US 20080058808 A1
An implant has a first hook and a second hook. A connector is coupled to the first and second hooks. The implant is adapted in a preferred embodiment to hook and look onto a spine.
1. A method of implanting an implant in a spine including the steps of:
locating a first hook relative to a part of the spine;
locating a second hook relative to a part of the spine;
locating a connector between the first hook and the second hook;
adjusting the first hook, the second hook and the connector to fit relative to the spine; and
locking the connector to the first hook and the second hook in order to lock the implant in the spine.
2. The method of
the first locating step locates the first hook adjacent to a facet of the spine; and
the second locating step locates the second hook adjacent to a facet of the spine and locking step locks the implant about the opposite facets on lateral sides of the spine.
3. The method of
4. The method of
5. The method of
6. The method of
7. The method of
8. The method of
9. The method of
selecting the connector to be a flexible rod;
and said first locking step locks the implant in the spine relative to a first vertebra;
locating a third hook relative to a part of the spine;
locating a fourth hook relative to a part of the spine;
selecting anther connector to be a flexible rod;
locating said another connector between the third hook and the fourth hook;
adjusting the third hook, the fourth hook and the another connector to fit relative to a first vertebra of the spine; and
locking the connector to the third hook and the fourth hook in order to lock the implant in the spine relative to the second vertebra; and
connecting a rigid vertical connector between the connector and the another connector so that any spinal load that the implant carries causes a deflection of one or both of the connector and the another connector.
10. A method of implanting an implant in the spine comprising the steps of:
selecting a first hook that conforms to the outer lateral side of a facet on a first vertebra and locating the first hook adjacent to the lateral side of the facet;
selecting a second hook that conforms to the outer lateral side of an opposite facet on the same first vertebra and locating the second hook adjacent to the lateral side of the opposite facet;
place a horizontal rod through the first hook and through the second hook so that the horizontal rod is about parallel to the first vertebra;
adjusting the position of the first hook relative to the facet;
adjusting the position of the second hook relative to the opposite facet; and
securing the first hook to the rod and securing the second hook to the rod in order to secure the implant to the spine.
11. The method of
12. The method of
13. The method of
14. The method of
15. The method of
16. A method to implant an implant in a spine comprising the steps of:
placing a first anchor in a first vertebra on one side of a spinous process;
placing a second anchor in the first vertebra on the opposite side of a spinous process;
in any order connecting a flexible horizontal rod to the first anchor and to the second anchor and positioning the flexible horizontal rod to be about parallel to the first vertebra as connected to and between the first and second anchors, wherein said connecting step causes the flexible horizontal rod to be received through a first head of the first anchor and causes the flexible horizontal rod to be received through a second head the second anchor;
locking the first anchor to the flexible horizontal rod and locking the second anchor to the flexible horizontal rod in order to secure the implant in the spine and to allow the horizontal rod to absorb and deflect with respect to motion of the spine.
17. The method of
18. The method of
19. The method of
placing a third anchor in a second vertebra on one side of another spinous process;
placing a fourth anchor in the second vertebra on the opposite side of the another spinous process;
in any order connecting another flexible horizontal rod to the third anchor and to the fourth anchor and positioning the another flexible horizontal rod to be about parallel to the second vertebra as connected to and between the third and fourth anchors, wherein said connecting step causes the another flexible horizontal rod to be received through a third head of the third anchor and causes the flexible horizontal rod to be received through a fourth head the fourth anchor;
locking the third anchor to the another flexible horizontal rod and locking the fourth anchor to the another flexible horizontal rod in order to secure the implant in the spine; and
in any order securing a rigid vertical rod to the flexible horizontal rod and the another flexible horizontal rod to allow the horizontal rods to absorb and deflect with respect to motion of the spine.
This application claims benefit to U.S. Provisional Application No. 60/801,871, filed Jun. 14, 2006, entitled “Implant Positioned Between the Lamina to Treat Degenerative Disorders of the Spine,” which is incorporated herein by reference and in its entirety.
This application relates to, and incorporates herein by reference, each of the following in its entirety: U.S. patent application Ser. No. 11/761,006, filed Jun. 11, 2007, entitled “Implant System and Method to Treat Degenerative Disorders of the Spine,” (Attorney Docket No.: SPART-01018US1); and
U.S. patent application Ser. No. 11/761,100, filed Jun. 11, 2007, entitled “Implant System and Method to Treat Degenerative Disorders of the Spine,” (Attorney Docket No.: SPART-01018US2).
The most dynamic segment of orthopedic and neurosurgical medical practice over the past decade has been spinal devices designed to fuse the spine to treat a broad range of degenerative spinal disorders. Back pain is a significant clinical problem and the annual costs to treat it, both surgically and medically, is estimated to be over $2 billion. Motion preserving devices to treat back and extremity pain have, however, created a treatment alternative to fusion for degenerative disc-disease. These devices offer the possibility of eliminating the long term clinical consequences of fusing the spine that is associated with accelerated degenerative changes at adjacent disc levels.
While total disc replacement is seen as a major advance over fusion, the procedure to implant the devices in the lumbar spine requires a major operation via an anterior approach, subjecting patients to the risk of significant complications. These include dislodgement of the device, which may damage the great vessels, and significant scarring as a consequence of the surgical procedure itself, which makes revision surgery difficult and potentially dangerous. Thus, there are advantages to spinal implants that can be inserted from a posterior approach, a technique with which spine surgeons are much more experienced. The posterior surgical approach also has the benefit of being able to directly address all pathologies that may be impinging the neural elements, which is not possible from an anterior approach. Motion preserving spinal devices that can be implanted with a minimally invasive, posterior procedure offer the benefit of less surgical trauma and faster patient recovery and also offer cost savings to payers with patients staying fewer days in the hospital.
Motion preserving devices placed posteriorly typically either rely on the spinous processes to support the implant or require pedicle screws to be inserted. However, spinous processes are not load bearing structures and are not rigid. In a population of patients with back pain, the laminae offer a much stronger structure to position an implant, since they consist of significantly stronger bone, and the laminae are also closer to the spine's axis of rotation. Pedicle screws have several disadvantages when used as attachments for motion preservation devices. The procedure to implant them is considered major surgery requiring a wide exposure. The screws are also subject to significant loads and screw loosening is a known consequence over time in these cases. Removing the screws and fusing the spine requires major revision surgery.
In one embodiment of the present invention, an implant is provided that can be placed between the lamina through a posterior, minimally invasive surgical technique and is designed to treat degenerative disorders of the spine. Degenerative disc disease results from the natural process of aging and ultimately affects all structures of the vertebral motion segment. The degenerative process causes loads that are normally borne by the intervertebral disc to be transferred to the articular facet joints, ligaments and other soft tissues of the spine.
The benefits of this implant are: The articular facets provide an excellent structure to which to attach an implant. They consist of very strong cortical bone, the strongest in the lumbar vertebra. There are no major nerves or vessels in the area approximate to the lateral aspect of facets, making them also a very safe point of attachment.
Attached to hooks, a crosslink can be positioned as far anterior as is possible without actually impinging on the spinal canal.
The implant can be inserted through two small incisions on either side of the mid-line, preserving the spinal ligament structures, including the supraspinous ligament and the interspinous ligament and permitting the implant to placed using a minimally invasive procedure.
An embodiment of the clamp implant system 20 of the invention is depicted in
Generally, the clamping implant system 20 (
The opposing clamps 30, 32, and opposing clamps 34, 36 as can be seen in
As can be seen in
The horizontal rods 24, 26 can have variable lengths and diameters in order accommodate the shape of the spine. Preferably, the diameters of the horizontal rods 24, 26 can be selected to adjust the dynamic stabilization, motion preservation feature afforded by these embodiments. Larger diameter, generally, will provide for a stiffer system while smaller diameters will provide for a less stiff system. For the same diameter, rods made of PEEK will provide for a stiffer system than rods made of a super elastic material. Also rods made of stainless steel will be stiffer than rods made of titanium. PEEK rods will be less stiff than rods made of titanium or stainless steel. Accordingly, the rods can be selected to give the degree of flex desired, and, thus, the degree of dynamic stabilization desired in response to dynamic loads placed on the system 20 by the spine in motion. It is to be understood that the horizontal rods can also be bent or bowed out in order to accommodate the anatomical structures of the spine.
The vertical connector system 28 in
In various embodiments, the implant (i) engages the laminae to stabilize the spine in a dynamic manner, and (ii) can be made stiff enough to rigidly stabilize the spine as an aid to a fusion.
In one embodiment, the first and second hooks have radii to provide conformance with the spine. As discussed below, the first and second hooks 102 and 104 can be symmetrical in a sagittal orientation and free to rotate around a coronal axis. The first and second hooks 102 and 104, can provide an ability to adjust to, and be affixed to, the articular facets. In one embodiment, the first and second hooks 102 and 104 include at least one member to engage with the articular facet. This member can be a fin, stud, spike, and the like, as discussed above with respect to other embodiments.
Further as seen in
As illustrated in
As depicted in
In the embodiment of
In one embodiment, the horizontal rod 106 has a flat surface that conforms to a laminar anatomy or a contoured surface to match the laminar anatomy.
In another embodiment of the present invention, the implant 100 includes an artificial ligament attached to the horizontal rod 106. The artificial ligament can be looped around the superior spinous process and then re-attached to the horizontal rod 106. The artificial ligament provides a limit to flexion and increases rigidity of the implant. The artificial ligament can be made of a biocompatible material.
In another embodiment of the present invention, an implant assembly is provided that has first and second implants 100. The first and second implants 100 can be coupled by at least one vertically running rod configured to provide rigid stability as an aid in fusing the spine.
It is to be understood that the various features, designs and functions of the various embodiments can be selected for and or combined in other embodiments as is advantageous.
With respect to the method of implantation (
Materials for use with the implant include the following:
As indicated above, the implant can be made of titanium, stainless steel, super elastic materials and/or polymers such as PEEK.
In addition to Nitinol or nickel-titanium (NiTi) other super elastic materials include copper-zinc-aluminum and copper-aluminum-nickel. However for biocompatibility the nickel-titanium is the preferred material.
Other suitable material include, by way of example, only polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), and polyetheretherketoneketone (PEEKK). Still, more specifically, the material can be PEEK 450G, which is an unfilled PEEK approved for medical implantation available from Victrex of Lancashire, Great Britain. (Victrex is located at www.matweb.com or see Boedeker www.boedeker.com). Other sources of this material include Gharda located in Panoli, India (www.ghardapolymers.com).
Preferably, the horizontal rods are made of PEEK or a similar polymer or a super elastic material, which materials are flexible, or the rods are made of another flexible material, and the anchors and the vertical systems are made of titanium or stainless steel which are stiff or made of another stiff material.
Further, it should be apparent to those skilled in the art that various changes in form and details of the invention as shown and described may be made. It is intended that such changes be included within the spirit and scope of the claims appended hereto. The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.