US20050060038A1 - Flexible implant for intervertebral disc repair - Google Patents

Abstract

Devices for implantation into an intervertebral disc can include a membrane support member to augment a disc having a defect. A defect in the anulus of a disc can be repaired using a prosthesis such as a barrier. The barrier can include a sealant and an enlarger. The barrier can be implanted into the disc using a delivery cannula, an advancer and at least one control filament to control the positioning of the barrier. A stiffening element can be included within the barrier to impart stiffness to the barrier. The support member can also be connected to an anchor.

Description

RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 10/237,332, filed on Sep. 5, 2002, which is a continuation 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. 6,425,915, and claims benefit to U.S. Provisional Application No. 60/149,490 filed Aug. 18, 1999, U.S. Provisional Application No. 60/161,085 filed Oct. 25, 1999 and U.S. Provisional Application No. 60/172,996 filed Dec. 21, 1999, the entire teachings of each of which are incorporated in their entirety into this disclosure by reference.
BACKGROUND OF THE INVENTION
• The present invention relates to the surgical treatment of intervertebral discs in the lumbar, cervical, or thoracic spine that have suffered from tears in the anulus fibrosis, herniation of the nucleus pulposus and/or significant disc height loss.
• The disc performs the important role of absorbing mechanical loads while allowing for constrained flexibility of the spine. The disc is composed of a soft, central nucleus pulposus (NP) surrounded by a tough, woven anulus fibrosis (AF). 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 posteriorly toward the spinal cord and major nerve roots. The most common resulting symptoms are pain radiating along a compressed nerve and low back pain, both of which can be crippling for the patient. The significance of this problem is increased by the low average age of diagnosis, with over 80% of patients in the U.S. being under 59.
• Since its original description by Mixter & Barr in 1934, discectomy has been the most common surgical procedure for treating intervertebral disc herniation. This procedure involves removal of disc materials impinging on the nerve roots or spinal cord external to the disc, generally posteriorly. Depending on the surgeon's preference, varying amounts of NP are then 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.
• Nevertheless, the most significant drawbacks of discectomy are recurrence of herniation, recurrence of radicular symptoms, and increasing low back pain. Re-herniation can occur in up to 21% of cases. The site for re-herniation is most commonly the same level and side as the previous herniation and can occur through the same weakened site in the AF. Persistence or recurrence of radicular symptoms happens in many patients and when not related to re-herniation, tends to be linked to stenosis of the neural foramina caused by a loss in height of the operated disc. Debilitating low back pain occurs in roughly 14% of patients. All of these failings are most directly related to the loss of NP material and AF competence that results from herniation and surgery.
• Loss of NP material 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. This can result in deterioration of facet cartilage and ultimately osteoarthritis and pain in this joint. As the joint space decreases the neural foramina formed by the inferior and superior vertebral pedicles also close down. This leads to foraminal stenosis, pinching of the traversing nerve root, and recurring radicular pain. Loss of NP also increases loading on the remaining AF, a partially innervated structure that can produce pain. Finally, loss of NP results in greater bulging of the AF under load. This can result in renewed impingement by the AF on nerve structures posterior to the disc.
• Persisting tears in the AF that result either from herniation or surgical incision also contribute to poor results from discectomy. The AF has limited healing capacity with the greatest healing occurring in its outer borders. Healing takes the form of a thin fibrous film that does not approach the strength of the uninjured disc. Surgical incision in the AF has been shown to produce immediate and long lasting decreases in stiffness of the AF particularly against torsional loads. This may over-stress the facets and contribute to their deterioration. Further, in as many as 30% of cases, the AF never closes. In these cases, not only is re-herniation a risk but also leakage of fluids or solids from within the NP into the epidural space can occur. This has been shown to cause localized pain, irritation of spinal nerve roots, decreases in nerve conduction velocity, and may contribute to the formation of post-surgical scar tissue in the epidural space.
• Other orthopedic procedures involving removal of soft tissue from a joint to relieve pain have resulted in significant, long lasting consequences. Removal of all or part of the menisci of the knee is one example. Partial and total meniscectomy leads to increased osteoarthritic degeneration in the knee and the need for further surgery in many patients. A major effort among surgeons to repair rather than resect torn menisci has resulted in more durable results and lessened joint deterioration.
• Systems and methods for repairing tears in soft tissues are known in the art. One such system relates to the repair of the menisci of the knee and is limited to a barbed tissue anchor, an attached length of suture, and a suture-retaining member, which can be affixed to the suture and used to draw the sides of a tear into apposition. The drawback of this method is that it is limited to the repair of a tear in soft tissue. In the intervertebral disc, closure of a tear in the AF does not necessarily prevent further bulging of that disc segment toward the posterior neural elements. Further, there is often no apparent tear in the AF when herniation occurs. Herniation can be a result of a general weakening in the structure of the AF (soft disc) that allows it to bulge posteriorly without a rupture. When tears do occur, they are often radial.
• Another device known in the art is intended for repair of a tear in a previously contiguous soft tissue. Dart anchors are placed across the tear in a direction generally perpendicular to the plane of the tear. Sutures leading from each of at least two anchors are then tied together such that the opposing sides of the tear are brought together. However, all of the limitations pertaining to repair of intervertebral discs, as described above, pertain to this device.
• Also known in the art is an apparatus and method of using tension to induce growth of soft tissue. The known embodiments and methods are limited in their application to hernias of the intervertebral disc in that they require a spring to apply tension. Aside from the difficulty of placing a spring within the limited space of the intervertebral disc, a spring will induce a continuous displacement of the attached tissues that could be deleterious to the structure and function of the disc. A spring may further allow a posterior bulge in the disc to progress should forces within the disc exceed the tension force applied by the spring. Further, the known apparatus is designed to be removed once the desired tissue growth has been achieved. This has the drawback of requiring a second procedure.
• There are numerous ways of augmenting the intervertebral disc disclosed in the art. In reviewing the art, two general approaches are apparent—implants that are fixed to surrounding tissues and those that are not fixed, relying instead on the AF to keep them in place.
• The first type of augmenting of the intervertebral disc includes generally replacing the entire disc. This augmentation is limited in many ways. First, by replacing the entire disc, they generally must endure all of the loads that are transferred through that disc space. Many degenerated discs are subject to pathologic loads that exceed those in normal discs. Hence, the designs must be extremely robust and yet flexible. None of these augmentation devices has yet been able to achieve both qualities. Further, devices that replace the entire disc must be implanted using relatively invasive procedures, normally from an anterior approach. They may also require the removal of considerable amounts of healthy disc material including the anterior AF. Further, the disclosed devices must account for the contour of the neighboring vertebral bodies to which they are attached. Because each patient and each vertebra is different, these types of implants must be available in many shapes and sizes.
• The second type of augmentation involves an implant that is not directly fixed to surrounding tissues. These augmentation devices rely on an AF that is generally intact to hold them in place. The known implants are generally inserted through a hole in the AF and either expand, are inflated, or deploy expanding elements so as to be larger than the hole through which they are inserted. The limitation of these concepts is that the AF is often not intact in cases requiring augmentation of the disc. There are either rents in the AF or structural weaknesses that allow herniation or migration of the disclosed implants. In the case of a disc herniation, there are definite weaknesses in the AF that allowed the herniation to occur. Augmenting the NP with any of the known augmentation devices without supporting the AF or implant risks re-herniation of the augmenting materials. Further, those devices with deployable elements risk injuring the vertebral endplates or the AF. This may help to retain the implant in place, but again herniations do not require a rent in the AF. Structural weakness in or delamination of the multiple layers of the AF can allow these implants to bulge toward the posterior neural elements. Additionally, as the disc continues to degenerate, rents in the posterior anulus may occur in regions other than the original operated site. A further limitation of these concepts is that they require the removal of much or all of the NP to allow insertion of the implant. This requires time and skill to achieve and permanently alters the physiology of the disc.
• Implanting prostheses in specific locations within the intervertebral disc is also a challenging task. The interior of the disc is not visible to the surgeon during standard posterior spinal procedures. Very little of the exterior of the disc can be seen through the small window created by the surgeon in the posterior elements of the vertebrae to gain access to the disc. The surgeon further tries to minimize the size of any annular fenestration into the disc in order to reduce the risk of postoperative herniation and/or further destabilization of the operated level. Surgeons generally open only one side of the posterior anulus in order to avoid scarring on both sides of the epidural space.
• The rigorous requirements presented by these limitations on access to and visualization of the disc are not well compensated for by any of the intradiscal prosthesis implantation systems currently available.
• The known art relating to the closure of body defects such as hernias through the abdominal wall involve devices such as planer patches applied to the interior of the abdominal wall or plugs that are placed directly into the defect. The known planar patches are limited in their application in the intervertebral disc by the disc's geometry.
• The interior aspect of the AF is curved in multiple planes, making a flat patch incongruous to the surface against which it must seal. Finally, the prior art discloses patches that are placed into a cavity that is either distended by gas or supported such that the interior wall of the defect is held away from internal organs. In the disc, it is difficult to create such a cavity between the inner wall of the anulus and the NP without removing nucleus material. Such removal may be detrimental to the clinical outcome of disc repair.
• One hernia repair device known in the art is an exemplary plug. This plug may be adequate for treating inguinal hernias, due to the low pressure difference across such a defect. However, placing a plug into the AF that must resist much higher pressures may result in expulsion of the plug or dissection of the inner layers of the anulus by the NP. Either complication would lead to extraordinary pain or loss of function for the patient. Further, a hernia in the intervertebral disc is likely to spread as the AF progressively weakens. In such an instance, the plug may be expelled into the epidural space.
• Another hernia repair device involves a curved prosthetic mesh for use in inguinal hernias. The device includes a sheet of material that has a convex side and a concave side and further embodiments with both spherical and conical sections. This device may be well suited for inguinal hernias, but the shape and stiffness of the disclosed embodiments are less than optimal for application in hernias of the intervertebral disc. Hernias tend to be broader (around the circumference of the disc) than they are high (the distance between the opposing vertebrae), a shape that does not lend itself to closure by such conical or spherical patches.
• Another device involves an inflatable, barbed balloon patch used for closing inguinal hernias. This balloon is left inflated within the defect. A disadvantage of this device is that the balloon must remain inflated for the remainder of the patient's life to insure closure of the defect. Implanted, inflated devices rarely endure long periods without leaks, particularly when subjected to high loads. This is true of penile prostheses, breast implants, and artificial sphincters.
• Another known method of closing inguinal hernias involves applying both heat and pressure to a planar patch and the abdominal wall surrounding the hernia. This method has the drawback of relying entirely on the integrity of the wall surrounding the defect to hold the patch in place. The anulus is often weak in areas around a defect and may not serve as a suitable anchoring site. Further, the planar nature of the patch has all of the weaknesses discussed above.
• Various devices and techniques have further been disclosed for sealing vascular puncture sites. The most relevant is a hemostatic puncture-sealing device that generally consists of an anchor, a filament and a sealing plug. The anchor is advanced into a vessel through a defect and deployed such that it resists passage back through the defect. A filament leading from the anchor and through the defect can be used to secure the anchor or aid in advancing a plug that is brought against the exterior of the defect. Such a filament, if it were to extend to the exterior of the disc, could lead to irritation of nerve roots and the formation of scar tissue in the epidural space. This is also true of any plug material that may be left either within the defect or extending to the exterior of the disc. Additionally, such devices and methods embodied for use in the vascular system require a space relatively empty of solids for the deployment of the interior anchor. This works well on the interior of a vessel, however, in the presence of the more substantial NP, the disclosed internal anchors are unlikely to orient across the defect as disclosed in their inventions.
SUMMARY OF THE INVENTION
• It is an object of the disclosed invention to reduce the long-term negative consequences of back injuries such as herniated discs by repairing and/or augmenting rather than resecting the soft tissues of the disc. It is a further object of this invention to prevent or reduce the occurrence of re-herniation and disc height loss following surgical therapy for herniated discs. It is a further object of this invention to increase the AF's resistance to posterior bulging and leakage of NP material while preferably increasing its stiffness under load. It is a further object of this invention to permit the augmentation of the soft tissues of the disc in such a way so as to limit the risk of the herniation of any augmentation materials toward nerve structures posterior to the disc. It is a further object of the present invention to shield the sensitive nerve fibers in the outer layers of the anulus from pressures within the nucleus.
• In one aspect of the present invention there is provided an in vivo augmented functional spine unit. The augmented functional spine unit includes the two adjoining vertebrae and the intervertebral disc, composed of a central region surrounded by an anulus fibrosis and situated in the intervertebral disc space between the vertebra, and a disc herniation constraining device situated within the intervertebral disc space. The disc herniation constraining device includes an anchor fixedly coupled to an anterior portion of one of the adjoining vertebrae or anulus fibrosis and is connected to a support member by a connecting member. The support member is positioned posterior to the central region, preferably in or posterior to the anulus fibrosis. In one embodiment the central region of the functional spine unit contains a nucleus pulposus. In another embodiment of the invention, the connection member is maintained under tension between the anchor and the support member. In yet another embodiment, augmentation material is secured along at least a portion of the length of the connection member, which serves to assist the function of the intervertebral disc in supporting and separating the vertebrae, and allowing motion of one vertebra relative to the other.
• In another aspect of the invention there is provided an in vivo augmented functional spine unit. The augmented functional spine unit includes the two adjoining vertebrae and the intervertebral disc, composed of a central region surrounded by an anulus fibrosis and situated in the intervertebral disc space between the vertebra, and a disc augmentation device situated within the intervertebral disc space. The disc augmentation device includes an anchor fixedly coupled to an anterior portion of one of the adjoining vertebrae or anulus fibrosis, augmentation material situated in the intervertebral disc space and restrained therein by a connection member secured between the anchor and the augmentation material. In an alternate embodiment, a support member is secured within the functional spine unit, the connection member extends between the anchor, the augmentation material and the support member, further restraining the movement of the augmentation material within the central region. In yet another embodiment, the central region may contain a nucleus pulposus.
• In yet another aspect of the present invention there are provided methods of augmenting a functional spine unit. These methods include using the disc herniation constraining devices and the disc augmentation devices disclosed herein.
• The present invention further relates to devices and methods for sealing defects in tissue walls separating two anatomic regions of the body. Specifically, prosthetic devices and methods are disclosed which allow the closure of a defect in the AF of the human intervertebral disc, preventing the egress of material from within the disc and/or distributing pressure within the disc space across an inner wall surface of the disc.
• Closure of the defect is achieved by placing a membrane or barrier on an interior aspect of the defect. In the case of the intervertebral disc, the barrier is positioned either on the interior aspect of the AF proximate to the NP or between layers of the AF. The barrier means may be inserted by dissecting a space between the anulus and nucleus. Alternatively, a portion of the nucleus and/or anulus may be resected to create adequate space.
• The barrier may be inserted into position directly through the defect or alternatively it may be advanced from a remote entry through the tissue wall or other tissue neighboring the defect.
• Various fixation devices can be used to secure the barrier to surrounding tissues. In the intervertebral disc, these tissues can include the surrounding AF, vertebral endplates, vertebral bodies, and even NP. Alternatively, the barrier can be held in place simply by the pressure the NP exerts on the barrier and AF where the stiffness and shape of the barrier patch may also help to maintain position and orientation within the disc. The barrier may further incorporate various self-retaining members that resist motion of the barrier within the disc. The barrier or membrane may incorporate a frame that can serve to enlarge or expand the dimensions of the barrier from a compressed state to an enlarged state. The frame can be a self expanding material such as a nickel titanium material. The barrier may further have properties that cause it to adhere to surrounding tissues either with an adhesive, by the application of heat, or ingrowth/ongrowth of surrounding tissue. Various embodiments of the disclosed barrier are composed of either singular materials and components or a multiplicity of materials and components.
• It is a further object of the present invention to reduce the limitations of current disc repair methods. It is a further object of the present invention to provide systems and methods for implanting a prosthesis along the interior aspect of the anulus through a single, small anulotomy from the posterior aspect of the disc.
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
• FIG. 1A shows a transverse section of a portion of a functional spine unit, in which part of a vertebra and intervertebral disc are depicted.
• FIG. 1B shows a sagittal cross section of a portion of a functional spine unit shown inFIG. 1A, in which two lumbar vertebrae and the intervertebral disc are visible.
• FIG. 1C shows partial disruption of the inner layers of an anulus fibrosis.
• FIG. 2A shows a transverse section of one aspect of the present invention prior to supporting a herniated segment.
• FIG. 2B shows a transverse section of the construct inFIG. 2A supporting the herniated segment.
• FIG. 3A shows a transverse section of another embodiment of the disclosed invention after placement of the device.
• FIG. 3B shows a transverse section of the construct inFIG. 3A after tension is applied to support the herniated segment.
• FIG. 4A shows a transverse view of an alternate embodiment of the invention.
• FIG. 4B shows a sagittal view of the alternate embodiment shown inFIG. 4A.
• FIG. 5A shows a transverse view of another aspect of the present invention.
• FIG. 5B shows the delivery tube ofFIG. 5A being used to displace the herniated segment to within its pre-herniated borders.
• FIG. 5C shows a one-piece embodiment of the invention in an anchored and supporting position.
• FIG. 6 shows one embodiment of the invention supporting a weakened posterior anulus fibrosis.
• FIG. 7A 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. 7B shows a sagittal view of the invention shown inFIG. 7A.
• FIG. 8 shows a transverse section of one aspect of the disclosed invention involving augmentation of the soft tissues of the disc and support/closure of the anulus fibrosis.
• FIG. 9A shows a transverse section of one aspect of the invention involving augmentation of the soft tissues of the disc with the flexible augmentation material anchored to the anterior lateral anulus fibrosis.
• FIG. 9B shows a transverse section of one aspect of the disclosed invention involving augmentation of the soft tissues of the disc with the flexible augmentation material anchored to the anulus fibrosis by a one-piece anchor.
• FIG. 10A shows a transverse section of one aspect of the disclosed invention involving augmentation of the soft tissues of the disc.
• FIG. 10B shows the construct ofFIG. 10A after the augmentation material has been inserted into the disc.
• FIG. 11 illustrates a transverse section of a barrier mounted within an anulus.
• FIG. 12 shows a sagittal view of the barrier ofFIG. 11.
• FIG. 13 shows a transverse section of a barrier anchored within a disc.
• FIG. 14 illustrates a sagittal view of the barrier shown inFIG. 13.
• FIG. 15 illustrates the use of a second anchoring device for a barrier mounted within a disc.
• FIG. 16A is an transverse view of the intervertebral disc.
• FIG. 16B is a sagittal section along the midline of the intervertebral disc.
• FIG. 17 is an axial view of the intervertebral disc with the right half of a sealing means of a barrier means being placed against the interior aspect of a defect in anulus fibrosis by a dissection/delivery tool.
• FIG. 18 illustrates a full sealing means placed on the interior aspect of a defect in anulus fibrosis.
• FIG. 19 depicts the sealing means ofFIG. 18 being secured to tissues surrounding the defect.
• FIG. 20 depicts the sealing means ofFIG. 19 after fixation means have been passed into surrounding tissues.
• FIG. 21A depicts an axial view of the sealing means ofFIG. 20 having enlarging means inserted into the interior cavity.
• FIG. 21B depicts the construct ofFIG. 21 in a sagittal section.
• FIG. 22A shows an alternative fixation scheme for the sealing means and enlarging means.
• FIG. 22B shows the construct ofFIG. 22A in a sagittal section with an anchor securing a fixation region of the enlarging means to a superior vertebral body in a location proximate to the defect.
• FIG. 23A depicts an embodiment of the barrier means of the present invention being secured to an anulus using fixation means.
• FIG. 23B depicts an embodiment of the barrier means ofFIG. 23A secured to an anulus by two fixation darts wherein the fixation tool has been removed.
• FIGS. 24A and 24B depict a barrier means positioned between layers of the anulus fibrosis on either side of a defect.
• FIG. 25 depicts an axial cross section of a large version of a barrier means.
• FIG. 26 depicts an axial cross section of a barrier means in position across a defect following insertion of two augmentation devices.
• FIG. 27 depicts the barrier means as part of an elongated augmentation device.
• FIG. 28A depicts an axial section of an alternate configuration of the augmentation device ofFIG. 27.
• FIG. 28B depicts a sagittal section of an alternate configuration of the augmentation device ofFIG. 27.
• FIGS.29A-D depict deployment of a barrier from an entry site remote from the defect in the anulus fibrosis.
• FIGS. 30A, 30B,31A,31B,32A,32B,33A, and33B depict axial and sectional views, respectively, of various embodiments of the barrier.
• FIG. 34A shows a non-axisymmetric expansion means or frame.
• FIGS. 34B and 34C illustrate perspective views of a frame mounted within an intervertebral disc.
• FIGS. 35 and 36 illustrate alternate embodiments of the expansion means shown inFIG. 34.
• FIGS.37A-C illustrate a front, side, and perspective view, respectively, of an alternate embodiment of the expansion means shown inFIG. 34.
• FIG. 38 shows an alternate expansion means to that shown inFIG. 37A.
• FIGS.39A-D illustrate a tubular expansion means having a circular cross-section.
• FIGS.40A-D illustrate a tubular expansion means having an oval shaped cross-section.
• FIGS. 40E, 40F and40I illustrate a front, back and top view, respectively of the tubular expansion means ofFIG. 40A having a sealing means covering an exterior surface of an anulus face.
• FIGS. 40G and 40H show the tubular expansion means ofFIG. 40A having a sealing means covering an interior surface of an anulus face.
• FIGS.41A-D illustrate a tubular expansion means having an egg-shaped cross-section.
• FIGS.42A-D depicts cross sections of a preferred embodiment of sealing and enlarging means.
• FIGS. 43A and 43B depict an alternative configuration of enlarging means.
• FIGS. 44A and 44B depict an alternative shape of the barrier means.
• FIG. 45 is a section of a device used to affix sealing means to tissues surrounding a defect.
• FIG. 46 depicts the use of a thermal device to heat and adhere sealing means to tissues surrounding a defect.
• FIG. 47 depicts an expandable thermal element that can be used to adhere sealing means to tissues surrounding a defect.
• FIG. 48 depicts an alternative embodiment to the thermal device ofFIG. 46.
• FIGS.49A-G illustrate a method of implanting an intradiscal implant.
• FIGS.50A-F show an alternate method of implanting an intradiscal implant.
• FIGS.51A-C show another alternate method of implanting an intradiscal implant.
• FIGS. 52A and 52B illustrate an implant guide used with the intradiscal implant system.
• FIG. 53A illustrates a barrier having stiffening plate elements.
• FIG. 53B illustrates a sectional view of the barrier ofFIG. 53A.
• FIG. 54A shows a stiffening plate.
• FIG. 54B shows a sectional view of the stiffening plate ofFIG. 54A.
• FIG. 55A illustrates a barrier having stiffening rod elements.
• FIG. 55B illustrates a sectional view of the barrier ofFIG. 55A.
• FIG. 56A illustrates a stiffening rod.
• FIG. 56B illustrates a sectional view of the stiffening rod ofFIG. 56A.
• FIG. 57 shows an alternate configuration for the location of the fixation devices of the barrier ofFIG. 44A.
• FIGS. 58A and 58B illustrate a dissection device for an intervertebral disc.
• FIGS. 59A and 59B illustrate an alternate dissection device for an intervertebral disc.
• FIGS.60A-C illustrate a dissector component.
• FIGS.61A-D illustrate a method of inserting a disc implant within an intervertebral disc.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The present invention provides 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. 1A and 1B show the general anatomy of afunctional 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. 1A is an axial view along the transverse axis M of a vertebral body with theintervertebral disc15 superior to the vertebral body. Axis M shows the anterior (A) and posterior (P) orientation of the functional spine unit within the anatomy. Theintervertebral disc15 contains the anulus fibrosis (AF)10 which surrounds a central nucleus pulposus (NP)20. AHerniated segment30 is depicted by a dashed-line. The herniatedsegment30 protrudes beyond the pre-herniatedposterior border40 of the disc. Also shown in this figure are the left70 and right70′ transverse spinous processes and the posteriorspinous process80.
• FIG. 1B is a sagittal section along sagittal axis N through the midline of two adjacent vertebral bodies50 (superior) and50′ (inferior).Intervertebral disc space55 is formed between the two vertebral bodies and containsintervertebral 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.
• Intervertebral disc15 is comprised of theouter AF10 which normally surrounds and constrains theNP20 to be wholly within the borders of the intervertebral disc space. InFIGS. 1A and 1B, herniatedsegment30, represented by the dashed-line, has migrated posterior to thepre-herniated border40 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 include facet joints60 and the superior90 and inferior90′ pedicle that form theneural foramen100. Disc height loss occurs when the superiorvertebral body50 moves inferiorly relative to the inferiorvertebral body50′.
• Partial disruption121 of the inner layers of theanulus10 without a true perforation has also been linked to chronic low back pain. Such adisruption4 is illustrated inFIG. 1C. It is thought that weakness of these inner layers forces the sensitive outer annular 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 devices13 provide support for returning all or part of the herniatedsegment30 to a position substantially within itspre-herniated borders40. 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. 2A and 2B depict one embodiment ofdevice13.FIG. 2A shows the elements of the constraining device in position to correct the herniated segment.Anchor1 is securely established in a location within the functional spine unit, such as the anterior AF shown in the figure.Support member2 is positioned in or posterior to herniatedsegment30. Leading from and connected to anchor1 isconnection member3, which serves to connectanchor1 to supportmember2. Depending on the location chosen forsupport member2, the connection member may traverse through all or part of the herniated segment.
• FIG. 2B shows the positions of the various elements of theherniation constraining device13 when thedevice13 is supporting the herniated segment. Tighteningconnection member2 allows it to transmit tensile forces along its length, which causes herniatedsegment30 to move anteriorly, i.e., in the direction of its pre-herniated borders. Once herniatedsegment30 is in the desired position,connection member3 is secured in a permanent fashion betweenanchor1 andsupport member2. This maintains tension betweenanchor1 andsupport member2 and restricts motion of the herniated segment to within thepre-herniated borders40 of the disc.Support member2 is used to anchor to herniatedsegment30, 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 herniatedsegment30.
• Anchor1 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.Anchor1 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,anchor1 should remain relatively stationary within the bone or tissue.
• Support member2 is also depicted in a representative format and shares the same flexibility in material and design asanchor1. 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 member2 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 member2 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 member3 is also depicted in representative fashion.Member3 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. 3A and 3B depict another embodiment ofdevice13. InFIG. 3A the elements of the herniation constraining device are shown in position prior to securing a herniated segment.Anchor1 is positioned in the AF andconnection member3 is attached toanchor1.Support member4 is positioned posterior to the posterior-most aspect of herniatedsegment30. In this way,support member4 does not need to be secured in herniatedsegment30 to cause herniatedsegment30 to move within thepre-herniated borders40 of the disc.Support member4 has the same flexibility in design and material asanchor1, 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 herniatedsegment30 or is simply in a form that is larger than any hole in the AF directly anterior to supportmember4.FIG. 3B shows the positions of the elements of the device when tension is applied betweenanchor1 andsupport member4 alongconnection member3. The herniated segment is displaced anteriorly, within thepre-herniated borders40 of the disc.
• FIGS. 4A and 4B show five examples of suitable anchoring sites within the FSU foranchor1.FIG. 4A shows an axial view ofanchor1 in various positions within the anterior and lateral AF.FIG. 4B similarly shows a sagittal view of the various acceptable anchoring sites foranchor1.Anchor1 is secured in the superiorvertebral body50, inferiorvertebral body50′ oranterior AF10, although any site that can withstand the tension betweenanchor1 andsupport member2 alongconnection member3 to support a herniated segment within itspre-herniated borders40 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 member3, herniatedsegment30 is returned to a site within the pre-herniated borders40. 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. 4A and 4B,anchor1 can be a single anchor in any of the shown locations, or there can bemultiple anchors1 affixed in various locations and connected to asupport member2 to support the herniated segment.Connection member3 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.
• FIGS.5A-C show an alternate embodiment of herniation constraining device13A. In this series of figures, device13A, a substantially one-piece construct, is delivered through adelivery tube6, although device13A could be delivered in a variety of ways including, but not limited to, by hand or by a hand held grasping instrument. InFIG. 5A, device13A indelivery tube6 is positioned against herniatedsegment30. InFIG. 5B, the herniated segment is displaced within itspre-herniated borders40 by device13A and/ordelivery tube6 such that when, inFIG. 5C, device13A has been delivered throughdelivery tube6, and secured within a portion of the FSU, the device supports the displaced herniated segment within itspre-herniated border40. Herniation constraining device13A can be made of a variety of materials and have one of many possible forms so long as it allows support of the herniatedsegment30 within thepre-herniated borders40 of the disc. Device13A can anchor the herniatedsegment30 to any suitable anchoring site within the FSU, including, but not limited to the superior vertebral body, inferior vertebral body, or anterior AF. Device13A may be used additionally to close a defect in the AF of herniatedsegment30. Alternatively, any such defect may be left open or may be closed using another means.
• FIG. 6 depicts the substantially one-piece device13A supporting a weakenedsegment30′ of theposterior AF10′. Device13A is positioned in or posterior to the weakenedsegment30′ and secured to a portion of the FSU, such as the superiorvertebral body50, shown in the figure, or the inferiorvertebral body50′ or anterior or anterior-lateral anulus fibrosis10. 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. 7A and 7B show one embodiment ofdevice13 securing augmentation material in theintervertebral disc space55. In the left side ofFIG. 7A, anchors1 have been established in theanterior AF10.Augmentation material7 is in the process of being inserted into the disc space alongconnection member3 which, in this embodiment, haspassageway9.Support member2′ is shown ready to be attached toconnection member3 once theaugmentation material7 is properly situated. In this embodiment,connection member3 passes through anaperture11 insupport member2′, although many other methods ofaffixing support member2′ toconnection member3 are possible and within the scope of this invention.
• Augmentation material7 may have apassageway9, such as a channel, slit or the like, which allows it to slide along theconnection member3, oraugmentation material7 may be solid, andconnection member3 can be threaded through augmentation material by means such as needle or other puncturing device.Connection member3 is affixed at one end toanchor1 and terminated at its other end by asupport member2′, one embodiment of which is shown in the figure in a cap-like configuration.Support member2′ can be affixed toconnection member3 in a variety of ways, including, but not limited to, swagingsupport member2′ toconnection member3. In a preferred embodiment,support member2′ is in a cap configuration and has a dimension (diameter or length and width) larger than theoptional passageway9, which serves to preventaugmentation material7 from displacing posteriorly with respect toanchor1. The right half of the intervertebral disc ofFIG. 7A (axial view) andFIG. 7B (sagittal view)show augmentation material7 that has been implanted into thedisc space55 alongconnection member3 where it supports thevertebral bodies50 and50′.FIG. 7A shows an embodiment in whichsupport member2′ is affixed toconnection member3 and serves only to preventaugmentation material7 from moving offconnection member3. The augmentation device is free to move within the disc space.FIG. 7B shows an alternate embodiment in whichsupport member2′ 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 material7 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.
• FIGS. 8, 9A,9B and10A and10B depict further embodiments of the disc herniation constraining device13B in use for augmenting soft tissue, particularly tissue within the intervertebral space. In the embodiments shown inFIGS. 8 and 9A, device13B is secured within the intervertebral disc space providing additional support forNP20.Anchor1 is securely affixed in a portion of the FSU, (anterior AF10 in these figures).Connection member3 terminates atsupport member2, preventingaugmentation material7 from migrating generally posteriorly with respect toanchor1.Support member2 is depicted in these figures as established in various locations, such as theposterior AF10′ inFIG. 8, butsupport member2 may be anchored in any suitable location within the FSU, as described previously.Support member2 may be used to close a defect in the posterior AF. It may also be used to displace a herniated segment to within the pre-herniated borders of the disc by applying tension between anchoring means1 and2 alongconnection member3.
• FIG. 9A depictsanchor1,connection member3,spacer material7 andsupport member2′ (shown in the “cap”-type configuration) inserted as a single construct and anchored to a site within the disc space, such as the inferior or superior vertebral bodies. This configuration simplifies insertion of the embodiments depicted inFIGS. 7 and 8 by reducing the number of steps to achieve implantation.Connection member3 is preferably relatively stiff in tension, but flexible against all other loads.Support member2′ is depicted as a bar element that is larger thanpassageway9 in at least one plane.
• FIG. 9B depicts a variation on the embodiment depicted inFIG. 9A.FIG. 9B shows substantially one-piece disc augmentation device13C, secured in the intervertebral disc space. Device13C hasanchor1,connection member3 andaugmentation material7.Augmentation material7 andanchor1 could be pre-assembled prior to insertion into thedisc space55 as a single construct. Alternatively,augmentation material7 could be inserted first into the disc space and then anchored to a portion of the FSU byanchor1.
• FIGS. 10A and 10B show yet another embodiment of the disclosed invention,13D. InFIG. 10A, twoconnection members3 and3′ are attached toanchor1. Two plugs ofaugmentation material7 and7′ are inserted into the disc space alongconnection members3 and3′.Connection members3 and3′ are then bound together (e.g., knotted together, fused, or the like). This formsloop3′ that serves to preventaugmentation materials7 and7′ from displacing posteriorly.FIG. 10B shows the position of theaugmentation material7 after it is secured by theloop3′ andanchor1. Various combinations of augmentation material, connecting members and anchors can be used in this embodiment, such as using a single plug of augmentation material, or two connection members leading fromanchor1 with each of the connection members being bound to at least one other connection member. It could further be accomplished with more than one anchor with at least one connection member leading from each anchor, and each of the connection members being bound to at least one other connection 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.
• FIGS. 11-15 illustrate devices used in and methods for closing a defect in an anulus fibrosis. One method involves the insertion of a barrier or barrier means12 into thedisc15. This procedure can accompany surgical discectomy. It can also be done without the removal of any portion of thedisc15 and further in combination with the insertion of an augmentation material or device into thedisc15.
• The method consists of inserting thebarrier12 into the interior of thedisc15 and positioning it proximate to the interior aspect of theannular defect16. The barrier material is preferably considerably larger in area than the size of thedefect16, such that at least some portion of the barrier means12 abutshealthier anulus fibrosis10. The device acts to seal theannular defect16, recreating the closed isobaric environment of ahealthy disc nucleus20. This closure can be achieved simply by an over-sizing of the implant relative to thedefect16. It can also be achieved by affixing the barrier means12 to tissues within the functional spinal unit. In a preferred aspect of the present invention, thebarrier12 is affixed to the anulus surrounding theannular defect16. This can be achieved with sutures, staples, glues or other suitable fixation means orfixation device14. The barrier means12 can also be larger in area than thedefect16 and be affixed to a tissue or structure opposite thedefect16, i.e. anterior tissue in the case of a posterior defect.
• The barrier means12 is preferably flexible in nature. It can be constructed of a woven material such as Dacron™ or Nylon™, a synthetic polymaide or polyester, a polyethylene, and can further be an expanded material, such as expanded polytetrafluroethelene (e-PTFE), for example. The barrier means12 can also be a biologic material such as cross-linked collagen or cellulous.
• The barrier means12 can be a single piece of material. It can have an expandable means or component that allows it to be expanded from a compressed state after insertion into the interior of thedisc15. This expandable means can be active, such as a balloon, or passive, such as a hydrophilic material. The expandable means can also be a self-expanding elastically deforming material, for example.
• FIGS. 11 and 12 illustrate abarrier12 mounted within ananulus10 and covering anannular defect16. Thebarrier12 can be secured to theanulus10 with a fixation mechanism or fixation means14. The fixation means14 can include a plurality of suture loops placed through thebarrier12 and theanulus10. Such fixation can prevent motion or slipping of thebarrier12 away from theannular defect16.
• The barrier means12 can also be anchored to thedisc15 in multiple locations. In one preferred embodiment, shown inFIGS. 13 and 14, the barrier means12 can be affixed to theanulus tissue10 in or surrounding the defect and further affixed to a secondary fixation site opposite the defect, e.g. theanterior anulus10 in a posterior herniation, or the inferior50′ or superior50 vertebral body. For example, fixation means14 can be used to attach thebarrier12 to theanulus10 near thedefect16, while ananchoring mechanism18 can secure thebarrier12 to a secondary fixation site. Aconnector22 can attach thebarrier12 to theanchor18. Tension can be applied between the primary and secondary fixation sites through aconnector22 so as to move theannular defect16 toward the secondary fixation site. This may be particularly beneficial in closingdefects16 that result in posterior herniations. By using this technique, the herniation can be moved and supported away from any posterior neural structures while further closing any defect in theanulus10.
• The barrier means12 can further be integral to a fixation means such that the barrier means affixes itself to tissues within the functional spinal unit.
• Any of the methods described above can be augmented by the use of a second barrier or a second barrier means24 placed proximate to the outer aspect of thedefect16 as shown inFIG. 15. Thesecond barrier24 can further be affixed to the inner barrier means12 by the use of a fixation means14 such as suture material.
• FIGS. 16A and 16B depictintervertebral disc15 comprising nucleus pulposus20 and anulus fibrosis I0.Nucleus pulposus20 forms a first anatomic region and extra-discal space500 (any space exterior to the disc) forms a second anatomic region wherein these regions are separated byanulus fibrosis10.
• FIG. 16A is an axial (transverse) view of the intervertebral disc. A posteriorlateral defect16 in anulus fibrosis1O has allowed asegment30 ofnucleus pulposus20 to herniate into an extradiscal space500.Interior aspect32 andexterior aspect34 are shown, as are the right70′ and left70 transverse processes andposterior process80.
• FIG. 16B is a sagittal section along the midline intervertebral disc.Superior pedicle90 andinferior pedicle90′ extend posteriorly from superior vertebral body95 and inferior vertebral body95′ respectively.
• To prevent further herniation of thenucleus20 and to repair any present herniation, in a preferred embodiment, a barrier or barrier means12 can be placed into a space between theanulus10 and thenucleus20 proximate to theinner aspect32 ofdefect16, as depicted inFIGS. 17 and 18. The space can be created by blunt dissection. Dissection can be achieved with a separate dissection instrument, with the barrier means12 itself, or a combined dissection/barrier delivery tool100. This space is preferably no larger than the barrier means such that the barrier means12 can be in contact with both anulus10 andnucleus20. This allows the barrier means12 to transfer load from thenucleus20 to theanulus10 when the disc is pressurized during activity.
• In position, the barrier means12 preferably spans thedefect16 and extends along theinterior aspect36 of theanulus10 until it contacts healthy tissues on all sides of thedefect16. Depending on the extent of thedefect16, the contacted tissues can include theanulus10, cartilage overlying the vertebral endplates, and/or the endplates themselves.
• In the preferred embodiment, the barrier means12 consists of two components a sealing means or sealingcomponent51 and an enlarging means or enlargingcomponent53, shown inFIGS. 21A and 21B.
• The sealing means51 forms the periphery of thebarrier12 and has aninterior cavity17. There is at least oneopening8 leading intocavity17 from the exterior of the sealing means51. Sealing means51 is preferably compressible or collapsible to a dimension that can readily be inserted into thedisc15 through a relatively small hole. This hole can be thedefect16 itself or a site remote from thedefect16. The sealing means51 is constructed from a material and is formed in such a manner as to resist the passage of fluids and other materials around sealing means51 and through thedefect16. The sealing means51 can be constructed from one or any number of a variety of materials including, but not limited to PTFE, e-PTFE, Nylon™, Marlex™, high-density polyethylene, and/or collagen. The thickness of the sealing component has been found to be optimal between 0.001 inches (0.127 mm) and 0.063 inches (1.600 mm).
• The enlarging means53 can be sized to fit withincavity17 of sealing means51. It is preferably a single object of a dimension that can be inserted through thesame defect16 through which the sealing means51 was passed. The enlarging means53 can expand the sealing means51 to an expanded state as it is passed intocavity17. One purpose of enlargingmeans53 is to expand sealing means51 to a size greater than that of thedefect16 such that the assembledbarrier12 prevents passage of material through thedefect16. Theenlarger53 can further impart stiffness to thebarrier12 such that thebarrier12 resists the pressures withinnucleus pulposus20 and expulsion through thedefect16. The enlarging means53 can be constructed from one or any number of materials including, but not limited to, silicon rubber, various plastics, stainless steel, nickel titanium alloys, or other metals. These materials may form a solid object, a hollow object, coiled springs or other suitable forms capable of fillingcavity17 within sealing means51.
• The sealing means51, enlargingmeans53, or the barrier means12 constructs can further be affixed to tissues either surrounding thedefect16 or remote from thedefect16. In the preferred embodiment, no aspect of a fixation means or fixation device or the barrier means12 nor its components extend posterior to thedisc15 or into theextradiscal region500, avoiding the risk of contacting and irritating the sensitive nerve tissues posterior to thedisc15.
• In a preferred embodiment, the sealing means51 is inserted into thedisc15 proximate theinterior aspect36 of the defect. The sealing means51 is then affixed to the tissues surrounding the defect using a suitable fixation means, such as suture or a soft-tissue anchor. The fixation procedure is preferably performed from the interior of the sealing meanscavity17 as depicted inFIGS. 19 and 20. Afixation delivery instrument110 is delivered intocavity17 throughopening8 in the sealing means51.Fixation devices14 can then be deployed through a wall of the sealing means53 into surrounding tissues. Once the fixation means14 have been passed into surrounding tissue, thefixation delivery instrument110 can be removed from thedisc15. This method eliminates the need for a separate entryway into thedisc15 for delivery of fixation means14. It further minimizes the risk of material leaking through sealing means51 proximate to the fixation means14. One or more fixation means14 can be delivered into one or any number of surrounding tissues including the superior95 and inferior95′ vertebral bodies. Following fixation of the sealing means51, the enlarging means53 can be inserted intocavity17 of the sealing means51 to further expand the barrier means12 construct as well as increase its stiffness, as depicted inFIGS. 21A and 21B. Theopening8 into the sealing means51 can then be closed by a suture or other means, although this is not a requirement of the present invention. In certain cases, insertion of a separate enlarging means may not be necessary if adequate fixation of the sealing means51 is achieved.
• Another method of securing thebarrier12 to tissues is to affix the enlarging means53 to tissues either surrounding or remote from thedefect16. The enlarging means53 can have anintegral fixation region4 that facilitates securing it to tissues as depicted inFIGS. 22A, 22B,32A and43B. Thisfixation region4 can extend exterior to sealing means51 either throughopening8 or through a separate opening.Fixation region4 can have a hole through which a fixation means orfixation device14 can be passed. In a preferred embodiment, thebarrier12 is affixed to at least one of the surrounding vertebral bodies (95 and95′) proximate to the defect using abone anchor14′. Thebone anchor14′ can be deployed into thevertebral bodies50,50′ at some angle between 0.degree. and 180.degree. relative to a bone anchor deployment tool. As shown thebone anchor14′ is mounted at 90.degree. relative to the bone anchor deployment tool. Alternatively, the enlarging means53 itself can have anintegral fixation device14 located at a site or sites along its length.
• Another method of securing the barrier means12 is to insert the barrier means12 through thedefect16 or another opening into thedisc15, position it proximate to theinterior aspect36 of thedefect16, and pass at least one fixation means14 through theanulus10 and into thebarrier12. In a preferred embodiment of this method, the fixation means14 can bedarts15 and are first passed partially intoanulus10 within afixation device120, such as a hollow needle. As depicted inFIGS. 23A and 23B, fixation means25 can be advanced into the barrier means12 andfixation device120 removed. Fixation means25 preferably have two ends, each with a means to prevent movement of that end of the fixation device. Using this method, the fixation means can be lodged in both thebarrier12 andanulus fibrosis10 without any aspect of fixation means25 exterior to the disc in theextradiscal region500.
• In another aspect of the present invention, the barrier (or “patch”)12 can be placed between twoneighboring layers33,37 (lamellae) of theanulus10 on either or both sides of thedefect16 as depicted inFIGS. 24A and 24B.FIG. 24A shows an axial view while24B shows a sagittal cross section. Such positioning spans thedefect16. The barrier means12 can be secured using the methods outlined.
• A dissecting tool can be used to form an opening extending circumferentially31 within the anulus fibrosis such that the barrier can be inserted into the opening. Alternatively, the barrier itself can have a dissecting edge such that it can be driven at least partially into the sidewalls of defect or opening16 in the anulus. This process can make use of the naturally layered structure in the anulus in whichadjacent layers33,37 are defined by acircumferentially extending boundary35 between the layers.
• Another embodiment of thebarrier12 is a patch having a length, oriented along the circumference of the disc, which is substantially greater than its height, which is oriented along the distance separating the surrounding vertebral bodies. Abarrier12 having a length greater than its height is illustrated inFIG. 25. Thebarrier12 can be positioned across thedefect16 as well as the entirety of the posterior aspect of theanulus fibrosis10. Such dimensions of thebarrier12 can help to prevent thebarrier12 from slipping after insertion and can aid in distributing the pressure of thenucleus20 evenly along the posterior aspect of theanulus10.
• Thebarrier12 can be used in conjunction with anaugmentation device11 inserted within theanulus10. Theaugmentation device11 can includeseparate augmentation devices42 as shown inFIG. 26. Theaugmentation device11 can also be asingle augmentation device44 and can form part of thebarrier12 asbarrier region300, coiled within theanulus fibrosis10, as shown inFIG. 27. Either thebarrier12 orbarrier region300 can be secured to the tissues surrounding thedefect16 by fixation devices ordarts25, or be left unconstrained
• In another embodiment of the present invention, the barrier orpatch12 may be used as part of a method to augment the intervertebral disc. In one aspect of this method, augmentation material or devices are inserted into the disc through a defect (either naturally occurring or surgically generated). Many suitable augmentation materials and devices are discussed above and in the prior art. As depicted inFIG. 26, the barrier means is then inserted to aid in closing the defect and/or to aid in transferring load from the augmentation materials/devices to healthy tissues surrounding the defect. In another aspect of this method, the barrier means is an integral component to an augmentation device. As shown inFIGS. 27, 28A and28B, the augmentation portion may comprise a length of elastic material that can be inserted linearly through a defect in the anulus. Aregion300 of the length forms the barrier means of the present invention and can be positioned proximate to the interior aspect of the defect once the nuclear space is adequately filled.Barrier region300 may then be affixed to surrounding tissues such as the AF and/or the neighboring vertebral bodies using any of the methods and devices described above.
• FIGS. 28A and 28B illustrate axial and sagittal sections, respectively, of an alternate configuration of anaugmentation device38. In this embodiment,barrier region300 extends across thedefect16 and hasfixation region4 facilitating fixation of thedevice13 to superiorvertebral body50 withanchor14′.
• FIGS.29A-D illustrate the deployment of abarrier12 from anentry site800 remote from the defect in theanulus fibrosis10.FIG. 29A showsinsertion instrument130 with a distal end positioned within the disc space occupied bynucleus pulposus20. FIG.29B depictsdelivery catheter140 exiting the distal end ofinsertion instrument130 withbarrier12 on its distal end.Barrier12 is positioned across the interior aspect of thedefect16.FIG. 29C depicts the use of anexpandable barrier12′ whereindelivery catheter140 is used to expand thebarrier12′ withballoon150 on its distal end.Balloon150 may exploit heat to further adherebarrier12′ to surrounding tissue.FIG. 29D depicts removal ofballoon150 anddelivery catheter140 from the disc space leaving expanded barrier means12′ positioned acrossdefect16.
• Another method of securing the barrier means12 is to adhere it to surrounding tissues through the application of heat. In this embodiment, the barrier means12 includes a sealing means51 comprised of a thermally adherent material that adheres to surrounding tissues upon the application of heat. The thermally adherent material can include thermoplastic, collagen, or a similar material. The sealing means51 can further comprise a separate structural material that adds strength to the thermally adherent material, such as a woven Nylon.™. or Marlex.™. This thermally adherent sealing means preferably has aninterior cavity17 and at least oneopening8 leading from the exterior of the barrier means intocavity17. A thermal device can be attached to the insertion instrument shown inFIGS. 29C and 29D. Theinsertion instrument130 having a thermal device can be inserted intocavity17 and used to heat sealing means51 and surrounding tissues. This device can be a simple thermal element, such as a resistive heating coil, rod or wire. It can further be a number of electrodes capable of heating the barrier means and surrounding tissue through the application of radio frequency (RF) energy. The thermal device can further be aballoon150,150′, as shown inFIG. 47, capable of both heating and expanding the barrier means.Balloon150,150′ can either be inflated with a heated fluid or have electrodes located about its surface to heat the barrier means with RF energy.Balloon150,150′ is deflated and removed after heating the sealing means. These thermal methods and devices achieve the goal of adhering the sealing means to the AF and NP and potentially other surrounding tissues. The application of heat can further aid the procedure by killing small nerves within the AF, by causing the defect to shrink, or by causing cross-linking and/or shrinking of surrounding tissues. An expander or enlargingmeans53 can also be an integral component ofbarrier12 inserted within sealing means51. After the application of heat, a separate enlargingmeans53 can be inserted into the interior cavity of the barrier means to either enlarge thebarrier12 or add stiffness to its structure. Such an enlarging means is preferably similar in make-up and design to those described above. Use of an enlarging means may not be necessary in some cases and is not a required component of this method.
• The barrier means12 shown inFIG. 25 preferably has a primary curvature or gentle curve along the length of the patch orbarrier12 that allows it to conform to the inner circumference of theAF10. This curvature may have a single radius R as shown inFIGS. 44A and 44B or may have multiple curvatures. The curvature can be fabricated into thebarrier12 and/or any of its components. For example, the sealing means can be made without an inherent curvature while the enlarging means can have a primary curvature along its length. Once the enlarging means is placed within the sealing means the overall barrier means assembly takes on the primary curvature of the enlarging means. This modularity allows enlarging means with specific curvatures to be fabricated for defects occurring in various regions of the anulus fibrosis.
• The cross section of thebarrier12 can be any of a number of shapes. Each embodiment exploits a sealing means51 and an enlargingmeans53 that may further add stiffness to the overall barrier construct.FIGS. 30A and 30B show an elongated cylindrical embodiment with enlargingmeans53 located about the long axis of the device.FIGS. 31A and 31B depict a barrier means comprising an enlargingmeans53 with acentral cavity49.FIGS. 32A and 32B depict a barrier means comprising a non-axisymmetric sealing means51. In use, the longer section of sealing means51 as seen on the left side of this figure would extend between opposingvertebra50 and50′.FIGS. 33A and 33B depict a barrier means comprising a non-axisymmetric sealing means51 andenlarger53. The concave portion of the barrier means preferably faces nucleus pulposus20 while the convex surface faces thedefect16 and the inner aspect of theanulus fibrosis10. This embodiment exploits pressure within the disc to compress sealing means51 against neighboringvertebral bodies50 and50′ to aid in sealing. The ‘C’ shape as shown inFIG. 33A is the preferred shape of the barrier wherein the convex portion of the patch rests against the interior aspect of the AF while the concave portion faces the NP. To improve the sealing ability of such a patch, the upper and lower portions of this ‘C’ shaped barrier means are positioned against the vertebral endplates or overlying cartilage. As the pressure within the nucleus increases, these portions of the patch are pressurized toward the endplates with an equivalent pressure, preventing the passage of materials around the barrier means. Dissecting a matching cavity prior to or during patch placement can facilitate use of such a ‘C’ shaped patch.
• FIGS. 34 through 41 depict various enlarging orexpansion devices53 that can be employed to aid in expanding asealing element51 within theintervertebral disc15. Each embodiment can be covered by, coated with, or cover the sealingelement51. The sealing means51 can further be woven through the expansion means53. The sealingelement51 or membrane can be a sealer which can prevent flow of a material from within the anulus fibrosis of the intervertebral disc through a defect in the anulus fibrosis. The material within the anulus can include nucleus pulposus or a prosthetic augmentation device, such as a hydrogel.
• FIGS. 34 through 38 depict alternative patterns to that illustrated inFIG. 33A.FIG. 33A shows theexpansion devices53 within the sealing means51. The sealing means can alternatively be secured to one or another face (concave or convex) of the expansion means53. This can have advantages in reducing the overall volume of the barrier means12, simplifying insertion through a narrow cannula. It can also allow the barrier means12 to induce ingrowth of tissue on one face and not the other. The sealing means51 can be formed from a material that resists ingrowth such as expanded polytetraflouroethylene (e-PTFE). The expansion means53 can be constructed of a metal or polymer that encourages ingrowth. If the e-PTFE sealing means51 is secured to the concave face of the expansion means53, tissue can grow into the expansion means53 from outside of thedisc15, helping to secure the barrier means12 in place and seal against egress of materials from within thedisc15.
• The expansion means53 shown inFIG. 33A can be inserted into the sealing means51 once the sealing means51 is within thedisc15. Alternatively, the expansion means53 and sealing means51 can be integral components of the barrier means12 that can be inserted as a unit into the disc.
• The patterns shown inFIGS. 34 through 38 can preferably be formed from a relatively thin sheet of material. The material may be a polymer, metal, or gel, however, the superelastic properties of nickel titanium alloy (Nitinol) makes this metal particularly advantageous in this application. Sheet thickness can generally be in a range of 0.1 mm to 0.6 mm and for certain embodiments has been found to be optimal if between 0.003″ to 0.015″ (0.0762 mm to 0.381 mm), for the thickness to provide adequate expansion force to maintain contact between the sealing means51 and surrounding vertebral endplates. The pattern may be Wire Electro-Discharge Machined, cut by laser, chemically etched, or formed by other suitable means.
• FIG. 34A shows an embodiment of anon-axisymmetric expander153 having asuperior edge166 and aninferior edge168. Theexpander153 can form a frame ofbarrier12. This embodiment comprises dissecting surfaces or ends160, radial elements orfingers162 and acentral strut164. The circular shape of the dissecting ends160 aids in dissecting through thenucleus pulposus20 and/or along or between an inner surface of theanulus fibrosis10. The distance between the left-most and right-most points on the dissecting ends is the expansion meanslength170. Thislength170 preferably lies along the inner perimeter of the posterior anulus following implantation. Theexpander length170 can be as short as 3 mm and as long as the entire interior perimeter of the anulus fibrosis. The superior-inferior height of these dissecting ends160 is preferably similar to or larger than the posterior disc height.
• This embodiment employs a multitude offingers162 to aid in holding a flexible sealer or membrane against the superior and inferior vertebral endplates. The distance between the superior-most point of the superior finger and the inferior-most point on the inferior finger is the expansion meansheight172. Thisheight172 is preferably greater than the disc height at the inner surface of the posterior anulus. Thegreater height172 of theexpander153 allows thefingers162 to deflect along the superior and inferior vertebral endplates, enhancing the seal of the barrier means12 against egress of material from within thedisc15.
• The spacing between thefingers162 along theexpander length170 can be tailored to provide a desired stiffness of the expansion means153. Greater spacing between any two neighboringfingers162 can further be employed to insure that thefingers170 do not touch if the expansion means153 is required to take a bend along its length. Thecentral strut164 can connect the fingers and dissecting ends and preferably lies along the inner surface of theanulus10 when seated within thedisc15. Various embodiments may employstruts164 of greater or lesser heights and thicknesses to vary the stiffness of the overall expansion means153 along itslength170 andheight172.
• FIG. 35 depicts an alternative embodiment to theexpander153 ofFIG. 34. Openings orslots174 can be included along thecentral strut164. Theseslots174 promote bending of theexpander153 andfingers162 along acentral line176 connecting the centers of the dissecting ends160. Such central flexibility has been found to aid against superior or inferior migration of the barrier means orbarrier12 when thebarrier12 has not been secured to surrounding tissues.
• FIGS. 34B and 34C depict different perspective views of a preferred embodiment of the expander/frame153 within anintervertebral disc15.Expander53 is in its expanded condition and lies along and/or within theposterior wall21 and extends around thelateral walls23 of theanulus fibrosis10. The superior166 and inferior168 facingfingers162 ofexpander153 extend along the vertebral endplates (not shown) and/or the cartilage overlying the endplates. Theframe153 can take on a 3-D concave shape in this preferred position with the concavity generally directed toward the interior of the intervertebral disc and specifically a region occupied by thenucleus pulposus20. The bending stiffness ofexpander153 can resist migration of the implant from this preferred position within thedisc15. The principle behind this stiffness-based stability is to place the regions ofexpander153 with the greatest flexibility in the regions of thedisc153 with the greatest mobility or curvature. These flexible regions ofexpander153 are surrounded by significantly stiffer regions. Hence, in order for the implant to migrate, a relatively stiff region of the expander must move into a relatively curved or mobile region of the disc.
• For example, in order forexpander153 ofFIG. 34B to move around the inner circumference of anulus fibrosis10 (i.e. from theposterior wall21 onto the lateral23 and/or anterior27 wall), the stiff central region ofexpander153 spanning theposterior wall21 would have to bend around the acute curves of the posterior lateral corners ofanulus10. The stiffer this section ofexpander153 is, the higher the forces necessary to force it around these corners and the less likely it is to migrate in this direction. This principle was also used in this embodiment to resist migration offingers162 away from the vertebral endplates: Theslots174 cut along the length ofexpander153 create a central flexibility that encouragesexpander153 to bend along an axis running through these slots as the posterior disc height increases and decreased during flexion and extension. In order for thefingers162 to migrate away from the endplate, this central flexible region must move away from theposterior anulus21 and toward an endplate. This motion is resisted by the greater stiffness ofexpander153 in the areas directly inferior and superior to this central flexible region.
• Theexpander153 is preferably covered by a membrane that acts to further restrict the movement of materials through the frame and toward the outer periphery of the anulus fibrosis.
• FIG. 36 depicts an embodiment of theexpander153 ofFIG. 33A with an enlargedcentral strut164 and a plurality ofslots174. Thiscentral strut164 can have a uniform stiffness against superior-inferior166 and168 bending as shown in this embodiment. Thestrut164 can alternatively have a varying stiffness along itsheight178 to either promote or resist bending at a given location along the inner surface of theanulus10.
• FIGS.37A-C depict a further embodiment of the frame orexpander153. This embodiment employs acentral lattice180 consisting of multiple, fineinterconnected struts182. Such alattice180 can provide a structure that minimizes bulging of the sealing means51 under intradiscal pressures. The orientation and location of thesestruts182 have been designed to give the barrier12 a bend-axis along the central area of theexpander height172. Thestruts182 support inferior168 and superior166fingers162 similar to previously described embodiments. However, thesefingers162 can have varying dimensions and stiffness along the length of thebarrier12.Such fingers162 can be useful for helping thesealer51 conform to uneven endplate geometries.FIG. 37B illustrates thecurved cross section184 of theexpander153 ofFIG. 37A. Thiscurve184 can be an arc segment of a circle as shown. Alternatively, the cross section can be an ellipsoid segment or have a multitude of arc segments of different radii and centers.FIG. 37C is a perspective view showing the three dimensional shape of theexpander153 ofFIGS. 37A and 37B.
• The embodiment of theframe153 as shown in FIGS.37A-C, can also be employed without the use of a covering membrane. The nucleus pulposus of many patients with low back pain or disc herniation can degenerate to a state in which the material properties of the nucleus cause it to behave much more like a solid than a gel. As humans age, the water content of the nucleus declines from roughly 88% to less than 75%. As this occurs, there is an increase in the cross linking of collagen within the disc resulting in a greater solidity of the nucleus. When the pore size or the largest open area of any given gap in the lattice depicted inFIGS. 37A, 37B, and37C is between 0.05 mm²(7.75×10-5 in²) and 0.75 mm²(1.16.×10-⁻³in²), the nucleus pulposus is unable to extrude through the lattice at pressures generated within the disc (between 250 KPa and 1.8 MPa). The preferred pore size has been found to be approximately 0.15 mm²(2.33×10⁻⁴in²). This pore size can be used with any of the disclosed embodiments of the expander or any other expander that falls within the scope of the present invention to prevent movement of nucleus toward the outer periphery of the disc without the need for an additional membrane. The membrane thickness is preferably in a range of 0.025 mm to 2.5 mm.
• FIG. 38 depicts anexpander153 similar to that ofFIG. 37A without fingers. Theexpander153 includes acentral lattice180 consisting ofmultiple struts182.
• FIGS. 39 through 41 depict another embodiment of theexpander153 of the present invention. These tubular expanders can be used in thebarrier12 embodiment depicted inFIG. 31A. Thesealer51 can cover theexpander153 as shown inFIG. 31A. Alternatively, thesealer51 can cover the interior surface of the expander or an arc segment of the tube along its length on either the interior or exterior surface.
• FIG. 39 depicts an embodiment of atubular expander154. The superior166 andinferior surfaces168 of thetubular expander154 can deploy against the superior and inferior vertebral endplates, respectively. Thedistance186 between the superior166 and inferior168 surfaces of theexpander154 are preferably equal to or greater than the posterior disc height at the inner surface of theanulus10. This embodiment has ananulus face188 and nucleus face190 as shown inFIGS. 39B, 39C and39D. Theanulus face188 can be covered by thesealer51 from the superior166 to inferior168 surface of theexpander154. Thisface188 lies against the inner surface of theanulus10 in its deployed position and can prevent egress of materials from within thedisc15. The primary purpose of thenucleus face190 is to prevent migration of theexpander154 within thedisc15. Thestruts192 that form thenucleus face190 can project anteriorly into thenucleus20 when thebarrier12 is positioned across the posterior wall of theanulus10. This anterior projection can resist rotation of the tubular expansion means154 about its long axis. By interacting with thenucleus20, thestruts192 can further prevent migration around the circumference of thedisc15.
• Thestruts192 can be spaced to providenuclear gaps194. Thesegaps194 can encourage the flow ofnucleus pulposus20 into the interior of theexpander154. This flow can insure full expansion of thebarrier12 within thedisc15 during deployment.
• The embodiments ofFIGS. 39, 40 and41 vary by their cross-sectional shape.FIG. 39 has acircular cross section196 as seen inFIG. 39C. If the superior-inferior height186 of theexpander154 is greater than that of thedisc15, thiscircular cross section196 can deform into an oval when deployed, as the endplates of the vertebrae compress theexpander154. The embodiment of theexpander154 shown inFIG. 40 is preformed into anoval shape198 shown inFIG. 40C. Compression by the endplates can exaggerate theunstrained oval198. This oval198 can provide greater stability against rotation about a long axis of theexpander154. The embodiment ofFIGS. 41B, 41C and41D depict an ‘egg-shaped’cross section202, as shown inFIG. 41C, that can allow congruity between the curvature of theexpander154 and the inner wall ofposterior anulus10. Any of a variety of alternate cross sectional shapes can be employed to obtain a desired fit or expansion force without deviating from the spirit of the present invention.
• FIGS. 40E, 40F, and40I depict theexpander154 of FIGS.40A-D having a sealing means51 covering the exterior surface of theanulus face188. This sealing means51 can be held against the endplates and the inner surface of the posterior anulus by theexpander154 in its deployed state.
• FIGS. 40G and 40H depict theexpander154 ofFIG. 40B with asealer51 covering the interior surface of theanulus face188. This position of thesealer51 can allow theexpander154 to contact both the vertebral endplates and inner surface of the posterior anulus. This can promote ingrowth of tissue into theexpander154 from outside thedisc15. Combinations ofsealer51 that cover all or part of theexpander154 can also be employed without deviating from the scope of the present invention. Theexpander154 can also have a small pore size thereby allowing retention of a material such as a nucleus pulposus, for example, without the need for a sealer as a covering.
• FIGS.42A-D depict cross sections of a preferred embodiment of sealing means51 and enlargingmeans53. Sealing means51 hasinternal cavity17 andopening8 leading from its outer surface intointernal cavity17.Enlarger53 can be inserted throughopening8 and intointernal cavity17.
• FIGS. 43A and 43B depict an alternative configuration ofenlarger53.Fixation region4 extends throughopening8 in sealing means51.Fixation region4 has a through-hole that can facilitate fixation ofenlarger53 totissues surrounding defect16.
• FIGS. 44A and 44B depict an alternative shape of the barrier. In this embodiment, sealing means51,enlarger53, or both have a curvature with radius R. This curvature can be used in any embodiment of the present invention and may aid in conforming to the curved inner circumference ofanulus fibrosis10.
• FIG. 45 is a section of a device used to affix sealing means51 to tissues surrounding a defect. In this figure, sealing means51 would be positioned acrossinterior aspect50 ofdefect16. The distal end ofdevice110′ would be inserted throughdefect16 andopening8 into theinterior cavity17. On the right side of this figure,fixation dart25 has been passed fromdevice110′, through a wall of sealing means51 and into tissues surrounding sealing means51. On the right side of the figure,fixation dart25 is about to be passed through a wall of sealing means51 by advancingpusher111 relative todevice110′ in the direction of the arrow.
• FIG. 46 depicts the use ofthermal device200 to heat sealing means51 and adhere it to tissues surrounding a defect. In this figure, sealing means51 would be positioned across theinterior aspect36 of adefect16. The distal end ofthermal device200 would be inserted through the defect andopening8 intointerior cavity17. In this embodiment,thermal device200 employs at its distal endresistive heating element210 connected to a voltage source bywires220. Covering230 is a non-stick surface such as Teflon tubing that ensures the ability to removedevice200 frominterior cavity17. In this embodiment,device200 would be used to heat first one half, and then the other half of sealing means51.
• FIG. 47 depicts an expandable thermal element, such as a balloon, that can be used to adhere sealing means51 to tissues surrounding a defect. As inFIG. 18, the distal end ofdevice130 can be inserted through the defect andopening8 intointerior cavity17, withballoon150′ on thedistal end device130 in a collapsed state.Balloon150′ is then inflated to expandedstate150, expanding sealing means51.Expanded balloon150 can heat sealing means51 and surrounding tissues by inflating it with a heated fluid or by employing RF electrodes. In this embodiment,device130 can be used to expand and heat first one half, then the other half of sealing means51.
• FIG. 48 depicts an alternative embodiment todevice130. This device employs an elongated,flexible balloon150′ that can be inserted into and completely fillinternal cavity17 of sealing means51 prior to inflation to an expandedstate150. Using this embodiment, inflation and heating of sealing means51 can be performed in one step.
• FIGS. 49A through 49G illustrate a method of implanting an intradiscal implant. An intradiscal implant system consists of anintradiscal implant400, a delivery device orcannula402, anadvancer404 and at least onecontrol filament406. Theintradiscal implant400 is loaded into thedelivery cannula402 which has aproximal end408 and adistal end410.FIG. 49A illustrates thedistal end410 advanced into thedisc15 through ananulotomy416. Thisanulotomy416 can be through any portion of theanulus10, but is preferably at a site proximate to a desired, final implant location. Theimplant400 is then pushed into thedisc15 through thedistal end410 of thecannula402 in a direction that is generally away from the desired, final implant location as shown inFIG. 49B. Once theimplant400 is completely outside of thedelivery cannula402 and within thedisc15, theimplant400 can be pulled into the desired implant location by pulling on thecontrol filament406 as shown inFIG. 49C. Thecontrol filament406 can be secured to theimplant400 at any location on or within theimplant400, but is preferably secured at least at asite414 or sites on adistal portion412 of theimplant400, i.e. that portion that first exits thedelivery cannula402 when advanced into thedisc15. These site orsites414 are generally furthest from the desired, final implant location once the implant has been fully expelled from the interior of thedelivery cannula402.
• Pulling on thecontrol filament406 causes theimplant400 to move toward theanulotomy416. Thedistal end410 of thedelivery cannula402 can be used to direct theproximal end420 of the implant400 (that portion of theimplant400 that is last to be expelled from the delivery cannula402) away from theanulotomy416 and toward an inner aspect of theanulus10 nearest the desired implant location. Alternately, the advancer404 can be used to position the proximal end of the implant toward an inner aspect of theanulus20 near the implant location, as shown inFIG. 49E. Further pulling on thecontrol filament406 causes theproximal end426 of theimplant400 to dissect along the inner aspect of theanulus20 until theattachment site414 or sites of theguide filament406 to theimplant400 has been pulled to the inner aspect of theanulotomy416, as shown inFIG. 49D. In this way, theimplant400 will extend at least from theanulotomy416 and along the inner aspect of theanulus10 in the desired implant location, illustrated inFIG. 49F.
• Theimplant400 can be any of the following: nucleus replacement device, nucleus augmentation device, anulus augmentation device, anulus replacement device, the barrier of the present invention or any of its components, drug carrier device, carrier device seeded with living cells, or a device that stimulates or supports fusion of the surrounding vertebra. Theimplant400 can be a membrane which prevents the flow of a material from within the anulus fibrosis of an intervertebral disc through a defect in the disc. The material within the anulus fibrosis can be, for example, a nucleus pulposus or a prosthetic augmentation device, such as hydrogel. The membrane can be a sealer. Theimplant400 can be wholly or partially rigid or wholly or partially flexible. It can have a solid portion or portions that contain a fluid material. It can comprise a single or multitude of materials. These materials can include metals, polymers, gels and can be in solid or woven form. Theimplant400 can either resist or promote tissue ingrowth, whether fibrous or bony.
• Thecannula402 can be any tubular device capable of advancing theimplant400 at least partially through theanulus10. It can be made of any suitable biocompatible material including various known metals and polymers. It can be wholly or partially rigid or flexible. It can be circular, oval, polygonal, or irregular in cross section. It must have an opening at least at itsdistal end410, but can have other openings in various locations along its length.
• The advancer404 can be rigid or flexible, and have one of a variety of cross sectional shapes either like or unlike thedelivery cannula402. It may be a solid or even a column of incompressible fluid, so long as it is stiff enough to advance theimplant400 into thedisc15. The advancer404 can be contained entirely within thecannula402 or can extend through a wall or end of the cannula to facilitate manipulation.
• Advancement of theimplant400 can be assisted by various levers, gears, screws and other secondary assist devices to minimize the force required by the surgeon to advance theimplant400. These secondary devices can further give the user greater control over the rate and extent of advancement into thedisc15.
• Theguide filament406 may be a string, rod, plate, or other elongate object that can be secured to and move with theimplant400 as it is advanced into thedisc15. It can be constructed from any of a variety of metals or polymers or combination thereof and can be flexible or rigid along all or part of its length. It can be secured to asecondary object418 or device at its end opposite that which is secured to theimplant400. Thissecondary device418 can include the advancer404 or other object or device that assists the user in manipulating the filament. Thefilament406 can be releasably secured to theimplant400, as shown inFIG. 49G or permanently affixed. Thefilament406 can be looped around or through the implant. Such a loop can either be cut or have one end pulled until the other end of the loop releases theimplant400. It may be bonded to theimplant400 using adhesive, welding, or a secondary securing means such as a screw, staple, dart, etc. Thefilament406 can further be an elongate extension of the implant material itself. If not removed following placement of the implant, thefilament406 can be used to secure theimplant400 to surrounding tissues such as the neighboringanulus10, vertebral endplates, or vertebral bodies either directly or through the use of a dart, screw, staple, or other suitable anchor.
• Multiple guide filaments can be secured to theimplant400 at various locations. In one preferred embodiment, a first or distal422 and a second or proximal424 guide filament are secured to anelongate implant400 at or near its distal412 and proximal420 ends atattachment sites426 and428, respectively. These ends412 and420 correspond to the first and last portions of theimplant400, respectively, to be expelled from thedelivery cannula402 when advanced into thedisc15. This double guide filament system allows theimplant400 to be positioned in the same manner described above in the single filament technique, and illustrated in FIGS.50A-C. However following completion of this first technique, the user may advance theproximal end420 of thedevice400 across theanulotomy416 by pulling on thesecond guide filament424, shown inFIG. 50D. This allows the user to controllably cover theanulotomy416. This has numerous advantages in various implantation procedures. This step may reduce the risk of herniation of either nucleus pulposus20 or the implant itself. It may aid in sealing the disc, as well as preserving disc pressure and the natural function of the disc. It may encourage ingrowth of fibrous tissue from outside the disc into the implant. It may further allow the distal end of the implant to rest against anulus further from the defect created by the anulotomy. Finally, this technique allows both ends of an elongate implant to be secured to the disc or vertebral tissues.
• Both the first422 and second424 guide filaments can be simultaneously tensioned, as shown inFIG. 50E, to ensure proper positioning of theimplant400 within theanulus10. Once theimplant400 is placed across the anulotomy, the first422 and second424 guide filaments can be removed from theinput400, as shown inFIG. 50F. Additional control filaments and securing sites may further assist implantation and/or fixation of the intradiscal implants.
• In another embodiment of the present invention, as illustrated in FIGS.51A-C, animplant guide430 may be employed to aid directing theimplant400 through theanulotomy416, through thenucleus pulposus10, and/or along the inner aspect of theanulus10. Thisimplant guide430 can aid in the procedure by dissecting through tissue, adding stiffness to the implant construct, reducing trauma to the anulus or other tissues that can be caused by a stiff or abrasive implant, providing 3-D control of the implants orientation during implantation, expanding an expandable implant, or temporarily imparting a shape to the implant that is beneficial during implantation. Theimplant guide430 can be affixed to either the advancer404 or theimplant406 themselves. In a preferred embodiment shown inFIGS. 52A and 52B, theimplant guide430 is secured to theimplant400 by the first424 and second426 guide filaments of the first426 and the second428 attachment sites, respectively. Theguide filaments424 and426 may pass through or around theimplant guide430. In this embodiment, theimplant guide430 may be a thin, flat sheet of biocompatible metal with holes passing through its surface proximate to the site orsites426 and428 at which theguide filaments422 and424 are secured to theimplant400. These holes allow passage of the securingfilament422 and424 through theimplant guide430. Such an elongated sheet may run along theimplant400 and extend beyond itsdistal end412. The distal end of theimplant guide430 may be shaped to help dissect through thenucleus10 and deflect off of theanulus10 as theimplant400 is advanced into thedisc15. When used with multiple guide filaments, such animplant guide430 can be used to control rotational stability of theimplant400. It may also be used to retract theimplant400 from thedisc15 should this become necessary. Theimplant guide430 may also extend beyond theproximal tip420 of theimplant400 to aid in dissecting across or through theanulus10 proximate to the desired implantation site.
• Theimplant guide430 is releasable from theimplant400 following or during implantation. This release may be coordinated with the release of theguide filaments422 and424. Theimplant guide430 may further be able to slide along theguide filaments422 and424 while these filaments are secured to theimplant400.
• Various embodiments of thebarrier12 orimplant400 can be secured to tissues within theintervertebral disc15 or surrounding vertebrae. It can be advantageous to secure the barrier means12 in a limited number of sites while still insuring that larger surfaces of thebarrier12 or implant juxtapose the tissue to which thebarrier12 is secured. This is particularly advantageous in forming a sealing engagement with surrounding tissues.
• FIGS. 53-57 illustrate barriers havingstiffening elements300. Thebarrier12 can incorporate stiffeningelements300 that run along a length of the implant required to be in sealing engagement. These stiffeningelements300 can be one of a variety of shapes including, but not limited to,plates302,rods304, or coils. These elements are preferably stiffer than the surroundingbarrier12 and can impart their stiffness to the surrounding barrier. These stiffeningelements300 can be located within an interior cavity formed by the barrier. They can further be imbedded in or secured to thebarrier12.
• Each stiffening element can aid in securing segments of thebarrier12 to surrounding tissues. The stiffening elements can have parts307, including throughholes, notches, or other indentations for example, to facilitate fixation of thestiffening element300 to surrounding tissues by any of a variety offixation devices306. Thesefixation devices306 can include screws, darts, dowels, or other suitable means capable of holding thebarrier12 to surrounding tissue. Thefixation devices306 can be connected either directly to thestiffening element300 or indirectly using an intervening length of suture, cable, or other filament for example. Thefixation device306 can further be secured to thebarrier12 near thestiffening element300 without direct contact with thestiffening element300.
• Thefixation device306 can be secured to or near thestiffening element300 at opposing ends of the length of thebarrier12 required to be in sealing engagement with surrounding tissues. Alternatively, one or a multitude offixation devices306 can be secured to or near thestiffening element300 at a readily accessible location that may not be at these ends. In anybarrier12 embodiment with aninterior cavity17 and anopening8 leading thereto, the fixation sites may be proximal to theopening8 to allow passage of thefixation device306 and various instruments that may be required for their implantation.
• FIGS. 53A and 53B illustrate one embodiment of abarrier12 incorporating the use of astiffening element300. Thebarrier12 can be a plate andscrew barrier320. In this embodiment, thestiffening element300 consists of two fixation plates, superior310 and inferior312, an example of which is illustrated inFIGS. 54A and 54B with twoparts308 passing through each plate. Theparts308 are located proximal to anopening8 leading into aninterior cavity17 of thebarrier12. Theseparts8 allow passage of afixation device306 such as a bone screw. These screws can be used to secure the barrier means12 to a superior50 and inferior50′ vertebra. As the screws are tightened against the vertebral endplate, thefixation plates310,312 compress the intervening sealing means against the endplate along the superior and inferior surfaces of thebarrier12. This can aid in creating a sealing engagement with the vertebral endplates and prevent egress of materials from within thedisc15. As illustrated inFIGS. 53A and 53B, only the superior screws have been placed in thesuperior plate310, creating a sealing engagement with the superior vertebra.
• FIGS. 55A and 55B illustrate another embodiment of abarrier12 havingstiffening elements300. Thebarrier12 can be an anchor androd barrier322. In this embodiment, the stiffeningelements300 consist of twofixation rods304, an example of which is shown inFIGS. 56A and 56B, imbedded within thebarrier12. Therods304 can include asuperior rod314 and aninferior rod316.Sutures318 can be passed around theserods314 and316 and through the barrier means10. Thesesutures318 can in turn, be secured to a bone anchor or othersuitable fixation device306 to draw thebarrier12 into sealing engagement with the superior and inferior vertebral endplates in a manner similar to that described above. Theopening8 andinterior cavity17 of thebarrier12 are not required elements of thebarrier12.
• FIG. 57 illustrates the anchor androd barrier322, described above, withfixation devices306 placed at opposing ends of eachfixation rod316 and318. Thesuture18 on the left side of thesuperior rod318 has yet to be tied.
• Various methods may be employed to decrease the forces necessary to maneuver thebarrier12 into a position along or within the lamellae of theanulus fibrosis10.FIGS. 58A, 58B,59A and59B depict two preferred methods of clearing a path for thebarrier12.
• FIGS. 58A and 58B depict one such method and an associateddissector device454. In these figures, the assumed desired position of the implant is along theposterior anulus452. In order to clear a path for the implant, ahairpin dissector454 can be passed along the intended implantation site of the implant. Thehairpin dissector454 can have ahairpin dissector component460 having afree end458. The dissector can also have an advancer464 to position thedissector component460 within thedisc15. Thedissector454 can be inserted throughcannula456 into anopening462 in theanulus10 along an access path directed anteriorly or anterior-medially. Once a free-end458 of thedissector component460 is within thedisc15, the free-end458 moves slightly causing the hairpin to open, such that thedissector component460 resists returning into thecannula456. Thisopening462 can be caused by pre-forming the dissector to the opened state. Thehairpin dissector component460 can then be pulled posteriorly, causing thedissector component460 to open, further driving the free-end458 along theposterior anulus458. This motion clears a path for the insertion of any of the implants disclosed in the present invention. The body ofdissector component460 is preferably formed from an elongated sheet of metal. Suitable metals include various spring steels or nickel titanium alloys. It can alternatively be formed from wires or rods.
• FIGS. 59A and 59B depict another method and associateddissector device466 suitable for clearing a path for implant insertion. Thedissector device466 is shown in cross section and consists of adissector component468, anouter cannula470 and an advancer orinner push rod472. A curved passage orslot474 is formed into anintradiscal tip476 ofouter cannula470. This passage or slot474 acts to deflect the tip ofdissector component468 in a path that is roughly parallel to the lamellae of theanulus fibrosis10 as thedissector component468 is advanced into thedisc15 by the advancer. Thedissector component468 is preferably formed from a superelastic nickel titanium alloy, but can be constructed of any material with suitable rigidity and strain characteristics to allow such deflection without significant plastic deformation. Thedissector component468 can be formed from an elongated sheet, rods, wires or the like. It can be used to dissect between theanulus10 andnucleus20, or to dissect between layers of theanulus10.
• FIGS.60A-C depict analternate dissector component480 ofFIGS. 59A and 59B. Only theintradiscal tip476 ofdevice460 and regions proximal thereto are shown in these figures. A push-rod472 similar to that shown inFIG. 59A can be employed to advancedissector480 into thedisc15.Dissector480 can include anelongated sheet482 with superiorly and inferiorly extending blades (or “wings”)484 and486, respectively. Thissheet482 is preferably formed from a metal with a large elastic strain range such as spring steel or nickel titanium alloy. Thesheet482 can have aproximal end488 and adistal end490. Thedistal end490 can have a flat portion which can be flexible. Astep portion494 can be located between thedistal end490 and theproximal end488. Theproximal end488 can have a curved shape. The proximal end can also includeblades484 and486.
• In the un-deployed state depicted inFIGS. 60A and 60B,wings484 and486 are collapsed withinouter cannula470 whileelongated sheet482 is captured within deflecting passage orslot474. As thedissector component480 is advanced into adisc15, passage or slot478 directs thedissector component480 in a direction roughly parallel to the posterior anulus (90 degrees to the central axis ofsleeve470 in this case) in a manner similar to that described for the embodiment inFIGS. 59A and 59B.Wings484 and486 open as they exit the end ofsleeve470 and expand toward the vertebral endplates. Further advancement ofdissector component480 allows the expandedwings484 and486 to dissect through any connections ofnucleus20 oranulus10 to the endplates that may present an obstruction to subsequent passage of the implants of the present invention. When used to aid in the insertion of a barrier, the dimensions ofdissector component480 should approximate those of the barrier such that the minimal amount of tissue is disturbed while reducing the forces necessary to position the barrier in the desired location.
• FIGS. 61A-61D illustrate a method of implanting a disc implant. Adisc implant552 is inserted into adelivery device550. Thedelivery device550 has aproximal end556 and adistal end558. Thedistal end558 of thedelivery device550 is inserted into an anulotomy illustrated inFIG. 61A. The anulotomy is preferably located at a site within theanulus10 that is proximate to a desired,final implant552 location. Theimplant552 is then deployed by being inserted into thedisc15 through thedistal end558 of thedelivery device550. Preferably the implant is forced away from the final implant location, as shown inFIG. 61B. Animplant guide560 can be used to position theimplant552. After deployment of theimplant552, anaugmentation material554 can be injected into thedisc15, shown inFIG. 61C. Theaugmentation material554 can include a hydrogel or collagen, for example. In one embodiment, thedelivery device550 is removed from thedisc15 and a separate tube is inserted into the anulotomy to inject theaugmentation material554. Alternately, thedistal end558 of thedelivery device550 can remain within the anulotomy and theaugmentation material554 injected through thedelivery device550. Next, thedelivery device550 is removed from the anulotomy and theintradiscal implant552 is positioned over the anulotomy in the final implant location, as shown inFIG. 61D. Theimplant552 can be positioned using control filaments described above.
• While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims (28)

1. An implant for treating an intervertebral disc comprising:

a barrier,

wherein said barrier has a first and a second axis, wherein said second axis is perpendicular to said first axis,

wherein said barrier has a variable flexibility along at least said first axis or said second axis; and

wherein at least a portion of said barrier has pre-formed concavity.

2. The implant ofclaim 1, wherein the barrier has a variable flexibility along at least a portion the first axis and along at least a portion the second axis.

3. The implant ofclaim 1, wherein the barrier has a flexibility along the first axis that differs from the flexibility of the second axis.

4. The implant ofclaim 1, wherein the barrier is invariably flexible or stiff along the second axis.

5. The implant ofclaim 1, wherein the first axis is the transverse axis.

6. The implant ofclaim 1, wherein the first axis is the longitudinal axis.

7. The implant ofclaim 1, wherein the first axis is along the height of the barrier.

8. The implant ofclaim 1, wherein the first axis is along the length of the barrier.

9. The implant ofclaim 1, wherein said variable flexibility enhances the barrier's ability to resist migration in the intervertebral disc spec.

10. The implant ofclaim 1, wherein the barrier comprises one or more struts.

11. The implant ofclaim 1, wherein the barrier comprises one or more struts that provide differing degrees of flexibility to the barrier.

12. The implant ofclaim 1, wherein the barrier comprises one or more slots.

13. The implant ofclaim 1, wherein the barrier comprises one or more slots that provide differing degrees of flexibility to the barrier.

14. The implant ofclaim 1, wherein the barrier comprises at least one expander and at least one membrane.

15. The implant ofclaim 14, wherein said at least one membrane covers at least a portion of said at least one expander.

16. The implant ofclaim 14, wherein said at least one membrane coats at least a portion of said at least one expander.

17. The implant ofclaim 14, wherein said at least one membrane comprises a sealant, wherein said sealant is adapted to minimize or prevent the flow of a material through a defect in the anulus fibrosis.

18. The implant ofclaim 14, wherein said at least one expander is comprised of a material selected from the group consisting of one or more of the following: silicon, rubber, plastic, stainless steel, and nickel titanium alloy.

19. The implant ofclaim 14, wherein said at least one expander comprises a lattice.

20. The implant ofclaim 1, wherein said variable flexibility causes a flexible bend axis along a central area of the height of the barrier and a stiff region along the length of the barrier.

21. The implant ofclaim 1, wherein the barrier comprises one or more fingers.

22. The implant ofclaim 1, wherein the barrier comprises one or more fingers that are adapted to vary the flexibility of the barrier.

23. The implant ofclaim 1, wherein said barrier is adapted to fit between opposing endplates adjacent an intervertebral disc.

24. The implant ofclaim 1, wherein said barrier has a length in the range of about 3 mm to a length corresponding to the entire inner perimeter of an anulus fibrosus.

25. An implant for treating an intervertebral disc comprising:

a sealing means adapted to seal at least a portion of a defect in the anulus fibrosis,

wherein said sealing means has a first and a second axis that is perpendicular to said first axis,

wherein said sealing means has a variable flexibility along at least said first axis or said second axis.

26. An implant for treating an intervertebral disc comprising:

a patch adapted to at least partially seal a defect in the intervertebral disc, wherein said patch has a height and a length,

wherein said patch is at least partially flexible along its height, thereby facilitating flexion and extension of the disc; and

wherein said patch is at least partially rigid along its length, thereby minimizing or preventing extrusion of undesired material through a defect in the intervertebral disc.

27. An implant for treating an intervertebral disc comprising:

a sealing means adapted to obstruct at least a portion of a defect in the anulus fibrosis thereby minimizing or preventing the expulsion of nucleus pulposus,

wherein said sealing means comprises a first region and a second region,

wherein said sealing means comprises a first axis and a second axis,

wherein said first region and said second region lie along said first axis,

wherein said first region and said second region are contiguous,

wherein said first region has a different flexibility than said second region thereby providing a patch with variable stiffness,

and wherein said variable stiffness enhances the sealing means' ability to resist migration within the intervertebral disc.

28. An implant for treating an intervertebral disc comprising:

a barrier,

wherein said barrier has a first and a second axis, wherein said second axis is perpendicular to said first axis, and

wherein said barrier has a variable flexibility along at least said first axis or said second axis.

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