Patent Application
20090264939
The present invention relates to a method and system for performing a spinal nuclectomy to create a nuclear cavity in an annulus located in an intervertebral disc space, and to prepare 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 posterio-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.
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, such as for example U.S. Pat. No. 5,425,772 (Brantigan) and U.S. Pat. No. 4,834,757 (Brantigan).
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); U.S. Pat. No. 5,888,220 (Felt et al.); U.S. Pat. No. 7,001,431 (Bao et al.); and U.S. Pat. No. 7,077,865 (Bao et al.), the disclosures of which are incorporated herein by reference. 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” the disclosures of which are incorporated herein by reference.
The methods of these references include, for example, the steps of inserting a 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 mold material expands with a flowable biomaterial that is adapted to cure in situ and provide a permanent disc replacement.
Nucleus replacement requires a simple and reliable method of removing the anatomical nucleus. Care must be taken to avoid damage to the annulus and the bony end plates of the adjacent vertebrae. The nuclear cavity is preferably symmetrical and centered along the axis of the spine. For many patients,
The present invention relates to a method and apparatus for performing a spinal nuclectomy to remove at least a portion of a nucleus from an a disc space to create a nuclear cavity in an intervertebral disc space, and to prepare the nuclear cavity to receive an intervertebral prosthesis. Various guide systems are disclosed to direct and limit the motion of the surgical tools in the instrument set during the procedure. The guide systems can provide visual, tactile and/or auditory signals to assist the surgeon.
The guide system can be part of a surgical tool or a separate structure. The guide system can optionally be attached to the surgical table, a catheter holder used to implant a spinal prosthesis, to the patient, or a variety of other structures in the operating room.
In one embodiment, the nuclectomy method includes removing at least a portion of a nucleus from an annulus to create a nuclear cavity in an intervertebral disc space and preparing the nuclear cavity to receive an intervertebral prosthesis. A plurality of regions in at least a portion of the nucleus and a sequence for removing the regions is identified. At least one annulotomy is formed in the annulus along an annular axis to provide access to the nucleus. A guide system is positioned relative to the annulotomy. The guide system is configured to limit motion of at least one surgical tool relative to the guide system. A portion of the nucleus is removed from a first region using the surgical tool. At least one of the guide system and the surgical tool are configured to remove a portion of the nucleus from a second region. A portion of the nucleus is removed from a second region using the surgical tool.
The guide system can be positioned inside or outside the intervertebral disc. The same or different surgical tools can be used to remove the nucleus from the first and second regions. The guide system can limit movement of the surgical tool relative to the guide system to one or two degrees of freedom.
In one embodiment, the geometry of the intervertebral disc space is evaluated prior to surgery using imaging techniques, such as for example, an x-ray, MRI, CAT-scan, or ultrasound. By knowing the geometry of the nucleus and/or the annulus, and the trajectory of the surgical approach into the nucleus, the present guide system and the surgical tools can be configured to perform each step of the nuclectomy procedure.
The present instrument set is preferably configured and sequenced before the surgery based on the geometry of the intervertebral disc space of the particular patient. Alternatively, the surgeon has the option to make adjustments to the guide system and/or instrument set during the procedure.
In one embodiment, a standard instrument set and guide system configuration and sequence is prepared for a particular entry path into the nucleus. The surgeon has the option to make adjustments during the procedure. The method and apparatus disclosed herein can be used for a single annulotomy procedures or multi-annulotomy procedures.
The surgeon preferably performs the nuclectomy using the pre-configured and pre-sequenced guide system and instrument set. The systematic approach to nuclectomy disclosed herein increases the likelihood that all of the targeted nucleus material will be removed, the nuclear cavity will be centered within the disc space, and/or the nuclear cavity will be symmetrical relative to the midline of the spine.
The step of evaluating the geometry of the nuclear cavity also provides an indication of the total volume. 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 can be used to estimate the quantity of nucleus material removed at any point in the nuclectomy procedure, as well as the position and shape of the nuclectomy cavity. Evaluating the quantity of nucleus material removed, as well as the position and shape of the resultant cavity, can be a primary or secondary method of determining whether the nuclectomy is completed.
In one embodiment, the method includes forming first and second annulotomies in the annulus. A portion of the nucleus is removed through the first annulotomy using at least a first surgical tool and a portion of the nucleus is removed through the second annulotomy using at least a second surgical tool.
As used herein the following words and terms shall have the meanings ascribed below:
“biomaterial” will generally refer to a material that is capable of being introduced to the site of a joint and cured to provide desired physical-chemical properties in vivo. In one embodiment the term will refer to a material that is capable of being introduced to a site within the body using minimally invasive mechanism, and cured or otherwise modified in order to cause it to be retained in a desired position and configuration. Generally such biomaterials are flowable in their uncured form, meaning they are of sufficient viscosity to allow their delivery through a delivery tube of on the order of about 1 mm to about 10 mm inner diameter, and preferably of about 2 mm to about 5 mm inner diameter. Such biomaterials are also curable, meaning that they can be cured or otherwise modified, in situ, at the tissue site, in order to undergo a phase or chemical change sufficient to retain a desired position and configuration;
“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 biomaterial 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 biomaterial, having the potential to be cured in vivo (as by catalysis or the application of a suitable energy source), as well as to the biomaterial in the process of curing. As further described herein, in selected embodiments the cure of a biomaterial can generally be considered to include three stages, including (a) the onset of gelation, (b) a period in which gelation occurs and the biomaterial becomes sufficiently tack-free to permit shaping, and (c) complete cure to the point where the biomaterial 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 annular wall (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.
“mold” will generally refer to the portion or portions of an apparatus of the invention used to receive, constrain, shape and/or retain a flowable biomaterial in the course of delivering and curing the biomaterial in situ. A mold may include or rely upon natural tissues (such as the annular shell of an intervertebral disc) for at least a portion of its structure, conformation or function. The mold, in turn, is responsible, at least in part, for determining the position and final dimensions of the cured prosthetic implant. 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, filled with biomaterial, prevent moisture contact, and optionally, then remain in place as or at the interface between cured biomaterial and natural tissue. In one embodiment the mold material can itself become integral to the body of the cured biomaterial. The mold can be elastic or inelastic, permanent or bio-reabsorbable, porous or non-porous.
The present nuclectomy method is the preferred precursor procedure to implanting certain intervertebral prostheses.
The surgeon selects the entry path 22-38 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, guide systems are positioned along two or more of the access paths 22 through 38 to facilitate preparation of the intervertebral disc 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, imaging of the annulus and/or the nuclear cavity, and positioning of a multi-lumen mold in the nuclear cavity. The multi-portal approach is particularly suited for use with the multi-lumen molds disclosed in U.S. Pat. Publication No. 2006/0253198, entitled Multi-Lumen Mold For Intervertebral Prosthesis And Method Of Using Same, previously incorporated by reference. Guide systems according to various embodiments are suitable for accessing the annulus from any of the available access directions, including posterior, posterior lateral, lateral, anterior, or anterolateral.
In the illustrated embodiment, the mounting fixture 54 is attached to a secondary holding device (not shown) that is preferably attached, directly or indirectly through additional components, to some fixed structure, such as an operating table. In another embodiment, the secondary holding device can include a handle that is gripped by a member of the operating staff to hold the guide system 50 in the desired location. In yet another alternate embodiment, the secondary holding device is attached, directly or indirectly through additional components, to the patient, such as for example, using a retractor, Steinmann pins, a harness fitted to the patient, or a variety of other devices. As used herein, “secondary holding device” refers to a mechanism that can be, directly or indirectly through additional components, releasably attached to the patient, releasably attached to an external structure, gripped by the surgical staff, or any combination thereof.
In the illustrated embodiment, guide 52 is hollow to provide access to the intervertebral disc space 70. In alternate embodiments, the guide 52 can be a rail, a shaft, or a variety of other structures. During the procedure, an annulotomy 73 is made in the annulus 74 to provide access to the nucleus 76.
Distal end 72 of the guide 52 preferably contacts annulus 74. In the illustrated embodiment, the distal end 72 extends into the annulotomy 73. It is also possible for the distal end 72 to contact the nucleus 76.
The guide 52 is attached to mounting fixture 54 by slide mechanism 56. Slide mechanism 56 includes an elongated portion 58 that slides in a channel 60 in the mounting fixture 54. Adjustable stop 62 is provided on distal end 64 of the elongated member 58 to limit the range of motion of the guide 52 around the Y axis (pitch). Set screw 66 is provided to secure the guide 52 at a particular position along the length of the elongated member 58. The slide mechanism 56 permits the pitch of the guide 52 to be controlled before and/or during the surgical procedure. An alternate structure is disclosed in U.S. Patent Publication No. 2006/0265076 entitled Catheter Holder for Spinal Implant, which is hereby incorporated by reference.
The guide 52 can also be used as an access port for performing other steps in the procedure. For example, the proximal end 72 can be used for evaluating the nuclectomy or the annulus 74; imaging the nucleus 76; implanting the mold 13; delivering the biomaterial; and/or cutting the catheter 11 as close to the neck of the mold 13 as possible. Disclosure related to evaluating the nuclectomy or the annulus is found in U.S. Pat. Publication No. 2005/0209602, entitled “Multi-Stage Biomaterial Injection System for Spinal Implants, which is incorporated by reference.
In the illustrated embodiment, proximal end 80 of the guide 52 includes adaptor 82. The adaptor 82 includes a slot 84 adapted to engage with a stop on a surgical tool (see e.g.,
In another embodiment, slot 90 is provided in the guide 52 near the distal end 72. In this embodiment, a feature on the surgical tools can be constrained by engagement with the slot 90, as will be discussed in detail below.
In one embodiment, the geometry of the intervertebral space 70 is evaluated prior to the surgical procedure using imaging techniques. The imaging techniques preferably identify the height 100, depth 102, and width 104 of the nucleus 76. By knowing the geometry of the nucleus 76 and the trajectory through the annulus 74, it is possible to configure the guide system 50 and surgical tools for each step of the nuclectomy procedure. In the embodiment illustrated in
In one embodiment, the set screw 128 acts as a stop that engages with slot 84 on the adaptor 82 illustrated in
In an alternate embodiment, the set screw 128 is temporarily removed and the guide system 122 is slid further along the length of the shaft 126. The set screw 128 is then engaged with the guide system 122 so that it is positioned in the slot 90 on the guide 52 illustrated in
Alternatively, protrusion 122 is optionally a spring-loaded detent, that can be depressed into the cylindrical member 130 to allow it to enter the guide 52. Once the protrusion 122 reaches the slot 90, the spring forces the protrusion 122 up, which limits motion of the rongeur 120 within the slot 90.
In one embodiment, distal end 156 is coupled to proximal end 80 of the guide 52 illustrated in
In one embodiment, guide system 150 includes sensors 170, 172 at the distal and proximal ends of the slot 154. When the stop 158 engages one of the sensors 170, 172 a signal is sent via cable 174 to signal generator 176. The signal generator can provide auditory, visual, and/or tactile signals to the surgeon indicating the maximum and minimum penetration of the surgical tool 160.
The adaptor 180 includes a slot 184 that directs the surgical tool down the X axis to a particular depth 186. Once the depth 186 has been reached, the angled portion 192 permits an angular offset 188 of the surgical tool. Sensor 190 is optionally located at the distal end of the angular offset 188. By selecting the appropriate surgical tool, the adaptor 180 directs the surgeon to a particular location in the nucleus 76. The adaptor 180 can be indexed around the X axis to remove remote portions of the nucleus 76.
In embodiments where the guide system 250 includes an opening 256 with a cross-sectional area greater than a cross-sectional area of the curved rongeur 252, one or more limits 270A-270D (referred to collectively as “270”), such as for example set screws, protrusions, pins, and the like, are optionally provided to limit movement of the curved rongeur 252 to a particular path or range of motion. For example, the set screws 270A and 270B in
In one embodiment, distal end 258 of the guide system 250 can be coupled to proximal end 80 of the guide 52 illustrated in
Surgical tool 310 is a curved rongeur in the illustrated embodiment. Shaft 312 of the curved rongeur 310 includes front ridge 314 and rear ridge 316. In the configuration illustrated in
As illustrated in
By changing the length of the front ridge 314, the guide system can be configured to restrict motion to the X axis until the target depth is reached. Once the target depth is reached, the surgical tool 310 can be rotated in the Y direction and/or Z direction. In one embodiment, the amount of articulation is controlled by the configuration of the interface 308. In an alternate embodiment, the amount of articulation is controlled by the height of the front ridge 314. For example, a sloped or angled front ridge 314 would permit progressively more or less pitch and/or yaw movement of the surgical tool 310 relative to the fixed portion 302. The guide system 300 can optionally be configured to limit motion around the X axis.
The present method and apparatus are directed to an improved nuclectomy 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.
The TNR is the preferred precursor procedure for deploying a nucleus replacement prosthesis, such as for example an inflatable or expandable prosthesis, a fixed geometry prosthesis, delivering a curable biomaterial directly into the nuclear cavity, a self-expanding prosthesis, and the like. The present TNR methodology permits the nucleus replacement prosthesis to be accurately and symmetrically positioned within an intervertebral disc space.
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. Various sequences for performing a nuclectomy are disclosed in U.S. Pat. Publication No. 2006/0253199 entitled Nuclectomy Method and Apparatus, which is hereby incorporated by reference.
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, reconfiguring the guide system permits a single surgical tool to 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.
In the step illustrated in
Commercially available straight rongeurs suitable for use in the present system are available from KMedic° under the product designation Intervertebral Disc Rongeurs KM 47-760 and KM 47-780. Commercially available up-biting rongeurs are available from KMedic® under the product designation KM 55-842. Commercially available Modified Wilde-style rongeurs are available from KMedic® under the product designation KM 47-707, KM 47-708, and KM 47-709. Commercially available curved rongeurs are available from Life Instruments under the product name Ferris Smith Pituitary/Foraminotomy Design. Alternatively, any instrument used for nucleus removal can be adapted for use with this system. These instruments include, but are not limited to, flexible ablation devices (Arthrocare's Coblation® technology featured in their SpineWand® instrument), radiofrequency (Ellman International) articulating shavers (Endius MDS Flex Tip® shaver, Clarus Medical Nucleotome®) or rongeurs (Richard Wolf grasping forceps), steerable lasers, water based systems (Hydrocision SpineJet Hydrosurgery System), heat or vaporization based systems.
The guide system 410 preferably extends into the nucleus 76. In the illustrated embodiment, the guide system 410 includes one or more shaped guide wires 412A, 412B, 412C, 412D (collectively “412”) each preferably with a stop 414. The guide wires 412 are shaped to direct surgical tool 416 to each of the regions 1, 2, 3 within the nucleus 76. More than one guide wire 412 may be required to remove the nucleus material 76 from a single region, such as the guide wires 412C, 412D in region 3. Alternatively, a single guide wire 412 can be repositioned to each of the regions 1, 2, 3 within the nucleus 76.
The guide wires 412 can be rigid or flexible, depending on the application. The guide wires 412 can be used alone or in combination with another guide system, such as the guide system 50 in
In the illustrated embodiment, the surgical tool 416 slides on a guide wire 412 and has a cutter 418 that cuts a path through the nucleus 76 established by the guide wire 412. The stop 414 limits the travel of the cutter 418. The cutter 418 optionally includes a heated cutting edge. Once the surgical tool 416 reaches the stop 414, the guide wire 412 is repositioned and another section of nucleus material 76 is removed from the annulus 74.
In one embodiment, the surgeon performs both sequences so as to maximize removal of nuclear material 76. In another embodiment, the surgeon starts by removing the nucleus material 76 from regions adjacent to the annulotomy 400, and then completes the procedure through the annulotomy 402. Alternatively, the surgeon may switching back and forth between annulotomies 400, 402 until the nucleus is adequately removed. The annulotomies 400, 402 need not have the same number regions, and the number of regions given the approach would depend on the surgeon preference, patient pathology, disc removal from a previous entrance, disc removal instruments, or the type of instrument to be used in the various regions.
Template 458 with a shape corresponding generally to the nucleus 76 is coupled to the surgical tool 454 by stylus 460. Movement of the surgical tool 454 within the nucleus 76 is limited by engagement of stylus 458 with template 456. In the illustrated embodiment, the template 458 identifies a plurality of regions 1A, 2A, 3A, 4A, that correspond generally to regions 1, 2, 3, 4 in the nucleus 76. The tool guide 452 is preferably repositioned before performing the nuclectomy in each of the regions 1, 2, 3, 4. The same or a different surgical tool 454 may be used for each of the regions 1, 2, 3, 4. The method and apparatus of
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. It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the various guide systems disclosed herein can be combined with any of the adaptors and surgical tools. The surgeon may use a variety of secondary holding devices during a single nuclectomy procedure. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
| Number | Date | Country | |
|---|---|---|---|
| 20090088848 A1 | Apr 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60636777 | Dec 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11304053 | Dec 2005 | US |
| Child | 11862633 | US |
