US20070233257A1 - Devices and Methods for Annular Repair of Intervertebral Discs - Google Patents

Abstract

Devices and methods for treating a damaged intervertebral disc to reduce or eliminate associated back pain. The present invention provides disc reinforcement therapy (DRT) which involves implanting one or more reinforcement members in and preferably around the annulus of the disc. The reinforcement members may be used to stabilize the annulus and/or compresses a portion of the annulus so as to reduce a bulge and/or close a fissure. The implantable devices and associated delivery tools may incorporate heating capabilities to thermally treat the annular tissue. Alternatively or in combination, other devices may be specifically employed for such thermal treatment.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• The present application is a continuation of U.S. application Ser. No. 10/943,525 filed Sep. 17, 2004; which is a continuation of U.S. application Ser. No. 10/390,970, filed Mar. 18, 2003, now U.S. Pat. No. 6,805,695; and is a continuation-in-part of Ser. No. 10/055,780, filed Jan. 22, 2002, now U.S. Pat. No. 6,689,125. U.S. application Ser. No. 10/390,970 is a continuation-in-part of Ser. No. 09/685,401, filed Oct. 10, 2000, now U.S. Pat. No. 6,579,291; which is a continuation-in-part of Ser. No. 10/093,990, filed Mar. 7, 2002, now U.S. Pat. No. 6,835,205; which is a continuation of Ser. No. 09/542,972, filed Apr. 4, 2002, now U.S. Pat. No. 6,402,750; and claims the benefit of U.S. Provisional Application No. 60/263,343, filed Jan. 22, 2001; and claims the benefit of U.S. Provisional Application No. 60/368,108 filed Mar. 26, 2002 entitled DEVICES AND METHODS FOR THE TREATMENT OF SPINAL DISORDERS, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
• The present invention generally relates to devices and methods for the repair of intervertebral discs. Specifically, the present invention relates to devices and methods for the treatment of spinal disorders associated with the annulus of an intervertebral disc.
BACKGROUND OF THE INVENTION
• Back pain is one of the most common and often debilitating conditions affecting millions of people in all walks of life. Today, it is estimated that over ten million people in the United States alone suffer from persistent back pain. Approximately half of those suffering from persistent back pain are afflicted with chronic disabling pain, which seriously compromises a person's quality of life and is the second most common cause of worker absenteeism. Further, the cost of treating chronic back pain is very high, even though the majority of sufferers do not receive treatment due to health risks, limited treatment options and inadequate therapeutic results. Thus, chronic back pain has a significantly adverse effect on a person's quality of life, on industrial productivity, and on heath care expenditures.
• Some forms of back pain are muscular in nature and may be simply treated by rest, posture adjustments and painkillers. For example, some forms of lower back pain (LBP) are very common and may be caused by unusual exertion or injury. Unusual exertion such has heavy lifting or strenuous exercise may result in back strain such as a pulled muscle, sprained muscle, sprained ligament, muscle spasm, or a combination thereof. An injury caused by falling down or a blow to the back may cause bruising. These forms of back pain are typically non-chronic and may be self-treated and cured in a few days or weeks.
• Other types of non-chronic back pain may be treated by improvements in physical condition, posture and/or work conditions. For example, being pregnant, obese or otherwise significantly overweight may cause LBP. A mattress that does not provide adequate support may cause back pain in the morning. Working in an environment lacking good ergonomic design may also cause back pain. In these instances, the back pain may be cured by eliminating the culprit cause. Whether it is excess body weight, a bad mattress, or a bad office chair, these forms of back pain are readily treated.
• However, some forms of back pain are the result of disorders directly related to the spinal column, which are not readily treated. While some pain-causing spinal disorders may be due to facet joint degradation or degradation of individual vertebral masses, disorders associated with the intervertebral discs are predominantly affiliated with chronic back pain (referred to as disc related pain). The exact origin of disc related pain is often uncertain, and although some episodes of disc related pain may be eased with conservative treatments such as bed-rest and physical therapy, future episodes of disc related pain are likely to occur periodically.
• There are a number of suspected causes of disc related pain, and in any given patient, one or more of these causes may be present. However, the ability to accurately diagnose a specific cause or locus of pain is currently difficult. Because of this uncertainty, many of the causes of disc related pain are often lumped together and referred to as degenerative disc disease (DDD).
• A commonly suspected source of disc related pain is physical impingement of the nerve roots emanating from the spinal cord. Such nerve root impingement may have a number of different underlying causes, but nerve root impingement generally results from either a disc protrusion or a narrowing of the intervertebral foramina (which surround the nerve roots).
• As a person ages, their intervertebral discs become progressively dehydrated and malnourished. Together with continued stressing, the disc begins to degenerate. With continued degeneration, or an excessive stressing event, the annulus fibrosus of the disc may tear, forming one or more fissures (also referred to as fractures). Such fissures may progress to larger tears which allow the gelatinous material of the nucleus pulposus to flow out of the nucleus and into the outer aspects of the annulus. The flow of the nucleus pulposus to the outer aspects of the annulus may cause a localized bulge.
• When bulging of the annulus occurs in the posterior portions of the disc, the nerve roots may be directly and physically impinged by the bulge. In more extreme or progressed instances of annular tears, the nuclear material may escape, additionally causing chemical irritation of the nerve roots. Depending on the cause and nature of the disc protrusion, the condition may be referred to as a disc stenosis, a disc bulge, a herniated disc, a prolapsed disc, a ruptured disc, or, if the protrusion separates from the disc, a sequestered disc.
• Dehydration and progressive degeneration of the disc also leads to thinning of the disc. As the height of the disc reduces, the intervertebral foraminae become narrow. Because the nerve roots pass through the intervertebral foraminae, such narrowing may mechanically entrap the nerve roots. This entrapment can cause direct mechanical compression, or may tether the roots, allowing them to be excessively tensioned during body movements.
• Nerve root impingement most often occurs in the lumbar region of the spinal column since the lumbar discs bear significant vertical loads relative to discs in other regions of the spine. In addition, disc protrusions in the lumbar region typically occur posteriorly because the annulus fibrosus is radially thinner on the posterior side than on the anterior side and because normal posture places more compression on the posterior side. Posterior protrusions are particularly problematic since the nerve roots are posteriorly positioned relative to the intervertebral discs. Lower back pain due to nerve root irritation not only results in strong pain in the region of the back adjacent the disc, but may also cause sciatica, or pain radiating down one or both legs. Such pain may also be aggravated by such subtle movements as coughing, bending over, or remaining in a sitting position for an extended period of time.
• Another suspected source of disc related back pain is damage and irritation to the small nerve endings which lie in close proximity to or just within the outer aspects of the annulus of the discs. Again, as the disc degenerates and is subjected to stressing events, the annulus fibrosus may be damaged forming fissures. While these fissures can lead to pain via the mechanisms described above, they may also lead to pain emanating from the small nerve endings in or near the annulus, due to mechanical or chemical irritation at the sites of the fissures. The fissures may continue to irritate the small nerve endings, as their presence cause the disc to become structurally weaker, allowing for more localized straining around the fissures. This results in more relative motion of edges of the fissures, increasing mechanical irritation. Because it is believed that these fissures have only limited healing ability once formed, such irritation may only become progressively worse.
• A common treatment for a disc protrusion is discectomy, a procedure wherein the protruding portion of the disc is surgically removed. However, discectomy procedures have an inherent risk since the portion of the disc to be removed is immediately adjacent the nerve root and any damage to the nerve root is clearly undesirable. Furthermore, discectomy procedures are not always successful long term because scar tissue may form and/or additional disc material may subsequently protrude from the disc space as the disc deteriorates further. The recurrence of a disc protrusion may necessitate a repeat discectomy procedure, along with its inherent clinical risks and less than perfect long term success rate. Thus, a discectomy procedure, at least as a stand-alone procedure, is clearly not an optimal solution.
• Discectomy is also not a viable solution for DDD when no disc protrusion is involved. As mentioned above, DDD causes the entire disc to degenerate, narrowing of the intervertebral space, and shifting of the load to the facet joints. If the facet joints carry a substantial load, the joints may degrade over time and be a different cause of back pain. Furthermore, the narrowed disc space can result in the intervertebral foramina surrounding the nerve roots to directly impinge on one or more nerve roots. Such nerve impingement is very painful and cannot be corrected by a discectomy procedure. Still furthermore, discectomy does not address pain caused by the fissures which may cause direct mechanical irritation to the small nerve endings near or just within the outer aspect of the annulus of a damaged disc.
• As a result, spinal fusion, particularly with the assistance of interbody fusion cages, has become a preferred secondary procedure, and in some instances, a preferred primary procedure. Spinal fusion involves permanently fusing or fixing adjacent vertebrae. Hardware in the form of bars, plates, screws and cages may be utilized in combination with bone graft material to fuse adjacent vertebrae. Spinal fusion may be performed as a stand-alone procedure or may be performed in combination with a discectomy procedure. By placing the adjacent vertebrae in their nominal position and fixing them in place, relative movement therebetween may be significantly reduced and the disc space may be restored to its normal condition. Thus, theoretically, aggravation caused by relative movement between adjacent vertebrae may be reduced if not eliminated.
• However, the success rate of spinal fusion procedures is certainly less than perfect for a number of different reasons, none of which are well understood. In addition, even if spinal fusion procedures are initially successful, they may cause accelerated degeneration of adjacent discs since the adjacent discs must accommodate a greater degree of motion. The degeneration of adjacent discs simply leads to the same problem at a different anatomical location, which is clearly not an optimal solution. Furthermore, spinal fusion procedures are invasive to the disc, risk nerve damage and, depending on the procedural approach, either technically complicated (endoscopic anterior approach), invasive to the bowel (surgical anterior approach), or invasive to the musculature of the back (surgical posterior approach).
• Another procedure that has been less than clinically successful is total disc replacement with a prosthetic disc. This procedure is also very invasive to the disc and, depending on the procedural approach, either invasive to the bowel (surgical anterior approach) or invasive to the musculature of the back (surgical posterior approach). In addition, the procedure may actually complicate matters by creating instability in the spine, and the long term mechanical reliability of prosthetic discs has yet to be demonstrated.
• Many other medical procedures have been proposed to solve the problems associated with disc protrusions. However, many of the proposed procedures have not been clinically proven and some of the allegedly beneficial procedures have controversial clinical data. From the foregoing, it should be apparent that there is a substantial need for improvements in the treatment of spinal disorders, particularly in the treatment of disc related pain associated with a damaged or otherwise unhealthy disc.
SUMMARY OF THE INVENTION
• The present invention addresses this need by providing improved devices and methods for the treatment of spinal disorders. The improved devices and methods of the present invention specifically address disc related pain, particularly in the lumbar region, but may have other significant applications not specifically mentioned herein. For purposes of illustration only, and without limitation, the present invention is discussed in detail with reference to the treatment of damaged discs in the lumbar region of the adult human spinal column.
• As will become apparent from the following detailed description, the improved devices and methods of the present invention may reduce if not eliminate back pain while maintaining near normal anatomical motion. Specifically, the present invention provides disc reinforcement devices to reinforce a damaged disc, while permitting relative movement of the vertebrae adjacent the damaged disc. The devices of the present invention are particularly well suited for minimally invasive methods of implantation.
• The reinforcement devices of the present invention may provide three distinct functions. Firstly, the reinforcement devices may mechanically stabilize and strengthen the disc to minimize if not eliminate chronic irritation of nerve roots and nerves around the periphery of the disc annulus. Secondly, the reinforcement devices may radially and/or circumferentially compress the disc to close fissures, fractures and tears, thereby preventing the ingress of nerves as well as potentially facilitating healing. Thirdly, the reinforcement devices may be used to stabilize the posterior disc after a discectomy procedure in order to reduce the need for re-operation.
• In an exemplary embodiment, the present invention provides disc reinforcement therapy (DRT) in which a reinforcement member is implanted in the annulus of an intervertebral disc. The implantation method may be performed by a percutaneous procedure or by a minimally invasive surgical procedure. The present invention provides a number or tools to facilitate percutaneous implantation. One or more reinforcement members may be implanted, for example, posteriorly, anteriorly, and/or laterally, and may be oriented circumferentially or radially. As such, the reinforcement members may be used to stabilize the annulus and/or compresses a portion of the annulus so as to reduce a bulge and/or close a fissure.
• In other embodiments, the implantable devices and associated delivery tools may incorporate heating capabilities to thermally treat the annular tissue. Alternatively or in combination, other devices may be specifically employed for such thermal treatment, and such thermal treatment may be applied by a device that is temporarily inserted into the annulus, or the thermal treatment may be applied by a chronically implanted device, either acutely or chronically.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIGS. 1A and 1B illustrate left lateral and posterior views, respectively, of a portion of the adult human vertebral (spinal) column;
• FIGS. 2A and 2B illustrate superior (top) views of a healthy disc and a degenerated disc, respectively, and an adjacent vertebral body;
• FIGS. 3A-3F schematically illustrate superior (top) views of reinforcement members disposed in degenerated discs;
• FIGS. 4A-4M schematically illustrate various features that may be incorporated into a straight or curved reinforcement member in accordance with an embodiment of the present invention;
• FIGS. 5A-5C schematically illustrate a circumferential reinforcement member in accordance with an embodiment of the present invention;
• FIGS. 6A-6H schematically illustrate components of a reinforcement member in accordance with an embodiment of the present invention;
• FIGS. 7A-7F illustrate tools of the present invention for implanting the reinforcement members shown inFIGS. 3A and 3B in accordance with the method illustrated inFIGS. 8A-8L;
• FIGS. 8A-8L illustrate a method for implanting the reinforcement members shown inFIGS. 3A and 3B in accordance with an embodiment of the present invention;
• FIGS. 9A-9F illustrate tools of the present invention for implanting the reinforcement member shown inFIG. 3C in accordance with the method illustrated inFIGS. 10A-10H;
• FIGS. 10A-10H illustrate a method for implanting the reinforcement member shown inFIG. 3C in accordance with an embodiment of the present invention;
• FIGS. 11A-11H illustrate a method for implanting the reinforcement member shown inFIG. 3D in accordance with an embodiment of the present invention;
• FIGS. 12A-12G and13-15 illustrate various tools of the present invention for implanting the reinforcement member shown inFIGS. 3E and 3F in accordance with the method illustrated inFIGS. 18A-18L;
• FIGS. 16A-16E illustrate a column support and advancement device for use with the tools illustrated inFIGS. 12A-12G and13;
• FIGS. 17A-17D illustrate an alternative column support and advancement device for use with the tools illustrated inFIGS. 12A-12G and13;
• FIGS. 18A-18L illustrate a method for implanting the reinforcement member shown inFIGS. 3E and 3F in accordance with an embodiment of the present invention;
• FIGS. 19A-19F illustrate various possible implant orientations of the reinforcement member shown inFIGS. 3E and 3F;
• FIGS. 20A-20J illustrate steps for implanting a self-expanding reinforcement member;
• FIGS. 20K-20L illustrate steps for implanting an inflatable reinforcement member;
• FIGS. 20M-20R illustrate steps for implanting a reinforcement bar;
• FIGS. 21A-21C illustrate a reinforcement member in accordance with an alternative embodiment of the present invention;
• FIGS. 22A-22D illustrate a reinforcement member in accordance with yet another alternative embodiment of the present invention;
• FIGS. 23A and 23B illustrate an alternative method for implanting a variation of the reinforcement member shown inFIG. 20J in accordance with an embodiment of the present invention;
• FIGS. 24A-24E illustrate various tools of the present invention for implanting a reinforcement member in accordance with the method illustrated inFIGS. 25A-25J;
• FIGS. 25A-25J illustrate an alternative method for implanting a reinforcement member in accordance with an embodiment of the present invention;
• FIGS. 26A-26G illustrate various tools of the present invention for implanting a reinforcement member in accordance with the method illustrated inFIGS. 27A-27H;
• FIGS. 27A-27H illustrate an alternative method for implanting a reinforcement member in accordance with an embodiment of the present invention; and
• FIGS. 28A-28C illustrate various heating probes of the present invention for temporarily heating annular tissue.
DETAILED DESCRIPTION OF THE INVENTION
• The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.
• With reference toFIGS. 1A and 1B, the lower portion of an adulthuman vertebral column10 is illustrated in left lateral and posterior views, respectively. The upper portion of thevertebral column10 includes the thoracic region and the cervical region, which are not shown for purposes of simplified illustration only. The lower portion of thevertebral column10 includes thelumbar region12, thesacrum14 and thecoccyx16. Thesacrum14 and thecoccyx16 are sometimes collectively referred to as the pelvic curvature.
• Thevertebral column10 includes an axis ofcurvature60 which generally forms a double-S shape when viewed laterally. Thevertebral column10 also includes amedian plane70 which is a sagittal plane bisecting thevertebral column10 into symmetrical left lateral and right lateral portions. In posterior views, themedian plane70 appears as a line.
• Thelumbar region12 of thevertebral column10 includes five (5) vertebrae20 (labeled L1, L2, L3, L4 and L5) separated byintervertebral discs50. Thesacrum14, which includes five (5) fused vertebrae30 (superior vertebra30 labeled S1), is separated by asingle disc50 from thecoccyx16, which includes four (4) fusedvertebrae40. Although not labeled, theintervertebral discs50 may be referenced by their respective adjacent vertebrae. For example, thedisc50 between the L4 and L5lumbar vertebrae20 may be referred to as the L4L5 disc. Similarly, thedisc50 between the L5lumbar vertebra20 and the S1sacral vertebra30 may be referred to as the L5S1 disc.
• Although eachvertebra20/30/40 is a unique and irregular bone structure, thevertebrae20 of the lumbar region12 (in addition to the thoracic and cervical regions) have common structures. Eachvertebra20 of thelumbar region12 generally includes abody portion21 and a vertebralarch portion22/23 which encloses the vertebral foramen (not visible) in which the spinal cord is disposed. Thevertebral arch22/23 includes twopedicles22 and twolaminae23. Aspinous process24 extends posteriorly from the juncture of the twolaminae23, and twotransverse processes25 extend laterally from eachlamina23. Fourarticular processes26/27 extend inferiorly26 and superiorly27 from thelaminae23. The inferiorarticular process26 rests in the superiorarticular process27 of the adjacent vertebra to form a facet joint28.
• The five (5)vertebrae30 of thesacrum14 are fused together to form a single rigid structure. Thesacrum14 includes a mediansacral crest31 which roughly corresponds to the spinous processes of thevertebrae30, and two intermediate sacral crests32 which roughly correspond to the articular processes of thevertebrae30. The sacral laminae33 are disposed between the median31 and intermediate32 sacral crests. Two lateral sacral crests34 are disposed on either side of thesacral foraminae35. Thesacrum14 also includes a pair ofsacral wings36 which defineauricular surfaces39. The superior (S1)sacral vertebra30 includes two superiorarticular processes37 which engage the inferior articular processes26 of theL5 lumber vertebra20 to form a facet joint, and thebase38 of the superior sacral vertebra S1 is joined to theL5S1 disc50.
• With reference toFIG. 2A, eachintervertebral disc50 includes anannulus fibrosus52 surrounding anucleus pulposus54. Theposterior annulus52 is generally thinner than theanterior annulus52, which may account for the higher incidence of posterior disc protrusions. Theannulus fibrosus52 comprises about 60% of thetotal disc50 cross-sectional area, and thenucleus pulposus54 only comprises about 40% of thetotal disc50 cross-sectional area. Theannulus fibrosus52 comprises 40-60% organized collagen in the form of a laminated structure. Thenucleus pulposus54 comprises 18-30% collagen in the form of a relatively homogenous gel.
• A common theory is that eachintervertebral disc50 forms one support point and the facet joints28 form two support points of what may be characterized as a three point support structure betweenadjacent vertebrae20. However, in thelumbar region12, the facet joints28 are substantially vertical, leaving thedisc50 to carry the vast majority of the load. As between theannulus fibrosus52 and the nucleus pulposus54 of thedisc50, it is commonly believed that thenucleus54 bears the majority of the load. This belief is based on the theory that thedisc50 behaves much like a balloon or tire, wherein theannulus22 merely serves to contain thepressurized nucleus54, and thenucleus54 bears all the load. However, this theory is questionable since theannulus fibrosus52 comprises 60% of thetotal disc50 cross-sectional area and is made of 40-60% organized collagen in the form of a laminated structure. By contrast, thenucleus pulposus54 only comprises 40% of thetotal disc50 cross-section and is made of 18-30% collagen in the form of a relatively homogenous gel. Thus, a more plausible theory is that theannulus fibrosus52 is the primary load bearing portion of thedisc50.
• With reference toFIG. 2B, theintervertebral discs50 become progressively dehydrated and malnourished with age. When combined with continued stressing, the disc begins to degenerate. With continued degeneration, or an excessive stressing event, the annulus fibrosus of the disc may tear, forming one or moreradial fissures56 orcircumferential fissures58, which may progress to larger tears. Larger tears may allow the gelatinous material of thenucleus pulposus54 to flow out of the nucleus and into the outer aspects of theannulus52. The flow of thenucleus pulposus54 to the outer aspects of theannulus52 may cause alocalized bulge60. Aposterior bulge60 may result in direct impingement of a nerve root (not shown). Nuclear material that escapes through an advanced tear may cause further mechanical irritation and additionally cause chemical irritation of a nerve root. A nerve root may also be compressed or tethered by a narrowing of the intervertebral foraminae, resulting from a loss in disc height caused by sustained degeneration of thedisc50. Small nerve endings (not shown) in or near the perimeter of theannulus52 may also be mechanically or chemically irritated at the sites of thefissures56/58. In all cases, degeneration of the disc eventually leads to disc related pain of some origin.
• FIGS. 3A-3F schematically illustratereinforcement members100/200/300/600 implanted in a degenerateddisc50. In all instances, thereinforcement members100/200/300/600 mechanically stabilize and strengthen thedisc50 to minimize if not eliminate chronic irritation of nerve roots and nerves around the periphery of thedisc annulus52. As can be seen inFIGS. 3A-3F, thereinforcement members100/200/300/600 also radially and/or circumferentially compress thedisc50 to closefissures56/58, thereby preventing the ingress of nerves and potentially facilitating healing. Thereinforcement members100/200/300/600 may further be used to stabilize the posterior portion of thedisc50 after a discectomy procedure in order to reduce the need for re-operation.
• FIGS. 3A-3F show examples of where thereinforcement members100/200/300/600 may be implanted in theannulus52. However, thereinforcement members100/200/300/600 may be implanted in any portion of theannulus52 including, without limitation, the posterior, anterior or lateral portions thereof. Because most disc related pain is associated with damage to the posterior portion of thedisc50, thereinforcement members100/200/300/600 preferably provide support to the posterior portion of theannulus52 and establish anchor points in the lateral and anterior portions of theannulus52, or completely encircle theannulus52. Thereinforcement members100/200/300/600 may be used individually as shown in FIGS.3A and3C-3F, or in combination as shown inFIG. 3B. Although not shown, any combination of the different types ofreinforcement members100/200/300/600 may be utilized.
• Thereinforcement members100/200/300/600 may be oriented generally parallel to the periphery of the annulus52 (e.g.,reinforcement members100A,100C,200,300,600), generally radial to the annulus52 (e.g.,reinforcement member100B), or any other orientation suitable for stabilizing and/or compressing the desired portion(s) of theannulus52. Generally, the closer thereinforcement members100/200/300/600 are to the periphery of theannulus52, the greater the amount of support and stabilization provided to thedisc50. As such, thereinforcement members100/200/300/600 preferably have a curvature conforming to the periphery of theannulus52 such that they may be implanted as close to the periphery of theannulus52 as possible. Thereinforcement members100/200/300/600 may have such a curvature in the relaxed (zero stress) state, or the curvature may be imparted by the insertion path or defined by the insertion tools used.
• Thereinforcement members100/200/300/600 may extend across andclose fissures56/58 as shown, or any other portion of theannulus52 to provide compression and stabilization of thedisc50. Although not shown, thereinforcement members100/200/300/600 may extend across or into thenucleus54. In such a case, it is preferred that thereinforcement members100/200/300/600 do not extend outside the periphery of theannulus52 in order to reduce the probability of nuclear material escaping from the outer aspects of theannulus52.
• Thereinforcement members100/200/300/600 are sized to fit within theannulus52 of ahuman disc50. Thus, the collective diameter and length of thereinforcement members100/200/300/600 implanted preferably does not exceed the height and circumference/diameter, respectively, of theannulus52, depending on the number and orientation of thereinforcement members100/200/300/600 implanted. Thereinforcement members100/200/300/600 may be made of a biocompatible material or coated with a biocompatible material. Suitable structural materials for thereinforcement members100/200/300/600 include stainless steel and super elastic alloys such as nickel titanium. All or a portion of thereinforcement members100/200/300/600 may be made of biodegradable or bioabsorbable material such as resorbable collagen, LPLA (poly(l-lactide)), DLPLA (poly(dl-lactide)), LPLA-DLPLA, PGA (polyglycolide), PGA-LPLA or PGA-DLPLA. Other metals, alloys, polymers, and composites having suitable tensile, compression and fatigue strength and elasticity may also be used. Thereinforcement members100/200/300/600 may further include growth factors to facilitate healing, agents which render nuclear matter inert or otherwise reduce chemical irritation thereof, and/or anesthetic agents to reduce nerve signal transmission (i.e., pain).
• Reinforcement member600, as illustrated inFIGS. 3E and 3F, is adapted to completely encircle theannulus52 to thereby apply uniform compressive forces about the periphery of theannulus52. Thereinforcement member600 has opposing ends which are secured together by apermanent connection610 such as a knot as seen inFIG. 3E. Optionally, apledget750 may be employed as illustrated inFIG. 3F and as discussed in more detail hereinafter.Reinforcement member600 may substantially reside within the confines of theannulus52, with theconnection610 andoptional pledget750 residing within or immediately outside the confines of theannulus52. Whilereinforcement member600 is shown within the outer aspect of theannulus52, it is also contemplated that all or portions ofreinforcement member600 may be implanted outside theannulus52. For example,reinforcement member600 may be placed in the tissue plane between the outside of theannulus52 and external connective tissues (not shown).
• Thereinforcement member600 may comprise a monofilament or multifilament structure that resists elongation in tension, but is otherwise very flexible. For example, thereinforcement member600 may comprise a polymeric or metallic fiber, cable, thread, suture, wire, ribbon, or the like. Suitable materials for thecircumferential reinforcement member600 include, but are not limited to, commercially available suture materials used in a variety of surgical procedures. Such exemplary suture materials include biodegradable suture made from polylactic acid and polyglycolic acid, and non-degradable materials such as monofilament and braided polypropylene and polyester (PET). Another suitable non-degradable suture material is made from expanded polytetrafluoroethylene (ePTFE). Other materials which are suitable for thecircumferential reinforcement member600 include braided ultra-high molecular weight fibers of polyethylene (UHMWPE), commercially available as Spectra™ or Dyneema™, as well as other high tensile strength materials such as Vectran™, Kevlar™, and natural or artificially produced silk.
• As an alternative, thereinforcement member100/200/300/600 may be designed for temporary heating (post-implantation) to cause thermal changes to the annulus. Because the annulus is comprised of overlapping bands of oriented collagen which tend to shrink in the direction of orientation when heated to temperatures of 50 to 90 degrees centigrade, temporarily heating thereinforcement member100/200/300/600 causes thermal reformation of the annulus. In addition, annular defects such as fissures and tears can refuse, particularly if the edges are brought into apposition prior to or during the heating step. Such annular defects may be closed (i.e., edges brought into apposition) by compression imparted by thereinforcement member100/200/300/600 during implantation or by collagen shrinkage imparted by heating thereinforcement member100/200/300/600.
• Thereinforcement member100/200/300/600 may be heated by inducing heat in the material of thereinforcement member100/200/300/600 or by incorporating one or more heating elements into thereinforcement member100/200/300/600. In both cases, a source of electric or magnetic power (e.g., electric power supply, magnetic field generator, RF transmitter, etc.) is used to provide energy to thereinforcement member100/200/300/600 which converts the electric/magnetic energy to thermal energy. Such a power source may be directly or remotely connected to thereinforcement member100/200/300/600.
• For example, thereinforcement members100/200/300/600 may include resistive heating elements directly connected to an internal (implanted) power supply or directly connected (transdermal) to an external electric power supply. Alternatively, the resistive heating elements may be connected to an implanted receiving antenna which receives a power signal from a remote external power signal transmitting antenna. As a further alternative, thereinforcement member100/200/300/600 may be heated by remote inductive heating via an external alternating magnetic field generator. Because significant portions of thereinforcement member100/200/300/600 may comprise a conductive metallic material, the presence of an alternating magnetic field will inductively heat thereinforcement member100/200/300/600. Further aspects of these and otherheated reinforcement member100/200/300/600 embodiments are discussed in more detail with reference toFIGS. 4H-4M.
• In all embodiments, various visualization techniques may be used to facilitate implantation of thereinforcement members100/200/300/600. For example, real time CT scanning, real time MR imaging, or a combination of preoperative CT or MR images superimposed onto a real time device tracking images such as the system commercially available under the trade name STEALTH™ available from Sofamor Danek.
• FIGS. 4A-4K illustrate various embodiments of thereinforcement member100 in accordance with the present invention. The embodiments ofFIGS. 4A-4K illustrate various features which may be combined in any way to provide the desiredreinforcement member100.Reinforcement member100 may be sized and oriented as shown and discussed with reference toFIGS. 3A and 3B.Reinforcement member100 includes abody portion110 and ananchor120. Theanchor120 serves to immobilize or limit movement of thereinforcement member100 relative to theannulus52.
• InFIGS. 4A, 4D and4F, the anchor is in the form ofthreads122 disposed about the periphery of thebody portion110, which behave like threads on a screw and engage theannulus52 upon rotation therein. Whenthreads122 are used, the proximal end of thebody110 may includeslots116 as shown inFIG. 4C, which is an end view taken alongline4C-4C inFIG. 4A. Theslots116, or any other suitable mating geometry, facilitate rotation with a driver having a mating distal end. InFIG. 4E, theanchor120 is in the form of slopedrings124 spaced along the length of thebody portion110, which behave like rings on a ring-shank nail to engage theannulus52 upon pushing therein. Those skilled in the art will recognize thatother anchor120 mechanisms such as barbs, expandable anchors, etc. may also be used.
• Theanchor120 may extend the full length of thebody portion110 as shown inFIGS. 4A and 4F, or may be disposed only on proximal and distal portions of the body as shown inFIGS. 4D and 4E. Thebody portion110 may be tubular defining alumen112 extending therethrough as shown inFIG. 4B, which is a cross-sectional view taken alongline4B-4B inFIG. 4A. Thelumen112 facilitates advancement of thereinforcement member100 over a stylet to facilitate insertion into theannulus52, as will be discussed in greater detail hereinafter. Alternatively, thebody portion110 may have a solid cross-section as shown inFIG. 4G, which is a cross-sectional view taken along line4G-4G inFIG. 4F. In this alternative embodiment, the solidcross-section body portion110 may include a sharpeneddistal tip114 as shown inFIG. 4F to facilitate insertion into theannulus52.
• Preferably, thethreads122 have a variable pitch such that the annulus is compressed as thereinforcement member100 is rotated and advanced into theannulus52.Variable pitch threads122, as shown inFIGS. 4A, 4D and4F, generally have a larger pitch at the distal end of thebody110 and a smaller pitch at the proximal end of thebody110. The larger pitchdistal threads122 pull the annular tissue52 a greater distance per revolution than the smaller pitchproximal threads122. Thus, as thereinforcement member100 is rotated and advanced into theannulus52, the distal threads pull the annular tissue together and the proximal threads hold the tissue in place thereby compressing theannulus52. By compressing theannulus52, thedisc50 is mechanically stabilized and thefissures56/58 are closed to facilitated healing.
• Although compression of theannulus52 is preferred, it is not necessary to have compression in order to provide some degree of mechanical stabilization. To the extent that compression is desired, thevariable pitch threads122 mentioned above are currently preferred. However, other compression techniques are equally useful. For example, standardconstant pitch threads122 andtapered rings124 may achieve compression by utilizing a step-wise advancement and tension technique as will be described in more detail hereinafter.
• In order to provide the ability to temporarily heat thereinforcement member100 as discussed previously, various modifications to the design of thereinforcement member100 may be made as described with reference toFIGS. 4H-4M. These design modifications may also be applied toreinforcement members200 and300, but are described with specific reference toreinforcement member100 for purposes of illustration only. Although numerous methods may be employed to temporarily heat thereinforcement member100, two preferred methods, resistive heating and inductive heating are described in detail.
• FIG. 4H illustrates ageneric reinforcement member100 includingbody portion110, anchors120 (not shown for sake of clarity) andheating element140 in the form of a resistive wire.FIG. 4I is a cross-sectional view taken along line41-41 inFIG. 4H.Resistive wire140 may be helically wound on the outer surface of thebody110, the inner surface of thebody110, or in the wall of thebody110. Preferablyresistance wire140 is helically incorporated into the wall of thebody portion110 at the time of fabrication, for example by insert/injection molding.Resistance wire140 may helically traverse the length of thebody110 in one pitch direction, then traverses back in the opposite direction in an opposite pitch direction. In this manner, a single wire traverses the length of thebody110, but has two ends at the proximal end of thebody110 available for connection to an electrical power source or receiving antenna.
• Resistance wire140 is conductive, but offers a high enough resistance to heat during the application of electrical current. The wire may be made of a variety of conductive metals, including copper, tungsten, platinum, or gold, and may be covered/coated with a biocompatible material. Preferably, theresistance wire140 is formed of a biocompatible metal, but this is not essential as long as direct tissue exposure is avoided such as when a biocompatible covering/coating is used or when thewire140 is embedded in the wall ofbody110. Since the wire will be heated to a relatively high temperature (e.g., 50 to 90 degrees centigrade), thebody110 or covering is preferably made of a material which can withstand elevated temperatures, preferably of a high temperature polymer such as Polyimide, PTFE, Kynar, or PEEK.
• Electrification ofresistance wire140 may be accomplished by initially incorporating a pair of releasable lowresistance lead wires142 to the ends of theresistance wire140, as shown inFIG. 4H. Thelead wires142 are passed through or reside alongsidedriver440 during the advancement ofreinforcement member100 as described with referenceFIGS. 8A-8L. If they are passed through thedriver440, the driver must be hollow. Once thereinforcement member100 is fully implanted, thelead wires142 are connected to apower source146, which delivers electrical current to thereinforcement member100, causing it and the surrounding tissue to heat to a desired temperature for a desired period of time. The temperature of theresistance wire140 may be monitored by measuring the current demand from thepower source146 or by positioning a thermocouple (not shown) adjacent the proximal end of thereinforcement member100. Once the heating step is finished, the releasable leads142 are removed from theresistance wires140 utilizingreleasable connection141. Removal of the releasable leads142 may be accommodated by providing a low tensile strength connection which separates by pulling, or by providing a fusible metal strip connection which separates by applying electric current above a threshold value. Such a fusible metal strip connection may also serve to self-limit the degree to which the reinforcement member is heated.
• Alternatively, theleads142 are not removable, but stay attached to theresistive wires140 andreinforcement member100, as illustrated inFIG. 4J. In this embodiment, and preferably after thereinforcement member100 is implanted, theleads142 are attached to an implantable receiver antenna such asconductive wire coil144. Thereceiver coil144 may be incorporated into ahousing145 having a flat disc shape which is subcutaneously positioned adjacent the access site. Since thelead wires142 and thereceiver coil144 are implanted within the body, thehousing145 and thelead wires142 are preferably encased in a biocompatible and stable material, for example silicone rubber.
• FIG. 4K illustrates an example of a suitable implant position for thereceiver coil144, relative to thevertebral column10, preferably adjacent the lumbar disc being treated. Thereceiver coil144 andhousing145 are oriented parallel to the surface of the skin, and the access site is then closed. Once positioned, a similarly shaped transmittingcoil148 is placed on the skin surface, adjacent and overlapping thesubcutaneous receiver coil144. The transmittingcoil148 is connected to apower source146 and associated transmission circuit. When an alternating current is delivered to the transmittingcoil148, a corresponding alternating current is generated in the receivingcoil144, which in turn causes theresistance wire140 and thereinforcement member100 to heat.
• One advantage of this resistive heating method is that the heating procedure can be repeated multiple times, without the need for reoperation or any other invasive procedure. For example, the patient may have the implanted reinforcement member(s)100 heated upon initial implantation, and have them re-heated at any such time as back pain may recur. One of the mechanisms by which heat is believed to minimize back pain is by the destruction of nerve endings at the periphery of the annulus. However, new nerve endings may permeate the annulus, necessitating a subsequent heating to return the patient to a pain-free state.
• As an alternative to theantennas144/148, atransdermal plug149 may be used to establish direct connection between theleads142 and thepower source146. The plug129 includes an internal implantable portion and an external portion. To facilitate immediate heating of thereinforcement member100, the internal and external portions of the plug129 may be connected just after implantation of thereinforcement member100, but prior to closing the access site. The internal portion of the plug129 is then positioned just below the skin and the access site is closed. To facilitate post-operative heating, a small incision may be made in the skin to connect the internal and external portions of the plug129.
• An alternate method ofheating reinforcement member100 and surrounding annular tissue is the use of inductive heating. Inductive heating is used in many industrial and some medical applications. Essentially, a high frequency alternating magnetic field is oriented on the object to be heated. The alternating magnetic field causes eddy currents in the object to be heated. These eddy currents then cause ohmic heating. As long as the object to be heated is conductive, usually metallic, it may be inductively heated.
• To facilitate inductive heating, all or a significant portion ofreinforcement member100 is fabricated of a conductive metal, such as stainless steel, carbon steel, MP35N, nickel titanium alloy, or tungsten. The choice of material will influence the parameters needed for the inducting power source. Preferably, theentire body110 is fabricated of the conductive metal.
• With reference toFIG. 4M, the inductor may include apower source152 coupled byleads154 to acoil150 which generates a large alternating magnetic field. Thecoil150 may have a long tubular shape, inside which the patient resides during heating, or may be of a smaller size (as illustrated) which is oriented toward thereinforcement member100. The main parameters which need to be adjusted to result in a desired heating of thereinforcement member100 are the frequency and amplitude of the alternating magnetic field. Typical frequencies will range from about 10 kHz to 10 MHz. Inductive heating also has the advantage of allowing for multiple subsequent heating treatments for the patient, should back pain recur.
• While thereinforcement member100 is preferably a permanently implanted device, the incorporation of temporary heating immediately or shortly after implantation allows for the possibility of temporary implantation. In this usage ofreinforcement member100, it is implanted using the methods and tools described in further detail below. But, once fully implanted, a transient heating step is performed. Because the reinforcement member causes the annular tissue to compress circumferentially and/or radially, the heating is particularly effective at remodeling the annular tissue to a more normal, pre-degenerated condition. Therefore, it may not be necessary to keep the reinforcement member implanted. Thereinforcement member100 can be removed by essentially reversing the implantation steps. In order to facilitate removal following heating, it is desirable to provide a lubricious coating such as a hydropholic polymer or PTFE coating on the surface of thereinforcement member100, including thebody110 andanchor120.
• FIGS. 5A-5C schematically illustrate acircumferential reinforcement member200, which is generally the same asreinforcement member100 except as described herein.FIG. 5B is a cross-sectional view taken alongline5B-5B inFIG. 5A, andFIG. 5C is an end view taken alongline5C-5C inFIG. 5A. Thecircumferential reinforcement member200 includes atubular body210 defining alumen212 to facilitate advancement over a stylet. Thecircumferential reinforcement member200 also includes ananchor220, preferably in the form ofvariable pitch threads222. The proximal end of thebody210 the may includeslots216 or other suitable mating geometry to facilitate rotation by a driver having a mating distal end. Any of the variants ofreinforcement member100 discussed with reference toFIGS. 4A-4G may be applied tocircumferential reinforcement member200.
• Thecircumferential reinforcement member200 may have a geometry (e.g., circle, ellipse, oval, etc.) corresponding to the geometry of the outer aspects of ahealthy annulus52, or themember200 may be naturally straight, taking on a curved shape during implantation. Because thecircumferential reinforcement member200 is implanted in theannulus52 around the entire periphery thereof, the reinforcement member maximizes anchoring strength and provides superior stabilization around theentire disc50. Thus, it is preferable that thereinforcement member200 define a closed geometry once implanted, or even have overlapping ends, but an open geometry (e.g., semi-ellipse or semi-circle) may also be employed. The size and shape of thereinforcement member200 may be pre-selected to accommodate anatomical variations of theannulus52 between patients. The reinforcement member may have a relaxed size that is smaller than the implanted size such that additional radial and circumferential compression is achieved.
• Circumferential reinforcement member200 may further incorporate design features which allow for temporary heating. As described in connection withreinforcement100 above, similar features which allow for resistive heating or inductive heating may be incorporated.
• FIGS. 6A-6H schematically illustratereinforcement member300, including a pair oftubular pins310, twoscrews320 and two connectingrings330 which may be assembled as shown inFIG. 6F. With reference toFIG. 6A, each of thetubular pins310 includes ashaft portion312, ahead portion314 and aconnection mechanism318. Theshaft312 is sized to fit within a hole of theconnection ring330 and thehead314 is sized larger than the same hole. Theconnection mechanism318 may comprises a threaded shaft insertable into a threaded hole as shown, or any other known mechanical releasable connection that maintains the profile of theshaft portion312. As seen inFIG. 6B, which is a cross-sectional view taken alongline6B-6B inFIG. 6A, theshaft portion312 includes alumen313 to facilitate advancement over a stylet. Theheads314 may each include aslot316 as seen inFIG. 6C, which is an end view taken alongline6C-6C inFIG. 6A, or other suitable geometry to mate with a distal end of a driver to facilitate rotation of thepins310 to screw the releasable connection together.
• Thescrews320 include ashaft322, ahead324,threads328 and a sharpenedtip323 as seen inFIG. 6D. Thescrews320 may comprise a wide variety of orthopedic screw designs, particularly those suitable for implantation into cartilage and other collagen-based tissues. Theshaft322 andthreads326 are sized to fit within a hole of theconnection ring330 and thehead324 is sized larger than the same hole. Thehead324 includesslots326 as seen inFIG. 6E, which is an end view taken alongline6E-6E inFIG. 6D, or other suitable mating geometry to facilitate rotation by a driver having a mating distal end.
• The connection rings330 each have first andsecond rings331/333 defining first andsecond holes332/334 as shown inFIG. 6F. Thefirst hole332 is sized to provide a sliding fit about theshaft312 of thepins310 and the second hole is sized to provide a sliding fit about theshaft322 andthreads326 of thescrews320. As seen in the side view shown inFIG. 6G, each of the connection rings330 also define anangle336 between therings331/333 to accommodate the implanted arrangement as shown inFIG. 6H.
• As described above in connection withreinforcement members100 and200,reinforcement member300 can also incorporated features to provide for temporary heating. For example,tubular pins310 can incorporate resistive wire, or can be fabricated of a conductive metallic material, in a manner similar to that described forreinforcement members100 or200 above.
• Referring now toFIGS. 7A-7F,various tools410,420,430 and440 are shown individually and assembled. Thetools410,420,430 and440 may be used to implant thereinforcement members100 discussed above. The tools include a rigid, sharpened,hollow trocar410 as shown inFIG. 7A, a semi-rigid, sharpened, hollowcurved needle420 as shown inFIG. 7B, a sharpenedcurved stylet430 as shown inFIG. 7C, and ahollow driver440 as shown inFIG. 7D. As seen inFIG. 7E, the sharpenedstylet430 fits into thesemi-rigid needle420 which fits into therigid trocar410. As seen inFIG. 7F, the sharpenedstylet430 fits into thehollow driver440 which fits into therigid trocar410.
• With specific reference toFIG. 7A, the rigidhollow trocar410 includes ahollow shaft412 and a grip or handle414. Theshaft412 includes a sharpenedtip413 to facilitate passage through the skin and back muscles, and insertion into theannulus52. Theshaft412 is preferably made of a rigid metal such as a stainless steel hypodermic tube. Thegrip414 may comprise a polymer and may be formed by insert injection molding with theshaft412 inserted into the mold.
• With specific reference toFIG. 7B, the semi-rigidcurved needle420 includes a hollow shaft422 ahub424. Theshaft422, which includes a sharpenedtip423, is longer than therigid trocar410 and has an outside diameter sufficiently small to fit into therigid trocar410. Theshaft422 is preferably made of a semi-rigid polymer or composite. Theshaft422 includes a curveddistal portion426 that may be straightened (shown in phantom) upon insertion of thesemi-rigid needle420 into the lumen of therigid trocar410. Thehub424 may include a fitting425 to facilitate connection to a fluid source or a pressure source (e.g., a syringe).
• With specific reference toFIG. 7C, the sharpenedcurved stylet430 includes aflexible shaft432 and a sharpeneddistal end433. Thedistal tip433 may optionally include ananchor435 such as threads, tapered rings or barbs to facilitate the step-wise advancement and tension technique as will be described in detail hereinafter. If threads are used for theanchor435, the curvature434 of the distal portion of theshaft432 may be eliminated to facilitate efficient torque transfer. Theshaft432 includes a curve434 which approximates the curvature and diameter of the outer aspects of the annulus where thereinforcement member100 is to be implanted. Theshaft432 is longer than the both therigid trocar410 and thesemi-rigid needle420, and may have a length on the order of 10 to 60 cm. Theshaft432 also has an outside diameter sufficiently small to fit into thesemi-rigid needle420. Theshaft422 preferably has a flexible but pushable construction incorporating a rigid metal such as stainless steel, or super-elastic nickel-titanium alloy. The sharpenedstylet430 is preferably highly elastic, to resist permanent set upon insertion into thecurved portion426 of thesemi-rigid needle420.
• With specific reference toFIG. 7D, thehollow driver440 includes ahollow shaft442 and a grip or handle444. The distal end of thehollow shaft442 includes atip446 defining a geometry which mates with an end of thereinforcement member100 to facilitate rotation thereof during implantation. Theshaft442 is preferably made of a torsionally rigid metal such as a stainless tool steel. Thegrip444 may comprise a polymer and may be formed by insert injection molding with theshaft442 inserted into the mold.
• With general reference toFIGS. 8A-8L, the steps for implantingreinforcement member100 are illustrated. It should be understood that the procedure for implanting asingle member100 in the posterior portion of theannulus52 is shown for purposes of illustration, not limitation. All of the variables with regard to quantity, location, orientation, etc. discussed previously may be implemented by varying the generic procedure described hereinafter.
• The method illustrated inFIGS. 8A-8L is a percutaneous procedure in which access to thedisc50 is achieved utilizing a number of small diameter tools which may be inserted through a patient's back (skin and back muscles), between adjacent vertebrae, and into the patient'sdisc50. This percutaneous method minimizes the invasiveness of the procedure thereby reducing procedure time, procedure cost, postoperative pain and recovery time.
• Initially, as shown inFIG. 8A, therigid trocar410 is positioned for insertion into thedisc50 as in a conventional discogram procedure. Therigid trocar410 is advanced until thedistal tip413 of thetrocar410 is proximate the outer periphery of the posterior portion of theannulus52 as seen inFIG. 8B.
• Thecurved portion426 of thesemi-rigid needle420 is straightened for insertion into thetrocar410 as shown inFIG. 8C. The semi-rigid needle420 (alone or with stylet430) is advanced relative to therigid trocar410 until thecurved portion426 of the semi-rigid needle exits thedistal tip413 of therigid trocar410 and the desired amount of curvature is established, as seen inFIG. 8D. Thecurved portion426 may be advanced until thetip423 is roughly parallel to the posterior curvature of theannulus52.
• The sharpenedstylet430 is then positioned for insertion into thesemi-rigid needle420 as shown inFIG. 8E. The sharpenedstylet430 is advanced relative to thesemi-rigid needle420 until thedistal tip433 of thestylet430 extends acrossradial fissures56, as shown inFIG. 8F.
• The semi-rigidcurved needle420 is removed from thestylet430 andtrocar410, and thereinforcement member100 is positioned for advancement over thestylet430 as shown inFIG. 8G. Thereinforcement member100 is advanced over thestylet430 and into thetrocar410, and thedriver440 is positioned for advancement over thestylet430 as shown inFIG. 8H. Thedriver440 is then rotated and advanced over thestylet430 in order to rotate and push thereinforcement member100 into the annulus and across the radial fissures56 as seen inFIG. 8I. If thereinforcement member100 utilizes an anchor other than threads, thedriver440 may be used to simply push or otherwise advance thereinforcement member100 through thetrocar410 and into theannulus52.
• If a solidcross-section reinforcement member100 is utilized, it is not necessary to utilize thestylet430. In this situation, the curvedsemi-rigid needle420 is left in place as shown inFIG. 8E and the solidcross-section reinforcement member100 is advanced therethrough. Thedriver440 is then rotated and advanced through the curvedsemi-rigid needle420 in order to rotate and push thereinforcement member100 into theannulus52 and across the radial fissures56. In this alternative method, it may be necessary to resize the curvedsemi-rigid needle420 to accommodate thedriver440 andreinforcement member100.
• The variable pitch threads on thereinforcement member100 compress thedisc50 and cause thefissures56 to close as discussed previously. If variable pitch threads are not utilized on thereinforcement member100, other techniques may be used to compress thedisc50 and close the radial fissures56. An example of analternative disc50 compression technique is a step-wise advancement and tension method. In this alternative method, thedistal tip433 of thestylet430 is incorporated with ananchor435 such as threads. After thedistal tip433 of thestylet430 has been advanced by rotation to extend across thefissures56, and before thereinforcement member100 has been advanced into theannulus52, the stylet is pulled in the proximal direction to apply tension thereto. Because the threaded anchor at thedistal end433 of thestylet430 grips theannulus52, tension applied to thestylet430 compresses a portion of thedisc50 and closes thefissures56. Once compression of thedisc50 and closure of thefissures56 are established, thereinforcement member100 may be advanced into theannulus52 to maintaindisc50 compression and hold thefissures56 closed. This method of step-wise advancement and tension may be repeated until thereinforcement member100 is fully implanted in the desired position within theannulus52.
• After thereinforcement member100 is positioned across the radial fissures56 as shown inFIG. 8I, the stylet is advanced until the distal tip extends across thecircumferential fissure58 as shown inFIG. 8J. Note that the curvature434 of thestylet430 defines the insertion path of thereinforcement member100. It has been observed that the preset curvature434 of thestylet430 will correspond to the insertion path if thetip433 is very sharp. With thestylet430 advanced such that the tip extends acrossfissure58, thedriver440 is then used to rotate and advance thereinforcement member100 across thefissure58 as shown inFIG. 8K. The variable pitch threads on thereinforcement member100 compress thedisc50 and cause thefissure58 to close as discussed previously. Once thereinforcement member100 is completely deployed within theannulus52 as shown inFIG. 8L, thetools410/430/440 may be removed from the patient and the procedure is essentially complete.
• With general reference toFIGS. 9A-9F, schematic illustrations ofadditional tools450/460/720 for use in the method of implantingreinforcement member200 are shown. The additional tools include avariable curvature stylet450 as shown inFIG. 9A, a stiffeningmandrel460 as shown inFIG. 9B, and anadvancement tool720 as shown inFIG. 9D. Thevariable curvature stylet450 is hollow which permits insertion of the stiffeningmandrel460 as shown inFIG. 9C.
• As seen inFIG. 9A, thevariable curvature stylet450 includes atubular shaft452, a curveddistal portion454 and a closeddistal end453 which is sharpened. Thevariable curvature stylet450 is substantially the same as thecurved stylet430 described previously, except for the provision of a lumen into which thestiffening mandrel460 is insertable. As seen inFIG. 9B, the stiffeningmandrel460 includes anelongate shaft462 and ablunt tip463. Theshaft462 and tip463 of the stiffeningmandrel460 are sized to be inserted into thehollow shaft452 of thestylet450. Thehollow stylet450 and the stiffeningmandrel460 may be made of stainless steel, nickel titanium alloy or the like.
• As can be seen from a comparison ofFIGS. 9A and 9C, upon insertion of the stiffeningmandrel460 into thehollow stylet450, the curvature increases. Preferably the stiffeningmandrel460 is inserted fully into thehollow stylet450 to increase the radius of curvature of the distal portion of thecurvature454, since the distal portion of thecurvature454 dictates the path that thestylet450 will follow. The relative stiffness of thestylet450 and stiffeningmandrel460 may be selected to vary the amount of change in thecurvature454. Thevariable curvature454 may be used to navigate around the changing curvature of theannulus52 as described hereinafter. At any point during advancement of thestylet450, thecurvature454 may be adjusted by insertion of an appropriatelystiff mandrel460. The path defined by thestylet450 may thus be customized to anyparticular disc50 anatomy.
• As seen inFIG. 9D,advancement tool720 may be optionally employed to drive the distal end of thehollow stylet450 throughannular tissue52. Theadvancement tool720 includes an elongatetubular shaft722, with ahandle724 connected to its proximal end and a plurality ofthreads726 connected to its distal end. Thetubular shaft722 of theadvancement tool720 includes a lumen which is sized to accommodate thevariable curvature stylet450 therein. To transfer forces from the distal end of theadvancement tool720 to the distal end of thestylet450, thevariable curvature stylet450 may include atapered collar456. With this arrangement, theadvancement tool720 may be advanced over thevariable curvature stylet450 until the distal end of theshaft722 abuts thecollar456 on thevariable curvature stylet450. During use, thethreads726 engage theannular tissue52 and upon rotation, apply longitudinal forces against thecollar456, and thereby cause distal advancement of thevariable curvature stylet450. Thethreads726 are rotated by manually rotatinghandle724, which transmits torsional forces along theelongate shaft722 to thedistal threads726. To provide adequate transmission of torsional forces, thetubular shaft722 may further comprise a composite structure as illustrated inFIG. 9E or metallic tubular structure as illustrated inFIG. 9F.
• With specific reference toFIG. 9E, thetubular shaft722 comprises a composite structure having anouter layer721 disposed about areinforcement layer723 disposed about aninner layer725. Theouter layer721 and theinner layer725 may comprise a polymeric material having a relatively low coefficient of friction such as PTFE or HDPE. Thereinforcement layer723 is preferably torsionally rigid in both directions of rotation, as may be provided by an interwoven wire braid or by multiple wire coils wound in opposite directions.
• With specific reference toFIG. 9F, the elongatetubular shaft722 comprises atube727 which may be formed of a highly elastic and rigid metal such as stainless steel, nickel titanium alloy, or the like. Themetallic tube727 includes a plurality ofslots729 spaced at regular increments along the length of theshaft722. Theslots729 extend through the wall of themetallic tube727, but do not extend about the entire circumference of themetallic tube727. Thus, theslots729 impart flexibility to theflexible tube727, while maintaining torsional rigidity thereof.
• With general reference toFIGS. 10A-10H, the steps for implantingcircumferential reinforcement member200 are illustrated. All of the variables with regard to quantity, location, orientation, etc. discussed previously may be implemented by varying the generic procedure described hereinafter. The method illustrated inFIGS. 10A-10H is a percutaneous procedure in which access to thedisc50 is achieved utilizing a number of small diameter tools which may be inserted through a patient's back (skin and back muscles), between adjacent vertebrae, and into the patient'sdisc50.
• Initially, as shown inFIG. 10A, therigid trocar410 is advanced into theannulus52 of thedisc50. Thetrocar410 is advanced until thedistal tip413 thereof is disposed in the lateral portion of theannulus52 roughly half way between the posterior and anterior portions of theannulus52 as seen inFIG. 10B. The hollowcurved stylet450 with the stiffeningmandrel460 inserted therein is then advanced into thetrocar410. Note that an appropriatestiff mandrel460 has been fully inserted into the hollow stylet450 a sufficient distance to define acurvature454 that approximates the curvature of the anterior portion of theannulus52. Continued advancement of thehollow stylet450 and stiffeningmandrel460 as a unit cause thestylet450 to traverse the anterior portion of theannulus52 as shown inFIG. 10C.
• After thedistal tip453 of thestylet450 is positioned roughly half way between the posterior and anterior portions of theannulus52 as seen inFIG. 10C, the stiffeningmandrel460 is retracted or removed from thestylet450 to define asmaller curvature454 that approximates the curvature of the posterior lateral portion of theannulus52. Thestylet450 is then advanced until thedistal tip453 thereof enters the posterior portion of theannulus52 as shown inFIG. 10D.
• An appropriatelystiff mandrel460 is then advanced or inserted into thehollow stylet450 to define acurvature454 that approximates the curvature of the posterior portion of theannulus52. The stylet is then advanced across the posterior portion of theannulus52. The stiffeningmandrel460 is then retracted or removed from thestylet450 to define asmaller curvature454 that approximates the curvature of the posterior lateral portion of theannulus52. Thestylet450 is then advanced until thedistal tip453 thereof is positioned adjacent thedistal tip413 of thetrocar410 as shown inFIG. 10E.
• Thetrocar410 is then removed from the patient leaving thestylet450 in theannulus52 to define the insertion path for thereinforcement member200 as shown inFIG. 10F. Thecircumferential reinforcement member200 anddriver440 are then advanced over thestylet450 as shown inFIG. 10G. Using thedriver440 to push and rotate thecircumferential reinforcement member200, themember200 is advanced into theannulus52 along the path defined by thestylet450 until the distal end of thereinforcement member200 is adjacent the proximal end of thereinforcement member200. Note that thevariable pitch threads222 compress thedisc50 and cause thefissure56/58 to close. If thereinforcement member200 includes ananchor220 other than threads (e.g., sloped rings, barbs, etc.) thedriver440 may be used to simply push thereinforcement member200 into theannulus52. Once thereinforcement member200 is in the desired position, thedriver440 andstylet450 may be removed from the patient to complete the procedure.
• With general reference toFIGS. 11A-11H, the steps for implantingreinforcement member300 are illustrated. All of the variables with regard to quantity, location, orientation, etc. discussed previously may be implemented by varying the generic procedure described hereinafter. The method illustrated inFIGS. 11A-11H is a percutaneous procedure in which access to thedisc50 is achieved utilizing a number of small diameter tools which may be inserted through a patient's back (skin and back muscles), between adjacent vertebrae, and into the patient'sdisc50.
• Initially, as shown inFIG. 11A, twotrocars410 are positioned for insertion into thedisc50. Thetrocars410 are advanced until thedistal tip413 of eachtrocar410 is proximate the outer periphery of the posterior portion of theannulus52 as seen inFIG. 11B. Thecurved stylet430 is then advanced into one of thetrocars410 and advanced into theannulus52 as shown inFIG. 11C. Thecurved stylet430 is then advanced across theposterior annulus52, into thedistal tip413 of theother trocar410, and out the proximal end of theother trocar410 as shown inFIG. 11D. The curvature434 of thestylet430 is selected such that thetip433 of thestylet430 traverses the posterior portion of theannulus52 and automatically enters into theother trocar410. To facilitate automatic insertion of the stylet into theother trocar410, the inside diameter of thetrocar410 may be tapered to increase the inside diameter closer to thetip413. As mentioned previously, thestylet430 will follow a path in theannulus52 corresponding to the curvature434 of thestylet430 if thetip433 is very sharp.
• Thetrocars410 are then removed from the patient leaving thestylet430 in place as shown inFIG. 11E. Also as shown inFIG. 11E, thescrews320 are placed in theholes334 of the connection rings330, and the connection rings330 are slid onto thestylet430 throughholes332. Thescrews320 are then screwed into theannulus52 as shown inFIG. 11F using a conventional driver (not shown). Placing thescrews320 in the lateral portions of theannulus52 takes advantage of the generally greater integrity (usually thicker and healthier) of the lateral portions of theannulus52 to establish firm anchor points.
• Also as shown inFIG. 11F, thetubular pins310 are positioned on thestylet430. Thetubular pins310 are then advanced over thestylet430, across the posterior portion of theannulus52, and screwed together as shown inFIG. 11G using driver440 (not shown). Thepins310 are have an assembled length which is shorter than the length of the stylet traversing theannulus52 such that connection of thepins310 causes compression of thedisc50 and closure of thefissures56/58. After removal of thestylet430, thescrews320 may be tightened further into theannulus52 in order to further compress thedisc50 and close thefissures56/58 as shown inFIG. 11H.
• With general reference toFIGS. 12A-12G,FIGS. 13-15,FIGS. 16A-16E, andFIGS. 17A-17D, schematic illustrations ofadditional tools710/730/740/750/800/900 are shown for use in implantingreinforcement member600 in accordance with the method illustrated inFIGS. 18A-18L. The additional tools include a curved stylet orneedle710 as shownFIGS. 12A-12G, a guide tube orsheath730 as shown inFIG. 13, apledget push rod740 as shown inFIG. 14, apledget750 as shown inFIGS. 14 and 15, a column support andadvancement device800 forstylet710 as shown inFIGS. 16A-16E, and a column support andadvancement device900 forstylet710 andsheath730 as shown inFIGS. 17A-17D.Tools710/730/800/900 and the associated method may be utilized to implant other reinforcement members described herein, includingreinforcement members100/200/300.
• With specific reference toFIGS. 12A-12G, the stylet orneedle710 includes a flexibleelongate shaft711 and a sharpeneddistal end714. Thestylet710 is similar to thecurved stylet430 described with reference toFIG. 7C, except as described herein and apparent from the drawings. The stylet orneedle710 may have a substantially straightdistal portion712A as shown inFIG. 12A. Alternatively, thestylet710 may be curved as illustrated inFIGS. 12B-12E.
• For example, inFIG. 12A, thestylet710A includes a straightdistal portion712A. InFIG. 12B, thestylet710B includes acurved portion712B having a curvature that may, for example, correspond to the anterior curvature of theannulus52. InFIG. 12C, thestylet710C includes acurved portion712C having a curvature that may, for example, correspond to the curvature of the lateral portions of theannulus52. InFIG. 12D, thestylet710D includes a distalcurved portion712D having a curvature that permits relatively sharp turns or counter-turns during navigation through theannulus52. InFIG. 12E, thestylet710E has aprimary curvature712E and a secondaryopposite curvature716E proximal thereon. The provision of aprimary curvature712E in addition to a secondaryopposite curvature716E allows thestylet710E to change directions during navigation within theannulus52. To this end, thesecondary curvature716E may have a curvature corresponding to the path already defined through theannulus52 during navigation, and theprimary curvature712E may have a curvature corresponding to the path to be taken by thestylet710E upon further advancement through theannulus52. Although a limited number ofdistal configurations712 have been illustrated, it is contemplated that a variety ofstylets710 having a variety ofdistal geometries712 may be employed during the implantation procedures described hereinafter.
• Theshaft711 of thestylet710 preferably has a flexible but pushable construction incorporating a rigid metal mandrel such as stainless steel, or a super-elastic alloy such as nickel-titanium. Highly elastic or super-elastic materials incorporated into theelongate shaft711 resist permanent deformation during insertion and navigation through theannulus52. Theshaft711 of thestylet710 may have a diameter ranging from 0.010 to 0.025 inches, which may vary depending on the tortuosity of the annular path and the characteristics (toughness, friction) of theannular material52. Theshaft711 may be coated with a lubricious material such as PTFE and a hydrophilic polymer.
• It has been found that if thetip714 is sufficiently sharp to easily penetrateannular tissue52, the path through theannular tissue52 taken by thestylet710 will substantially conform to the geometry of thedistal portion712 of thestylet710. In particular, if thedistal portion712 is substantially straight, thestylet710 will define a linear path through theannular tissue52. Alternatively, if thedistal portion712 has a curve or other nonlinear geometry (in a relaxed state), thestylet710 will define a path through theannular tissue52 corresponding to the shape of thedistal portion712. To this end, it is desirable to provide atip714 having sufficient sharpness to readily penetrateannular tissue52, which tends to be relatively fibrous and tough. Thedistal tip714 may have asymmetrical geometry714A as illustrated inFIG. 12F or anasymmetrical geometry714B as illustrated inFIG. 12G, and preferably has a fine to micro-fine sharpness. By providing a sufficientlysharp tip714, navigation through theannulus52 may be performed in a predictable manner as described in more detail hereinafter.
• With specific reference toFIG. 13, the guide tube orsheath730 includes an elongatetubular shaft732 having a lumen extending therethrough sized to accommodate thestylet710. The guide tube orsheath730 preferably has a relatively thin wall structure so as to minimize the increase in profile relative to thestylet710. In addition, the inside surface of theshaft732 preferably has a low friction coating or liner such as PTFE to minimize friction between theguide sheath730 and thestylet710. Theguide sheath730 preferably is able to withstand relatively high longitudinal compressive forces and therefore, preferably comprises a relatively rigid but flexible material such as PTFE or polyimide. For example, thetubular shaft732 may comprise a polyimide tube having an inside diameter approximately 0.0005 to 0.001 inches greater than the outside diameter of thestylet710, with a wall thickness of approximately 0.0005 to 0.003 inches. Thetubular shaft732 may further incorporate a reinforcement layer such as a metallic braid or the like to help prevent various modes of buckling.
• With specific reference toFIG. 14, thepledget push rod740 includes an elongaterigid shaft742 comprising, for example, a stainless steel rod. The distal end of theshaft742 is connected to pledget750 by way of areleasable connection744.Releasable connection744 may comprise, for example, a weakened area of therod742 orpledget750 that may be broken by application of torsional forces to therod742.
• With specific reference toFIG. 15, thepledget750 includes abody portion752 and twoholes754 sized to accommodate thestylet710 andreinforcement member600. Thebody portion752 may comprise a metallic or polymeric material. Examples of suitable metallic materials include stainless steel and super-elastic alloys such as nickel-titanium. If thebody portion752 comprises a polymeric material, the polymeric material may be biologically inert, biodegradable or bioabsorbable. Examples of suitable polymeric materials comprising biologically stable or inert materials include HDPE and PTFE. Examples of biodegradable or bioabsorbable materials include resorbable collagen, LPLA (poly(l-lactide)), DLPLA (poly(dl-lactide)), LPLA-DLPLA, PGA (polyglycolide), PGA-LPLA or PGA-DLPLA. Thebody portion752 of thepledget750 may be coated with biocompatible materials, growth factors to facilitate healing, agents which render the nuclear matter inert or otherwise reduce chemical irritation thereof, and/or anesthetic agents to reduce nerve signal transmission (i.e., pain).
• With specific reference toFIGS. 16A-16E, the column support andadvancement device800 for use withstylet710 is shown.Device810 includes ashaft portion810 which extends through and is rigidly connected to aproximal handle assembly812. The distal end of theshaft810 may incorporate a plurality ofthreads814 to rotationally engage and bore through tissues in the back (dermal and muscular tissues) and anchor against tissues immediately adjacent the point of entry into theannulus52. Thedistal tip815 of theshaft810 may also be sharpened to facilitate penetration through tissues in the back. Theshaft810 comprises a rigid metal tube having a lumen extending therethrough adapted to receive thestylet710. The inside surface of thetubular shaft810 may be provided with a low friction liner or coating such as PTFE. Within thehandle812, theshaft810 includes a slot aligned with a slot orkeyway816 in thehandle812, which is sized and shaped to accommodate key820. The slot in theshaft810 contained within thehandle assembly812 has a width that is less than that of the outside diameter of thestylet710 such that thestylet710 cannot pass therethrough and such that theshaft810 provides column support to thestylet710 and prohibits buckling thereof.
• Key820 includes athumb button822 which may incorporate a plurality ofgrip members828. Ametallic plate824 extends downwardly from thebody portion822 and has a geometry which substantially conforms to keyway816. The bottom of theplate824 incorporates one ormore protrusions826.Protrusions826 engage and mate withrecesses715 formed in the proximal end of thestylet710.Protrusions826 and recesses715 may be replaced by a wide variety of mating geometries to facilitate engagement between the key820 and the proximal end of thestylet710.
• Upon depression of thethumb button822 relative to thehandle812, theplate824 travels in a downward direction to force theprotrusions826 into therecesses715. Thethumb button822 may then be advanced in the distal direction, while maintaining downward pressure, to advance thestylet710 in the distal direction relative to theshaft810 intoannular tissue52. Although thestylet710 may encounter substantial resistance during advancement throughannular tissue52, and despite the relative flexibility of thestylet710, theshaft810 of theadvancement device800 provides sufficient column strength to thestylet710 to resist buckling during advancement.
• After the key820 has been advanced to the distal end of thehandle812, the downward force applied to thethumb button822 may be removed to disengage theprotrusions826 from therecesses715 in thestylet710. To facilitate disengagement of theteeth826 from therecesses715, a pair ofleaf springs825 may be provided on either side of theplate824 to urge the key820 in the upward direction relative to thehandle812. In the disengaged position, the key820 may be moved to the proximal end of thehandle812, and a downward force may be reapplied to thethumb button822 to cause engagement of theprotrusions826 with therecesses715. Thethumb button822 may then be advanced again in the distal direction relative to thehandle812 to advance thestylet710 further into theannular tissue52.
• This procedure may be repeated until thestylet710 is advanced the desired distance. In addition, with the key820 in the disengaged position, thestylet710 may be removed for adifferent stylet710 having a different distal curvature, for example. To exchange thestylet710, downward pressure against thethumb button822 is removed to allow the key820 to be urged in the upward direction bysprings825, to thereby disengage theprotrusions826 from therecesses715. In the disengaged position, thestylet710 may be removed from thedevice800 by pulling thestylet710 in the proximal direction. Asecond stylet710 may be inserted into thedevice800 by inserting the distal end of thestylet710 into the proximal end of the lumen of theshaft810 located at the proximal end of thehandle assembly812. The stylet may then be advanced until the distal end thereof exits the distal end of theshaft810.
• With specific reference toFIGS. 17A-17D, column support andadvancement device900 for use withstylet710 andsheath730 is shown.Device900 includes a rigid metallictubular shaft910 having ahandle912 connected to its proximal end. A plurality ofthreads914 are provided at the distal end of theshaft910 to facilitate advancement through tissues up to the perimeter of theannulus52, and to facilitate anchoring of thetubular shaft910 adjacent the periphery of theannulus52. Thedistal tip915 of thetubular shaft910 is sharpened to facilitate advancement through dermal and muscular tissues in the back up to and adjacent theannulus52. Thetubular shaft910 has an inside diameter sized to accommodate theguide sheath730 which is sized to accommodate thestylet710. The inside diameter of thetubular shaft910 may incorporate a low friction coating such as PTFE to minimize friction between thetubular shaft910 and thetubular sheath730.
• Thetubular shaft910 includes ahelical slot916 which passes through the wall thereof and extends from a point adjacent thehandle912 to a mid portion of theshaft910. Aproximal nut920 and adistal nut930 are disposed about theshaft910 and cooperate with thehelical slot916 such that they may be independently longitudinally advanced and retracted by rotation thereof relative to theshaft910.
• As best seen inFIG. 17B, theproximal nut920 abuts a collar918 fixedly connected to thestylet710. Similarly, thedistal nut930 abuts acollar732 fixedly attached to thetubular sheath730. Thus, longitudinal advancement ofnut920 by rotation thereof relative to theshaft910 causes corresponding longitudinal advancement of thestylet710. Similarly, longitudinal advancement ofnut930 by rotation thereof relative toshaft910 causes corresponding longitudinal advancement of thetubular sheath730.
• As seen inFIG. 17C,proximal nut920 includes acollar924 connected to abearing926 by a pair ofarms922. Thearms922 extend through thehelical slot916 in theshaft910. Thecollar924 extends around the outside of theshaft910, and thebearing926 fits within the lumen of theshaft910. Thebearing926 has an inside diameter sized to accommodate thestylet710 in an outside diameter sufficient to engage and abut thecollar718, while permitting relative rotational movement. Theside openings928 in thecollar924 and bearing926 permit theproximal nut920 to be removed from theshaft910, which in turn permits thestylet710 to be removed from thedevice900 and replaced with adifferent stylet710 having a different distal curvature, for example.
• As seen inFIG. 17D, thedistal nut730 includes acollar934 connected to abearing936 by a pair ofarms932. Thecollar934 has an inside diameter sufficient to accommodate the outside diameter of theshaft910. Thebearing936 has an outside diameter sized to fit within the lumen of theshaft910 and sized to engage and abut thecollar732 on thetubular sheath730. The bearing936 also has an inside diameter sufficient to accommodate thetubular sheath730, while allowing relative rotational movement.
• With this arrangement, thestylet710 may be advanced independently of thesheath730, and visa-versa. In addition, with this arrangement, both thetubular sheath730 and thestylet710 have column support proximal of the path being navigated through theannulus52.
• With general reference toFIGS. 18A-18L, the steps for implantingreinforcement member600 are illustrated. The method illustrated inFIGS. 18A-18L utilizesstylet710 to navigate through theannulus52 andimplant reinforcement member600. The method illustrated inFIGS. 18A-18L may be modified to make use ofhollow stylet450 and stiffeningmandrel460 to navigate through theannulus52 andimplant reinforcement member600. All of the variables with regard to quantity, location, orientation, etc., discussed previously may be implemented by varying the generic procedure described hereinafter. The method illustrated inFIGS. 18A-18L is a percutaneous procedure in which access to thedisc50 is achieved utilizing a number of small diameter tools which may be inserted through a patient's back (skin and back muscles), between adjacent vertebrae, and adjacent the patient'sdisc50.
• Initially, as shown inFIG. 18A, therigid trocar410 is advanced until the distal tip thereof is disposed immediately adjacent the periphery of theannulus52 of thedisc50. Astylet710C, withtubular sheath730 disposed thereon, is inserted into therigid trocar410. Thestylet710C, having a curveddistal portion712C, is advanced out the distal end of thetrocar410 into theannulus52 until the distal end of thestylet710C is located in the anterior portion of theannulus52 as shown inFIG. 18B. Note that the curvature of thedistal portion712C roughly corresponds to the curvature of thelateral annulus52. Thesheath730 may then be advanced over thestylet710C until the distal end of the sheath is adjacent the distal end of thestylet710.
• Thestylet710C may then be removed from thesheath730, and anotherstylet710B, having a curveddistal portion712B, may be advanced through thesheath730 as shown inFIG. 18C. In this manner, thetubular sheath730 maintains the path defined by the penetratingstylet710C, and allows thenext stylet710B to begin penetration wherestylet710C left off. Thestylet710B is advanced until the distal tip is positioned in the lateral portion of the annulus, after which thetubular sheath730 may be advanced thereover. Note that the curvature of thedistal portion712B roughly corresponds to the curvatures of theanterior annulus52. Thestylet710B may be exchanged forstylet710C having acurved portion712C to traverse the lateral side of theannulus52. Thestylet710C may then be exchanged for anotherstylet710A having a relatively straightdistal portion712A to traverse the posterior portion of theannulus52 as shown inFIG. 18D. Thetubular sheath730 is then advanced over thestylet710A until the distal end of thesheath730 is adjacent the distal end of thestylet710A.
• Once the distal end of thestylet710A and the distal end of thetubular sheath730 are disposed adjacent the opening to the distal end of thetrocar410, thestraight stylet710A may be exchanged fordouble curve stylet710E as shown inFIG. 18E. The distal tip of thestylet710E is navigated into the distal end of thetrocar410 utilizing the visualization techniques described previously. Once the distal end of thestylet710 is disposed in thetrocar410, thetubular sheath730 may be removed. With the distal end of thestylet710E reentered into the distal end of thetrocar410, thestylet710E may be freely advanced until the distal portion thereof exits the proximal portion of thetrocar410 as shown inFIG. 18F.
• At this point, thetrocar410 may also be removed, but may optionally be left in place, depending on the means employed to connect the ends of thereinforcement member600. As illustrated inFIG. 18G, oneend602 of thereinforcement member600 is connected to the proximal end of thestylet710. This may be accomplished, for example, by threading the reinforcement member through a hole (not shown) in the proximal end of thestylet710 similar to the threading a sewing needle. Immediately before or immediately after thereinforcement member600 is attached to the proximal end of thestylet710, thepledget push rod740 may be used to push thepledget750 over the opposite ends of thestylet710 until thepledget750 is positioned immediately adjacent the entry and exit points in theannulus52 as illustrated inFIG. 18G.
• The distal end of thestylet710 may then be pulled while applying a push force to thepush rod740 to pull the reinforcement member along the path defined thestylet710 through theannulus52, after which thereinforcement member600 may be disconnected from the stylet as shown inFIG. 18H. A connection (e.g., knot)610 may be made in thereinforcement member600 and advanced to thepledget750 utilizing a conventional knot pusher (not shown) as shown inFIG. 18I. While the knot is being tightened, thereinforcement member600 applies compressive forces about the perimeter of theannulus52 thereby closing fractures and fissures56/58. Once theknot610 has been tightened, thereinforcement member600 may be cut immediately proximal of theknot610 adjacent thepledget750 as shown inFIG. 18J utilizing a conventional suture cutting device (not shown).
• Alternatively, as shown inFIGS. 18K and 18L, thepledget750 may be omitted. In particular, a connection (e.g., knot)610 may be made in thereinforcement member600 and advanced to the entry and exit point in theannulus52 utilizing a conventional knot pusher (not shown) as shown inFIG. 18K. While the knot is being tightened, thereinforcement member600 applies compressive forces about the perimeter of theannulus52 thereby closing fractures and fissures56/58. Once theknot610 has been tightened, the reinforcement member may be cut utilizing a conventional suture cutting device (not shown) immediately proximal of theknot610 as shown inFIG. 18L.
• The path navigated through theannulus52 by the foregoing method may be a function of the individual anatomical geometry of the patient and/or the particular portion of theannulus52 requiring compression. Accordingly, as shown inFIGS. 19A-19F, the path620 defined by thestylet710 andreinforcement member600 through theannulus52 may vary. For example, a substantialrectangular path620A with rounded corners may be employed as illustrated inFIG. 19A. Alternatively, a substantiallytrapezoidal path620B having rounded corners may be employed as shown inFIG. 19B. Alternatively, a substantiallyoval path620C may be employed as shown inFIG. 19C. Each of these paths may be defined by the particular sequence ofcurved stylets710 utilized in accordance with the method described previously.
• Although it is preferable to define a path620 substantially confined to theannulus52, the path620 may also extend through a portion of thenucleus54 as illustrated inFIGS. 19D and 19E. In such circumstances, it is preferable to not define a direct path from thenucleus54 to the exterior of theannulus52, to thereby minimize the likelihood that nuclear material will leak out of thedisc50. For example, as shown inFIG. 19D, the path through thenucleus54 may enter at one lateral side, and exit at the opposite lateral side thereof. Alternatively, as shown inFIG. 19E, thepath620E may enter on the anterior side and exit on the posterior side of thenucleus54.FIG. 19F illustrates apath620F which is just external to the outer surface of theannulus52.
• While a single path620 followed by asingle reinforcement member600 is illustrated, it is also contemplated thatmultiple reinforcement members600 may be implanted. For example, onereinforcement member600 could be implanted proximate the lower (inferior) portion of theannulus52 and onereinforcement member600 could be implanted in the upper (superior) portion of theannulus52. Any number ofreinforcement members600 could be implanted in a single disc, either through asingle trocar410 placement, or multiple trocar placements.
• With general reference toFIGS. 20A-20R, alternative embodiments of reinforcement members and methods of implantation are disclosed. Thereinforcement members510/520/530 may be used to reinforce the disc, restore disc height and/or bear some or all of the load normally carried by the annulus. Thereinforcement members510/520/530 are relatively rigid and thus serve to reinforce thedisc50, and particularly theannulus52, where inserted. In addition, thereinforcement members510/520/530 may have a relatively large profile when implanted and thus increase disc height.
• The reinforcingmembers510/520/530 may be used singularly or in groups, depending on the increase indisc50 height desired and/or the amount of reinforcement of theannulus52 desired. For example, the reinforcingmembers510/520/530 may be stacked or inserted side-by-side. In addition, the reinforcingmembers510/520/530 may be located in virtually any portion of theannulus52. Preferably, the reinforcingmembers510/520/530 are substantially symmetrically disposed about themedian plane70 to avoid causing curvature of thespine10. Although the reinforcingmembers510/520/530 may be inserted, in part or in whole, into thenucleus54, it is preferable to insert them into theannulus52 for purposes of stability and load carrying. Specifically, to provide stability, it is desirable to symmetrically locate the reinforcingmembers510/520/530 as far as reasonably possible from themedian plane70, or to span as great a distance as possible across themedian plane70. In addition, because theannulus52 of thedisc50 is believed to carry the majority of the load, particularly in thelumbar region12, the reinforcingmembers510/520/530 are preferably placed in theannulus52 to assume the load normally carried thereby, and reinforce the load bearing capacity of theannulus52, without hindering the normal mobility function of thedisc50.
• The reinforcingmembers510/520/530 may comprise expandable members such as self-expandingmembers510 orinflatable members520. Alternatively, the reinforcingmembers510/520/530 may comprise unexpandable members such as reinforcement bars530. When implanting each type ofreinforcement member510/520/530, it is preferable to maintain the integrity of theannulus52. Accordingly, space in theannulus52 for the reinforcingmembers510/520/530 is preferably established by dilation or the like, although some amount of tissue removal may be used.
• Theexpandable reinforcement members510/520 are useful because they may be delivered in a low profile, unexpanded condition making it easier to traverse the very tough and fibrous collagen tissue of theannulus52. For similar reasons, the reinforcement bars530 are useful because they may have a small diameter and a sharpened tip. Although it is possible to insert theexpandable reinforcing members510/520 into theannulus52 in their final expanded state, it is desirable to deliver theexpandable reinforcing members510/520 into theannulus52 in an unexpanded state and subsequently expand them in order to minimize invasiveness and resistance to insertion.
• The self-expanding reinforcingmember510 may comprise a solid or semi-solid member that self-expands (e.g., by hydration) after insertion into the annulus. Examples of suitable materials for such solid or semi-solid members include solid fibrous collagen or other suitable hard hydrophilic biocompatible material. If the selected material is degradable, the material may induce the formation of fibrous scar tissue which is favorable. If non-degradable material is selected, the material must be rigid and bio-inert. The self-expanding reinforcingmember510 preferably has an initial diameter that is minimized, but may be in the range of 25% to 75% of the final expanded diameter, which may be in the range of 0.3 to 0.75 cm, or 10% to 75% of the nominal disc height. The length of the self-expandingmember510 may be in the range of 1.0 to 6.0 cm, and preferably in the range of 2.0 to 4.0 cm.
• The inflatable reinforcingmember520 may comprise an expandable hollow membrane capable of inflation after insertion into the annulus. An example of a suitable inflatable structure is detachable balloon membrane filled with a curable material. The membrane may consist of a biocompatible and bio-inert polymer material, such as polyurethane, silicone, or polycarbonate-polyurethane (e.g., Corethane). The curable filler material may consist of a curable silicone or polyurethane. The filler material may be curable by chemical reaction (e.g., moisture), photo-activation (e.g., UV light) or the like. The cure time is preferably sufficiently long to enable activation just prior to insertion (i.e., outside the body) and permit sufficient time for navigation and positioning of themember520 in the disc. However, activation may also take place inside the body after implantation. The inflatable reinforcingmember520 preferably has an initial deflated diameter that is minimized, but may be in the range of 25% to 75% of the final inflated diameter, which may be in the range of 0.3 to 0.75 cm, or 10% to 75% of the nominal disc height. The length of theinflatable member520 may be in the range of 1.0 to 6.0 cm, and preferably in the range of 2.0 to 4.0 cm.
• The reinforcement bars530 may comprise a rigid, solid or hollow bar having a sharpened tip. The reinforcement bars530 may comprises stainless steel mandrels, for example, having a diameter in the range of 0.005 to 0.100 inches, preferably in the range of 0.010 to 0.050 inches, and most preferably in the range of 0.020 to 0.040 inches, and a length in the range of 1.0 to 6.0 cm, and preferably in the range of 2.0 to 4.0 cm. The reinforcement bars530 may be straight for linear insertion, or curved to gently wrap with the curvature of the annulus during insertion. In addition, the outer surface of the reinforcement bars530 may have circular ridges or the like that the permit easy insertion into theannulus52 but resist withdrawal and motion in the annulus following implantation. Other suitable materials for reinforcement bars530 include titanium alloy 6-4, MP35N alloy, or super-elastic nickel-titanium alloy.
• With general reference toFIGS. 20A-20J, the steps for implanting a self-expandingreinforcement member510 are illustrated. It should be understood that the procedure for implanting asingle member510 in theanterior annulus52 is shown for purposes of illustration, not limitation. All of the variables with regard to quantity, location, orientation, etc. discussed previously may be implemented by varying the generic procedure described hereinafter.
• Initially, the sharpenedstylet430,semi-rigid needle420 andrigid trocar410 are assembled. As shown inFIG. 20A, the distal portion of theassembly410/420/430 is inserted into thedisc50 as in a conventional discogram procedure. Theassembly410/420/430 is advanced until thedistal tip413 of the rigid needle is proximate the anterior curvature of theannulus52, near the anterior side of thenucleus54, as seen inFIG. 20B. The semi-rigid needle420 (alone or with stylet430) is advanced relative to therigid trocar410 until thecurved portion426 of the semi-rigid needle exits thedistal tip413 of therigid trocar410 and the desired amount of curvature is established, as seen inFIG. 20C. Thecurved portion426 may be advanced until thetip423 is substantially parallel to the tangent of theanterior annulus52 curvature. The sharpenedstylet430 is advanced relative to thesemi-rigid needle420 to the desired position within theanterior annulus52, as shown inFIG. 20D. Thesemi-rigid needle420 and therigid trocar410 are completely withdrawn from thestylet430, leaving the stylet in position as shown inFIG. 20E.
• Aflexible dilator470 is advanced over thestylet430 to dilate theannulus52, as seen inFIG. 20F. Theflexible dilator470 is similar tosemi-rigid needle420 except that the dilator includes a blunt distal tip and is relatively more flexible, and has larger inner and outer diameters. Note that one ormore dilators470 may be advanced co-axially about thestylet430 until the annulus is sufficiently dilated to accept the self-expandable member510. Thestylet430 is then withdrawn from theflexible dilator470 and the self-expandable member510 is introduced into the lumen of theflexible dilator470 using apush bar480, as shown inFIG. 20G. Alternatively, thedilator470 may be removed in favor of a flexible hollow catheter with a large inner diameter to facilitate delivery ofmember510. Thepush bar480 is similar tostylet430 except that the distal tip of thepush bar480 is blunt. Alternatively, thepush bar480 may simply comprise thestylet430 turned around, thus using the proximal blunt end of thestylet430 as thepush bar480. Thepush bar480 is advanced until themember510 is in the desired position, as seen inFIG. 20H. To facilitate positioning themember510, radiographic visualization may be used to visualize the distal end of thepush bar480, which is formed of radiopaque material and may include radiopaque markers. In addition, the member may be loaded with a radiopaque material to facilitate radiographic visualization thereof.
• After themember510 is in the desired position, theflexible dilator470 is retracted from thepush bar480 while maintaining position of themember510 with the push bar. Thepush bar480 is then removed leaving themember510 in place. If necessary, the procedure may be repeated foradditional member implants510. Themember510 is then allowed to expand over time, perhaps augmented by placing thespine10 in traction. Alternatively, thespine10 may be placed in traction prior to beginning the procedure.
• With reference toFIGS. 20K-20L, the steps for implanting aninflatable reinforcement member520 are illustrated. In this procedure, the steps outlined with reference toFIGS. 20A-20F are followed. Specifically, the same steps are followed up to and including the step of advancing theflexible dilator470 over thestylet430 to dilate theannulus52, and thereafter removing thestylet430 from theflexible dilator470. Using acatheter490, theinflatable member520 is introduced into thedilator470 and advanced until themember520 is in the desired position, as shown inFIG. 20K. Theinflatable member520 is connected to the distal end of thecatheter490, which includes a flexible butpushable shaft492 and aninflation port494. Theflexible dilator470 is retracted from thecatheter490 while maintaining position of themember520.
• With themember520 in the desired position, which may be confirmed using radiographic visualization as described above, theproximal inflation port494 is connected to a syringe (not shown) or other suitable inflation apparatus for injection of the curable filler material. The filler material is then activated and the desired volume is injected into thecatheter490 via theinflation port494, as seen ifFIG. 20L. The filler material is allowed to cure and thecatheter490 is gently torqued to break thecatheter490 from thesolid member520. This break-away step may be facilitated by an area of weakness at the juncture between the distal end of thecatheter490 and the proximal end of themember520. Thecatheter490 is then removed leaving themember520 in place. If necessary, the procedure may be repeated foradditional member implants520.
• With reference toFIGS. 20M-20R, the steps for implanting areinforcement bar530 are illustrated. As seen inFIG. 20M, thedisc50 includes a protrusion orbulge60, which is preferably, but not necessarily, reduced or eliminated before insertion of thereinforcement bar530. This may be done by separating theadjacent vertebrae20. In order to establish separation of thevertebrae20, thespine10 may be placed in traction or conventional intervertebral separation tools may be used. After thebulge60 is reduced or eliminated, similar steps are followed as outlined with reference toFIGS. 20A-20C.
• Delivery of asingle reinforcement bar530 into theposterior annulus52 is illustrated. Specifically, the distal portion of theassembly410/420/480 is inserted into thedisc50 as in a conventional discogram procedure. Theassembly410/420/480 is advanced until thedistal tip413 of therigid trocar410 just penetrates the posterior side of theannulus52, as seen inFIG. 20N. The semi-rigid needle420 (alone or with bar530) is advanced relative to therigid trocar410 until thecurved portion426 of thesemi-rigid needle420 exits thedistal tip413 of therigid trocar410 and the desired amount of curvature is established, as shown inFIG. 20N. Thecurved portion426 may be advanced until thetip423 is substantially parallel to theposterior annulus52.
• Using thepush bar480, thereinforcement bar530 with its sharpened tip is pushed into theannulus52 as seen inFIG. 200. Thereinforcement bar530 is advanced into theannulus52 with thepush bar480 until thebar530 is in the desired position, as seen inFIG. 20P, which may be confirmed using radiographic visualization as described above. Thepush bar480 is then retracted, leaving thereinforcement bar530 in place, as shown inFIG. 20P. Thesemi-rigid needle420 and therigid trocar410 are then removed, as shown inFIG. 20Q, or, if necessary, the procedure may be repeated for additionalreinforcement bar implants530, as shown inFIG. 20R. Presence of the reinforcement bars530 serves to keep thedisc50, and particularly thebulge60, in a more normal condition, and to protect against continued bulging, thus easing nerve impingement.
• With reference toFIGS. 21A-21C, analternative reinforcement member540 is illustrated. In this embodiment,reinforcement member540 includes ananchor arm542 having ananchor mechanism544 attached to a distal end thereof. Theanchor mechanism54 may comprise circular ridges, barbs or the like which are readily advanced into theannular tissue52, but resist retraction.Reinforcement member540 also includes alever arm546 including a distal sharpenedtip548. The distal end of theanchor arm542 also incorporates a sharpenedtip548. Thereinforcement member540 preferably comprises a highly elastic or super-elastic metal such as stainless steel or a nickel titanium alloy.
• FIG. 21A illustrates the reinforcement member in a relaxed state, andFIG. 21B illustrates the reinforcement member in a compressed delivery state sized to fit withintrocar410. Thereinforcement member540 may be delivered into theannulus52 in a compressed state throughtrocar410 utilizingpush rod480 as shown inFIG. 21C. As thereinforcement member540 is pushed out the distal end of thetrocar410 utilizingpush rod480, the sharpened ends548 penetrate the tissue and theanchor mechanism544 engages the tissue to define the deployed configuration shown inFIG. 21C. In the deployed configuration, the anchor arm and the lever arm are forced to pivot relative to each other thereby building a bias force at the elbow connecting theanchor arm542 and thelever arm546. In the deployed configuration, thelever arm546 applies a compressive force to the exterior portion of theannulus52 to minimize protrusions and bulges along the posterior periphery of theannulus52.
• With reference now toFIGS. 22A-22D,alternative reinforcement members570 and580 are illustrated.Reinforcement members570 and580 are similar toreinforcement600 except for the provision ofdistal anchors574/584. Except as described herein and apparent from the drawings, the function and delivery ofreinforcement members570 and580 are substantially the same asreinforcement member600.
• As shown inFIG. 22A,reinforcement member570 comprises a monofilament ormultifilament structure572 that is highly flexible and has a high tensile strength. The ends of thefilament structure572 incorporateanchors574, which may comprise circular ridges, barbs or the like which are readily advanced into theannular tissue52, but resist retraction. As shown inFIG. 22B, thereinforcement member570 may be deployed in theannulus52 with the anchors residing in healthy annular tissue and the filament structure partially surrounding the fractures and fissures56/58 in a circumferential manner. By advancing theanchors574 during deployment, theannular tissue52 is compressed along the length of thefilament structure572, thereby closing fractures and fissures56/58 and reducing posterior protrusions.
• A similar arrangement is shown inFIGS. 22C and 22D. In this embodiment, areinforcement member580 comprises a monofilament or amultifilament structure582 having a singledistal anchor584 attached thereto. The proximal end of thefilament structure582 is otherwise free. During implantation, one ormore reinforcement members580 may be utilized as shown inFIG. 22D. The free ends of thefilament structure582 are connected using, for example, aknot586 with or without the use of apledget750.
• Refer now toFIGS. 23A and 23B which illustrate an alternative method for implanting a variation of thereinforcement member510, and optionally utilize anotherreinforcement member600 to anchorreinforcement member510 in place.Reinforcement member510 may be implanted in a void left by discectomy utilizing a method such as described with reference toFIGS. 20A-20L. Other reinforcement members may used in place ofreinforcement member510 such asreinforcement members100/200. Other reinforcement members may optionally be used as anchor means. By way of example, not limitation,reinforcement member600 is shown as a means to anchorreinforcement member510 relative to theannulus52 utilizing a method such as described with reference toFIGS. 25A-25J orFIGS. 27A-27H, for example.
• Following a discectomy, a portion of theannulus52 is typically removed as shown inFIG. 23A. The void left by the discectomy procedure may expose thedisc50 to increased stress due to loss of surface area and/or leakage of fluid from thenucleus54. By implanting areinforcement member510 in the void as seen inFIG. 23B, thereinforcement member510 acts as a barrier to nuclear leakage and acts as a support member to minimize disc height loss.Reinforcement member510 acts as a support to adjacent vertebrae by having a height substantially equal to the nominal height of the disc (in a healthy state) and by providing an expanded volume substantially equal to the void, to thereby share the load of adjacent vertebrae. This combination of functions (barrier and volume) reduces the rate of degeneration or possibly eliminates further degeneration of thedisc50.
• Refer now toFIGS. 24A-24E which illustratevarious tools760/770 for implanting thereinforcement member600 in accordance with the method illustrated inFIGS. 25A-25J. As seen inFIG. 24A,dual tube trocar760 includes tworigid tubes762 formed of stainless steel, for example, secured to ahandle764. Thetubes762 may be substantially the same size and symmetric. Eachtube762 includes a sharpenedtip763 and a lumen (not visible) fully extending therethrough to slidably accommodatestylet770 shown inFIG. 24B. The lumen of thesecond tube762 which accommodates reentry of thestylet770 may be made even larger (e.g., 2-3 times) to permit variability in reentry as will be discussed in more detail hereinafter. Abracket766 may be disposed between therigid tubes762 to maintain spacing and alignment therebetween.
• With reference toFIG. 24B,stylet770 is substantially the same asstylet710 described previously.Stylet770 includes an elongateflexible shaft772 and a sharpeneddistal end773. The stylet orneedle770 has acurved portion774 with a diameter substantially equal to the distance between the centerlines of thetubes762 of thetrocar760. Thecurved portion774 preferably has at least 180 degrees of curvature or more to define at least a full semi-circle. Theshaft772 of thestylet770 preferably has a flexible but pushable construction incorporating a rigid metal mandrel such as stainless steel, or a super-elastic alloy such as nickel-titanium. Highly elastic or super-elastic materials incorporated into theelongate shaft772 resist permanent deformation during insertion and navigation through theannulus52. Theshaft772 of thestylet770 may have a diameter ranging from 0.010 to 0.025 inches and is sized to fit within the lumens of thetubes762 of thetrocar760. Theshaft772 may be coated with a lubricious material such as PTFE and a hydrophilic polymer.
• If thetip773 is sufficiently sharp to easily penetrateannular tissue52, the path through theannular tissue52 taken by thestylet770 will substantially conform to the geometry of the distalcurved portion774 of thestylet770. In particular, if thedistal portion774 has a curve with a diameter substantially equal to the distance between the centerlines of thetubes762 of thetrocar760, thestylet770 will exit the distal end of onetube762 and naturally define a path through theannular tissue52 to reenter the distal end of theother tube762. To this end, it is desirable to provide atip773 having sufficient sharpness to readily penetrateannular tissue52, which tends to be relatively fibrous and tough. By providing a sufficientlysharp tip773, thestylet770 will naturally navigate through theannulus52 from the end of onetube762 into the end of theother tube762, without requiring visualization or steering of thestylet770.
• Refer now toFIGS. 24C and 24D which illustrate alternativedual tube trocar760 designs which utilizes means765/767 to ensure proper alignment of the stylet700 as it exits the distal end of one of thetubes762. In particular, in order for thestylet770 to reenter the distal end of thesecond tube762, thestylet770 preferably exits the distal end of thefirst tube762 with thecurved portion774 of thestylet770 in substantially the same plane as the twotubes762. This may be accomplished manually by rotating thestylet770 prior to exit from thefirst tube762, or this may be accomplished automatically by providing a keyed passageway or by providingmechanisms765/767.
• Because thecurved portion774 will align itself with any curvature provided in the lumen of thetubes762, the distal end of one or both of thetubes762 may be provided with agentle curvature765 as seen inFIG. 24C which will provide a corresponding curvature to the lumen extending therethrough. Alternatively, the distal end of one of thetubes762 may be provided with anindentation767 as seen inFIG. 24D which will define a corresponding curved path in the lumen extending therethrough. In particular, with reference toFIG. 24E, theindent767 impinges on aninner tube768 which is otherwise centered in the lumen of thetube762 bycollars769. By virtue of theindent762, thelumen761 defined through theinner tube768 is provided with a curved path. Whether provided by a curve in thetube762, by anindent762 impinging on aninner tube768, or by other means to define a curved path within thetube762, thecurved portion774 of the stylet will naturally align itself with such a curvature, thereby automatically providing alignment between thestylet770 and thesecond tube762 as the distal end of thestylet770 reenters thetrocar760 as will be described in more detail hereinafter.
• Refer now toFIGS. 25A-25J which illustrate an alternative method for implanting thereinforcement member600. The method illustrated inFIGS. 25A-25J utilizesstylet770 to navigate through theannulus52 andimplant reinforcement member600. The method illustrated inFIGS. 25A-25J is similar to the method illustrated inFIGS. 18A-18L, except with regard to path defined byreinforcement member600 and the automatic navigation ofstylet770 out of and into thetrocar760. The method illustrated inFIGS. 25A-25J is particularly suited for a post discectomy procedure to close the opening (not shown) created thereby. Further, the method illustrated inFIGS. 25A-25J is particularly suited for a post annular compression procedure (e.g., contraction of annular tissue by thermal means) to maintain the re-compressed annulus (not shown) created thereby. All of the variables with regard to quantity, location, orientation, etc., discussed previously may be implemented by varying the generic procedure described hereinafter. The method illustrated inFIGS. 25A-25J is a percutaneous procedure in which access to thedisc50 is achieved utilizing a number of small diameter tools which may be inserted through a patient's back (skin and back muscles), between adjacent vertebrae, and adjacent the patient'sdisc50.
• Initially, as shown inFIG. 25A, the rigiddual tube trocar760 is advanced until the distal tips thereof are disposed in the anterior portion of theannulus52. Thestylet770 is then inserted into thefirst tube762 of the rigiddual tube trocar760. Thestylet770, having a curveddistal portion774, is advanced out the distal end of thefirst tube762 into theannulus52 as shown inFIG. 25B. Thestylet770 is advanced until thedistal tip773 reenters thetrocar760 at the distal end of thesecond tube762 as shown inFIG. 25C. Note that thecurvature774 corresponds to the distance between the centerlines of thetubes762, and that thecurvature774 is at least semi-circular (180 degrees or more) to thereby automatically reenter thetrocar760 at the distal end of thesecond tube762.
• Thestylet770 is advanced until thedistal tip773 exits the proximal end of thesecond tube762 as shown inFIG. 25D. One end of thereinforcement member600 is attached to the proximal end of thestylet770 as shown inFIG. 25E. This may be accomplished, for example, by threading the reinforcement member through a hole (not shown) in the proximal end of thestylet770 similar to the threading a sewing needle. The distal end of thestylet770 is pulled proximally to pull the stylet out of thetrocar760 and thread thereinforcement member600 along the path defined by thestylet770 as shown inFIG. 25F. At this point, thetrocar760 may be removed as shown inFIG. 25H, but may optionally be left in place, depending on the means employed to connect the ends of thereinforcement member600.
• Although not shown, immediately before or immediately after thereinforcement member600 is attached to the proximal end of thestylet770, thepledget push rod740 may be used to push thepledget750 over the opposite ends of thereinforcement member600 until thepledget750 is positioned immediately adjacent the entry and exit points in theannulus52. A connection (e.g., knot)610 may be made in thereinforcement member600 and advanced to the entry points of in theannulus52 utilizing a conventional knot pusher (not shown) as shown inFIG. 25I. While theknot610 is being tightened, thereinforcement member600 applies compressive forces about theannulus52 thereby closing fractures and fissures56. Once theknot610 has been tightened, thereinforcement member600 may be cut immediately proximal of the knot610 (proximal ofpledget750 if used) as shown inFIG. 25J utilizing a conventional suture cutting device (not shown).
• Refer now toFIGS. 26A-26G which illustratevarious tools780/790/840 for implanting thereinforcement member600 in accordance with the method illustrated inFIGS. 27A-27H. As seen inFIG. 26A, adual lumen trocar780 includes adual lumen shaft782 and aproximal handle784.Rigid shaft782 includes a sharpenedtip783 and a laterally facingopening785. Therigid shaft782 may be formed of stainless steel and may comprises a rigidouter tube788 and a rigidinner tube786 disposed eccentrically therein as seen inFIG. 26B.Inner tube786 defines alumen787 extending through theentire shaft782 and is sized to accommodatehollow stylet790. A crescent-shapedlumen789 is defined between theouter tube788 and theinner tube786. The crescent-shapedlumen789 extends through theentire shaft782 and is sized to accommodatehollow stylet790.Opening785 is also sized to accommodate thehollow stylet790, and may be made even larger (e.g., 2-3 times larger) to accommodate variability in reentry as will be discussed in more detail hereinafter.
• With reference toFIGS. 26C and 26D,hollow stylet790 is substantially the same asstylet710 except as described herein and illustrated in the drawings.Hollow stylet790 includes an elongateflexible shaft792 and a sharpeneddistal end793. Alumen791 extends through theentire shaft792 and is sized to accommodatereinforcement member600.
• Theshaft792 of thehollow stylet790 preferably has a flexible but pushable construction incorporating a rigid metal tube such as stainless steel hypotubing, or a super-elastic alloy tube such as nickel-titanium. Highly elastic or super-elastic materials incorporated into theelongate shaft792 resist permanent deformation during insertion and navigation through theannulus52. Theshaft792 of thestylet790 may have a diameter ranging from 0.010 to 0.025 inches and is sized to fit within thelumens787/789 of theshaft792 of thetrocar790. Theshaft792 may be coated with a lubricious material such as PTFE and a hydrophilic polymer.
• The stylet orneedle790 has acurved portion794 and a separablecurved tip796. The separablecurved tip796 is connected to thereinforcement member600 as shown inFIGS. 26E and 26F, but is separable from the remainder of theshaft792. Thecurved portion794 and the separablecurved tip796 may have the same diameter which may vary as described with reference tocurved portion712 ofstylet710 shown inFIGS. 12A-12E. Thecurved portion774 together withseparable tip796 may have at least 360 degrees of curvature or more to define at least a full circle. Two example curvatures of the separablecurved tip796 are shown inFIGS. 26E and 26F.
• Thetip793 of thehollow stylet790 is sufficiently sharp to easily penetrateannular tissue52, such that the path through theannular tissue52 taken by thehollow stylet790 will substantially conform to the geometry of the distalcurved portion794 and the curvedseparable tip796. In particular, if the distalcurved portion794 and the curvedseparable tip796 have a curve with at least 360 degrees of curvature or more, thehollow stylet790 will exit thelumen787 at the distal end of theinner tube786 and naturally define a path through theannular tissue52 to reenter thetrocar780 throughopening785 and into thelumen789 of theouter tube788. To this end, it is desirable to provide atip793 having sufficient sharpness to readily penetrateannular tissue52, which tends to be relatively fibrous and tough. By providing a sufficientlysharp tip793 with the appropriate geometry described above, thestylet790 will naturally navigate through theannulus52 and renter thetrocar780 without requiring visualization or steering of thestylet790.
• Pushrod840 may comprise a rigid mandrel having a length sufficient to extend through theshaft782 of thetrocar780 and a diameter sufficient to permit passage throughlumen789. The distal end of thepush rod840 is adapted to engage theseparable tip796 as it renters thetrocar780 throughopening785, and lock thetip796 relative toshaft782 by mechanical compression, for example.
• Refer now toFIGS. 27A-27H which illustrate a method for implanting thereinforcement member600. The method illustrated inFIGS. 27A-27H utilizeshollow stylet790 to navigate through theannulus52 andimplant reinforcement member600. The method illustrated inFIGS. 27A-27H is similar to the method illustrated inFIGS. 18A-18L, except with regard to the automatic navigation ofstylet770 out of and back into thetrocar780. The method illustrated inFIGS. 27A-27H is particularly suited for a post discectomy procedure to close the opening (not shown) created thereby. Further, the method illustrated inFIGS. 27A-27H is particularly suited for a post annular compression procedure (e.g., contraction of annular tissue by thermal means) to maintain the re-compressed annulus (not shown) created thereby. All of the variables with regard to quantity, location, orientation, etc., discussed previously may be implemented by varying the generic procedure described hereinafter. The method illustrated inFIGS. 27A-27H is a percutaneous procedure in which access to thedisc50 is achieved utilizing a number of small diameter tools which may be inserted through a patient's back (skin and back muscles), between adjacent vertebrae, and adjacent the patient'sdisc50.
• Initially, as shown inFIG. 27A, the rigiddual lumen trocar780 is advanced until the distal tip thereof is disposed in the anterior portion of theannulus52. Thehollow stylet790 is then inserted into theinner tube786 of the rigiddual lumen trocar780. Thehollow stylet790, having a curveddistal portion794 andseparable tip portion796, is advanced out the distal end of theshaft782 into theannulus52 as shown inFIG. 27B. Thehollow stylet790 is advanced until thedistal tip793 reenters thetrocar780 through theopening785 at thedistal end shaft782 as shown inFIG. 27B. Note that the curvature of thecurved portion794, the curvature of theseparable tip796 is selected to automatically align with theopening785 and thereby automatically reenter thetrocar780.
• The proximal portion of theshaft792 of thehollow stylet790 is then withdrawn leavingseparable tip796 andreinforcement member600 in place as shown inFIG. 27C. Thepush rod840 is then advanced into thetrocar780 throughlumen789 until its distal end mechanically engagestip796 and pinches or traps it relative to the distal end of theshaft782 of thetrocar780 as shown inFIG. 27D. The proximal end of thepush rod840 and thehandle784 of the trocar are then grasped and pulled proximally while maintaining engagement of the distal end of thepush rod840 against theseparable tip796. As the proximal end of thepush rod840 and thehandle784 of the trocar are pulled proximally, thereinforcement member600 is not grasped or otherwise restrained such that thereinforcement member600 is free to be advanced distally and threaded along the path previously defined byhollow stylet790 as shown inFIG. 27E.
• Although not shown, thepledget push rod740 may be used to push thepledget750 over the opposite ends of thereinforcement member600 until thepledget750 is positioned immediately adjacent the entry and exit points in theannulus52. A connection (e.g., knot)610 may be made in thereinforcement member600 and advanced to the entry points of in theannulus52 utilizing a conventional knot pusher (not shown). While theknot610 is being tightened, thereinforcement member600 applies compressive forces about theannulus52 thereby closing fractures and fissures56 and reducingbulge60. Once theknot610 has been tightened, thereinforcement member600 may be cut immediately proximal of the knot610 (or proximal ofpledget750 if used) as shown inFIG. 27F utilizing a conventional suture cutting device (not shown).
• While a single path followed by asingle reinforcement member600 is illustrated inFIGS. 27A-27F, it is also contemplated thatmultiple reinforcement members600 may be implanted as shown inFIG. 27G. For example, onereinforcement member600 could be implanted proximate the lower (inferior) portion of theannulus52 and onereinforcement member600 could be implanted in the upper (superior) portion of theannulus52. Any number ofreinforcement members600 could be implanted in a single disc, either through asingle trocar780 placement, or multiple trocar placements.
• The path navigated through theannulus52 by the foregoing method may be a function of the individual anatomical geometry of the patient and/or the particular portion of theannulus52 requiring compression. Accordingly, the path defined by thestylet790 andreinforcement member600 through theannulus52 may vary as shown inFIGS. 19A-19F by utilizingdifferent stylet790 curvatures and a sheath, similar to the method described with reference toFIGS. 18A-18L. By way of example, not limitation, a substantial rectangular path with rounded corners may be employed as illustrated inFIG. 27H.
• From the foregoing, those skilled in the art will appreciate that the present invention providesreinforcement devices100,200,300,600,510,520,530,540,570 and580, which may be used to reinforce a damaged disc, while permitting relative movement of the adjacent vertebrae. The present invention also provides minimally invasive methods of implanting such devices as described above.
• All of the implantable devices and delivery tools therefor described above may incorporate heating mechanisms (e.g., resistive wire coils) to allow for heating the surrounding tissue, such as temporarily and directly heating annular tissue. In addition or in the alternative, a separate device may be provided specifically for heating annular tissue, which may be used to accomplish results similar to those described with reference toFIG. 4H. By way of example, not limitation, the following is a description of a device specifically adapted to heat annular tissue, but the methods and principles of operation are equally applicable to all devices disclosed herein that come into contact with annular tissue.
• FIG. 28A illustrates an exemplary embodiment of athermal probe1010 which may be temporarily positioned within the annulus and heated. Thethermal probe1010 may comprise ahollow shaft1015, which contains a heating element extending at least a portion of the length of theshaft1015. Thethermal probe1010 may be advanced through the annulus over one or more stylets in the same fashion assheath730 as described with reference toFIGS. 18A through 18F utilizing one or a series ofstylets1035 incorporating curvatures as shown and described with reference toFIGS. 12A through 12E.
• The heating element may comprise, for example, a coil or braid of resistive metallic wire. As seen inFIG. 28B, a detailed view of a distal portion of theprobe1010 is shown, which includes aresistive wire coil1020 encapsulated by the polymeric material of theshaft1015. The polymeric shaft material may comprise electrically insulative material and may be selected to tolerate relatively high temperatures, such as PTFE or polyimide. At the distal end of thecoil1020, the resistive wire may extend proximally as areturn wire1025. Aplug1030, connected to the proximal end of thethermal probe1010 may provide connection to a power source (not shown). Direct or alternating current may be used to electrify theresistive wire coil1020, causing heating, which in turn heats the annular tissue. Temperature may be controlled by the amount of electric power delivered. One or more thermocouples may be included in theshaft1015 of the probe1010 (not shown).
• Analternative probe1040 is illustrated inFIG. 28C. Thestylet1045 used for delivery ofthermal probe1040 could also be used as the return electrode. As shown inFIG. 28C, theshaft1050 includes aresistive coil1055, terminating near the distal end at acontact1060. Thecontact1060 provides electrical connection between thestylet1045 and theresistive wire coil1055. In this embodiment, thestylet1045 may be electrically conductive, and is preferably metallic. Thestylet1045 optionally includes ashoulder1065 which allows for theprobe1040 to be advanced in a “fixed wire” fashion, together with thestylet1045. This “fixed wire” approach incorporating anoptional shoulder1065 on thestylet1045 is also applicable to the above described implants and delivery devices,e.g. stylet710 andsheath730 illustrated inFIGS. 18A through 18F.
• Thethermal probe1010/1040 may be positioned directly within the annulus, in the same manner as described in connection with the positioning of theimplant100 shown inFIGS. 8A through 8K. But rather thanimplant100,thermal probe1010/1040 would be positioned and activated. These figures illustrate positioning in the posterior annulus, but it is within the scope of this invention that thethermal probe1010/1040 could be positioned anywhere within the annulus or across the disc, including the positions illustrated inFIGS. 19A through 19F. For example, theprobe1010/1040 could be positioned in the lateral annulus, anterior annulus, or multiple regions of the annulus, including circumferentially in the annulus, as illustrated for thesheath730 illustrated inFIGS. 18A through 18F.
• Thethermal probe1010/1040 may also incorporate an anchoring mechanism to facilitate compression of the annular tissue prior to heating. For example, theprobe1010/1040 could include progressive external threads such as described in connection with the implant ofFIG. 4A.
• Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.

Claims (11)

1. A system for delivering an implant within an intervertebral disc comprising:

(1) at least one tube, said tube adapted to receive an implant,

(2) an implant adapted to be received into the at least one tube and placed into an intervertebral disc, and

(3) an advancer to effect said placement,

wherein said advancer is releasably attached to said implant.

2. The system ofclaim 1 wherein said implant is expandable.

3. The system ofclaim 1 wherein said implant is inflatable.

4. The system ofclaim 1 wherein said advancer is positioned at least partially within the at least one tube.

5. The system ofclaim 4 wherein said advancer is slidably housed within said at least one tube.

6. The system ofclaim 1 wherein said implant is a barrier.

7. The system ofclaim 1 wherein said implant is initially provided in a compressed configuration.

8. The system ofclaim 1 wherein said at least one tube comprises a handle.

9. The system ofclaim 1 wherein said implant is provided in a folded configuration.

10. The system ofclaim 1, wherein said implant is comprised of a biocompatible material.

11. The system ofclaim 1, wherein said implant is comprised of a compressible polymer.

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