U.S. patent number 3,875,595 [Application Number 05/460,726] was granted by the patent office on 1975-04-08 for intervertebral disc prosthesis and instruments for locating same.
Invention is credited to Edward C. Froning.
United States Patent |
3,875,595 |
Froning |
April 8, 1975 |
INTERVERTEBRAL DISC PROSTHESIS AND INSTRUMENTS FOR LOCATING
SAME
Abstract
A collapsible plastic bladder-like prosthesis of the same
external form as the nucleus pulposis of an intervertebral disc has
a stem through which liquid and/or plastic is introduced to inflate
the prosthesis to natural form. The top and bottom have stud-like
protrusions which fit into sockets which have been forced through
the bony end plates of the bodies of adjacent vertebrae anchoring
the prosthesis against slippage. To install the prosthesis, the
first step is to insert a transparent tube to the situs with a
projecting pin fitting into an adjacent vertebrae to hold the
distal end against slippage. A cystoscope may be inserted through
the tube to check its location. The degenerated nucleus pulposis of
the natural disc is removed in pieces by a forceps inserted through
the tube and an incision in the disc wall. The tube provides
controlled depth of penetration of this forceps into the disc and
acts as a safety feature against injury to blood vessels, nerves
and other structures adjacent to the disc. The socket members are
inserted through the tube by a specially formed forceps and forced
into the adjacent vertebrae. The collapsed prosthesis is then
inserted through the stem, the studs pushed into the sockets.
Pressure may be adjusted over a period of time; and when finally
determined, the stem is severed.
Inventors: |
Froning; Edward C. (San Mateo,
CA) |
Family
ID: |
23829835 |
Appl.
No.: |
05/460,726 |
Filed: |
April 15, 1974 |
Current U.S.
Class: |
623/17.12 |
Current CPC
Class: |
A61F
2/442 (20130101); A61F 2/4611 (20130101); A61F
2/441 (20130101); A61F 2002/444 (20130101); A61B
2017/3488 (20130101); A61B 2017/00261 (20130101) |
Current International
Class: |
A61F
2/46 (20060101); A61F 2/44 (20060101); A61B
17/34 (20060101); A61B 17/00 (20060101); A61f
001/24 (); A61b 017/00 () |
Field of
Search: |
;3/1,36
;128/92C,92CA,92R,334R,92E,92EA,92G,33R,35R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
1,122,634 |
|
May 1956 |
|
FR |
|
476,492 |
|
Sep 1969 |
|
CH |
|
Primary Examiner: Frinks; Ronald L.
Attorney, Agent or Firm: Caplan; Julian
Claims
What is claimed is:
1. A prosthesis for the nucleus pulposis of an intervertebral disc
comprising a bladder-like member having a stem for insertion of
liquid or plastic into said member, said member shaped to simulate
said nucleus pulposis of a human disc and to fit within the annulus
fibrosis of said disc and at least one stud on an exterior face of
said member shaped to engage a socket forming member on one end of
said disc formed for installation in the vertebrae along or below
said disc.
2. A prosthesis according to claim 1 in which said bladder-like
member is a thin-walled plastic member capable of being rolled up
preliminary to installation formed of a material having
approximately the electrical conductivity of a natural disc, and
capable of holding fluid or water under pressure substantially
duplicating the corresponding characteristics of a natural disc
nucleus pulposis.
3. A prosthesis according to claim 2 in which said stud is radio
opaque.
4. A prosthesis according to claim 1 which further comprises a
valve in said stem.
5. A prosthesis according to claim 1 which further comprises
material inserted through said stem substantially filling said
bladder-like member, said material being radio opaque, said
material being fluid or plastic.
6. A prosthesis according to claim 5 in which said material is
radio opaque.
7. A prosthesis according to claim 1 which further comprises at
least one socket forming member having a flange and shaped with a
point to imbed said socket-forming member into a vertebrae above or
below said flange, said socket-forming member formed with a socket
complementary to said stud.
8. A prosthesis according to claim 7 in which said socket-forming
member is radio opaque.
9. In combinaton with a prosthesis of claim 1, a tube for
surgically locating said prosthesis, said tube being transparent in
at least a portion of its distal end for checking location of said
tube with a cystoscope inserted into said tube, said tube having
locating means operable from its proximal end to drive at least one
pin at its distal end into a vertebrae to locate said tube fixed
relative to a disc in which said prosthesis is to be installed.
10. The combination of claim 9 which further comprises a
socket-forming member having a flange, a point and a socket
complementary to said stud, and a forceps dimensioned to fit inside
said tube and having one end formed to hold said flange for
insertion of said point into an adjacent vertebrae by operation of
said forceps.
11. The combination of claim 9 in which the wall of said tube is
formed with a longitudinal hole and said locating means comprises a
pin reciprocable in said hole and having a point in its distal
end.
12. The combination of claim 11 in which the wall of said tube is
formed with a second longitudinal hole diametrically opposite said
first-mentioned hole and which further comprises a second pin in
said second hole to locate said tube fixed relative to said
first-mentioned vertebrae and a second vertebrae on the side of
said disc opposite said first-mentioned vertebrae.
13. The combination of claim 9 which further comprises a stop and
means adjustably securing said stop on said pin outside said tube
to limit inward projection of said pin into said tube.
Description
This invention relates to a new and improved intervertebral disc
prosthesis and instruments for locating the same in place.
A principal purpose of the present invention is to provide a
prosthesic replacement for a damaged intervertebral disc. The
prosthesis resembles in plan view the nucleus pulposis of the
natural disc which it replaces. Since no spine fusion is employed
bending of the spine in a natural manner is not inhibited.
In the lumbar area the entry to the disc is laterally, thereby
reducing the complexity and risk of intraspinal surgery
traditionally employed. The danger of perforation of the nerve,
dural sac, arteries and other organs is reduced. In cervical
surgery, the approach is frontally and again the complexity and
risk of the surgery is greatly reduced by avoiding transgression of
the spinal canal.
A further principal purpose of the invention is the provision of
means shielding the instruments which are used from the surrounding
anatomy and thus damage to such anatomy, such as the cutting of
nerves, is eliminated.
A still further purpose of the invention is the provision of
anchoring means which prevent slippage of the prosthesis after
applied.
A still further feature of the invention is the fact that the
prosthesis is a hollow, flexible bladder-like member which is
filled with a fluid and/or plastic under adjustable pressure. The
pressure may be increased or decreased while the prosthesis is in
place over a period of time to determine by trial and error the
optimum pressure, and thereupon the stem of the prosthesis is
removed. The optimum pressure is maintained over an indefinite
period of time by providing an inflating fluid or plastic having
properties for holding fluid or water under pressure normally
occurring within the disc sufficient to avoid depletion of the
inflating contents, a feature which would duplicate the feature of
the normal disc. The inflatable prosthesis and its inflating
contents will conform to electrical conductive or insulating
properties found in the natural state.
Other objects of the present invention will become apparent upon
reading the following specification and referring to the
accompanying drawings in which similar characters of reference
represent corresponding parts in each of the several views.
In the drawings:
FIG. 1 is a perspective view of the third and fourth lumbar
vertebraes from the back and showing a tube and pin inserted.
FIG. 2 is a schematic sectional view showing tube and pin in place
and also showing use of a forceps to remove the nucleus of the
disc.
FIG. 3 is similar to FIG. 2 showing insertion of sockets in the
upper and lower surfaces of the adjacent vertebrae.
FIG. 4 is a view similar to FIG. 2 showing insertion of the
collapsed prosthesis.
FIG. 5 shows inflation of the prosthesis and the studs thereof
fitting into the sockets.
FIG. 6 is a view similar to FIG. 1 showing the prosthesis in
place.
FIG. 7 is an enlarged fragmentary view showing interfitting of stud
and socket.
FIG. 8 is a schematic vertical sectional view of cervical
vertebrae, showing the prosthesis in place.
FIG. 9 is an enlarged section view taken substantially along line
9--9 of FIG. 8.
A natural vertebral disc 12 comprises an outer annulus fibrosis 13
and an inner nucleus pulposis 14. The disc functions to permit
flexible articulation of the adjacent vertebrae 11 and an internal
resistance to flexion (or a bending torque) which lends intrinsic
stability to this multisegmented column. The nucleus is removed in
accordance with the method of the surgical treatment hereinafter
described, preferably being removed by the method of
chemonucleolysis an injection treatment with an enzyme such as
chymopapain, a papaya derivative, which dissolves out the nucleus.
It will be understood that the nucleus may be removed in other
manners.
The body 16 of vertebrae 11 has concave upper and lower surfaces 17
with raised marginal edges 18. A layer of cartilage 19 covers the
surfaces 17. Various processes 21 extend from body 16 and these
shield the spinal cord 22 and provide attachment for muscles.
Nerves 23 extend from cord 22 in the interstices of the processes
21.
The function of the present invention is to replace the nucleus 14
of a disc 12 with a prosthesis 46.
In replacing the lumbar intervertebral disc 12, a tube 31 is
inserted laterally to a location abutting the injured disc 12. The
tube 31 is inserted in such manner as to move out of the way the
adjacent nerves 23. Tube 31 has a longitudinal hole 32 in its wall
to receive a pin 33 having an outwardly curved sharpened point 34
which is imbedded in the adjacent vertebrae to secure the anterior
of tube 31 in the desired location. To prevent excessive
penetration of pin 33, a stop 56 slips over the pin 33 on the
exterior of tube 31 and is held in place by set screw 57 so that
point 34 projects from tube 31 the desired amount. Optionally, an
instrument (not shown) is inserted through the bore into tube 31 to
spread the adjacent vertebrae 11 apart by tilting same as shown in
FIG. 3, whereupon a second pin 33a is installed in a hole 32a
diametrically opposite hole 32 and a second pin 33a having point
34a is driven into the vertebrae 11a holding the vertebrae in
spread apart condition and affording greater space for the surgical
treatment hereinafter described. Preferably, tube 31 is transparent
or has a transparent window or is formed with a slot so that a
cystoscope (not shown) may be inserted in the bore of tube 31 and
the location of the tube relative to disc 12 and also relative to
the nerve and adjacent anatomy may be checked.
The annulus 13 adjacent tube 31 is penetrated and a forceps 36
having pincers 37 at the anterior thereof is used to remove the
remaining nucleus of disc 12. Thus a void 27 is created inside the
annulus fibrosis of disc 12 into which the prosthesis 46 is
subsequently installed.
A second forceps 38 having fitted ends 39 is used to insert socket
members 41. Each socket member 41 has a peripheral flange 42 and a
hollow pointed prong. Preferably the socket forming members 41 are
inserted serially, the flange 42 being captured in one end 39 and
inserted through the tube 31 into the void 27 in the disc 12. The
prong 43 is imbedded through the cartilage 19 and bony end plate
into the surface 17 of the adjacent vertebrae 11. Thereupon a
second socket member 41 is installed in the opposite vertebrae in
the same manner. Socket members 41 may be of ceramic, plastic, or
autogenous bone material and are preferably opaque in
radiology.
Prosthesis 46 is a hollow, bladder-like member having in expanded
shape the appearance of the natural nucleus 14 of a natural disc
12. It has a wall approximately 0.040 inches in thickness and for a
typical lumbar disc has a width on its major axis of 1.375 inches
and on its minor axis of 0.800 inches. Projecting at an angle of
approximately 45.degree. relative to the major axis of the
prosthesis is a stem 47 of 0.125 inches inside diameter tubing.
Preferably a valve 48 is similar to a ball check valve is installed
in the stem 47. On the top and bottom surfaces of prosthesis 46 are
studs 49 preferably bulbous and integrally formed with the bladder
of the prosthesis. The studs 49 are dimensioned to fit into the
hollow prongs 43 of the socket members 41. The material of
construction of prosthesis 46 preferably has certain
characteristics. It has properties of holding fluid or water under
pressure substantially duplicating the normal disc. It has
electrical conductivity conforming to the normal disc. The fluid or
plastic within the disc preferably has similar conductivity and is
opaque in radiology.
As viewed in FIG. 6, the prosthesis 46 is installed through tube 31
flattened and preferably folded. The flattened condition may be
best attained by evacuation of the bladder. After the prosthesis is
in place in the void 27, the studs 49 are located in alignment with
the hollow prongs 43, a probe being used for this purpose and the
location being checked by television fluoroscopic radiography. To
facilitate this operation, members 43 and 49 are preferably radio
opaque. Thereupon, fluid is pumped through the stem 47 past the
check valve 48 to expand the prosthesis to the condition shown in
FIG. 5, filling the void 27 and functioning as a healthy nucleus 14
would function in a natural disc 12. The stem 47 may be left in
place for some time, preferably terminating near the skin so that
from time to time the amount of fluid may be increased or reduced
until the desired pressure is determined by trial and error.
Subsequently, the stem 47 may be cut off adjacent the valve 48.
Various fluids may be used to expand the prosthesis, but preferably
one which offers a radio opague feature to assist in checking
position by radiography.
Directing attention to FIGS. 8 and 9, use of prostheses 46b in
cervical vertebrae is shown. The prosthesis is the same in
structure and function, but of reduced size from that previously
described.
However, installation is somewhat simplified. Incision is made
frontally to one side of windpipe 53, the adjacent artery 51 and
vein 52 being retracted. Thus use of tube 31 may not be
advantageous in the neck.
The cervical vertebrae and prosthesis are marked with reference
numerals as in the preceding modification, followed by subscript
b.
* * * * *