Patent Application
20090112221
The present invention relates to systems and methods for evaluating and assessing an internal shape of a body cavity, and for preparing the body cavity to receive a prosthetic device. More particularly, the present invention relates to a method for evaluating a nuclear cavity in an annulus located in an intervertebral disc space and for preparing the nuclear cavity to receive an intervertebral prosthesis.
The intervertebral discs, which are located between adjacent vertebrae in the spine, provide structural support for the spine as well as the distribution of forces exerted on the spinal column. An intervertebral disc consists of three major components: cartilage endplates, nucleus pulpous, and annulus fibrosus. The central portion, the nucleus pulpous or nucleus, is relatively soft and gelatinous; being composed of about 70 to 90% water. The nucleus pulpous has a high proteoglycan content and contains a significant amount of Type II collagen and chondrocytes. Surrounding the nucleus is the annulus fibrosus, which has a more rigid consistency and contains an organized fibrous network of approximately 40% Type I collagen, 60% Type II collagen, and fibroblasts. The annular portion serves to provide peripheral mechanical support to the disc, afford torsional resistance, and contain the softer nucleus while resisting its hydrostatic pressure.
Intervertebral discs, however, are susceptible to a number of injuries. Disc herniation occurs when the nucleus begins to extrude through an opening in the annulus, often to the extent that the herniated material impinges on nerve roots in the spine or spinal cord. The posterior and postero lateral portions of the annulus are most susceptible to attenuation or herniation, and therefore, are more vulnerable to hydrostatic pressures exerted by vertical compressive forces on the intervertebral disc. Various injuries and deterioration of the intervertebral disc and annulus fibrosus are discussed by Osti et al., Annular Tears and Disc Degeneration in the Lumbar Spine, J. Bone and Joint Surgery, 74-B(5), (1982) pp. 678-682; Osti et al., Annulus Tears and Intervertebral Disc Degeneration, Spine, 15(8), (1990) pp. 762-767; Kamblin et al., Development of Degenerative Spondylosis of the Lumbar Spine after Partial Discectomy, Spine, 20(5), (1995) pp. 599-607.
Many treatments for intervertebral disc injury have involved the use of nuclear prostheses or disc spacers. A variety of prosthetic nuclear implants are known in the art. For example, U.S. Pat. No. 5,047,055 (Bao et al.) teaches a swellable hydrogel prosthetic nucleus. Other devices known in the art, such as intervertebral spacers, use wedges between vertebrae to reduce the pressure exerted on the disc by the spine. Intervertebral disc implants for spinal fusion are known in the art as well, such as disclosed in U.S. Pat. No. 5,425,772 (Brantigan) and U.S. Pat. No. 4,834,757 (Brantigan).
Further approaches are directed toward fusion of the adjacent vertebrate, e.g., using a cage in the manner provided by Sulzer. Sulzer's BAK® Interbody Fusion System involves the use of hollow, threaded cylinders that are implanted between two or more vertebrae. The implants are packed with bone graft to facilitate the growth of vertebral bone. Fusion is achieved when adjoining vertebrae grow together through and around the implants, resulting in stabilization.
Apparatuses and/or methods intended for use in disc repair have also been described but none appear to have been further developed, and certainly not to the point of commercialization. See, for instance, French Patent Appl. No. FR 2 639 823 (Garcia) and U.S. Pat. No. 6,187,048 (Milner et al.).
Prosthetic implants formed of biomaterials that can be delivered and cured in situ, using minimally invasive techniques to form a prosthetic nucleus within an intervertebral disc have been described in U.S. Pat. No. 5,556,429 (Felt) and U.S. Pat. No. 5,888,220 (Felt et al.), and U.S. Patent Publication No. US 2003/0195628 (Felt et al.), the disclosures of which are incorporated herein by reference. The disclosed method includes, for instance, the steps of inserting a collapsed mold apparatus (which in a preferred embodiment is described as a “mold”) through an opening within the annulus, and filling the mold to the point that the evaluation material expands with a flowable biomaterial that is adapted to cure in situ and provide a permanent disc replacement. Related methods are disclosed in U.S. Pat. No. 6,224,630 (Bao et al.), entitled “Implantable Tissue Repair Device” and U.S. Pat. No. 6,079,868 (Rydell), entitled “Static Mixer.”
A nuclectomy is a surgical procedure during which at least a portion of a nucleus material is removed from a disc to create a nuclear cavity in an intervertebral disc space. A nuclectomy is typically performed to prepare a nuclear cavity to receive an intervertebral prosthesis. One embodiment of the present invention relates to a method and system of evaluating the geometry of the nuclear cavity within the annulus. A three-dimensional mold of the nuclear cavity is created in situ. The three-dimensional mold is preferably removed from the nuclear cavity. The three-dimensional mold can be used for qualitative and quantitative analysis of the nuclear cavity. According to various embodiments of the present invention, the three-dimensional mold can be used to evaluate the size and shape of the cavity.
The method includes forming at least one annulotomy in the annulus to provide access to a nucleus. In an embodiment where primary and secondary annulotomies are formed, a separate removal sequence is preferably identified for each of the annulotomies. Nucleus material is removed using one or more surgical tools. Various sequences for removing the nuclear material are disclosed in U.S. Patent Publication No. 2006/0135959, entitled Nuclectomy Method and Apparatus, the complete disclosure of which is incorporated by reference.
In one embodiment, a three-dimensional mold system is used to form a mold in situ in the nuclear cavity. The three-dimensional mold is then preferably removed from the nuclear cavity and evaluated by the surgeon. The three-dimensional mold permits the surgeon to evaluate the internal geometric features of the nuclear cavity and/or to estimate the quantity of nucleus material removed as well as the geometry of the nuclear cavity. For example, the evaluation mold can be used to determine whether all of the targeted nucleus material has been removed, whether the nuclear cavity is centered within the annulus, and/or whether the nuclear cavity is symmetrical relative to the midline of the spine. One or more of the removing steps are optionally repeated as necessary until an adequate amount of the nucleus is removed from the annulus. Other determinations regarding the internal features of the nuclear cavity can also be made. For example, determination regarding the presence of bone spurs or other patient specific bone/endplate anatomy can be made.
The present three-dimensional mold system can be use with or without a balloon. In one embodiment, the evaluation balloon is positioned in the nuclear cavity and a fluid is delivered to the evaluation balloon so that the balloon substantially fills the nuclear cavity. A method and apparatus for using the evaluation balloon is disclosed in U.S. Patent Publication No. 2005/0209601, entitled Multi-Stage Biomaterial Injection System For Spinal Implants, the disclosure of which is incorporated by reference.
In one embodiment, a three-dimensional mold system includes a catheter having at least one lumen and a balloon which serves as a mold form. The catheter is used to position the balloon within the nuclear cavity. A flowable, evaluation material is delivered through the catheter to the balloon. The balloon expands within the nuclear cavity and conforms to the internal geometry of the nuclear cavity. The evaluation material is then cured to form a three-dimensional mold of the nuclear cavity. The cured evaluation material is sufficiently deformable and resilient such that the three-dimensional mold can be removed from the nuclear cavity via the annulotomy through which it was inserted. In another embodiment, the flowable, evaluation material is injected directly into the nuclear cavity.
In one embodiment, the evaluation material is a low density polymer foam that is cured in situ. The cured foam is sufficiently deformable such that it permits removal of the three-dimensional mold from the nuclear cavity via the annulotomy. Upon removal, the mold is sufficiently resilient such that it returns to its cured shape.
In one embodiment, the evaluation material is a two-part reactive system that, upon mixing, cures in situ within the nuclear cavity to form the solid, three-dimensional mold. The two-part reactive system can be mixed outside or within the nuclear cavity. In one embodiment, the two-part reactive system reacts to form a foam material. In another embodiment, the two-part reactive system reacts to form a solid polymer. In yet another embodiment, the two part reactive system reacts to form a gel. In each embodiment, the solid, three-dimensional mold is sufficiently deformable that it permits removal of the three-dimensional mold from the nuclear cavity via the annulotomy. Upon removal, the mold is sufficiently resilient such that it returns to its cured shape.
According to another embodiment of the present invention, a three-dimensional mold system includes a catheter having at least one lumen and a compliant balloon that is adapted to remember an expanded configuration as defined by the inner constraints of the nuclear cavity. The compliant balloon includes a shape memory material. The shape memory properties of the balloon material are activated by the application of an external or internal stimulus to “set” the balloon material in its expanded shape. The balloon is deflated and removed from the nuclear cavity. Upon re-inflation of the balloon, the balloon returns to its “set” expanded shape as defined by the inner constraints of the nuclear cavity.
According to another embodiment of the present invention, a three-dimensional mold system includes a multi-lumen catheter and a secondary balloon disposed within a primary balloon. Each of the balloons are in fluid connection with a catheter lumen. In one embodiment, the primary balloon is made from a biocompatible material that has a high compliance allowing the primary balloon to stretch without breaking. The secondary balloon includes a shape memory material, such as for example Nitinol, another shape memory alloy, or a curable polymer material, embedded within the balloon wall. The secondary balloon is inflated within the primary balloon until both balloons substantially fill the nuclear cavity such that they conform to the features of the internal geometry of nuclear cavity. An activating mechanism is then inserted into the secondary balloon in order to activate the shape memory properties of the shape memory material embedded within the balloon walls and set the expanded shape of the secondary balloon. In another embodiment, the activating system is pre-positioned between the primary and secondary balloons.
A vacuum is optionally applied to the primary balloon to force the secondary balloon to collapse in order to permit removal of the balloons from the nuclear cavity. Upon removal, the secondary balloon is then allowed to return to its set shape as defined by the inner constraints of the nuclear cavity. According to one embodiment, the secondary balloon automatically expands to its “set” expanded shape. According to another embodiment, the secondary balloon is re-inflated until it reaches a predetermined pressure at which the secondary balloon provides a representative three-dimensional model of the nuclear cavity. The compliance of the primary balloon permits the expansion of the secondary balloon.
According to yet another embodiment of the present invention, a three-dimensional mold system includes a multi-lumen catheter and a secondary balloon disposed within a primary balloon. A shape memory mesh framework is disposed between the outer circumference of the secondary balloon and the inner circumference of the primary balloon. The secondary balloon is inflated within the primary balloon forcing the primary balloon and the shape memory mesh to conform to the internal geometry of the nuclear cavity. The shape memory properties of the shape memory mesh are then activated to set the shape of the three-dimensional mold. The inflation medium is then evacuated from the balloons. A vacuum can be applied to assist in the deflation of the balloons. The collapse of the primary balloon forces the collapse of the shape memory mesh and permits the removal of the balloons from the nuclear cavity via the annulotomy.
Upon removal, the shape memory material allows the three-dimensional mold to return to its set shape as defined by the inner constraints of the nuclear cavity. According to one embodiment, the shape memory mesh automatically expands to its “set” expanded shape. According to another embodiment, the secondary balloon is re-inflated until it reaches a predetermined pressure or temperature at which the shape memory mesh assumes its set expanded shape and provides a representative three-dimensional model of the nuclear cavity. The elasticity of the primary balloon permits the re-expansion of the shape memory mesh.
The present method is the preferred precursor procedure to implanting certain intervertebral prosthesis. In one embodiment, the intervertebral prosthesis is a mold fluidly coupled to a delivery cannula. A flowable biomaterial is delivered through a cannula into the mold located in the annulus. The delivered biomaterial is allowed to cure a sufficient amount to permit the cannula to be removed. Various implant procedures, implant molds, surgical procedures, and biomaterials related to intervertebral disc replacement suitable for use with the present invention are disclosed in U.S. Pat. No. 5,556,429 (Felt); U.S. Pat. No. 6,306,177 (Felt et al.); U.S. Pat. No. 6,248,131 (Felt et al.); U.S. Pat. No. 5,795,353 (Felt); U.S. Pat. No. 6,079,868 (Rydell); U.S. Pat. No. 6,443,988 (Felt et al.); U.S. Pat. No. 6,140,452 (Felt et al.); U.S. Pat. No. 5,888,220 (Felt et al.); U.S. Pat. No. 6,224,630 (Bao et al.), U.S. Pat. No. 7,001,431 (Felt et al.); U.S. Pat. No. 7,077,865 (Felt et al.); and U.S. Patent Publication No. 2006/0253198, entitled Multi-Lumen Mold for Intervertebral Prosthesis and Method of Using Same filed Nov. 8, 2005; 2006/0253199, entitled Lordosis Creating Nucleus Replacement Method and Apparatus filed Nov. 8, 2005 ; 2006/0265076, entitled Catheter Holder for Spinal Implant filed Nov. 8, 2005; and U.S. Ser. No. 11/420,055 entitled Mold Assembly for Intervertebral Prosthesis filed May 24, 2006, all of which are hereby incorporated by reference.
As used herein the following words and terms shall have the meanings ascribed below:
“cure” and inflections thereof, will generally refer to any chemical transformation (e.g., reacting or cross-linking), physical transformation (e.g., hardening or setting), and/or mechanical transformation (e.g., drying or evaporating) that allows the evaluation material to change or progress from a first physical state or form (generally liquid or flowable) that allows it to be delivered to the site, into a more permanent second physical state or form (generally solid) for final use in vivo. When used with regard to the method of the invention, for instance, “curable” can refer to uncured evaluation material, having the potential to be cured in vivo (as by catalysis or the application of a suitable energy source), as well as to the evaluation material in the process of curing. As further described herein, in selected embodiments the cure of a evaluation material can generally be considered to include three stages, including (a) the onset of gelation, (b) a period in which gelation occurs and the evaluation material becomes sufficiently tack-free to permit shaping, and (c) complete cure to the point where the evaluation material has been finally shaped for its intended use.
“minimally invasive mechanism” refers to a surgical mechanism, such as microsurgical, percutaneous, or endoscopic or arthroscopic surgical mechanism, that can be accomplished with minimal disruption to the entry site of the body cavity (e.g., incisions of less than about 4 cm and preferably less than about 2 cm). In some embodiments, minimally invasive mechanisms also refers to minimal disruption of the pertinent musculature, for instance, without the need for open access to the tissue injury site or through minimal skin incisions. Such surgical mechanism are typically accomplished by the use of visualization such as fiberoptic or microscopic visualization, and provide a post-operative recovery time that is substantially less than the recovery time that accompanies the corresponding open surgical approach.
“body cavity” refers to an internal three-dimensional space located within a patient's body. The space can be a natural space such as, for example, an internal region of an organ or vessel, or the space can be created via a surgical procedure, such as for example a nuclear cavity. Additionally, the space can be a natural space created through injury or abnormal development of a bodily structure.
“mold” and “balloon” will generally refer to the portion or portions of an apparatus used to receive, constrain, shape and/or retain a flowable evaluation material. A mold may include or rely upon natural tissues (such as the annular shell of an intervertebral disc or the bony shell of a vertebrae) for at least a portion of its structure, conformation or function. The mold may also be responsible to assist in removal of the three-dimensional mold from the body cavity into which it has been inserted. As such, its dimensions and other physical characteristics can be predetermined to provide an optimal combination of such properties as the ability to be delivered to a site using minimally invasive mechanism. The mold can be elastic, inelastic, porous, or non-porous.
“evaluation material” refers to a material or structure that is adapted to set to a shape generally corresponding to at least a portion of a body cavity, but be sufficiently deformable to be removed through a point of entry without damaging the entry site Examples of such evaluation materials include low density polymer foam, a balloon containing a low density polymer foam, a shaped memory material structure, a balloon containing shaped memory materials, and a balloon or other similar structure formed from a material adapted to be set by the application of an external stimulus, including heat.
“set” or “setting” refer to fixing or converting a material to substantially retain its shape when the set occurred. Examples of set or setting include curing, cross-linking, and heating.
In one embodiment, the present systems and methods are directed to an improved nucletomy or total nucleus removal (TNR). Total nucleus removal refers to removal of substantially all of the nucleus from an intervertebral disc. In one embodiment, total nucleus removal is preferably removal of at least 70% of the nucleus, and more preferably at least 80% of the nucleus is removed, and most preferably at least 90% of the nucleus is removed from the intervertebral disc. TNR is the preferred precursor procedure for deploying a nucleus replacement prosthesis. The present TNR methodology, using the systems and methods according to the various embodiments of the present invention described herein, permits the nucleus replacement prosthesis to be accurately positioned within the disc space, and optimally symmetric relative to the midline of the spine.
In another embodiment, the systems and methods as described herein may be used for the evaluation of body cavities prepared for interbody fusion. With interbody fusion systems, a body cavity between the vertebrae is created. This involves removal of the nucleus, some of the annulus, and preparation of the vertebral endplates. The latter refers to the process whereby the disc and cartilage endplates are removed, exposing a portion of the endplates. To some degree a bleeding bed of vertebral endplate bone is achieved, which enhances the fusion process (allowing bone to grow from one endplate, through the interbody implant, to the other endplate). Typically during interbody fusion procedures, after removal of the disc and preparation of the endplates, the internal shape and size of the body cavity can be assessed in order to determine which size of implant is needed.
In other embodiments, the systems and methods as described herein may also be applied to kyphoplasty and vertebroplasty procedures. During a kyphoplasty procedure, a body cavity is created within the vertebral body to restore, to some extent, the natural shape of the deformed body. Typically, the vertebral body is compressed in the anterior portion, resulting in a kyphotic wedge shape. The kyphoplasty procedure seeks to distract this compressed region. Access to the vertebral body is typically obtained via a posterior or posterolateral approach, although any approach could be used. A distraction mechanism is then placed into the vertebral body, distraction is applied, and a cavity is then created once the distraction has been completed. The systems and methods as described herein can be applied to assess and evaluate the resultant cavity.
In yet other embodiments, the systems and methods as described herein may also be applied to annular repair and corpectomy procedures. In still other embodiments, the systems and methods as described herein may also be applied to non-spinal surgical procedures including meniscus repair and/or replacement, joint resurfacing, repair and/or replacement, cosmetic surgery, and drug delivery.
Although the nucleus replacement scenario is used to describe the methods and systems of this application, this is not meant to be limiting, but rather illustrative. Other cavities within the body can be assessed using these systems and methods described herein according to the various embodiments.
In one embodiment, the nucleus is divided into a plurality of regions. A preferred sequence for removing the nucleus material from each of the regions is established. The regions are preferably arranged to take into consideration the three-dimensional nature of the nucleus material. At least two different surgical instruments are typically used to remove the nucleus material from at least two of the regions. The surgical instruments are selected for optimum removal of the nucleus material from a given region. In some embodiments, different functions of multi-function surgical tools can be used to remove the nucleus material from two of the regions. In some embodiments, indicia are provided on the surgical tools to measure depth of penetration into the annulus Various sequences and surgical instruments for performing a nuclectomy are disclosed in U.S. Patent Publication No. 2006/0253199, entitled NUCLECTOMY METHOD AND APPARATUS, which is hereby incorporated by reference.
Depending on the disc level being operated on, and the patient anatomy, generally, the aorta and vena cava split at the L4 vertebral body. At L5S1 the approach is typically a midline anterior approach. At L4/5 the approach may be either midline anterior or anterolateral, depending on the patient anatomy and how easy it is to retract the vessels. In some usages, the anterior approach is deemed a midline approach and the anterolateral approach is deemed an angled approach offset from the midline anterior approach.
The present method and apparatus use one or more of the access paths 22 through 38. While certain of the access paths 22 through 38 may be preferred depending on a number of factors, such as the nature of the procedure, any of the access paths can be used with the present invention.
In one embodiment, delivery catheter instruments are positioned along two or more of the access paths 22 through 38 to facilitate preparation of the intervertebral disc space 40. Preparation includes, for example, formation of two or more annulotomies through the annular wall, removal of some or all of the nucleus pulposus to form a nuclear cavity 50, imaging of the annulus and/or the nuclear cavity 50, and positioning of the present three-dimensional mold in the nuclear cavity. In another embodiment, the present three-dimensional mold is positioned in the nuclear cavity 50 without use of delivery catheters.
In one embodiment, an evaluation mold is positioned in the nuclear cavity and a fluid is delivered to the evaluation mold so that the mold substantially fills the nuclear cavity. The evaluation mold is used to estimate the quantity of nucleus material removed as well as the position of the mold within the nuclear cavity. The evaluation mold can also be used to estimate the geometry of the nuclectomy. A method and apparatus for using the evaluation mold is disclosed in U.S. Patent Publication No. 2005/0209601, entitled Multi-Stage Biomaterial Injection System For Spinal Implants, the disclosure of which is incorporated by reference.
Imaging techniques known to those of skill in the art can be used to estimate the volume, three-dimensional geometry, and position of the evaluation mold and/or the three-dimensional mold in the nuclear cavity. Exemplary imaging techniques include arthroscopic and fluoroscopic imaging. The visual estimations of the volume and geometry of the evaluation mold can be compared to the volume and geometry of the three-dimensional mold that is formed in accordance with various embodiments of the present invention. This further aids the surgeon performing the procedure in determining whether additional removal of the nucleus is required. Imaging techniques can be used throughout the entire procedure of forming a three-dimensional mold system. The balloon and or evaluation material can be radiopaque. A radiopaque mold can assist in imaging the mold in the cavity and can eliminate the need for additional imaging equipment.
The balloon 84 is made from a biocompatible material that has a high compliance allowing the balloon 84 to stretch without breaking. More particularly, the compliance of the balloon 84 facilitates conformal expansion of the balloon within the nuclear cavity at inflation pressures ranging from about 20 psi to about 200 psi. Additionally, the balloon 84 should exhibit a high tensile strength and a high tear resistance. The balloon material may or may not adhere to the evaluation material. Exemplary balloon materials include, but are not limited to, the following: silicone elastomers, soft grades of polyurethane, latex rubber, nitrile rubber, polyvinylchloride, and polyethylene terephthalate, and other similar materials exhibiting the desired physical properties. According to a further embodiment, the balloon 84 can include a shape memory material.
Additionally, a lubricant or other surface modifying agent may be applied to the outer surface of the balloon 84 to enhance the lubricity of the balloon. Enhanced lubricity of the balloon outer surface aids in removal of the balloon 84 and/or mold, reducing the risk of damage to the annulus and surrounding tissue. The enhanced lubricity of the balloon 84 may be achieved through chemical modification of the outer surface of the balloon 84. Alternatively, the lubricant may be introduced directly into the nuclear cavity 50 prior to insertion of the balloon 84.
Once removed from the nuclear cavity, the three-dimensional mold 90 can be evaluated quantitatively and qualitatively. For example, the mold 90 can be computer scanned to create a computer model of the mold 90, and hence, a computer image approximating the internal geometry of the nuclear cavity 50.
According to another embodiment, a balloon 84 is not required. The evaluation material may be delivered directly into the nuclear cavity 50 via injection. The evaluation material 80 can then be cured within the nuclear cavity 50 to form a three-dimensional mold. The three-dimensional mold 90 is illustrated in
According to one embodiment of the present invention, the three-dimensional mold 90 should have the ability to reversibly deform. Additionally, the three-dimensional mold 90 should exhibit high compliance, high tear resistance, and low residual deformation. According to a further embodiment of the present invention, the mold 90 should be able to compress to about 10% to about 40% of its fully deployed size and then re-expand about 90% to about 100% of its fully deployed size upon removal from the nuclear cavity.
The three-dimensional mold 90, according to various embodiments of the present invention, may be formed from a wide variety of biocompatible materials, including elastomers, polyurethanes, elastomeric polyolefins and polyolefin blends, silicone rubbers, silicone based polymer systems, gels including hydrogels, or composites thereof. Exemplary elastomers include copolymers of silicone and polyurethane, polyolefins, such as polyisobutylene and polyisoprene, neoprene, nitrile, vulcanized rubber and combinations thereof. Suitable hydrogels include natural hydrogels, and those formed from polyvinyl alcohol, acrylamides such as polyacrylic acid and poly (acrylonitrile-acrylic acid), polyurethanes, polyethylene glycol, poly (N-vinyl-2-pyrrolidone), acrylates such as poly (2-hydroxy ethyl methacrylate) and copolymers of acrylates with N-vinyl pyrrolidone, N-vinyl lactams, acrylamide, polyurethanes and polyacrylonitrile. The hydrogel materials may further be cross-linked to provide further strength to the implant. Other useful gel and gel foamed materials for forming a three-dimensional mold 90 are described in U.S. Pat. Nos. 7,222,380 and 7,226,484, both of which are herein incorporated by reference in their entirety. In certain instances a foaming agent may be added to produce a foam of one or more of the materials provided above.
In a further embodiment, the evaluation material 80 may be a two-part reactive system that upon mixing cures in situ within the nuclear cavity 50 to form the solid, three-dimensional mold 90. The two-part reactive system can be mixed inside or outside the nuclear cavity. Whatever the materials used to form the two-part system, the resultant three-dimensional mold 90 should be sufficiently deformable such that it can be removed from the nuclear cavity 50 through the annulotomy 82 without damaging the annulus 81. When cured, the evaluation material 80 is able to conform to the internal geometry of the nuclear cavity 50 and annulus 81 and retain its adopted shape upon removal.
According to another further embodiment of the present invention, the evaluation material 80 may be a reactive two part system forming a soft resilient foam upon mixing. A first flowable material forming the first part (Part A) of the two part reactive system is delivered through a first catheter lumen and into the balloon 84. The first flowable material fills the balloon 84 such that the balloon 84 substantially fills the nuclear cavity 50. A second flowable material (Part B) is delivered through a second catheter lumen and into the balloon 84. Part A reacts with Part B upon contact to form the three-dimensional mold 90. The three-dimensional mold 90 is constrained by and conforms to the internal geometry of the nuclear cavity 50. In one embodiment, the cured material is sufficiently deformable such that it permits removal of the three-dimensional mold from the nuclear cavity 50 via the annulotomy 82. The foam mold is sufficiently resilient such that it returns to its cured shape outside of the nuclear cavity. In one embodiment, the evaluation material 80 is cured using one or more of heat, ultraviolet radiation, visible light, or radio frequency energy.
According to a further embodiment, the evaluation material may be a reactive two part system forming a highly stretchable polymer upon mixing and curing in situ.
According to another further embodiment, the evaluation material may be a reactive two part system containing a significant amount of an inert solvent (plasticizer) to form a gel.
According to yet another embodiment of the present invention, the evaluation material includes a biocompatible polymer having a thermal transition between about 35° C. and about 75° C. The evaluation material is injectable above the thermal transition temperature. Below the thermal transition temperature the evaluation material is solid, pliable, and is able to retain the shape of the nuclear cavity. According to one embodiment, the evaluation material is heated above the thermal transition temperature and then injected to fill the balloon. Once inside the body the evaluation material cools to body temperature below the thermal transition temperature to form the three-dimensional mold.
Whatever the selected material or materials used to form the mold 90, the mold 90 should exhibit high compliance, a high tensile strength, and a high tear resistance. According to one embodiment, the mold 90 should exhibit a Young's modulus that allows the mold 90 to be deformed up to about 200% to about 500% of its original shape with out tearing or breaking in response to a tensile forces ranging from about 0.1 MPa to about 10 MPa are placed upon it, and then return to its original shape once the force is removed.
The system 60 may be provided with one or more removal mechanisms according to various embodiments of the present invention, as illustrated in
According to one embodiment, shown in
Upon curing, the mold 90 forms around the flexible threaded member 95. To facilitate removal of the mold 90, a torque T is applied to the threaded member 95 by rotating or twisting the threaded member 95 in a clockwise or counter clockwise direction as determined by the inner geometry of the nuclear cavity and/or the surgeon's preference. As shown in
According to another embodiment, as illustrated in
According to yet another embodiment, as shown in
According to one embodiment, as shown in
According to another embodiment, as shown in
According to yet another embodiment as shown in
According to one embodiment, the flexible mesh compression member 116 includes a mesh frame work having at least one tension member 118 accessible to the surgeon. The compression material 116 forming the framework may allow for some seepage of the evaluation material 80 through its pores. The compression member 116 is inserted into the nuclear cavity 50 prior to the delivery of the evaluation material 80. The evaluation material 80 is delivered to the nuclear cavity 50 within the compression member 116 substantially filling the nuclear cavity 50. The evaluation material is then cured such that a mold 90 of the cavity 50 is created.
To remove the mold 90, tension is applied to the tension member 118 by placing a force on the tension member 118 in a proximal direction causing the compression member 116 to compact and compress the mold 90, facilitating its removal from the nuclear cavity 50. As shown in
According to a further embodiment, as shown in
The compression member 124 preferably includes a plurality of apertures 126 through which the evaluation material 80 is delivered. Once the tension member 120 and the compression member 124 are positioned in the nuclear cavity 50, the evaluation material 80 is delivered via the compression member 124. The evaluation material expands the mesh of the tension member 120 to substantially fill the nuclear cavity 50.
The evaluation material 80 is then cured to form the mold 90. To remove the mold 90, force F is applied to the members 122 by the surgeon in a proximal direction 121. Simultaneously, opposing force F1 is applied to the compression member 124 to resist the force F. The combination of forces F and F1 cause the evaluation material 80 to compress, permitting removal from the nuclear cavity 50 through the annulotomy 82. Once the forces F and F1 are released, the mold 90 returns to its adopted shape.
According to a further embodiment, a removal assist device 130, shown in
According to yet another embodiment, the mold 90 also can be removed using one or more surgical instruments adapted for removal and retrieval of the three-dimensional mold. According to various embodiments of the present invention, the mold 90 may be removed using any one of a blunt edge trephine, graspers, hemostat, pliers, hooks, etc.
The catheter 150 can include one or more lumens 160 in fluid connection with the balloon 155. At least one lumen 160 is configured to deliver an inflation medium to the balloon 155. For example, the inflation medium can be a sterile saline solution or a gel. Alternatively, the inflation medium can be carbon dioxide, air or other gas. Contrast media, such as radiopaque dye or another contrast solution, may also be delivered to the balloon 155 such that the filling of the nuclear cavity 50 can be visualized by the surgeon performing the procedure.
The inflation media is preferably delivered through the catheter lumen 160 to the balloon 155 via an injection manifold 165 accessible to the surgeon external of the patient's body. The injection manifold 165 includes one or more appropriate mechanisms 170 (e.g. sealing valves) for maintaining sufficient pressure in the balloon 155 to allow the balloon 155 to fill the nuclear cavity 50 and conform to the internal geometry of the nuclear cavity 50 such that a representative mold of the nuclear cavity 50 can be obtained.
In one embodiment, the catheter 150 is configured to allow for the continuous delivery of inflation medium to the balloon 155 in order to maintain a constant pressure in the balloon 155. The pressure required to inflate the balloon 155 and fill the nuclear cavity 50 such that the balloon 155 conforms to the internal geometry of the nuclear cavity 155 can be referred to as the predetermined pressure. Later, when the balloon 155 is deflated and removed from the nuclear cavity, the balloon 155 can be re-inflated to the predetermined pressure in order to give a representative three-dimensional model of the internal geometry of the nuclear cavity 50. Alternatively, the pressure can be combined with an activating mechanism, such as heated gas, to cause the balloon 155 to fill the nuclear cavity 50, and take a set shape conforming to the internal geometry of the cavity. When the balloon 155 is deflated and removed, it can be re-inflated to the predetermined pressure, or less, as appropriate to give a representative three-dimensional model.
In one embodiment, the balloon 155 includes a shape memory material or a material that takes a set when exposed to an external stimuli. Shape memory materials are materials that have one or more properties that are altered in a controlled fashion by the application of an external stimuli, such as stress, temperature, moisture, pH, electric, or magnetic fields. For example, shape memory polymers are polymer materials which may be returned from a deformed state to their original shape or “permanent configuration” via an external stimulus. The external stimulus is usually temperature, as in the case of thermally activated shape memory polymers, but can also be the application of an electric or magnetic field, light, or a change in pH. Magnetic shape memory alloys are materials that change their shape in response to a significant change in the magnetic field.
According to one embodiment, the balloon 155 includes a shape memory polymer. Upon inflation and expansion of the balloon 155 within the constraint of internal cavity 50, the polymer chains become permanently stretched in areas where substantially all of the nuclear material has been removed and remain un-stretched over areas where removal of the nucleus material is still desirable. The balloon 155 is deflated and withdrawn from the nuclear cavity 50. The balloon 155 can then be re-inflated to the same approximate pressure that was reached during inflation within the nuclear cavity. The stretching of the polymer chains allows the balloon 155 to “remember” its expanded shape within the constrains within the nuclear cavity 50. Exemplary polymers include, but are not limited to, the following: polyurethanes, polyethylene terephthalate, polyvinylchloride, silicone elastomers, and other suitable polymers.
The primary balloon 265 is made from a biocompatible material having a high compliance facilitating the balloon 265 to stretch without breaking. Additionally the balloon 265 should exhibit a high tensile strength and a high tear resistance. Exemplary balloon materials include, but are not limited to, the following: silicone elastomers, soft grades of polyurethane, latex rubber, nitrile rubber, and other similar materials exhibiting the desired properties.
In one embodiment, the secondary balloon 270 includes a shape memory material, such as Nitinol or another shape memory alloy, embedded within the balloon wall. The secondary balloon 270 is inflated within the primary balloon 265 until both balloons substantially fill the nuclear cavity 50 such that they conform to the features of the internal geometry of nuclear cavity 50. An activating mechanism is then inserted into the secondary balloon in order to activate the shape memory properties of the shape memory alloy embedded within the balloon walls. According to one embodiment of the present invention, the temperature of the inflation media (either heat or cold), such as water or contrast solution, is used to activate the shape memory alloy.
Once in the expanded configuration, as defined by the inner constraint of the nuclear cavity 50, of the secondary balloon is set, the inflation medium is evacuated from the balloons. The secondary balloon 270 can be further collapsed by the application of a vacuum to the outer, primary balloon. The force of the primary balloon collapsing about the secondary balloon, causes the collapse of the secondary balloon, such that it can be removed through the annulotomy through which the balloons were inserted. Once outside the constraints of the nuclear cavity 50, the secondary balloon automatically expands to its set shape to give a three-dimensional model or mold of the nuclear cavity. The compliance of the primary balloon 265 permits the expansion of the secondary balloon 270.
Once the expanded configuration of the mesh 280, as defined by the inner constraint of the nuclear cavity 50, is set, the inflation medium is evacuated from the balloons. The mesh framework 280 can be collapsed by the application of a vacuum to the primary balloon 265. The force of the primary balloon 265 collapsing about the mesh framework 280 causes the mesh framework to also collapse such that mesh framework 280 can be removed through the annulotomy through which the balloons were inserted. Once outside the constraints of the nuclear cavity 50, the mesh framework 280 automatically expands to substantially the set shape to give a three-dimensional model or mold of the nuclear cavity 50. The elasticity of the primary balloon 265 permits the expansion of the mesh framework 280. The secondary balloon 270 need not be inflated for the mesh framework 280 to return to its set expanded configuration as defined by the constraints of the nuclear cavity 50. Alternatively, the second balloon 270 can be re-inflated to a predetermined pressure in order for the mesh 280 to return to its set expanded shape as defined by the inner constraints of the nuclear cavity 50.
According to yet another embodiment of the present invention, as shown in
Upon removal from the nuclear cavity 50, the three-dimensional mold 318 is able to return to its cured shape, as shown in
In an alternate embodiment, the gel material 316 is introduced directly into the nuclear cavity 50 without the balloon 320.
An illustration of the surgical use of one embodiment of the nuclectomy procedure including the formation of a three-dimensional mold of the internal geometry of the nuclear cavity is outlined below:
Patents and patent applications disclosed herein, including those cited in the Background of the Invention, are hereby incorporated by reference. Other embodiments of the invention are possible. Although the description above contains many specificities, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of this invention should be determined by the appended claims and their legal equivalents. Therefore, it will be appreciated that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.
The present application claims the benefit of U.S. Provisional Application Ser. No. 60/982,665 entitled SYSTEM AND METHOD FOR MEASURING THE SHAPE OF INTERNAL BODY CAVITIES, filed on Oct. 25, 2007, which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60982665 | Oct 2007 | US |
