figs. 1 and 3), or other
long, thin member made of X-ray opaque material, em-
bedded in the base plate 14, parallel to and generally
centered between the guide rails 16 and 18.
The C-arm 108 is then maneuvered into the
position shown in Fig. 5 so that the line-of-sight 114
passes laterally through a target 116 within the pa-
tient, in this case the spinal disc on which the disc-
ectomy is to be performed, to give a lateral view as
shown on the display 115. The device 10 is then man-
euvered, along the Z-axis by moving the slider blocks
20 and 22 along the guide rails 16 and 18, and along
the Y-axis by moving the vertical slider blocks 34
along the vertical slider rods 28, until it can be
seen on the display 115 that the Y-Z sighting means 96
is aligned with the line-of-sight 114.- In the pre-
ferred embodiment, the device 10 includes Z-axis rul-
ers 120 (Figs. 1 and 3) attached to the base plate 14
2~3~ ~tj
adjacent to and parallel to each of the guide rails 16
and 18. These rulers 120 are provided to permit the
operator to ensure that the two base slider blocks 20
and 22 are aligned with each other, that is, at the
same position along the respective guide rails 16 and
18 with respect to each other in the Z direction.
Similarly, a Y-axis ruler 122 (Figs. 1 and 2) is at-
tached to each of the stop blocks 32, reaching down-
ward therefrom, so as to permit the operator to ensure
that each of the two vertical slider blocks 34 is at
the same position along the respective vertical slider
rods 28, in order to make sure that the vertical slid-
er blocks 34 are properly aligned with each other in
the Y direction. Once the device 10 is properly ar-
ranged with respect to the patient 92 by use of sight-
ing means 96 and the base slider blocks 20 and 22 with
respect to each other by use of rulers 120, then the
set screws 24 are tightened so as to prevent any fur-
ther movement in the Z direction. The vertical slider
blocks 34 are then properly arranged with respect to
each other by use of rulers 122, again while maintain-
ing the sighting means 92 on the target 116.
As can be seen by comparing Fi~gs. 2 and 6,
the device 10 is next aligned in the X direction by
use of X-axis sighting means 73. The C-arm is maneu-
vered into the position shown in Fig. 6 so that the
line-of-sight 114 passes vertically through the target
116, to give an a-p view on the display 115. The
transverse slider means 52 is then moved along the
horizontal slider rods 50 until it can be seen on the
display 115 that the cross hairs 74 and dot 76 are
aligned with the line-of-sight 11~. The transverse
slider means 52 is then secured in that position by
use of nuts 58, as described above.
With the device 10 positioned as just de-
2~8~
- 14 -
scribed, the target 116 is aligned with both sighting
means 73 and 96. That is, the lines created by sight-
ing means 73 and 96 define a point 118 (shown in a
different position in ~ig. 2), which in the position
just described coincides with the target 116 inside
the patient 92. As can be seen in Fig. 2, this point
118 is the center of the arc of the arc member 78.
The device 10 is constructed, including the curvature
of the arc member 78 as can be seen in Fig. 2, and the
length of the support arm 88 as can be seen in Figs.
1 and 3, so that this point 118 is always pointed to
by the tool guide 82, regardless of the position of
the tool guide on the arc member 78, regardless of the
position of the arc member in the arc holder 62, and
regardless of the rotation of the arc holder 62 with
respect to the lateral slider ~block 54. Therefore,
once the device 10 is aligned and tightened as de-
scribed above, with the point 118 being coincident
with the target 116, the operator may move the tool
guide 82 to practically any usable position, by slid-
ing the tool guide slider 90 along the arc member 78,
by sliding the arc member 78 with respect to the arc
holder 62, and by rotating the arc holder 62 with re-
spect to the lateral slider block 54, with complete
confidence that the target is still coincident with
the point, and with complete stability. This func-
tionality is not available in the prior art. Using
the structure of the device 10 the operator can, for
instance, begin the operation intending to insert the
cannula 84 from the left side and, without reposition-
ing the transverse slider means 52 in any way with
respect to the patient 92, rotate the arc holder 62
and insert the cannula from the right side. This is
but one example of the many benefits provided by this
device 10 over the prior art.
2~89~1~
- 15 -
While the apparatus hereinbefore described
is effectively adapted to fulfill the aforesaid ob-
jects, it is to be understood that the invention is
not intended to be limited to the specific preferred
embodiment of spinal stereotaxic device set forth
above. Rather, it is to be taken as including all
reasonable equivalents within the scope of the follow-
ing claims.
