System and methods for inserting a vertebral spacer
The present invention provides vertebral spacers having a lower surface and an upper surface, an anterior face and a posterior face extending from the lower surface, and at least one guiding groove for engaging an insertion tool. A system for delivering a vertebral spacer to the spinal column of a patient, includes an insertion tool, an optional guiding tool, a pusher, a vertebral spacer, and a cutting tool. The insertion tool accepts any of a pusher, a vertebral spacer, or a cutting tool and has at least one spacer guide for engaging with a guiding groove of a vertebral spacer. The vertebral spacer is inserted into a patient by inserting the insertion tool into an intervertebral space, engaging the guiding groove of a vertebral spacer with a space guide of the insertion tool, advancing a pusher into the insertion tool, thereby pushing the vertebral spacer into the intervertebral space and thereafter removing the pusher and the insertion tool. The cutting tool is optionally used to chisel at least one vertebral space receiving slot in the vertebrae. A hardening biocompatible composition also maybe delivered, to bond the vertebral spacer to an adjacent vertebra or be an osteogenic composition to promote bone growth.
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The present application claims the benefit of the provisional U.S. Application Ser. No. 60/231,142 filed Sep. 8, 2000, which is incorporated herein by reference in its entirety.
FIELD OF INVENTIONThe present invention generally relates to a vertebral spacer to be inserted into an intervertebral space, thereby supporting the spinal column of a patient. The present invention further relates to a system and methods for implanting the vertebral spacer into the spinal column and securing the spacer therein.
BACKGROUND OF THE INVENTIONThe spinal column, which is the central support to the vertebrate skeleton and a protective enclosure for the spinal cord, is a linear series of vertebral bones. Intervertebral discs separate and reduce friction between adjacent vertebrae and absorb compression forces applied to the spinal column. Spinal nerves that extend from each side of the spinal cord exit the column at intervertebral forama.
A typical vertebra comprises an anterior body, and a posterior arch that surrounds the spinal cord lying within the vertebral foramen formed by the arch. The muscles that flex the spine are attached to three processes extending from the posterior arch. On the upper surface of each vertebra in a standing human, are two superior articulated processes that oppose two inferior articulated processes extending from the lower surface of an adjacent vertebra. Facets on the opposing processes determine the range and direction of movement between adjacent vertebrae, hence the flexibility of the spinal column.
The intervertebral discs include the fibrillar cartilage of the anulus fibrosus, a fibrous ring, the center of which is filled with an elastic fibrogelatinous pulp that acts as a shock absorber. The outer third of the anulus fibrosus is innervated. The entire spinal column is united and strengthened by encapsulating ligaments.
Back pain is one of the most significant problems facing the workforce in the United States today. It is a leading cause of sickness-related absenteeism and is the main cause of disability for people aged between 19 and 45. Published reports suggest that the economic cost is significant, treatment alone exceeding $80 billion annually. Although acute back pain is common and typically treated with analgesics, chronic pain may demand surgery for effective treatment.
Back pain can occur from pinching or irritation of spinal nerves, compression of the spine, vertebral shifting relative to the spinal cord axis, and bone spur formation. The most common cause of disabling back pain, however, stems from trauma to a intervertebral disc, resulting from mechanical shock, stress, tumors or degenerative disease, which may impair functioning of the disc and limit spinal mobility. In many cases, the disc is permanently damaged and the preferred treatment becomes partial or total excision.
Another cause of back injury is herniation of the intervertebral disc, wherein the gelatinous fluid of the nucleus pulposus enters the vertebral canal and pressures the spinal cord. Again, surgery is often the only method available for permanent relief from pain or the neurological damage ensuing from the pressure of fluid on the spinal cord, and requires replacement of the damaged disc.
Traumatic injury to an intervertebral disc that is not removed will frequently promote scar tissue formation. Scar tissue is weaker than original healthy tissue so that the disc will progressively degenerate, lose water content, stiffen and become less effective as a shock absorber. Eventually, the disc may deform, herniate, or collapse, limiting flexibility of the spinal column at that position. The only option is for the intervertebral disc to be partially or totally removed.
When the disc is partially or completely removed, it is necessary to replace the excised material to prevent direct contact between hard bony surfaces of adjacent vertebrae. One vertebral spacer that may be inserted between adjacent vertebrae, according to U.S. Pat. No. 5,989,291 to Ralph et al., includes two opposing plates separated by a belleville washer or a modified belleville washer. The washer functions to provide a restorative force to mimic the natural functions of the disc of providing a shock absorber and mobility between adjacent vertebrae. However, mechanical devices intended to replicate intervertebral disc function have had only limited success. An alternative approach is a “cage” that maintains the space usually occupied by the disc to prevent the vertebrae from collapsing and impinging the nerve roots.
Spinal fusion may be used to restrict motion occurring between two vertebrae due to spinal segmental instability. Fusing the vertebrae together, however, reduces the mechanical back pain by preventing the now immobile vertebrae from impinging on the spinal nerve.
The disadvantage of such spacers is that stability is created at the expense of spinal flexibility.
Surgical procedures for replacing intervertebral disc material, rather than the fusing of the vertebrae, have included anterior approaches and posterior approaches to the spinal column. The posterior approach (from the back of the patient) encounters the spinous process, superior articular process, and the inferior articular process that must be removed before insertion of the disc replacement material into the intervertebral space. Excessive removal of the bony process triggers further degradation and impediment of the normal movement of the spine. The anterior approach to the spinal column is complicated by the internal organs that must be bypassed or circumvented to access the vertebrae.
Many intervertebral spacers require preparation of the surfaces of the adjacent vertebrae to accommodate the spacer, causing significant tissue and bone trauma. For example, chiseling or drilling of the vertebral surface may be required to prepare a receiving slot. They may also require screwing the spacer into the intervertebral space, making installation difficult and increasing trauma to the vertebral tissue. Many spacers include complex geometries and are costly to manufacture. Examples of such geometrically complex spacers are described in U.S. Pat. No. 5,609,636 to Kohrs et al., U.S. Pat. No. 5,780,919 to Zdeblick et al., U.S. Pat. No. 5,865,848 to Baker and U.S. Pat. No. 5,776,196 to Matsuzaki et al. Many of these complex spacers may require screwing the spacer into the intervertebral space, thereby making installation difficult and traumatic to the vertebral tissue.
SUMMARY OF THE INVENTIONThere is a need for a vertebral spacer having a simple geometry that is easily insertable into an intervertebral space while causing minimal trauma to the surface of the vertebrae as well as the bony processes thereof. The present invention provides a vertebral spacer having a simple geometry for supporting adjacent vertebrae after excision, at least partially or wholly, of an intervertebral disc. The spacer includes a body having a lower surface and an upper surface. The lower surface will be supported by a lower vertebra; the upper surface supports the adjacent upper vertebra. The body of the vertebral spacer of the present invention, therefore, provides support between the two adjacent vertebrae and to the spinal column.
The body of the vertebral spacer of the present invention additionally has an anterior face and a posterior face extending from the lower surface. The height of the anterior face of the body may be less than, or greater than, the height of the posterior face to maintain the curvature of the spine when the vertebral spacer is inserted between two vertebrae. The body of the vertebral spacer also includes at least one guiding groove suitable for engaging with an insertion tool for delivering the vertebral spacer to an intervertebral space.
The present invention further provides a system for delivering a vertebral spacer to the spinal column of a patient, comprising an insertion tool with a channel; (b) an optional guiding tool for directing the insertion tool to a selected point of insertion of a vertebral spacer; (c) a pusher; (d) a vertebral spacer slideably disposed in the channel of the insertion tool; and (e) a cutting tool. The cutting tool can be slid into the channel of the insertion tool providing that the pusher and the vertebral spacer are not therein.
The channel of the insertion tool is configured to slideably accept any of a vertebral spacer, a pusher, a vertebral spacer , or a cutting tool. The insertion tool further comprises a spacer guide or a plurality of spacer guides for engagement with a first guiding groove or a second guiding groove of a vertebral spacer.
In one embodiment of the insertion tool the spacer guide is a flange extending from the channel. In another embodiment, the spacer guide is two opposing flanges configured to slideably engage with a first guiding groove and a second guiding groove, respectively.
In another embodiment of the insertion tool, the spacer guide is at least one rib longitudinally placed on the inner surface of the channel of the insertion tool.
Other embodiments of the insertion tool of the present invention include spacer guides that may be, but are not limited to, a segmented longitudinal rib, or a linear series of protrusions, also on the inner surface of the channel.
The present invention further provides a method for delivering a vertebral spacer to a patient, comprising the steps of inserting the insertion tool into an intervertebral space of the spinal column of a patient, engaging at least one guiding groove of a vertebral spacer with a space guide of the insertion tool, sliding a pusher into the channel of the insertion tool, advancing the pusher and thereby pushing the vertebral spacer into the intervertebral space and removing the pusher and the insertion tool from the patient.
The method of the present invention may further comprise the optional step of inserting a guiding tool into an intervertebral space for directing the insertion tool into the intervertebral space. The insertion tool may be slid along the guide tool to a selected position suitable for insertion of a vertebral spacer in the intervertebral space. The guide tool is then extracted from the insertion tool leaving the insertion tool inserted between adjacent vertebrae.
The cutting tool is optionally slid along the channel of the insertion tool to engage a vertebra and generally is used to chisel at least one vertebral space receiving slot in the vertebrae. The cutting tool is removed from the patient by sliding the cutting tool back through the channel of the insertion tool. A vertebral spacer may then be slideably engaged with the insertion tool, with a space guide on the insertion tool engaging with a guiding groove of the vertebral spacer. The pusher may be engaged and advanced along the channel, thereby delivering the vertebral spacer into the vertebral spacer receiving slot (or receiving slots) in the adjacent vertebrae. It is also contemplated that a vertebral spacer receiving slot may not be cut in the adjacent vertebrae and that the inserted vertebral spacer optionally may contact only the uncut surface of the vertebrae.
One embodiment of the method of the present invention comprises the additional step of delivering a hardening biocompatible composition to the vertebral spacer. The hardening biocompatible composition may be used, for example, to bond the vertebral spacer to an adjacent vertebra or be an osteogenic composition to promote bone growth from the adjacent vertebrae into the vertebral spacer. The hardening biocompatible composition can be, for example, an organic polymer, a mineral composition such as a hydroxyapatite-based composition, methyl methacrylate, or the like, or a combination thereof. A hydroxyapatite-based composition is especially useful in the context of the present invention for promoting osteocyte growth and bone deposition.
Various objects, features, and advantages of the invention will become more apparent upon review of the detailed description set forth below when taken in conjunction with the accompanying drawing figures, which are briefly described as follows.
BRIEF DESCRIPTION OF THE FIGURES
A full and enabling disclosure of the present invention, including the best mode known to the inventor of carrying out the invention, is set forth more particularly in the remainder of the specification, including reference to the accompanying drawings, wherein like reference numerals designate corresponding parts throughout several figures. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in the limiting sense.
One aspect of the present invention is a vertebral spacer for insertion between two adjacent vertebrae 20, thereby maintaining the intervertebral space 23 and preventing compression of the spinal cord therein. Various embodiments of the vertebral spacer 10 in accordance with the present invention are shown in
The vertebral spacer 10 of the present invention may have a plurality of surfaces, including a lower surface 15 and an upper surface 16, with the lower surface 15 having an anterior face 13 and a posterior face 14 extending therefrom, as shown in
It is contemplated that the vertebral spacer 10 of the present invention may be of any biocompatible or physiologically inert material or combination of such materials having the mechanical strength capable of maintaining the intervertebral space 23 (
It is further contemplated that the vertebral spacer 10 of the present invention may comprise a bone core 12 such as a femur and a sheath 35 as shown in
In one embodiment, the sheath 35 is metallic, such as a tungsten sheath. In another embodiment the sheath comprises a biocompatible polymer. In one embodiment, shown in
The vertebral spacer 10 of the present invention may have any conformation that will allow the spacer 10 to be positioned in an intervertebral space 23 between adjacent vertebrae 20 and which will maintain an intervertebral space 23 and the natural curvature of a spinal column when in the desired position. Referring to
As shown in
When the vertebral spacer 10 comprises a section of a femur and wherein the femur medullary cavity 19 connects the anterior face 13 and the posterior face 14 of the vertebral spacer 10, as shown in
The direction of insertion of the vertebral spacer 10 by the methods of the present invention can be selected by the surgeon according to the needs of the patient. The anterior face 13 of the vertebral spacer 10, for example, may be positioned relative to the spine to maintain a desired curvature thereof, as shown in
In another embodiment of the vertebral spacer 10 of the present invention, at least one slot 11 may be formed in the upper surface 16 and extend towards, but not connecting with, the opposing lower surface 15, as shown in
In still another embodiment of the vertebral spacer 10 of the present invention, the at least one slot 11 has a bone core 12 disposed therein, as shown in
In another embodiment of the vertebral spacer 10 of the present invention, shown in
Referring now to
Referring now to
Another aspect of the present invention is a system for delivering a vertebral spacer 10 to the spinal column of a patient, generally illustrated in
The channel 61 of the insertion tool 60 of the system of the present invention generally is configured to slideably accept any of the various vertebral spacers 10, according to the present invention, a pusher 63 and/or a cutting tool 70. The insertion tool 60 further comprises at least one spacer guide 66 for slideably engaging with a first guiding groove 17 or a second guiding groove 18 of a vertebral spacer 10.
Referring now to
In still another embodiment of the insertion tool 60 of the present invention as shown in
In other embodiments of the insertion tool 60 of the present invention, the spacer guide 66 may be formed by at least one segmented longitudinal rib disposed on the inner surface 62 of the channel 61, as shown in
As shown in
The present invention also provides an optional guide tool 80 that can be slideably disposed in the channel 61 of the insertion tool 60. The elongated optional guide tool can be inserted into an intervertebral space 23 as indicated in
As shown in
In one embodiment of the pusher of the present invention as illustrated in
As illustrated in
The cutting head 71 of the cutting tool 70 may be an integral configuration of the distal end 74 of the shaft 72, or connected to the distal end 74 of the shaft 72. In one embodiment of the cutting tool 70 of the present invention, the cutting head 71 is connected to the shaft by an attachment member 76 which may be, for example, a threaded attachment member 76, as shown in
Another aspect of the present invention is a method for delivering a vertebral spacer 10 to a patient using the system of the present invention comprising the insertion tool 60, an optional guide tool 80, the vertebral spacer 10, the pusher 63 and the cutting tool 70. Such a method is generally illustrated in
The insertion tool 60 further optionally may be directed into the selected position within the intervertebral space 23 by the guide tool 80 that may be inserted by the surgeon into the intervertebral space 23. The method of the present invention, therefore, further comprises the optional step of inserting a guiding tool 80 into an intervertebral space 23.
The insertion tool 60 may then be slid along the guide tool 80 until the insertion tool 60 is at the selected position for insertion of a vertebral spacer 10 in the intervertebral space 23. The guide tool 80 is then removed from the channel 61 of the insertion tool 60, as shown in
As shown in
As shown in
It is to be understood that the methods of the present invention for the delivery of a vertebral spacer 10 to an intervertebral space 23 may also be used to deliver two vertebral spacers 10, as shown in
Yet another aspect of the present invention is a kit for delivering a vertebral spacer to the spinal column of a patient, comprising an insertion tool for delivering a vertebral spacer to the spinal column of a patient and having a channel having an inner surface, a pusher having a distal end is slideably disposable in the channel of the insertion tool, a vertebral spacer slideably disposable in the channel of the insertion tool, a cutting tool having a shaft with a distal end and a proximal end, and a cutting head secured to the distal end of the shaft, wherein the cutting tool is slideably disposable in the insertion tool providing that the pusher and the vertebral spacer are not disposed therein. Instructions for the use of the system and its various components to deliver a vertebral spacer to the spinal column of a patient also generally are included or provided.
The kit of the present invention further can include an optional guiding tool configured to slideably engage the channel of the insertion device, and instructions for the operation thereof.
With respect to the above description, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly, and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawing and described in the specification are intended to be encompassed by the present invention. Further, the various components of the embodiments of the invention may be interchanged to produce further embodiments and these further embodiments are intended to be encompassed by the present invention.
Although the invention has been described in detail for the purpose of illustration, it is understood that such detail is solely for that purpose, and variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention which is defined by the following claims.
Claims
1. A vertebral spacer comprising:
- (a) a body having an upper surface and a lower surface, an anterior face and a posterior face, the anterior face and the posterior face extending from the lower surface to the upper surface; and
- (b) a first guiding groove in one of the upper surface and the lower surface.
2.-38. (Canceled)
Type: Application
Filed: Aug 20, 2004
Publication Date: Mar 31, 2005
Applicant:
Inventors: Nabil Muhanna (Gainesville, GA), David Schalliol (Oakwood, GA)
Application Number: 10/923,499