U.S. patent application number 09/755944 was filed with the patent office on 2001-12-06 for prosthetic cage for spine.
Invention is credited to Ahn, Jae Yong, Han, Jung Soo, Jun, Chang Hun, Kim, Byung Soo, Kim, Jung Sung, Kim, Kyung Tae, Koo, Ja Kyo, Min, Ki Sik, Shin, Chan Soo.
Application Number | 20010049559 09/755944 |
Document ID | / |
Family ID | 19636387 |
Filed Date | 2001-12-06 |
United States Patent
Application |
20010049559 |
Kind Code |
A1 |
Koo, Ja Kyo ; et
al. |
December 6, 2001 |
Prosthetic cage for spine
Abstract
A prosthetic cage for spine adapted to be implanted in an
intervertebral disc space between two vertebral bodies in a spine
and to accommodate fusion of the disc space, said cage being a
tubular body with an internal aperture, an external surface of
which having a plurality of wall apertures each perpendicular to
the longitudinal axis thereof and communicating with the internal
aperture, and dual convex screw threads extended therefrom, such
that the cage of the present invention has an advantage that the
stability of fixation between the cage and the vertebral body can
be achieved by simple variation of its shape
Inventors: |
Koo, Ja Kyo; (Seoul, KR)
; Han, Jung Soo; (Seoul, KR) ; Kim, Kyung Tae;
(Seoul, KR) ; Kim, Jung Sung; (Seoul, KR) ;
Min, Ki Sik; (Bucheon-City, KR) ; Kim, Byung Soo;
(Seoul, KR) ; Shin, Chan Soo; (Seoul, KR) ;
Ahn, Jae Yong; (Seoul, KR) ; Jun, Chang Hun;
(Seoul, KR) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
19636387 |
Appl. No.: |
09/755944 |
Filed: |
January 5, 2001 |
Current U.S.
Class: |
623/17.16 ;
606/247; 606/65 |
Current CPC
Class: |
A61F 2002/30851
20130101; A61F 2002/30787 20130101; A61F 2002/30593 20130101; A61F
2/446 20130101; A61F 2002/2835 20130101 |
Class at
Publication: |
623/17.16 ;
606/65; 606/61 |
International
Class: |
A61F 002/44 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 6, 2000 |
KR |
2000-261(U.M.) |
Claims
What is claimed is:
1. A prosthetic cage for spine adapted to be implanted in an
intervertebral disc space between two vertebral bodies in a spine
and to accommodate fusion of the disc space, said cage being a
tubular body with an internal aperture, an external surface of
which being a plurality of wall apertures, each perpendicular to
the longitudinal axis thereof and communicating with the internal
aperture, and dual convex screw threads extended therefrom.
2. The prosthetic cage for spine of claim 1, wherein each inclined
plane of said dual convex screw threads is oppositely directed.
3. The prosthetic cage for spine of claim 2, wherein the dual
convex screw threads are spaced apart from each other and the wall
apertures are also available between the dual convex screw
threads.
4. The prosthetic cage for spine of one of claims 1 to 3, wherein a
first end of the cage for introduction has a sharpened section for
stimulating an intervertebral disc space
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a prosthetic device implanted in
vertebrae for treatment or prevention of back pain in patients with
ruptured or degenerated intervetebral discs.
[0003] 2. Description of the Prior Art
[0004] The spine of human is constituted of backbone and
fibrocartilaginous disc.
[0005] FIG. 1 shows a lumbar (200) of human, which consists of
vertebral body (220), two pedicles (210) and two intervertebral
discs (230). The intervertebral disc (230) is frequently referred
to as "disc" and consists of annulus fibrous and nucleus
pulpous.
[0006] Low back pain is known to be caused by collapse of the disc
(230) and adverse effects of bearing the majority of the body
weight through a damaged unstable vertebral joint. In the past,
clinical attention has been focused on relief of a sciatic pain by
removal of pressure from a nerve root. This kind of surgical
treatment falls into the following groups.
[0007] A 1st method is "Excision of the Ruptured Soft Disc". This
procedure removes a portion of the disc compressing the spinal
nerve and is generally successful in relieving the sciatic leg pain
but in more than half the cases, there is a recurrence of back
pain. Over a period of time the disc gradually loses height due to
the rupture and said loss of height causes the posterior facet
joints of the vertebrae to fit incorrectly, resulting in arthritic
change in all elements of the spinal segment.
[0008] A 2nd method is "Disc Excision With Posterior Fusion". It
prevents motion between adjacent vertebrae but does not alter the
fact that approximately 90% of the body weight must be transmitted
through degenerated discs, causing pain. Further, posterior fusion
tends to bring about bony overgrowth, leading to nerve root
compression by spinal stenosis.
[0009] A 3rd method is "Disc Excision With Anterior Interbody
Fusion". In this method, a soft disc is completely excised and
replaced with either a patient's own bone (autologous bone) or with
transplant. Banked bones (homologous bone) are generally successful
if solid fusion can be obtained between adjacent vertebrae bodies,
The success rate has been only about 50%.
[0010] A 4th method is "Disc Excision With Posterior Lumbar
Intervertebral Fusion (PLIF)". This procedure reconstructs a normal
anatomic relationship between the bony and the neural structures
and has many advantages. However, this procedure has several
serious disadvantages in that it is technically very difficult, and
is therefore not as successful or widely used as it might be.
[0011] In the art of spinal surgery, various devices and methods
for interbody fusion have been developed and are described in U.S.
Pat. No. 5,772,661 issued Jun. 30, 1998 to Michelson. U.S. Pat. No.
5,683,391 issued Nov. 4, 1997 to Lawrence M. Boyd describes a
system for attachment of cylindrical interbody fusion devices to a
spinal rod to which bone screws are also attached and anchored in
the vertebral bodies. It is desirable that an interbody fusion
construct be as stable as possible. Also, it is desirable to use an
endoscopic procedure, if possible. U.S. Pat. No.6,156,037 issued
Dec. 5,2000 is a system for achieving these benefits.
[0012] It discloses an interbody fusion cage having an externally
threaded stem (119) projecting from a domed outer end (122). In
this invention, a contoured plate is provided with an aperture
receivable on the stem. The stem threads receive a nut (121) to fix
the plate (111) to a cage (112). A plate (111) has additional
apertures receiving bone screws anchoring the plate to vertebral
bodies (113,114). The plate (111) has a hemispherical surface
surrounding the stem-receiving aperture and bearing on the dome,
accommodating universal angulation of the plate relative to the
cage.
SUMMARY OF THE INVENTION
[0013] However, in such devices with an externally threaded
cylindrical body, there was a concern in that the body could slide
backward or forward to make a fixed state become unstable,
resulting in requirement for complicated fixing device.
[0014] Therefore, it is an object of this invention to provide a
device for overcoming the above-mentioned problem without recourse
to complicated device.
[0015] According to one feature of the invention, a prosthetic cage
for spine, which is adapted to be implanted in the intervertebral
disc space between two vertebral bodies in a spine and to
accommodate fusion of the disc space, is a tubular body with an
internal aperture, and its external surface has a plurality of wall
apertures each perpendicular to the longitudinal axis thereof and
communicating with the internal aperture, and dual convex screw
threads extended therefrom.
[0016] According to another feature of the invention, the
prosthetic cage for spine has dual convex screw threads, the
inclined planes of which are oppositely directed from each
other.
[0017] According to still another feature of the invention, the
prosthetic cage for spine has dual convex screw threads that are
spaced apart from each other and wall apertures are available also
between the dual convex screw threads.
[0018] According to still another feature of the invention, an
introduction end portion of the cage has a sharpened section for
stimulating an intervertebral disc space.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a side view of the vertebral column.
[0020] FIG. 2 is a side view of the vertebral column with implants
of prior art.
[0021] FIG. 3 is a perspective view of one form of prosthetic cage
for spine according to the present invention.
[0022] FIG. 4 is a side view of FIG. 3
[0023] FIG. 5 is a side view of another form of prosthetic cage for
spine according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] For the purpose of promoting an understanding of the
principles of the present invention, reference will now be made to
the embodiment illustrated in the drawings and specific language
will be used to describe the same. It will nevertheless be
understood that no limitation of the scope of the invention is
thereby intended, such alterations and further modifications in the
illustrated device, and such further applications of the principles
of the invention as illustrated therein being contemplated as would
normally occur to one skilled in the art to which the invention
relates.
[0025] Referring now to the drawings wherein like numerals indicate
like parts, the cage of this invention is generally indicated by
the numeral 1 FIGS. 3 and 4 each show an example of prosthetic cage
for spine according to the present invention. The prosthetic cage 1
for spine according to the present invention has a tubular body 20.
The tubular body 20 is elongate and has an internal aperture formed
in a longitudinal direction of the tubular body 20.
[0026] An external surface of the tubular body 20 has convex screw
threads 11,12 which are expanded from the external surface of the
tubular body 20. The screw threads 11,12 are dual and coupled
therebetween. In the example, the two screw threads 11,12 are
slightly inclined and the inclined plane of the two screw threads
is oppositely directed.
[0027] On the other hand, remaining external surface of the tubular
body 20 contains a plurality of wall apertures 30. The wall
apertures 30 are each perpendicular to the longitudinal axis of the
tubular body 20 and communicate with the above internal aperture
40.
[0028] In operation, before inserting the cage 1 into the adjacent
vertebrae bodies, transverse opposed channel should be cut in the
disc space between spaced opposed faces of the adjoining vertebrae
bodies with peripheral hard cortex bone surrounding soft cancellous
bone.
[0029] The above cage 1 is screwed through said open ends of the
transverse channels into the disc space 230 of a patient from
posterior side of the adjacent vertebrae bodies. For installation
in the intervertebral space, the cage 1 is guided and installed in
the space in the usual manner, using a general installation tool
such as a handle for turning the cage into the space 230.
[0030] During the above process, the threads 11,12 scratch the
inner wall of the disc space 230 and the fragments of ingrowth
materials are cumulated into the internal aperture inside tubular
body 20 through the wall apertures 30 which communicate with the
internal aperture 40.
[0031] In the present invention, the external screw threads 11,12
are dually formed, such that the fixation between the cage 1 and
the disc space 230 could be more rigid, compared with the case
where the external screw thread of the cage 1 is single.
[0032] Further, the coupled screw threads 11,12 may be formed in
such a way that their incident planes are opposed each other. In
this case, once the cage 1 is located correctly in the channel, the
movement of the cage 1 is further prevented to make the setting
state of the cage 1 become more stable.
[0033] FIG. 5 shows another example of the present invention In
this example, the coupled dual screw threads 11', 12' are spaced
each other and the spaced surface 50 between the dual screw threads
11, 12'also has wall apertures 70.
[0034] On the other hand, in this example, the cage 1 has a
sharpened section 60 on a first end of the cage 1 which enters the
transverse channel formed in the disc space 230.
[0035] The sharpened section 60 is so formed as to stimulate the
inner wall of the intervertebral disc space 230 when the cage 1
goes inside the channel of the disc space 230. As the cage 1 is
screwed into the channel of the disc space 230, it scratches the
inner wall of the channel and facilitate the generation of the
debris of the disc space 230 , so that the bone ingrowth in the
cage 1 from the disc spaces 230 is more promoted.
[0036] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *