Patent Application
20090222096
Within the spine, the intervertebral disc functions to stabilize and distribute forces between vertebral bodies. The intervertebral disc comprises a nucleus pulposus which is surrounded and confined by the annulus fibrosus. Intervertebral discs are prone to injury and degeneration. For example, herniated discs typically occur when normal wear, or exceptional strain, causes a disc to rupture. Degenerative disc disease typically results from the normal aging process, in which the tissue gradually loses its natural water and elasticity, causing the degenerated disc to shrink and possibly rupture.
Intervertebral disc injuries and degeneration are frequently treated by replacing or augmenting the existing disc material. Current methods and instrumentation used for treating the disc require a relatively large hole to be cut in the disc annulus to allow introduction of the implant. After the implantation, the large hole in the annulus must be plugged, sewn closed, or other wise blocked to avoid allowing the implant to be expelled from the disc. Besides weakening the annular tissue, creation of the large opening and the subsequent repair adds surgical time and cost. A need exists for devices, instrumentation, and methods for implanting an intervertebral implant using minimally invasive surgical techniques.
In one embodiment, a method of augmenting the nucleus pulposus of an intervertebral disc comprises forming a passage through an annulus fibrosus surrounding the nucleus pulposus and inserting a space creating device comprising a plurality of chambers. Without removing a portion of the nucleus pulposus, plurality of chambers are filled to expand the space creating device to create a space within the nucleus pulposus. The method further comprises injecting at least one biocompatible material into the space within the nucleus pulposus.
In another embodiment, a device for supplementing a nucleus pulposus comprises an expandable central body comprising a cylindrical portion bounded by a pair of curved surfaces and adapted to receive a first biocompatible material. At least one of the pair of curved surfaces is adapted to penetrate a vertebral endplate adjacent the nucleus pulposus. The device also comprises an expandable ring member surrounding the cylindrical portion and adapted to receive a second biocompatible material.
In another embodiment, a system for treating a nucleus pulposus of an intervertebral disc comprises a cannula adapted to access an annulus fibrosus of the intervertebral disc and a multi-chamber spacing device comprising at least three inflatable chambers. Each of the inflatable chambers is connected to at least one other of the inflatable chambers and the spacing device is collapsible for passage through the cannula. The system further comprises a catheter connected to the spacing device and extendable through the cannula.
A system for treating a nucleus pulposus of an intervertebral disc comprises a cannula adapted to access an annulus fibrosus of the intervertebral disc and a multi-chamber spacing device comprising two connected and inflatable chambers One of the inflatable chambers is expandable along the annulus fibrosus. The system further comprises a catheter connected to the spacing device and extendable through the cannula.
Additional embodiments are included in the attached drawings and the description provided below.
The present disclosure relates generally to methods and devices for augmenting an intervertebral disc, and more particularly, to methods and devices for minimally invasive nucleus augmentation procedures. For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments, or examples, 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. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.
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In this embodiment, the nucleus is accessed using a posterolateral approach. In alternative embodiments, the annulus may be accessed with a lateral approach, an anterior approach, a trans-pedicular/vertebral endplate approach or any other suitable nucleus accessing approach. Although a unilateral approach is described, a multi-lateral approach may be suitable. For example, a suitable bilateral approach to nucleus augmentation may involve a combination approach including an annulus access opening and an endplate access opening.
It is understood that any cannulated instrument including a guide needle or a trocar sleeve may be used to guide the accessing instrument.
In this embodiment, the natural nucleus, or what remains of it after natural disease or degeneration, may remain intact with no tissue removed. In alternative embodiments, partial or complete nucleotomy procedures may be performed.
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The balloon can be of various shapes including conical, spherical, square, long conical, long spherical, long square, tapered, stepped, dog bone, offset, or combinations thereof. Balloons can be made of various polymeric materials such as polyethylene terephthalates, polyolefins, polyurethanes, nylon, polyvinyl chloride, silicone, polyetheretherketone, polylactide, polyglycolide, poly(lactide-co-glycoli-de), poly(dioxanone), poly(.epsilon.-caprolactone), poly(hydroxylbutyrate), poly(hydroxylvalerate), tyrosine-based polycarbonate, polypropylene fumarate or combinations thereof. Additionally, the expandable device may be molded or woven.
In alternative embodiments, the space creating device may have multiple catheter portions with each separately feeding a different compartment of the spacing portion.
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As the spacing portion 40 is gradually filled and inflated, the surrounding nucleus tissue may become displaced or stretched, creating a space 52. The inflation may also cause the intradiscal pressure to increase. Both the pressure increase and the direct expansion of the spacing portion 40 may cause the endplates 16, 18 to distract.
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Examples of biocompatible materials 48 which may be used for disc augmentation include natural or synthetic and resorbable or non-resorbable materials. Natural materials include various forms of collagen that are derived from collagen-rich or connective tissues such as an intervertebral disc, fascia, ligament, tendon, skin, or demineralized bone matrix. Material sources include autograft, allograft, xenograft, or human-recombinant origin materials. Natural materials also include various forms of polysaccharides that are derived from animals or vegetation such as hyaluronic acid, chitosan, cellulose, or agar. Other natural materials include other proteins such as fibrin, albumin, silk, elastin and keratin. Synthetic materials include various implantable polymers or hydrogels such as silicone, polyurethane, silicone-polyurethane copolymers, polyolefin, polyester, polyacrylamide, polyacrylic acid, polyvinyl alcohol, polyethylene oxide, polyethylene glycol, polylactide, polyglycolide, poly(lactide-co-glycolide), poly(dioxanone), poly(.epsilon.-caprolactone), poly(hydroxylbutyrate), poly(hydroxylvalerate), tyrosine-based polycarbonate, polypropylene fumarate or combinations thereof. Suitable hydrogels may include poly(vinyl alcohol), poly(acrylic acids), poly(methacrylic acids), copolymers of acrylic acid and methacrylic acid, poly(acrylonitrile-acrylic acid), polyacrylamides, poly(N-vinyl-2-pyrrolidone), polyethylene glycol, polyethyleneoxide, polyacrylates, poly(2-hydroxy ethyl methacrylate), copolymers of acrylates with N-vinyl pyrrolidone, N-vinyl lactams, polyurethanes, polyphosphazenes, poly(oxyethylene)-poly(oxypropylene) block polymers, poly(oxyethylene)-poly(oxypropylene) block polymers of ethylene diamine, poly(vinyl acetate), and sulfonated polymers, polysaccharides, proteins, and combinations thereof.
The selected biocompatible material may be curable or polymerizable in situ. The biocompatible material may transition from a flowable to a non-flowable state shortly after injection. One way to achieve this transition is by adding a crosslinking agent to the biomaterial before, during, or after injection. The biocompatible material in its final state may be load-bearing, partially load-bearing, or simply tissue augmenting with minimal or no load-bearing properties.
Proteoglycans may also be included in the injectable biocompatible material 48 to attract and/or bind water to keep the nucleus 24 hydrated. Regnerating agents may also be incorporated into the biocompatible material. An exemplary regenerating agent includes a growth factor. The growth factor can be generally suited to promote the formation of tissues, especially of the type(s) naturally occurring as components of an intervertebral disc. For example, the growth factor can promote the growth or viability of tissue or cell types occurring in the nucleus pulposus, such as nucleus pulposus cells and chondrocytes, as well as space filling cells, such as fibroblasts and connective tissue cells, such as ligament and tendon cells. Alternatively or in addition, the growth factor can promote the growth or viability of tissue types occurring in the annulus fibrosus, as well as space filling cells, such as fibroblasts and connective tissue cells, such as ligament and tendon cells. An exemplary growth factor can include transforming growth factor-β (TGF-β) or a member of the TGF-β superfamily, fibroblast growth factor (FGF) or a member of the FGF family, platelet derived growth factor (PDGF) or a member of the PDGF family, a member of the hedgehog family of proteins, interleukin, insulin-like growth factor (IGF) or a member of the IGF family, colony stimulating factor (CSF) or a member of the CSF family, growth differentiation factor (GDF), cartilage derived growth factor (CDGF), cartilage derived morphogenic proteins (CDMP), bone morphogenetic protein (BMP), or any combination thereof. In particular, an exemplary growth factor includes transforming growth factor β protein, bone morphogenetic protein, fibroblast growth factor, platelet-derived growth factor, insulin-like growth factor, or any combination thereof.
Therapeutic or biological agents may also be incorporated into the biomaterial. An exemplary therapeutic or biological agent can include a soluble tumor necrosis factor α-receptor, a pegylated soluble tumor necrosis factor α-receptor, a monoclonal antibody, a polyclonal antibody, an antibody fragment, a COX-2 inhibitor, a metalloprotease inhibitor, a glutamate antagonist, a glial cell derived neurotrophic factor, a B2 receptor antagonist, a substance P receptor (NK1) antagonist, a downstream regulatory element antagonistic modulator (DREAM), iNOS, a inhibitor of tetrodotoxin (TTX)-resistant Na+-channel receptor subtypes PN3 and SNS2, an inhibitor of interleukin, a TNF binding protein, a dominant-negative TNF variant, Nanobodies™, a kinase inhibitor, or any combination thereof. These regenerating, therapeutic, or biological agents may promote healing, repair, regeneration and/or restoration of the disc, and/or facilitate proper disc function.
In an alternative embodiment, the material delivery device 46 may contain an inflation medium instead of a biocompatible material. The inflation medium may be pressurized and injected through the catheter portion 38 of the space creating device 36 to pressurize and inflate the compartments 42, 44 of the spacing portion 40. The inflation of the spacing portion 40 may be controlled by the control mechanism 49. The inflation medium may be injected under pressure supplied by a hand, electric, or other type of powered pressurization device. The internal balloon pressure may be monitored with the pressure gauge 50. The pressure gauge 50 or a pressure limiter may be used to avoid over inflation or excessive injection. The rate of inflation and level of inflation of the spacing portion 40 can be varied between patients depending on disc condition. The inflation medium may be a saline and/or radiographic contrast medium such as sodium diatrizoate solution sold under the trademark Hypaque by Amersham Health, a division of GE Healthcare (Amersham, UK).
As the spacing portion 40 is gradually inflated, the surrounding nucleus tissue may become displaced or stretched, creating a space within the nucleus pulposus 24. The inflation may also cause the intradiscal pressure to increase. Both the pressure increase and the direct expansion of the spacing portion 40 may cause the endplates 16, 18 to distract.
In this alternative embodiment, the space creating portion 40 may be deflated and removed and the biocompatible material 48 injected into the space formed within the nucleus pulposus 24 and vacated by the space creating portion 40. The material 48 may be injected after the space creating portion 40 has been deflated and removed or may be injected while the space creating portion 40 is being deflated and removed. For example, the biomaterial 48 may become increasingly pressurized while the pressure in the space creating portion 40 is lowered. In some procedures, the material 48 may be injected before the space creating portion 40 is removed. With the material 48 injected and the space creating portion 40 removed, the cannula 30 may be removed and the minimally invasive surgical incision closed.
Any of the steps of the above described methods including expansion of the space creating portion 40 and filling the space created by the space creating portion 40 may be monitored and guided with the aid of imaging methods such as fluoroscopy, x-ray, computed tomography, magnetic resonance imaging, and/or image guided surgical technology such as a Stealth Station surgical navigation system (Medtronic, Inc., Minneapolis, Minn.) or a BrainLab system (Heimstetten, Germany).
In another alternative embodiment, the space creating portion may be inflated with an inflation medium and the inflation medium replaced with a biocompatible material. The space creating portion filled with biocompatible material may be detached from the catheter portion and may remain in the nucleus 24 as an implant.
Alternative space creating portions and space creating methods are described in the currently pending applications “Devices, Apparatus, and Methods for Improved Disc Augmentation” (Attorney Docket No. 31132.512) and “Devices, Apparatus, and Methods for Bilateral Approach to Disc Augmentation” (Attorney Docket No. 31132.513), both filed Apr. 27, 2006 and incorporated herein by reference.
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As used in this description, the term “filled” should be broadly construed describe those chambers that are not only completely filled, but also partially filled. It is understood that some chambers of a filled multi-chamber space creating device may be unfilled or partially filled.
Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this disclosure. Accordingly, all such modifications and alternative are intended to be included within the scope of the invention as defined in the following claims. Those skilled in the art should also realize that such modifications and equivalent constructions or methods do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. It is understood that all spatial references, such as “horizontal,” “vertical,” “top,” “upper,” “lower,” “bottom,” “left,” “right,” “anterior,” “posterior,” “superior,” “inferior,” “upper,” and “lower” are for illustrative purposes only and can be varied within the scope of the disclosure. In the claims, means-plus-function clauses are intended to cover the elements described herein as performing the recited function and not only structural equivalents, but also equivalent elements.
