US20120289865A1 - Monitoring characteristics of an intervertebral disc and/or prosthesis material - Google Patents

Abstract

A vertebral disc prosthesis, a method of implanting a prosthesis and a deployment device is provided. The prosthesis may be implanted into the interior region of the vertebral disc so as to displace existing vertebral tissue, such as NP. The size or amount of the prosthesis inserted into the interior region of the vertebral disc may be a characteristic of the disc or the prosthesis. For example, the amount or size of prosthesis inserted into the disc may be dependent upon restoring the functionality of the disc (e.g., the ability of the disc to transfer nutrients or otherwise survive, the ability of the disc to carry the required loads and absorb stress or the reduction of pain). The method may include monitoring at least one of: a) one or more characteristics of the vertebral disc, and b) one or more characteristics of the prosthesis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 11/417,757, filed May 3, 2006, which is a continuation of U.S. application Ser. No. 10/431,648, filed May 7, 2003, which claims the benefit of U.S. Provisional Application Ser. Nos. 60/439,261, filed on Jan. 10, 2003, 60/438,022, filed on Jan. 3, 2003, and 60/417,219, filed Oct. 9, 2002, and wherein application Ser. No. 10/431,648 is a continuation-in-part of U.S. application Ser. No. 10/055,504 filed on Oct. 25, 2001, now pending, which is a continuation-in-part of U.S. application Ser. No. 09/696,636 filed on Oct. 25, 2000, now U.S. Pat. No. 6,508,839, which is a continuation-in-part of U.S. application Ser. No. 09/642,450 filed on Aug. 18, 2000, now U.S. Pat. No. 6,482,235, which is a continuation-in-part of U.S. application Ser. No. 09/608,797 filed on Jun. 30, 2000, now U.S. Pat. No. 6,425,919, and wherein application Ser. No. 10/055,504 claims the benefit of U.S. Provisional Application Ser. No. 60/311,586 filed on Aug. 10, 2001; and wherein application Ser. Nos. 09/642,450 and 09/608,797 each claim the benefit of U.S. Provisional Application Ser. Nos. 60/172,996, filed on Dec. 19, 1999; 60/161,085, filed on Oct. 25, 1999; and 60/149,490 filed Aug. 18, 1999, all of which are incorporated by reference herein.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present inventions relate generally to treatment of vertebral discs in the lumbar, cervical, or thoracic spine.
• 2. Description of the Related Art
• The disc performs the role of absorbing mechanical loads while allowing for constrained flexibility of the spine. The vertebral tissue forming the disc includes a soft, central nucleus pulposus (NP) surrounded by a tough, woven annulus fibrosis (AF) and superior and inferior endplates. Herniation is a result of a weakening in the AF. Symptomatic herniations occur when weakness in the AF allows the NP to bulge or leak, for example, toward the spinal cord and major nerve roots. The most common resulting symptoms are pain radiating along a nerve and low back pain, both of which can be crippling for the patient.
• Discectomy has been the most common surgical procedure for treating vertebral disc herniation. This procedure involves removal of disc materials impinging on the nerve roots or spinal cord external to the disc. Depending on the surgeon's preference, varying amounts of NP may also be removed from within the disc space either through the herniation site or through an incision in the AF. This removal of extra NP is commonly done to minimize the risk of recurrent herniation.
SUMMARY OF THE INVENTION
• In one embodiment, a vertebral disc prosthesis is provided. The prosthesis includes a mass of material that is adapted to be inserted into the interior region of the vertebral disc. The mass of material has a compressive strength of less than 4 MN/m².
• In another embodiment, a prosthesis for implantation into an interior region of a vertebral disc is provided. The vertebral disc includes first and second endplates. The prosthesis includes a mass of material that is adapted for insertion into the interior region of the vertebral disc so as to displace existing vertebral tissue. The mass of material is sized so as to be spaced from both the first and second endplates when implanted into the interior region of the vertebral disc such that the mass of material is surrounded with nucleus pulposus within the interior region of the vertebral disc when implanted therein.
• In yet another embodiment, a prosthesis for implantation into an interior region of a vertebral disc is provided. The prosthesis includes an isotropic mass of biocompatible hydrogel having a compressive strength of less than 4 MN/m²and a volume between a range of approximately 0.1 ml and approximately 6.0 ml.
• In another embodiment, a method of implanting a prosthesis material into an interior region of a vertebral disc is disclosed. The method includes locating an access site on the disc; inserting, through an opening of the disc at the access site, the prosthesis material into the interior region of the vertebral disc; and monitoring at least one of: a) one or more characteristics of the vertebral disc, and b) one or more characteristics of the prosthesis material.
• In still another embodiment, a method of restoring function of a vertebral disc is disclosed. The method includes locating an access site on the disc; and inserting, through an opening of the disc at the access site, a prosthesis material into an interior region of the vertebral disc without removing a substantial amount of nucleus pulposus from the interior region so as to augment existing nucleus pulposus.
• In still another embodiment, a method of implanting a prosthesis material into an interior region of a vertebral disc is disclosed. The vertebral disc has first and second endplates. The method includes locating an access site on the disc; inserting, through an opening of the disc at the access site, the prosthesis material into the interior region of the vertebral disc without removing a substantial amount of nucleus pulposus; spacing the prosthesis material from the endplates of the vertebral disc such that the nucleus pulposus substantially surrounds the prosthesis material. The method also includes monitoring at least one of: a) one or more characteristics of the vertebral disc, and b) one or more characteristics of the prosthesis material.
• In yet another embodiment, a method of increasing a height of a vertebral disc is disclosed. The method includes locating an access site on the disc; and inserting, through an opening of the disc at the access site, an amount of prosthesis material into an interior region of the vertebral disc without removing a substantial amount of nucleus pulposus from the interior region so as to augment existing nucleus pulposus. The method also includes monitoring the disc height to determine whether a desired disc height is achieved.
• In another embodiment, a method of increasing a intradiscal pressure of a vertebral disc is disclosed. The method includes locating an access site on the disc; and inserting, through an opening of the disc at the access site, an amount of prosthesis material into an interior region of the vertebral disc without removing a substantial amount of nucleus pulposus from the interior region so as to augment existing nucleus pulposus. The method also includes monitoring the intradiscal pressure to determine whether a desired intradiscal pressure is achieved.
• In still another embodiment, a device for delivering a prosthesis material to an interior region of a vertebral disc is provided. The device includes a body having a proximal end and a distal end and a holder region disposed adjacent the distal end of the body. The holder region being adapted to hold the prosthesis material prior to delivery into the interior region of the vertebral disc. The device further includes a plunger disposed within the body. The plunger and body are adapted to move relative to each other to dispense the prosthesis material. A stop is disposed on the body. The stop is adapted to allow positioning of the body relative to the interior region of the vertebral body such that the prosthesis material can be dispensed within the interior region of the vertebral body at a desired location.
• In another embodiment, a device for delivering a prosthesis material to an interior region of a vertebral disc is disclosed. The device includes a body having a proximal end and a flexible distal end. The body defines a longitudinal axis. The flexible distal end is adapted to articulate relative to the axis. A holder region is disposed adjacent the distal end of the body. The holder region is adapted to hold the prosthesis material prior to delivery into the interior region of the vertebral disc. A plunger is disposed within the body. The plunger and body are adapted to move relative to each other to dispense the prosthesis.
• In another embodiment, a device for delivering a prosthesis material to an interior region of a vertebral disc is disclosed. The device includes a body having a proximal end and a distal end. The body is formed as a hollow sleeve. A holder region is disposed adjacent the distal end of the body. The holder region is adapted to hold the prosthesis material prior to delivery into the interior region of the vertebral disc. A plunger is axially disposed within the sleeve. The sleeve is adapted to be retracted relative to the plunger to dislodge the prosthesis material from the holder region upon retraction of the sleeve.
• In yet another embodiment, a device for delivering a prosthesis material to an interior region of a vertebral disc is disclosed. The device includes a body having a proximal end and a distal end. A holder region is disposed adjacent the distal end. The holder region is adapted to hold the prosthesis material prior to delivery into the interior region of the vertebral disc. The holder region includes a plurality of openings, with each opening adapted to allow prosthesis material to be dispensed from within the holder region. A plunger is disposed within the body. The plunger and body are adapted to move relative to each other to dispense the prosthesis material.
• In still another embodiment, a device for delivering a prosthesis material to an interior region of a vertebral disc is disclosed. The device includes a body having a proximal end and a distal end. A holder region is disposed adjacent the distal end of the body. The holder region is adapted to hold the prosthesis material prior to delivery into the interior region of the vertebral disc. A plunger is disposed within the body. The plunger and body are adapted to move relative to each other to dispense the prosthesis material. A gauge cooperates with the device and is adapted to measure the insertion force of the prosthesis material into the inner region of the vertebral disc.
• In another embodiment, a method for delivering a prosthesis material into an interior region of a vertebral disc is disclosed. The method includes providing a delivery device having a body having a proximal end and a distal end and a holder region disposed adjacent the distal end. The holder region is adapted to hold the prosthesis material prior to delivery into the interior region of the vertebral disc. The delivery device further including a plunger cooperating with the body. The method further includes loading the holder region with the prosthesis material, advancing at least a portion of the device to a desired location within the vertebral disc, and moving the plunger relative to the body to dislodge the prosthesis material from the device.
• In still another embodiment, a kit of parts for use in augmenting vertebral tissue is disclosed. The kit includes a prosthesis according to any of the embodiments described herein; and a device for inserting the prosthesis into the interior region of the vertebral disc.
• In yet another embodiment, a kit of parts for use in augmenting vertebral tissue is disclosed, the kit includes a prosthesis adapted for insertion into the vertebral disc; a delivery device for inserting the prosthesis into the interior region of the vertebral disc; and instructions for inserting the prosthesis, the instructions comprising instructions for inserting the prosthesis material into an interior region of the vertebral disc without removing a substantial amount of nucleus pulposus from the disc.
• In still another embodiment, a kit of parts for use in augmenting vertebral tissue is disclosed. The kit includes a prosthesis adapted for insertion into the vertebral disc; a delivery device for inserting the prosthesis into the interior region of the vertebral disc; and instructions for inserting the prosthesis. The instructions comprising the any of the methods disclosed herein.
• In still another embodiment, a kit of parts for use in augmenting vertebral tissue is disclosed. The kit includes a prosthesis adapted for insertion into the vertebral disc; and a delivery device according to any of the embodiments described herein.
• In another embodiment, a vertebral disc prosthesis for displacing nucleus, annulus, or vertebral body endplate tissue of a vertebral disc is disclosed. The prosthesis includes a grouping of at least two discrete components. The grouping is constructed and configured to be inserted together as a group into the interior region of a vertebral disc to displace at least a portion of the nucleus, annulus, or vertebral body endplate tissue.
• In yet another embodiment, a method of restoring function of an vertebral disc is disclosed. The vertebral disc has vertebral disc tissue comprising a nucleus, an annulus, and vertebral body endplate tissue. The method includes locating an access site on the vertebral disc; and inserting, at one time, a prosthesis comprising a grouping of at least two discrete components through the access site and into an interior region of the vertebral disc to displace at least a portion of the vertebral disc tissue without removing a substantial amount of nucleus tissue.
• Various embodiments of the present invention provide certain advantages and overcome certain drawbacks of prior prostheses. Embodiments of the invention may not share the same advantages, and those that do may not share them under all circumstances. Further features and advantages of the present invention, as well as the structure of various illustrative embodiments, are described in detail below with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• Various embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
• FIG. 1A is a cross-sectional view of a portion of a functional spine unit, in which part of a vertebra and vertebral disc are depicted;
• FIG. 1B is a side view of a portion of the functional spine unit shown inFIG. 1A, in which two lumbar vertebrae and the vertebral disc are visible, and wherein a prosthesis of the present invention is shown;
• FIG. 2 is a side view of the functional spine unit shown inFIG. 1A, wherein a prosthesis according to another aspect to the invention is shown;
• FIGS. 3A and 3B are views of the vertebral disc, wherein a prosthesis according to yet another aspect of the invention is shown;
• FIG. 4 is a cross-sectional view of a portion of a functional spine unit, wherein a prosthesis according to still another aspect of the invention is shown;
• FIG. 5 is a cross-sectional view of a portion of a functional spine unit, wherein a prosthesis according to yet another aspect of the invention is shown;
• FIGS. 6A and 6B are views of a portion of a functional spine unit, wherein a prosthesis according to yet another aspect of the invention is shown;
• FIGS. 7A and 7B are views of a functional spine unit, wherein a prosthesis according to yet another aspect of the invention is shown;
• FIG. 8 is a cross-sectional view of a portion of a functional spine unit, wherein a prosthesis according to still another aspect of the invention is shown;
• FIG. 9 is a cross-sectional view of a portion of a functional spine unit, wherein a prosthesis according to still another aspect of the invention is shown;
• FIG. 10 is a cross-sectional view of a portion of a functional spine unit showing the prosthesis cooperating with a barrier according to another aspect of the invention;
• FIG. 11 is diagrammatic representation of the vertebral disc showing a barrier positioned within the interior region of the disc;
• FIGS. 12A through 12C are cross-sectional representations of a deployment device used to deploy the prosthesis according to one aspect of the invention;
• FIG. 13 is an alternative embodiment of the deployment device shown inFIGS. 12A-12C;
• FIGS. 14A-14D show alternative embodiments of a portion of the deployment device encircled by line14 ofFIG. 12A;
• FIG. 15 is a cross-sectional representation of a portion of the deployment device showing yet another alternative embodiment to the invention;
• FIGS. 16 and 17 are cross-sectional views of a portion of the deployment device according to alternative embodiments of the invention;
• FIGS. 18A-18C are cross-sectional representations of deployment device according to an alternative embodiment of the invention;
• FIG. 19 is a diagrammatic prospective view of a portion of the deployment device shown inFIGS. 18A-18C;
• FIG. 20A is a diagrammatic cross-section representation of a portion of an alternative embodiment of the deployment device;
• FIG. 20B is a diagrammatic cross-section representation of a portion of another alternative embodiment of the deployment device;
• FIGS. 21A and 21B are diagrammatic cross-sectional representations of alternative embodiments of the deployment device;
• FIG. 22 is a diagrammatic cross-sectional representation of yet another alternative embodiment of the deployment device;
• FIGS. 23A through 23C are cross-sectional representations of a deployment device used to deploy the prosthesis according to one aspect of the invention; and
• FIGS. 24A through 24C are cross-sectional representations of a deployment device used to deploy the prosthesis according to one aspect of the invention.
• FIG. 25A shows a transverse section of a portion of a functional spine unit, in which part of a vertebra and intervertebral disc are depicted.
• FIG. 25B shows a sagittal cross section of a portion of a functional spine unit shown inFIG. 25A, in which two lumbar vertebrae and the intervertebral disc are visible.
• FIG. 25C shows partial disruption of the inner layers of an anulus fibrosis.
• FIG. 26A shows a transverse section of one aspect of the present invention prior to supporting a herniated segment.
• FIG. 26B shows a transverse section of the construct inFIG. 26A supporting the herniated segment.
• FIG. 27A shows a transverse section of another embodiment of the disclosed invention after placement of the device.
• FIG. 27B shows a transverse section of the construct inFIG. 27A after tension is applied to support the herniated segment.
• FIG. 28A shows a transverse view of an alternate embodiment of the invention.
• FIG. 28B shows a sagittal view of the alternate embodiment shown inFIG. 28A.
• FIG. 29 shows one embodiment of the invention supporting a weakened posterior anulus fibrosis.
• FIG. 30A shows a transverse section of another aspect of the disclosed invention demonstrating two stages involved in augmentation of the soft tissues of the disc.
• FIG. 30B shows a sagittal view of the invention shown inFIG. 30A.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
• Loss of vertebral disc tissue, such as NP, deflates the disc, causing a decrease in disc height. Significant decreases in disc height have been noted in up to 98% of operated patients. Loss of disc height increases loading on the facet joints, which may result in deterioration of facet cartilage and ultimately osteoarthritis and pain. As the joint space decreases, the neural foramina formed by the inferior and superior vertebral pedicles also close down which could lead to foraminal stenosis, pinching of the traversing nerve root, and recurring radicular pain. Loss of NP also increases loading on the remaining AF, and can produce pain. Finally, loss of NP results in greater bulging of the AF under load, which may result in renewed impingement by the AF on nerve structures posterior to the disc. Removal of NP may also be detrimental to the clinical outcome of disc repair.
• Applicants own U.S. Pat. Nos. 6,425,919; 6,482,235; 6,508,839 and Published U.S. patent application Ser. No. 2002/0,151,979, each of which is hereby incorporated by reference in its entirety, and discloses, inter alia, methods and devices directed to reinforcing and augmenting the annulus of an vertebral disc. As will be explained, such devices and methods can be used with the inventions described herein.
• In various aspects of the invention, a vertebral disc prosthesis, a method of implanting a prosthesis and a deployment device are disclosed.
• In one aspect of the invention, the prosthesis is implanted into the interior region of the vertebral disc to move or displace, but not replace, the autologous or existing NP, AF or one or both endplates. The tissues of the AF, NP or endplate(s) is therefore displaced relative to the amount of prosthesis added. While a deminimis amount of vertebral tissue may be removed, a substantial amount of material (such as the NP) is not removed. In this manner, as will be explained, a more natural biomechanical state is achieved and functionality of the disc is retained. Prior methods include removal of some of the vertebral tissue, such as a substantial amount or all of the NP, which may disrupt the biomechanical function of the disc as well as the ability of the disc to survive. According to aspects of the present invention, the size or amount of prosthesis inserted into the interior region of the vertebral disc is a function of certain characteristics of the disc or the prosthesis. For example, the amount or size of prosthesis inserted into the disc may be dependent upon restoring the functionality of the disc (e.g., the ability of the disc to transfer nutrients or otherwise survive, the ability of the disc to carry the required loads and absorb stress or the reduction of pain). Restoring disc function may be determined by the resulting disc height desired, the resulting disc pressure desired or the resulting disc volume desired. The prosthesis may also be sized or positioned within the interior region of the vertebral disc such that it is spaced from at least one of the endplates of the vertebral disc. In this manner, the natural ability for the disc to transfer nutrients to and from the AF and the endplates by allowing a more natural diffusion of enriched fluids may be achieved. As will be explained in more detail below, in another aspect, the prosthesis may be formed of any suitable material as the present invention is not limited in this respect. In one embodiment, however, the prosthesis is formed of a material having a compression strength that is less than 4 MN/m². For example, a hydrogel material may be employed. As will be apparent to one of skill in the art, the hydrogel may be processed with suitable cross-linking agents or formed with a desired degree of cross-linking, or processed using a suitable freeze/thaw cycle to produce a material with the desired compressive strength.
• In yet another aspect of the invention, to facilitate placement of the prosthesis within the vertebral disc, a deployment device is disclosed. The deployment device may include a number of features that, either singularly or in any suitable combination, enhance placement of the prosthesis. The deployment device may include at least one or more of the following: a depth stop to facilitate placement of the prosthesis relative to an anatomical feature; a curved or atriculatable end to facilitate inserting the prosthesis in a desired location; a plurality of openings formed on the insertion end of the device to allow a more uniform distribution of the prosthesis material within the disc; and a gauge to allow a determination as to whether a sufficient amount of the prosthesis material is placed within the vertebral disc. Further, rather than forcing the prosthesis into the interior region, the deployment device may be constructed such that upon retraction, the prosthesis is left behind.
• The prosthesis may be shaped and sized or otherwise configured to be inserted through an opening in the vertebral disc. Such an opening may be a defect in the AF such as a hernia site, or may be a surgically created opening. The prosthesis may also be positioned within the interior region of the vertebral disc so as to be spaced away from the access opening and therefore reduce the likelihood that the prosthesis may be dispensed or extruded therefrom. Surgical approaches including transpsoas, presacral, transsacral, tranpedicular, translaminar, or anteriorly through the abdomen, may be used. The access opening can be located anywhere along the surface of the AF or even through the vertebral endplates.
• Turning now to the figures, illustrative embodiments of the prosthesis and deployment device, and illustrative methods for inserting the prosthesis will now be described. Although certain features will be described with reference to a specific embodiment, the present invention is not limited in this respect, as any of the features described herein, and other suitable features, may be employed singularly or any suitable combination to form any suitable embodiment.
• A functional spine unit includes the bony structures of two adjacent vertebrae (or vertebral bodies), the soft tissue (annulus fibrosis (AF), nucleus pulposus (NP), and endplates) of the vertebral disc, and the ligaments, musculature and connective tissue connected to the vertebrae. The vertebral disc is substantially situated in the vertebral space formed between the adjacent vertebrae.
• FIGS. 1A and 1B show the general anatomy of afunctional spine unit10. As used herein, the terms ‘anterior’ and ‘posterior’, ‘superior’ and ‘inferior’ are defined by their standard usage in anatomy, i.e., anterior is a direction toward the front (ventral) side of the body or organ, posterior is a direction toward the back (dorsal) side of the body or organ; superior is upward (toward the head) and inferior is lower (toward the feet).
• FIG. 1A is a cross-sectional view of a vertebral body with thevertebral disc15 superior to the vertebral body. Anterior (A) and posterior (P) sides of the functional spine unit are also shown. Thevertebral disc15 contains an annulus fibrosis (AF)17 surrounding a central nucleus pulposus (NP)20. Also shown in this figure are the left22 and right22′ transverse spinous processes and the posteriorspinous process24.
• FIG. 1B is a side view of two adjacent vertebral bodies28 (superior) and30 (inferior).Vertebral disc space32 is formed between the two vertebral bodies and containsvertebral disc15, which supports and cushions the vertebral bodies and permits movement of the two vertebral bodies with respect to each other and other adjacent functional spine units.
• Vertebral disc15 includes theAF17, which normally surrounds and constrains theNP20 to be wholly within the borders of the vertebral disc space. Thevertebral disc15 also includessuperior endplate34 andinferior endplate36 that cooperate with theAF17 to contain theNP20 within the borders of the vertebral disc space. The vertebral bodies also include facet joints38 and the superior40 and inferior42′ pedicle that form theneural foramen44. Loss of disc height (H) occurs when the superiorvertebral body28 moves inferiorly relative to the inferiorvertebral body30.
• In one illustrative embodiment, theprosthesis50 is inserted into theinterior region52 of thevertebral disc15 so as to displace existing NP, AF or the endplate(s). That is, existing tissue, such as NP material, is not removed during insertion of the prosthesis, as is done in prior methods. As discussed above, prior methods include removal of some or all of the NP from the vertebral disc, which may disrupt the biomechanical function of the disc as well as the ability of the disc to survive. Also, prior prostheses were sized to merely fill the surgically created void within the interior region of the disc. Rather, according to aspects of the present invention, the prosthesis augments existing NP within the interior region of the vertebral disc rather than merely replace NP that was removed. In this manner, as will be explained, existing vertebral tissue may be displaced and a more natural biomechanical state is achieved, disc height is restored, and pain resulting from impingement by the AF on nerve structures, loading of facet joints or pinching of the transverse nerve root due to reduced joint space is minimized. A barrier may be employed to reduce the likelihood of the prosthesis escaping from the interior region. A barrier may also be employed to support the AF during and/or after the prosthesis is inserted.
• In some instances, it may be desirable to monitor whether a sufficient amount of prosthesis orprosthesis material50 is placed into theinterior region52 or whether the size of the prosthesis orprosthesis material50 is sufficient to achieve the desired result, such as, for example, restoring the functionality of the disc. Thus, in one embodiment, certain disc characteristics are monitored during the implantation procedure. In one embodiment, disc height (H) is monitored such that the amount of prosthesis orprosthesis material50 inserted into thedisc15 is a function of the desired height (H) of thedisc15. As explained above, restoring disc height may be beneficial in reducing pain.
• As will become clear hereinafter, it is to be appreciated that the prosthesis or prosthesis material implanted into the interior region of the vertebral disc may have a predetermined geometry or may be initially in bulk form allowing a surgeon or other technician to insert a desired amount of the prosthesis or prosthesis material into the interior region of the disc. Thus, in embodiments where the prosthesis or prosthesis material is of a pre-formed geometry, the term “prosthesis” may be used. In embodiments where the prosthesis or prosthesis material is a portion of a bulk material (such as when the prosthesis or prosthesis material is formed from a liquid or fluid material) the phrase “prosthesis material” may be used. In both embodiments, however, reference numeral “50” is used. Nevertheless, the present invention is not limited in this respect, as the term “prosthesis” may be used to refer to a portion of a bulk material and the term “prosthesis material” may be used to refer to a pre-formed geometry. As such, the term “prosthesis” is used herein to generically refer to either embodiment.
• Determining the height (H) may be performed using any suitable means or method, as the present invention is not limited in this respect. In one embodiment, a caliper or other measuring device to determine the disc height may be used. Alternatively, disc height may be monitored using any suitable imaging system, such as MRI, X-ray or CT Scan, as the present invention is not limited in this respect. Further, such height data may be obtained either during the procedure or post-operatively by, for example, comparing pre- and post-operative disc heights. Once the desired disc height (H) is achieved, continued insertion of theprosthesis50 into the interior region is terminated. The desired disc height (H) may be determined on a case by case basis. In one embodiment, the disc height (H) may be increased by an amount ranging between approximately 1 mm and approximately 10 mm. Other suitable ranges include 0.1 mm-5 mm and 5 mm-10 mm or even a narrower range, such as 0.1 mm-3 mm, 3 mm-6 mm and 6 mm-9 mm. It should be appreciated that the present invention is not limited to any particular resulting disc height (H), as other final disc heights or ranges may be desired.
• According to one aspect of the invention, increasing disc pressure may be desirable to restore natural disc function. However, care should be taken so as not to exceed pressure limits of the disc. Studies have shown that pressures exceeding much more than 6 atmospheres may damage the endplates of the vertebral disc. Therefore, instead of or in addition to monitoring the disc height, the pressure withindisc15 may be monitored. That is, the amount ofprosthesis material50 inserted or the size of the prosthesis itself may be a function of an increase in disc pressure. In one embodiment, the amount of prosthesis implanted results in an increase in pressure ranging from approximately 0.1 atmospheres to approximately 5 atmospheres. It should be appreciated however that the present invention is not limited in this respect and that other suitable pressure ranges may be desirable. For example, pressure increases ranging from 0.1-2 atmospheres, 2-4 atmospheres or even 4-6 atmospheres may be achieved.
• Typically, the disc pressure is intradiscal pressure and the pressure is monitored while thedisc15 is in a resting state, e.g., when there is no substantial axial force on thedisc15.
• The disc pressure may be monitored using any suitable technique, as the present invention is not limited in this respect. As will be described in greater detail, the actual pressure within the interior region of the disc may be monitored or it may be measured indirectly by measuring the force required to insert theprosthesis50. That is, as theprosthesis50 is inserted into theinterior region52, the force resisting the insertion may increase. Measuring or monitoring this resistance force may indicate the internal pressure within thedisc15.
• According to one aspect of the invention, increasing disc volume may be desirable to restore natural disc function. Also, increasing disc volume may be employed as a method of indirectly increasing disc pressure or disc height. Thus, in another illustrative embodiment, the volume of thedisc15 may be monitored. Monitoring this characteristic may be employed in combination with monitoring the disc pressure and/or monitoring the disc height. Monitoring the disc volume may be achieved by CT scanning, X-ray imaging or MRI as the present invention is not limited in this respect. Also, such monitoring may be performed by comparing pre- and post-operative disc volumes.
• Alternatively, the volume ofprosthesis material50 being inserted into theinterior region52 may be measured directly by monitoring the amount or size of the prosthesis itself. It should be appreciated that the present invention is not limited in this respect, as other suitable methods of monitoring disc or prosthesis volume may be employed. The volume of the prosthesis material may also be adjusted to compensate for extra swelling due to, for example, any existing herniations in theAF17. For example, the volume of theprosthesis material50 inserted into theinterior region52 may be increased to accommodate such swelling.
• A direct measurement of the amount of prosthesis material being inserted may be employed, such as by the use of a metered dispensing implement. Alternatively, because the volume of the prosthesis material is a function of the specific dimensions of the vertebral disc, the prosthesis volume may be gathered from CT scan data, MRI data or other similar data from another imaging protocol. Thus, for example, prostheses with lesser volume can be used with smaller discs and those with limited herniation and those that otherwise require less NP displacement to increase disc height or intradiscal pressure.
• In one illustrative embodiment, the volume ofprosthesis material50 inserted into the interior region of the vertebral disc may range between approximately 0.1 ml and approximately 6 ml. Other suitable volume ranges, such as between approximately 1 ml and approximately 2 ml or between approximately 0.5 ml to approximately 2 ml, may be employed, as the present invention is not limited in this respect. The amount ofprosthesis material50 implanted depends upon a number of factors, including the amount of vertebral tissue, such as NP, lost through any herniation or degeneration and any increase in stiffness vertebral tissue, such as NP, as it is displaced with the prosthesis material. Further, the amount of prosthesis material inserted may depend upon the resulting augmentation volume of the vertebral disc desired.
• Typical failure modes with existing vertebral disc implants may be caused by placing the implant directly between two opposing endplates where the implant functions to resist compression. In this respect, the mechanical properties of the prosthesis may create a stress concentration along the endplates and fracturing of the endplates may occur. Furthermore, placing the prosthesis against both endplates may interfere with fluid and nutrient transfer in and out of the vertebral disc. Thus, in one illustrative embodiment, as shown inFIGS. 1A and 1B, theprosthesis50 is sized and shaped so as not to occupy the entire volume of theinterior region52 of the vertebral disc. In another embodiment, as shown inFIG. 2, theprosthesis50 is sized and positioned within the interior region so as to be spaced from at least oneendplate34. In another embodiment, theprosthesis50 is sized so as to be spaced from bothendplates34,36. In this manner, theprosthesis50 may be partially or wholly surrounded by NP material.
• Upon insertion of theprosthesis50 into thevertebral disc15, displacement of the vertebral tissue occurs, such that the vertebral tissue is pushed and expands radially. For example, when the prosthesis displaces NP, the NP moves in opposite directions, i.e., towards theendplates34,36. TheNP20 cushions theprosthesis50 and at least one of theendplates34,36, and preferably both endplates, and allows for a more natural diffusion of fluids and nutrients. In the above embodiments, theprosthesis50 is surrounded by NP; however, it need not be. For example, in another embodiment, theprosthesis50 is placed so as to lie adjacent theAF17, as shown inFIG. 2.
• The position of the prosthesis within the interior region of the vertebral disc may also be selected so as to alter the axis of rotation or reaction forces acting on a given functional spinal unit. A functional spinal unit moves with an axis of rotation that dictates which part of the functional spinal unit experiences the most motion or loading. The reaction force of the vertebral disc controls the axis of rotation, therefore altering the reaction force location changes the axis of rotation to reduce relative motion of parts of a functional spinal unit. For example, as shown inFIGS. 3A and 3B, adding theprosthesis50 to the posterior ofvertebral disc15 shifts the axis of rotation closer to thefacets38, thereby reducing facet loading and facet pain. Furthermore, positioning the prosthesis posteriorly has the effect of increasing the disc height near the facets, which could also have the effect of reducing and relieving pain.
• Other suitable positions for the prosthesis also may be employed. For example, as shown inFIG. 4, theprosthesis50 may be positioned on one side of thevertebral disc15 to restore symmetrical lateral height and bending that may have been altered by disc degeneration or an AF defect. Acircumferential prosthesis50, as shown inFIG. 5, or multiple prosthesis positioned about the circumference of the inner region (not shown) may also be employed. Other suitable combinations of positions for the prosthesis also may be employed to achieve other desired results.
• Prosthesis50 can be formed into any suitable shape.Prosthesis50 may be cube-like, spherical, disc-like, ellipsoid, rhoinbohedral, cylindrical, kidney, wedge, planar, or amorphous in shape as shown inFIGS. 6A and 6B. Further, a single prosthesis or prosthesis formed from multiple sections or separate pieces may be employed. A plurality of prostheses also may be employed and may be formed as beads, as shown inFIG. 8, substantially straight and/or spiral rods, as shown inFIG. 9, geometric solids, irregular solids, sheets or any other suitable shape disclosed herein or otherwise formed. Of course, any suitable combination of the above mentioned or other shapes may be employed.
• In another embodiment, theprosthesis50 is shaped to resist being extruded from the interior region of thevertebral disc15. In one example, as shown in the illustrative embodiment ofFIGS. 7A and 7B, theprosthesis50 is sized to be larger than the access opening60 formed in thevertebral disc15 for inserting theprosthesis50. Alternatively, or in addition, the prosthesis may be formed as a wedge, as shown, with the larger end of the wedge facing theopening60 such that any force tending to push the wedge out the access opening would cause the prosthesis to occlude theaccess opening60. Of course, the prosthesis may be shaped such that any axial loads on the prosthesis would tend to cause the prosthesis to move away from the access opening. For example, a wedge-shaped prosthesis with the smaller end facing theopening60 may respond to axial loads by tending to move away from the opening.
• To aid in healing of the disc or otherwise provide therapy, the prosthesis may be impregnated, coated or otherwise deliver various therapeutic agents, such as drugs, time-release drugs, genetic vectors, naked genes or the like to renew growth, reduce pain, aid healing, or reduce infection.
• The prosthesis may be formed of any suitable material, as the present invention is not limitated in this respect. The prosthesis may be formed as a fluid (e.g., liquid or gas), a solid, a gel, a semi-solid, or any suitable combination thereof. Exemplary fluid prostheses or prosthesis materials include, but are not limited to, various pharmaceuticals (steroids, antibiotics, tissue necrosis factor alpha or its antagonists, analgesics); growth factors, genes or gene vectors in solution; biologic materials (hyaluronic acid, non-crosslinked collagen, fibrin, liquid fat or oils); synthetic polymers (polyethylene glycol, liquid silicones, synthetic oils); and saline.
• In one illustrative embodiment, theprosthesis50 is formed of a biocompatible material. Examples include biocompatible viscoelastic materials such as hydrophilic polymers, hydrogels, homopolymer hydrogels, copolymer hydrogels, multi-polymer hydrogels, or interpenetrating hydrogels, acrylonitrile, acrylic acid, acrylimide, acrylimidine, including but not limited to PVA, PVP, PHEMA, PNVP, polyacrylainides, poly(ethylene oxide), polyvinyl alcohol, polyarylonitrile, and polyvinyl pyrrolidone, or combinations thereof. It is preferred, but not required, that such materials may exhibit mechanical properties, swelling pressures and/or diffusion capabilities similar to the natural NP in order to supplement the NP without causing undo stress concentrations.
• In other embodiments, theprosthesis50 may be formed from solid material, such as woven or non-woven materials or may include minute particles or even powder. Theprosthesis50 also may be porous or semi-porous. Candidate materials include, but are not limited to: metals, such as titanium, stainless steels, nitinol, cobalt chrome; resorbable or non-resorbing synthetic polymers, such as polyurethane, polyester, PEEK, PET, FEP, PTFE, ePTFE, Teflon, PMMA, nylon, carbon fiber, Delrin, polyvinyl alcohol gels, polyglycolic acid, polyethylene glycol; elastin; fibrin; ceramics, silicone, gel or rubber, vulcanized rubber or other elastomers; gas filled vesicles, biologic materials such as morselized or block bone, hydroxy apetite, collagen or cross-linked collagen, muscle tissue, fat, cellulose, keratin, cartilage, protein polymers, transplanted or bioengineered materials; various pharmacologically active agents in solid form; or any combination thereof. The solid or gel prosthesis materials may be rigid, wholly or partially flexible, elastic or viscoelastic in nature. The prosthesis material may be hydrophilic or hydrophobic. Hydrophilic materials, mimicking the physiology of the NP, may be delivered into the disc in a hydrated or dehydrated state. Biologic materials may be autologous, allograft, zenograft, or bioengineered. Where rigid materials are employed, the prosthesis may be shaped as small particles, powders, balls or spheres.
• In some embodiments of the present invention, a multiphase system may be employed; for example, a combination of solids, fluids or gels may be used. Such materials may create primary and secondary levels of flexibility within an vertebral disc space. Thus, in use, the spine will flex easily at first as the vertebral disc pressure increases and the fluid flows, loading the annulus. Then, as the disc height decreases flexibility may decrease. This combination may also prevent damage to the AF under excessive loading as the prosthesis may be designed to resist further compression such that further pressure on the AF is limited.
• Any of a variety of additional additives such as thickening agents, carriers, polymerization initiators or inhibitors may also be included, depending upon the desired infusion and long-term performance characteristics. In general, “fluid” is used herein to include any material which is sufficiently flowable at least during the infusion (i.e., implantation) process, to be infused by a delivery device into the interior region of the vertebral disc. The prosthesis material may remain “fluid” after the infusion step, or may polymerize, cure, or otherwise harden to a less flowable or nonflowable state.
• In one embodiment, in situ polymerizing prosthesis materials that are well-known in the art and are described in U.S. Pat. No. 6,187,048, incorporated herein by reference, may be used. Phase changing augmentation preferably changes from a liquid to a solid or gel. Such materials may change phases in response to contact with air, increases or decreases in temperature, contact with biologic liquids or by the mixture of separate reactive constituents. These materials may be delivered through an opening in the AF or down a tube or cannula placed percutaneously into the disc. Once the materials have solidified or gelled, they may exhibit the previously described characteristics of a solid prosthesis material.
• Additional additives and components of the prosthesis material are recited below. In general, the nature of the material may remain constant during the deployment and post-deployment stages or may change, from a first infusion state to a second, subsequent implanted state. For example, any of a variety of materials may desirably be infused using a carrier such as a solvent or fluid medium with a dispersion therein. The solvent or liquid carrier may be absorbed by the body or otherwise dissipate from the disc space post-implantation, leaving the material behind. For example, any of a variety of the powders identified below may be carried using a fluid carrier. In addition, hydrogels or other materials may be implanted or deployed while in solution, with the solvent dissipating post-deployment to leave the hydrogel or other media behind. In this type of application, as discussed above, the disc space may be filled under higher than ultimately desired pressure, taking into account the absorption of a carrier volume.
• In one embodiment, the prosthesis material comprises a material having a compressive strength that is less than approximately 4 MN/m². In another embodiment, the prosthesis material has a compressive strength of approximately 2.5 MN/m²to approximately 3.5 MN/m². Other suitable prosthesis materials having compressive strengths less than or equal to approximately 2.5 MN/m²or approximately 3.5 MN/m²to approximately 4 MN/m²may be employed.
• In addition, the prosthesis material may have a Poisson's ratio that is between approximately 0.30 and approximately 0.49. Such a Poisson's ratio may be employed to effectively distribute the load outward toward the AF. In one embodiment, the Poisson's ratio is between a range of approximately 0.35 and approximately 0.49. Rubber and polymeric materials may be used or otherwise formed to produce the desired Poisson ratio. In one embodiment, a hydrogel, such as PVA, PGA or PMMA, may be used.
• As discussed above, it may be desirable to provide a prosthesis material that mimics as closely as possible the NP within the interior region of the vertebral disc. Thus, the prosthesis may be formed of a material that absorbs and/or releases fluids within a certain period of time and under certain conditions similar to the absorption and release of fluids from the natural NP. Upon high axial loads of the vertebral disc, the prosthesis may release fluids to help diffuse shock loading. Similarly, the ability for the prosthesis to absorb fluid should be sufficiently rapid so as to rebulk when fluid is otherwise released from the prosthesis. In one embodiment, it may be desirable for the prosthesis to absorb fluids during a 5 to 10 hour sleep cycle so as to restore any fluid loss during the day. In one embodiment, the prosthesis is formed of a material that may enable it to absorb approximately 50% to 100% of its volume. However, the present invention is not limited in this respect and other suitable prosthesis materials or characteristics of a prosthesis material may be employed to achieve other rehydration volumes. Rubber and polymeric materials may be used. In one embodiment, a hydrogel, such as PVA, PGA or PMMA, may be used.
• In one embodiment, the prosthesis material has a swelling pressure between approximately 0.1 MN/m²and approximately 9 MN/m²for given volume range between approximately 0.1 mL and 6.0 mL. This may have the advantage of allowing a smaller prosthesis to swell and fit into the irregularities within the natural NP until equilibrium pressure is achieved. Rubber and polymeric materials may be used. In one embodiment, a hydrogel, such as PVA, PGA or PMMA, may be used.
• In one embodiment, the prosthesis material may be formed as a hydrogel having a compressive strength ranging between approximately 2.5 MN/m²and approximately 3.5 MN/m². In addition, the prosthesis material may preferably have a swelling characteristics that enables it to rehydrate approximately 50% to 100% of its volume within a 1 hour to 8 hour time period under a compressive stress ranging from approximately 0.2 MN/m²and approximately 0.8 MN/m². Further, the prosthesis material may hydrate in less time when in an unloaded or unconstrained environment. Further, in this embodiment, the prosthesis material may have a Poisson's ratio ranging from approximately 0.35 to approximately 0.49 under a compressive stress ranging from approximately 0.5 MN/m²to approximately 2 MN/m². Rubber and polymeric materials may be used. In one embodiment, a hydrogel, such as PVA, PGA or PMMA, may be used.
• In some embodiments it may be desirable to provide a more uniform loading at the junction between the prosthesis material and the NP, AF or endplates to reduce stress concentration and limit damage to any of the foregoing. Thus, in one embodiment, the prosthesis material may be a relatively soft and flexible material. In addition, in one embodiment, the prosthesis material may be isotropic. Rubber and polymeric materials may be used. In one embodiment, a hydrogel, such as PVA, PGA or PMMA, may be used.
• In one embodiment, the prosthesis is a biocompatible isotropic hydrogel, such as PVA, PGA or PMMA, having a compressive strength of less than 4 MN/m².
• In some instances it may be desirable to remove the prosthesis material from the interior region of the vertebral disc. Thus, in one embodiment, the prosthesis is sized, shaped or otherwise configured so as to be relatively easily removed after having been implanted. In one embodiment, this result may be achieved by selecting the shape of the prosthesis and/or the rigidity or deformability of the material.
• The prosthesis implanted into the interior region of the disc may also be used in conjunction with a barrier that blocks, covers or otherwise occludes the access opening, whether it be surgically created or a hernia site. After theprosthesis50 is inserted into the interior region, a barrier70 (seeFIG. 10), such as that disclosed in applicants commonly assigned patents and patent application, including U.S. application Ser. No. 10/055,504, U.S. Pat. Nos. 6,425,919 and 6,508,839, each of which is hereby incorporated by reference, is inserted. Of course, other suitable barriers or no barrier may be employed.
• As shown inFIG. 10, and as described in one or more of the above-mentioned patents or application, thebarrier70, if used, may be sized to sufficiently cover the defect or access opining60 and reduce the likelihood of thebarrier70 extruding or slipping from covering theaccess opening60. Thebarrier70 may be sized, such that at least some portion of the barrier abuts the AF surrounding theaccess opening60. Thebarrier70 may act to seal theopening60, recreating the closed isobaric environment of a healthy disc. Thebarrier70 also may be affixed to tissues within the functional spinal unit or to the AF surrounding theopening60. Such attachment may be facilitated with the use of sutures, staples, glues or other suitable fixation means or fixation devices.
• In use, the pressurized disc tissue andprosthesis50 applies force on the inwardly facing surface of thebarrier70. This pressure may be exploited by the design of the barrier to reduce the likelihood of it dislodging or moving from its intended position. One exemplary barrier is shown inFIG. 11, where thebarrier70 includes inwardly facingsurfaces72 that expand upon the application of pressure. As the barrier expands, it becomes less likely to be expelled from the disc. Thebarrier70 may be formed with a concavity facing inwardly to promote such expansion. In addition, as shown inFIG. 10, theprosthesis material50 typically is positioned adjacent to thebarrier70 such that the likelihood of natural NP escaping through the access opening60 is further minimized.
• The barrier may be flexible in nature. It can be constructed of a woven material such as Dacron or Nylon, a synthetic polyamide or polyester, a polyethylene, or can be an expanded material, such as expanded polytetrafluroethylene (e-PTFE). The barrier may also be a biologic material such as cross-linked collagen or cellulous.
• The barrier typically is a single piece of material, and may be expandable or include a component that allows it to be expanded from a compressed state after insertion into the interior of the disc. This expansion may be active, such as a balloon, or passive, such as a hydrophilic material. The expansion may also occur via a self-expanding deforming barrier or by incorporating such a material, such as a shape-memory material, for example. In the example shown inFIG. 11, thebarrier70 includes acage74 formed from a shape-memory material, such as nitinol. A cover (not shown) may be employed over thecage74.
• When a phase changing prosthesis material is used, the barrier or other annulus augmentation may be permanently implanted or used only temporarily until the desired phase change has occurred. For example, a sufficient amount of fluid orliquid prosthesis50 may be implanted into the disc.Barrier70 is then implanted to occlude theaccess opening60. Theprosthesis50 is then cured or dried (or otherwise allowed to cure or dry) to a solid or semi-solid state, wherein the resulting prosthesis form is larger than the access opening. Thebarrier70 then may be removed, as, due to the resulting size and/or shape of the prosthesis, the likelihood of the prosthesis escaping back through the access opening60 is low.
• As discussed above, theprosthesis50 typically is placed within theinterior region52 of thevertebral disc15 by a delivery device. Examples of suitable delivery devices are shown inFIGS. 12-22 In one illustrative embodiment, thedelivery device80 comprises abody82 defining alongitudinal axis83. Thebody82 may be formed as an elongate cannula or other hollow tubular sleeve. Thebody82 includes aproximal end81 and adistal end84, which is adapted to pass through the access opening60 in the AF and deploy theprosthesis50 into theinterior region52. Thedistal end84 may be rounded (not shown) to limit any damage to the AF or other anatomical structure. A push rod orplunger86 is axially slidable within thecannula82 and together with theend portion84 of the cannula defines aholder region87. Theplunger86 includes anend89 that acts on theprosthesis50 to dislodge the prosthesis from theholder region87. Theplunger86 is pushed in the direction of arrow A shown inFIG. 12B to eject theprosthesis50 from theholder region87.
• The plunger is axially slidable within the body so as to dislodge the prosthesis material therefrom. As shown for example inFIGS. 12A-12C, in one embodiment, thebody82 includes afirst handle160 or region to allow the surgeon to grasp the outside of the body. Theplunger86 includes asecond handle162, allowing the surgeon to actuate theplunger86 to dislodge theprosthesis material50.
• Theprosthesis material50 may be inserted into theholder region87 of thedeployment device80 using any suitable means. In this manner, a single use deployment device may be provided. In one embodiment, the deployment device may be preloaded with a desired amount of prosthesis material. In other embodiments, the deployment device may be placed in a vat of prosthesis material and actuated, in a manner similar to a syringe, to draw the prosthesis material into the deployment device. Alternatively, a surgeon or other assistant may place a desired amount of the prosthesis material within the deployment device. Of course, it should be appreciated that the present invention is not limited in this respect and that any suitable means or method for inserting the prosthesis may be used. And, the chosen means or method may depend upon the type of prosthesis material employed.
• In one embodiment, any of the deployment devices and/or the prosthesis described herein may be supplied in a kit. The kit may include one or more of the same or different prostheses or components and/or one or more of the same or different deployment devices. The kit may include materials or devices to be used with the prosthesis. For example, the kit may include the above-mentioned therapeutic agents or agents to cure the prosthesis, if a curable prosthesis is employed. Also, the kit may include components, devices or other materials to aid in deploying the prosthesis. The kit further may include one or more of the same or different barriers. The kit also may include monitoring devices to monitor the amount of prosthesis being deployed and also may include instructional information, including any of the methodologies described herein. It should be appreciated that the present invention is not limited in this respect, as the herein noted or other suitable components or devices may be supplied with the kit.
• In some instances, it may be desirable to locate the prosthesis material within a certain position in the interior region of the vertebral disc. Thus, in one illustrative embodiment as shown inFIGS. 12A-12C, the deployment device includes adepth stop88 that limits how deeply into the interior region of the vertebral disc the prosthesis is placed. For example, thedepth stop88 may seat against thevertebral bodies28,30, as shown inFIG. 12C, or theAF17. In this manner, thetip84 of thedelivery device80 is inserted into the access opening60 in the AF until the depth stop88 contacts the outer layer of the AF to prevent further insertion of the tip of the delivery device into the interior region of the vertebral disc. Once in this position, the delivery device is actuated to deliver theprosthesis50 to the desired location. Although in this embodiment thedepth stop88 abuts the vertebral body to limit the insertion depth, the delivery device may be configured such that the depth stop abuts other anatomical features. For example, the depth stop may be located on a delivery device such that it is adapted to contact the AF or other bone or tissue located in the region.
• In the embodiment shown inFIGS. 12A-12C, thedepth stop88 is located on the outside of the delivery device. However, in other embodiments, an example of which is shown inFIG. 13, it may be desirable to configure thedelivery device80 with aninternal depth stop90. In this manner, the tip of the delivery device is placed through the access opening in the AF and is advanced until the internal depth stop90 contacts the opposite wall of the AF or other structure within the interior region of the vertebral disc. Once the tip is in the proper position, the delivery device is actuated to deploy the prosthesis material at the suitable location within the interior region of the vertebral disc.
• The depth stop also may be adjustable, giving the surgeon the flexibility to locate the prosthesis in any desired position. In one example, as shown inFIG. 14A, thebody82 may include a threadedsection92 and adepth stop88′ may be formed as a threadedring94 that engages thebody82. By rotating thering94 relative to the body, the location of the depth stop may be adjusted.
• Although a thread is shown and described, other suitable adjustment mechanisms may be employed. For example, as shown inFIGS. 14B and 14C, a depth stop may be slidingly engaged on thebody82 and locked in a position using a suitable locking device, such as a clamp or thumb-screw96 for adepth stop88″ shown inFIG. 14B,ball98 anddetent99 mechanism for adepth stop88′″ shown inFIG. 14C, or other ratcheting-type mechanisms.
• In another embodiment, as shown inFIG. 14D adepth stop88″″ is formed as a plurality of washer-like rings100 that can slip over the body and abut a fixeddepth stop102. In this manner, the depth may be set by adding rings onto the body until the desired depth is achieved. The rings may be locked in position or freely retained on the body.
• An internal depth stop may be adjustable providing the desired flexibility as to where to locate the prosthesis. One example is shown inFIG. 15, in which adepth stop90′ is threaded into a wall of thebody82 to enable depth adjustment in a telescoping manner.
• To further enhance placement of the prosthesis in a desired location within the interior of the vertebral disc, thedelivery device80 may include a curved or otherwisearticuatable end84 that can be either actively or passively manipulated to alter its position, as shown inFIG. 16. With a deployment device having a straight end as shown, for example, inFIG. 12A, the prosthesis may only be deployed along the longitudinal axis of the delivery device. In embodiments employing a curved or articuatable end, the prosthesis may be deployed at any desired angle relative to the longitudinal axis. For example, the prosthesis may be deployed adjacent one of the endplates, in the middle of the interior region of the vertebral disc, or adjacent the AF.
• One illustrative embodiment of an articulatable end is shown inFIG. 16.Guide wires110 are fixed to thetip84 of the delivery device, and in one embodiment, theguide wires110 are anchored using suitable anchors, such as eyelets, in the interior region of thebody82. Thewires110 extend internally throughbody82 toward theproximal end81 of thebody82 andexit end81. Retracting thewires110 causes thetip84 to articulate relative to the longitudinal axis of the delivery device. Other mechanisms for causing the tip to curve or bend may be employed. To provide for an articulating end, thedistal end84 is formed of a flexible material or in a flexible configuration.
• In another embodiment, rather than actively deforming the tip of the delivery device, the tip itself may be configured such that it bends into a predetermined configuration upon insertion. For example, the tip of the delivery device may include a kink point or a change in the stiffness along the length of the tip that causes the tip to assume a predetermined configuration. In one embodiment, as shown inFIG. 17, thedelivery device80 includes a relatively stiff outertubular member112 that contains thebody82. Further,body82 may be formed of, or otherwise include, a relatively flexible material, such as a spring member, that holds the tip in a bent configuration. When inside thesleeve112, the tip is retained in a straight configuration to allow insertion into the vertebral disc. Whenbody82 is displaced with respect tomember112 in the direction of arrow B, thetip84 emerges from thesleeve112 and assumes its bent configuration, as shown.
• When a curved or otherwise articuatable end is employed,plunger86 should be sufficiently flexible to conform to the shape of the tip of the delivery device when in its bent configuration so as to be able to dislodge the prosthesis material.
• In some circumstances, it may be desirable to place the prosthesis at a desired location within the interior region of the vertebral disc upon retracting a portion of the delivery device rather than by extruding the prosthesis material from thedelivery device80, as in the embodiment shown inFIGS. 12A-12C. Thus, in this embodiment shown inFIGS. 18A-18C, andFIG. 19, aretrograde delivery device80 is shown, wherein thebody82 is retracted in the direction of arrow C (seeFIG. 18B) relative to theplunger86. Once the prosthesis material has been deployed within the interior region, the delivery device may be removed from the vertebral disc.
• The delivery device of this embodiment may also include a curved or articulatable end as described above and/or a depth stop, whether or not adjustable, to place the prosthesis at the desired location.
• As shown inFIGS. 18A-18C, the delivery device may include adepth stop88. To provide thedepth stop88 while allowing the body to be retracted along arrow C as described, the body includes aslot120, as shown inFIG. 19. Thus, thetip84 of the delivery device is inserted into the interior region of the vertebral disc until the depth stop88 contacts the desired anatomy. Then, thebody82 may be retracted along arrow C while thedepth stop88 is held against the anatomy. Theslot120 in thebody82 allows thebody82 to be retracted such that thestop88 may move relative to thebody82 within theslot120.
• As discussed above, the prosthesis may be formed of any suitable material including solids, semi-solids or even materials in liquid or fluid form. However, injecting a fluid or liquid prosthesis material may increase the risk of adding localized pressure as the fluid works its way through the interior region of the vertebral disc, which may result in damage to the disc. In addition, merely injecting the fluid into the interior region can result in imprecise placement within the interior region or possibly inadvertently deliver the material into undesired locations, such as near the endplates or at fissures or tears in the AF, all potentially increasing the likelihood of pain or reducing the effectiveness of the prosthesis.
• In one embodiment as shown inFIG. 20A, thedelivery device80 is adapted to deliver a prosthesis that is in fluid or liquid font. In this embodiment, end84′ is generally closed, but includesperforations132 and the prosthesis is held withinholder region87. Upon advancing theplunger86, the liquid or fluid prosthesis material within theholder87 is extruded, ejected or otherwise dispensed through theperforations132 in the direction of arrow D.
• The perforations formed in the tip may be any suitable perforations including holes, as shown, or other openings. Alternatively, as shown inFIG. 20B, the perforations may be in the form offins132′ that direct the liquid or fluid prosthesis material in the direction of arrow D′. In one embodiment, the delivery device includes perforations extending only radially outwardly. In this manner, direct pressure through the end of the delivery device onto the NP or locating the prosthesis in an otherwise undesirable location may be avoided.
• In another embodiment, the deployment device monitors the amount of material being delivered. In one illustrative embodiment as shown inFIGS. 21A-21B and20, thedelivery device80 includes a gauge140 such that the surgeon, for example, may quickly determine the amount of prosthesis material being deployed from the delivery device. In one embodiment, the gauge140 may be a pressure gauge that may be used to determine the increase in pressure within the vertebral disc as the prosthesis material is being deployed. In one embodiment as shown inFIG. 21A, the gauge may include a pressuresensitive transducer142 disposed on or within theplunger86 and suitable electronics (not shown) to record and measure the pressure within the disc. The pressure transducer may be situated on the delivery device such that it records the resistance to insertion force. The resistance force is correlated to the pressure increase within the vertebral disc such that the surgeon would know when enough prosthesis material has been deployed. The pressure also may be determined with the use of a suitably placed strain gauge.
• Alternatively, the gauge may be a mechanical gauge144 as shown inFIG. 21B, that employs aspring146 and anindicator148 coupled to the spring that moves in response to the resistance to insertion force. Again, the resistance force may be correlated to the increase in pressure in the interior region of the disc such that when a certain resistance force is obtained, further insertion of prosthesis material may be terminated. In this embodiment, theplunger149 is formed as a two-part plunger having afirst plunger149A and asecond plunger149B.Spring146 is disposed between the two plungers. Movingplunger149A causesspring146 to compress and act onplunger149B, which in turn dislodgesprosthesis50. As the resistance to insertion increases,plunger149A moves further intoplunger149B and a higher pressure reading is indicated atindicator148. It should be appreciated that the present invention is not limited to any particular gauge as any suitable gauge may be employed to determine the increase in pressure in the interior region of the vertebral disc.
• In another embodiment as shown inFIG. 22, the gauge may be avolume gauge150 to indicate the volume of prosthesis material being delivered to the interior region of the vertebral disc. In this respect, the delivery device may be configured similar to a syringe and includes a series of lines on the body that correlates to the volume of material being deployed.
• In yet another embodiment (not shown), a combination of gauges may be employed. For example, a deployment including both a pressure gauge (such as pressure transducer142) and a volume gauge (such as indicator150) may be employed.
• Thedelivery device80 may be formed from any suitable material, as the present invention is not limited in this respect. Thus, the delivery device may be formed from a plastic material, such as a polycarbonate, or a metal material, such as stainless steel, or any suitable combination of materials. In addition, the delivery device may be formed of a material that can be readily sterilized. Further, the delivery device may be formed as a single use device such that resterilization is not required after use.
• In another embodiment, in addition to the shapes described above, the prosthesis may include a grouping of multiple components of the same or different shapes that can be inserted into the interior region of the vertebral disc as a group. By grouping smaller discrete component prostheses together, the prosthesis may perform differently than a single unit which can be advantageous. The volume of an individual component prosthesis can range between approximately 10 mm³and approximately 500 mm³. Each component of the group, or at least one component, may be formed of the same or different materials or material characteristics as other components of the group, such as those materials or characteristics described herein, as the present invention is not limited in this respect.
• Thedelivery device80 may deploy the grouping of prosthesis components of any desired shape. When delivering a grouping of components, each (or at least one) prosthesis component may be in the form of spheres or beads (seeFIG. 8), rods or spirals (seeFIG. 9), geometric solids, irregular solids, sheets or any other suitable shape disclosed herein or otherwise formed. The components typically are deployed in a group and in a single step. At least one component prosthesis from the group, or the entire group, may be deployed to any desired location, examples of which are discussed above. In one embodiment, the grouping includes at least two components forming the prosthesis. In another embodiment, the grouping includes at least three components forming the prosthesis. Other suitable grouping sizes, such as four, five and six, may be employed, as the present invention is not limited in this respect. In one embodiment, the multi-component prosthesis can, for example, comprise hydrogel spheres, that can be extruded, elected or otherwise dispensed from the delivery device, thereby displacing, without removing, autologous vertebral tissues. As is apparent from the above discussion, the size of the group may depend upon certain factors. For example, as is apparent from the above discussion, the group size may be a function of the desired disc height, the desired disc pressure or the desired disc volume, such as the desired augmentation volume.
• FIG. 23A is a cross-sectional view of adelivery device80 loaded with a grouping of spherical or bead shapedprosthetic components50′ and with theplunger86 in the retracted position.FIG. 23B shows theplunger86 in the advanced position, with thecomponents50′ of the prosthesis deployed as a group from thedistal tip84.FIG. 23C shows a view of two adjacentvertebral bodies28,30, with thetip84 of thedelivery device80 inserted within the vertebral disc.Depth stop88 is placed against at least a portion of the annulus or vertebral body. Theplunger86 is shown in the advanced position in which theprosthesis50′ has been delivered within the area bounded by the annulus, causing the tissues of the annulus, nucleus, or vertebral endplates to be displaced in relation to the amount of prosthesis added.
• FIG. 24A is a cross-sectional view of a retrograde delivery device (such as that described above with respect toFIGS. 18A-18C), which is loaded with rod- or spiral-shapedprosthetic components50″ and with thebody82 advanced relative to theplunger86.FIG. 24B shows thebody82 in the retracted position relative to theplunger86, in which thecomponents50″ of the prosthesis are deployed as a grouping from thedistal tip84.FIG. 24C shows a view of two adjacentvertebral bodies28,30, with thetip84delivery device80 inserted within the vertebral disc.Depth stop88 is placed against at least a portion of the annulus or vertebral body. Thebody82 of the delivery device is shown in the retracted position relative to theplunger86, with theprosthesis50 delivered within the area bounded by the annulus, causing the tissues of the annulus, nucleus, or vertebral endplates to be displaced in relation to the amount of prosthesis added.
• Although the spherical- or bead-shapedprosthesis50′ is shown in the delivery device ofFIGS. 23A-23C and the rod- or spiral-shapedprosthesis50″ is shown in the delivery device ofFIGS. 24A-24C, the present invention is not limited in this respect. Thus, the spherical- or bead-shapedprosthesis50″ may be deployed with any delivery device described herein or otherwise, including the delivery device shown inFIGS. 24A-24C and the rod- or spiral-shapedprosthesis50′ may be deployed with any delivery device described herein or otherwise, including the delivery device shown inFIGS. 23A-23C.
• Embodiments provide for an in vivo augmented functional spine unit. A functional spine unit includes the bony structures of two adjacent vertebrae (or vertebral bodies), the soft tissue (anulus fibrosis (AF), and optionally nucleus pulposus (NP)) of the intervertebral disc, and the ligaments, musculature and connective tissue connected to the vertebrae. The intervertebral disc is substantially situated in the intervertebral space formed between the adjacent vertebrae. Augmentation of the functional spine unit can include repair of a herniated disc segment, support of a weakened, torn or damaged anulus fibrosis, or the addition of material to or replacement of all or part of the nucleus pulposus. Augmentation of the functional spine unit is provided by herniation constraining devices and disc augmentation devices situated in the intervertebral disc space.
• FIGS. 25A and 25 show the general anatomy of a functional spine unit45. In this description and the following claims, the terms ‘anterior’ and ‘posterior’, ‘superior’ and ‘inferior’ are defined by their standard usage in anatomy, i.e., anterior is a direction toward the front (ventral) side of the body or organ, posterior is a direction toward the back (dorsal) side of the body or organ; superior is upward (toward the head) and inferior is lower (toward the feet).
• FIG. 25A is an axial view along the transverse axis M of a vertebral body with theintervertebral disc1015 superior to the vertebral body. Axis M shows the anterior (A) and posterior (P) orientation of the functional spine unit within the anatomy. Theintervertebral disc1015 contains the anulus fibrosis (AF)1010 which surrounds a central nucleus pulposus (NP)1020. AHerniated segment1030 is depicted by a dashed-line. The herniatedsegment1030 protrudes beyond the pre-herniatedposterior border1040 of the disc. Also shown in this figure are the left1070 and right1070′ transverse spinous processes and the posteriorspinous process1080.
• FIG. 25B is a sagittal section along sagittal axis N through the midline of two adjacent vertebral bodies1050 (superior) and1050′ (inferior).Intervertebral disc space1055 is formed between the two vertebral bodies and containsintervertebral disc1015, which supports and cushions the vertebral bodies and permits movement of the two vertebral bodies with respect to each other and other adjacent functional spine units.
• Intervertebral disc1015 is comprised of theouter AF1010 which normally surrounds and constrains theNP1020 to be wholly within the borders of the intervertebral disc space. InFIGS. 25A and 25B, herniatedsegment1030, represented by the dashed-line, has migrated posterior to thepre-herniated border1040 of the posterior AF of the disc. Axis M extends between the anterior (A) and posterior (P) of the functional spine unit. The vertebral bodies also includefacet joints1060 and the superior1090 and inferior1090′ pedicle that form theneural foramen1100. Disc height loss occurs when the superiorvertebral body1050 moves inferiorly relative to the inferiorvertebral body1050′.
• Partial disruption1121 of the inner layers of theanulus1010 without a true perforation has also been linked to chronic low back pain. Such a disruption is illustrated inFIG. 25C. It is thought that weakness of these inner layers forces the sensitive outer anulus lamellae to endure higher stresses. This increased stress stimulates the small nerve fibers penetrating the outer anulus, which results in both localized and referred pain.
• In one embodiment of the present invention, the discherniation constraining devices1013 provide support for returning all or part of the herniatedsegment1030 to a position substantially within itspre-herniated borders1040. The disc herniation constraining device includes an anchor which is positioned at a site within the functional spine unit, such as the superior or inferior vertebral body, or the anterior medial, or anterior lateral anulus fibrosis. The anchor is used as a point against which all or part of the herniated segment is tensioned so as to return the herniated segment to its pre-herniated borders, and thereby relieve pressure on otherwise compressed neural tissue and structures. A support member is positioned in or posterior to the herniated segment, and is connected to the anchor by a connecting member. Sufficient tension is applied to the connecting member so that the support member returns the herniated segment to a pre-herniated position. In various embodiments, augmentation material is secured within the intervertebral disc space, which assists the NP in cushioning and supporting the inferior and superior vertebral bodies. An anchor secured in a portion of the functional spine unit and attached to the connection member and augmentation material limits movement of the augmentation material within the intervertebral disc space. A supporting member, located opposite the anchor, may optionally provide a second point of attachment for the connection member and further hinder the movement of the augmentation material within the intervertebral disc space.
• FIGS. 26A and 26B depict one embodiment ofdevice1013.FIG. 26A shows the elements of the constraining device in position to correct the herniated segment.Anchor1001 is securely established in a location within the functional spine unit, such as the anterior AF shown in the figure.Support member1002 is positioned in or posterior to herniatedsegment1030. Leading from and connected to anchor1001 isconnection member1003, which serves to connectanchor1001 to supportmember1002. Depending on the location chosen forsupport member1002, the connection member may traverse through all or part of the herniated segment.
• FIG. 26B shows the positions of the various elements of theherniation constraining device1013 when thedevice1013 is supporting the herniated segment. Tighteningconnection member1003 allows it to transmit tensile forces along its length, which causes herniatedsegment1030 to move anteriorly, i.e., in the direction of its pre-herniated borders. Once herniatedsegment1030 is in the desired position,connection member1003 is secured in a permanent fashion betweenanchor1001 andsupport member1002. This maintains tension betweenanchor1001 andsupport member1002 and restricts motion of the herniated segment to within thepre-herniated borders1040 of the disc.Support member1002 is used to anchor to herniatedsegment1030, support a weakened AF in which no visual evidence of herniation is apparent, and may also be used to close a defect in the AF in the vicinity of herniatedsegment1030.
• Anchor1001 is depicted in a representative form, as it can take one of many suitable shapes, be made from one of a variety of biocompatible materials, and be constructed so as to fall within a range of stiffness. It can be a permanent device constructed of durable plastic or metal or can be made from a resorbable material such as polylactic acid (PLA) or polyglycolic acid (PGA). Specific embodiments are not shown, but many possible designs would be obvious to anyone skilled in the art. Embodiments include, but are not limited to, a barbed anchor made of PLA or a metal coil that can be screwed into the anterior AF.Anchor1001 can be securely established within a portion of the functional spine unit in the usual and customary manner for such devices and locations, such as being screwed into bone, sutured into tissue or bone, or affixed to tissue or bone using an adhesive method, such as cement, or other suitable surgical adhesives. Once established within the bone or tissue,anchor1001 should remain relatively stationary within the bone or tissue.
• Support member1002 is also depicted in a representative format and shares the same flexibility in material and design asanchor1001. Both device elements can be of the same design, or they can be of different designs, each better suited to being established in healthy and diseased tissue respectively. Alternatively, in other forms,support member1002 can be a cap or a bead shape, which also serves to secure a tear or puncture in the AF, or it can be bar or plate shaped, with or without barbs to maintain secure contact with the herniated segment.Support member1002 can be established securely to, within, or posterior to the herniated segment.
• The anchor and support member can include suture, bone anchors, soft tissue anchors, tissue adhesives, and materials that support tissue ingrowth although other forms and materials are possible. They may be permanent devices or resorbable. Their attachment to a portion of FSU and herniated segment must be strong enough to resist the tensional forces that result from repair of the hernia and the loads generated during daily activities.
• Connection member1003 is also depicted in representative fashion.Member1003 may be in the format of a flexible filament, such as a single or multi-strand suture, wire, or perhaps a rigid rod or broad band of material, for example. The connection member can further include suture, wire, pins, and woven tubes or webs of material. It can be constructed from a variety of materials, either permanent or resorbable, and can be of any shape suitable to fit within the confines of the intervertebral disc space. The material chosen is preferably adapted to be relatively stiff while in tension, and relatively flexible against all other loads. This allows for maximal mobility of the herniated segment relative to the anchor without the risk of the supported segment moving outside of the pre-herniated borders of the disc. The connection member may be an integral component of either the anchor or support member or a separate component. For example, the connection member and support member could be a length of non-resorbing suture that is coupled to an anchor, tensioned against the anchor, and sewn to the herniated segment.
• FIGS. 27A and 27B depict another embodiment ofdevice1013. InFIG. 27A the elements of the herniation constraining device are shown in position prior to securing a herniated segment.Anchor1001 is positioned in the AF andconnection member1003 is attached toanchor1001.Support member1004 is positioned posterior to the posterior-most aspect of herniatedsegment1030. In this way,support member1004 does not need to be secured in herniatedsegment1030 to cause herniatedsegment1030 to move within thepre-herniated borders1040 of the disc.Support member1004 has the same flexibility in design and material asanchor1001, and may further take the form of a flexible patch or rigid plate or bar of material that is either affixed to the posterior aspect of herniatedsegment1030 or is simply in a form that is larger than any hole in the AF directly anterior to supportmember1004.FIG. 27B shows the positions of the elements of the device when tension is applied betweenanchor1001 andsupport member1004 alongconnection member1003. The herniated segment is displaced anteriorly, within thepre-herniated borders1040 of the disc.
• FIGS. 28A and 28B show five examples of suitable anchoring sites within the FSU foranchor1001.FIG. 28A shows an axial view ofanchor1001 in various positions within the anterior and lateral AF.FIG. 28B similarly shows a sagittal view of the various acceptable anchoring sites foranchor1001.Anchor1001 is secured in the superiorvertebral body1050, inferiorvertebral body1050′ oranterior AF1010, although any site that can withstand the tension betweenanchor1001 andsupport member1002 alongconnection member1003 to support a herniated segment within itspre-herniated borders1040 is acceptable.
• Generally, a suitable position for affixing one or more anchors is a location anterior to the herniated segment such that, when tension is applied alongconnection member1003, herniatedsegment1030 is returned to a site within thepre-herniated borders1040. The site chosen for the anchor should be able to withstand the tensile forces applied to the anchor when the connection member is brought under tension. Because most symptomatic herniations occur in the posterior or posterior lateral directions, the preferable site for anchor placement is anterior to the site of the herniation. Any portion of the involved FSU is generally acceptable, however the anterior, anterior medial, or anterior lateral AF is preferable. These portions of the AF have been shown to have considerably greater strength and stiffness than the posterior or posterior lateral portions of the AF. As shown inFIGS. 28A and 28B,anchor1001 can be a single anchor in any of the shown locations, or there can bemultiple anchors1001 affixed in various locations and connected to asupport member1002 to support the herniated segment.Connection member1003 can be one continuous length that is threaded through the sited anchors and the support member, or it can be several individual strands of material each terminated under tension between one or more anchors and one or more support members.
• In various forms of the invention, the anchor(s) and connection member(s) may be introduced and implanted in the patient, with the connection member under tension. Alternatively, those elements may be installed, without introducing tension to the connection member, but where the connection member is adapted to be under tension when the patient is in a non-horizontal position, i.e., resulting from loading in the intervertebral disc.
• FIG. 29 depicts the substantially one-piece device1013asupporting a weakenedsegment1030′ of theposterior AF1010′.Device1013ais positioned in or posterior to the weakenedsegment1030′ and secured to a portion of the FSU, such as the superiorvertebral body1050, shown in the figure, or the inferiorvertebral body1050′ or anterior or anterior-lateral anulus fibrosis1010. In certain patients, there may be no obvious herniation found at surgery. However, a weakened or torn AF that may not be protruding beyond the pre-herniated borders of the disc may still induce the surgeon to remove all or part of the NP in order to decrease the risk of herniation. As an alternative to discectomy, any of the embodiments of the invention may be used to support and perhaps close defects in weakened segments of AF.
• A further embodiment of the present invention involves augmentation of the soft tissues of the intervertebral disc to avoid or reverse disc height loss.FIGS. 30A and 30B show one embodiment ofdevice1013 securing augmentation material in theintervertebral disc space1055. In the left side ofFIG. 30A, anchors1001 have been established in theanterior AF1010.Augmentation material1007 is in the process of being inserted into the disc space alongconnection member1003 which, in this embodiment, haspassageway1009.Support member1002′ is shown ready to be attached toconnection member1003 once theaugmentation material1007 is properly situated. In this embodiment,connection member1003 passes through anaperture1011 insupport member1002′, although many other methods ofaffixing support member1002′ toconnection member1003 are possible and within the scope of this invention.
• Augmentation material1007 may have apassageway1009, such as a channel, slit or the like, which allows it to slide along theconnection member1003, oraugmentation material1007 may be solid, andconnection member1003 can be threaded through augmentation material by means such as needle or other puncturing device.Connection member1003 is affixed at one end to anchor1001 and terminated at its other end by asupport member1002′, one embodiment of which is shown in the figure in a cap-like configuration.Support member1002′ can be affixed toconnection member1003 in a variety of ways, including, but not limited to, swagingsupport member1002′ toconnection member1003. In a preferred embodiment,support member1002′ is in a cap configuration and has a dimension (diameter or length and width) larger than theoptional passageway1009, which serves to preventaugmentation material1007 from displacing posteriorly with respect toanchor1001. The right half of the intervertebral disc ofFIG. 30A (axial view) andFIG. 30B (sagittal view)show augmentation material1007 that has been implanted into thedisc space1055 alongconnection member1003 where it supports thevertebral bodies1050 and1050′.FIG. 30A shows an embodiment in whichsupport member1002′ is affixed toconnection member1003 and serves only to preventaugmentation material1007 from moving offconnection member1003. The augmentation device is free to move within the disc space.FIG. 30B shows an alternate embodiment in whichsupport member1002′ is embedded in a site in the functional spine unit, such as a herniated segment or posterior anulus fibrosis, to further restrict the movement ofaugmentation material1007 or spacer material within the disc space.
• Augmentation or spacer material can be made of any biocompatible, preferably flexible, material. Such a flexible material is preferably fibrous, like cellulose or bovine or autologous collagen. The augmentation material can be plug or disc shaped. It can further be cube-like, ellipsoid, spheroid or any other suitable shape. The augmentation material can be secured within the intervertebral space by a variety of methods, such as but not limited to, a suture loop attached to, around, or through the material, which is then passed to the anchor and support member.
• Any of the devices described herein can be used for closing defects in the AF whether created surgically or during the herniation event. Such methods may also involve the addition of biocompatible material to either the AF or NP. This material could include sequestered or extruded segments of the NP found outside the pre-herniated borders of the disc.
• It should be understood that the foregoing description of the invention is intended merely to be illustrative thereof and that other embodiments, modifications, and equivalents of the invention are within the scope of the invention recited in the claims appended hereto. Further, although each embodiment described above includes certain features, the invention is not limited in this respect. Thus, one or more of the above-described or other features of the prosthesis, method of implantation, or delivery device, may be employed singularly or in any suitable combination, as the present invention is not limited to a specific embodiment.

Claims (26)

1. A method or implanting a prosthesis material into an interior region of a vertebral disc, the vertebral disc having first and second endplates, the method comprising:

locating an access site on the disc;

inserting, through an opening of the disc at the access site, the prosthesis material into the interior region of the vertebral disc without removing a substantial amount of nucleus pulposus;

spacing the prosthesis material from the endplates of the vertebral disc such that the nucleus pulposus substantially surrounds the prosthesis material; and

monitoring at least one of: a) one or more characteristics of the vertebral disc, and b) one or more characteristics of the prosthesis material.

2. The method according toclaim 1, wherein locating an access site comprises forming an opening in the annulus fibrosis of the vertebral disc.

3. The method according toclaim 1, wherein locating an access site comprises locating a defect in the annulus fibrosis of the vertebral disc.

4. The method according toclaim 1, wherein monitoring one or more characteristics of the vertebral disc comprises monitoring a disc height of the vertebral disc.

5. The method according toclaim 1, wherein inserting the prosthesis material into the interior region of the vertebral disc comprises inserting an amount of prosthesis material into the interior region of the vertebral disc until a desired increased disc height is achieved.

6. The method according toclaim 5, wherein inserting an amount of prosthesis material into the interior region of the vertebral disc until a desired increased disc height is achieved comprises inserting an amount of prosthesis material into the interior region of the vertebral disc until a height ranging between approximately 1 mm and approximately 10 mm is achieved.

7. The method according toclaim 5, wherein inserting an amount of prosthesis material into the interior region of the vertebral disc until a desired increased disc height is achieved comprises inserting an amount of prosthesis material into the interior region of the vertebral disc until a height ranging between approximately 0.1 mm and approximately 3 mm is achieved.

8. The method according toclaim 5, wherein inserting an amount of prosthesis material into the interior region of the vertebral disc until a desired increased disc height is achieved comprises inserting an amount of prosthesis material into the interior region of the vertebral disc until a height ranging between approximately 3 mm and approximately 6 mm is achieved.

9. The method according toclaim 5, wherein inserting an amount of prosthesis material into the interior region of the vertebral disc until a desired disc height is achieved comprises inserting an amount of prosthesis material into the interior region of the vertebral disc until a height ranging between approximately 6 mm and approximately 9 mm is achieved.

10. The method according toclaim 1, wherein monitoring one or more characteristics of the prosthesis material comprises monitoring a volume of prosthesis material inserted into the interior region of the vertebral disc.

11. The method according toclaim 10, wherein inserting the prosthesis material into the interior region of the vertebral disc comprises inserting approximately 0.1 ml to approximately 6 ml of the prosthesis material into the interior region of the vertebral disc.

12. The method according toclaim 1, wherein monitoring one or more characteristics of the vertebral disc comprises monitoring a disc pressure of the vertebral disc.

13. The method according toclaim 12, wherein inserting the prosthesis material into the interior region of the vertebral disc comprises inserting an amount of prosthesis material into the interior region of the vertebral disc until a desired disc pressure is achieved.

14. The method according toclaim 13, wherein inserting an amount of prosthesis material into the interior region of the vertebral disc until a desired disc pressure is achieved comprises inserting an amount of prosthesis material into the interior region of the vertebral disc until a disc pressure ranging between approximately 1 atmospheres and 5 atmospheres is achieved.

15. The method according toclaim 1, wherein inserting the prosthesis material into the interior region of the vertebral disc comprises inserting hydrogel material into the interior region of the vertebral disc.

16. The method according toclaim 1, wherein inserting the prosthesis material into the interior region of the vertebral disc comprises inserting an isotropic mass of material into the interior region of the vertebral disc.

17. The method according toclaim 1, further comprising shaping the prosthesis material so as to resist extrusion from the interior region of the vertebral disc.

18. The method according toclaim 1, further comprising positioning the prosthesis material so as to alter an axis of rotation of the spine.

19. The method according toclaim 1, further comprising forming the prosthesis material with a therapeutic amount of a desired substance.

20. The method according toclaim 1, wherein inserting the prosthesis material into the interior region of the vertebral disc comprises inserting a prosthesis material having compressive strength that is less than 4 MN/m².

21. The method according toclaim 1, further comprising locating the prosthesis material within the interior region of the vertebral disc and adjacent the annulus fibrosis.

22. The method according toclaim 1, wherein the step of monitoring at least one of: a) one or more characteristics of the vertebral disc, and b) one or more characteristics of the prosthesis material comprises:

monitoring at least one said characteristic of the disc and at least one said characteristic of the prosthesis material.

23. The method according toclaim 1, wherein the step of monitoring a disc characteristic comprises:

monitoring a characteristic selected from the group consisting of one or more of the following: disc height, disc pressure, and disc volume.

24. The method according toclaim 1, wherein the step of monitoring occurs during insertion of said prosthesis material.

25. The method according toclaim 1, wherein the step of monitoring at least one of: a) one or more characteristics of the vertebral disc, and b) one or more characteristics of the prosthesis material comprises:

monitoring the height of the disc at one or more of the following times: during the implantation procedure, prior to the implantation procedure or after the implantation procedure.

26. The method according toclaim 25, further comprising

obtaining comparative data obtained from monitoring the height of the disc at two or more of the following times: during the implantation procedure, prior to the implantation procedure or after the implantation procedure; and

using said data to evaluate disc height.

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