Abstract:
This invention proposes a device directed to rapid surgical removal of the nucleus pulposus from the spine intervertebral space. The invention is manipulated within the intervertebral space to engage and dislodge small pieces of nucleus material that are mobilized proximally for disposal. Aspects of the invention are included to protect the endplate tissue of vertebrae and limit damage to the integrity of the disc annulus.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This utility application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/747,089, filed May 11, 2006, incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to devices and methods for use in interventions to restore spinal function. More specifically, the invention removes nucleus pulposus from the intact spine intervertebral disc during surgical therapy to treat herniation or degenerated discs.  
       BACKGROUND OF THE INVENTION  
       [0003]     Back and spinal ailments trouble thousands of Americans every year. In 2003 approximately 11 million people had impaired movement because of back pain, resulting in $80 billion of lost work and productivity. Back pain is a top cause of health care expenditures, amounting to $50 billion in the USA alone. However, only 2 percent of patients seek current implant therapies that create spinal fusion, and they typically do so only at an advanced stage of disease.  
         [0004]     Disc degeneration is part of the natural process of aging and has been documented in approximately 30% of 30 year olds. As the population ages, it is even more common for individuals to have signs of disc degeneration. Disc degeneration is an expected finding over the age of 60.  
         [0005]     Many back problems result from failure of the annulus (also called the disc annulus or outer fibrous ring) and from herniation of the nucleus pulposus (also called the disc nucleus) through the annulus of the intervertebral disc to compress the spinal cord or nerve roots. Currently, there are only limited treatments for these ailments. First, if the nucleus is still relatively intact, a physician can remove the herniating portion and leave the remaining nucleus in an effort to maintain the integrity and mobility of that spinal region. Successful surgery depends on integrity of the annulus and involves the assessed risk of additional future herniation. Or, physicians can remove much of the intervertebral disc with the intention of preventing future herniations by facilitating a fusion of adjacent discs.  
         [0006]     These interventions are great advancements over treatments that were available just decades ago. But, they introduce several concerns and difficulties. One of the most difficult decisions that physicians face is to determine the amount of nucleus to remove. If too much is removed then mobility can be reduced, too little and the herniation may recur. There is also substantial risk of damage to the annulus that could impair healing. Procedures that remove the complete intervertebral disc, discectomy, damage the vertebral end plate. Due to the similar texture of the ligamentum flavum and the dura there is also concern of cutting into the dura, which could result in neurological complications. Finally, these procedures produce large amounts of scarring, which limits the scope of revision surgeries.  
         [0007]     A new treatment uses intervertebral implants to replace the nucleus with materials that restore mobility and avoid adjacent segment deterioration without the risk of herniation. Manufacturers have developed implants to the point that several forms of the prostheses are in clinical trials. Although there are associated problems and difficulties, these implants are poised to be a major breakthrough treatment of failed intervertebral discs, particularly in young people. The implants are placed within the space defined by the annulus after as much of the nucleus as possible has been removed. Because the goal of the surgery is to restore mobility, the annulus, vertebral endplates and other disc structures must be undamaged.  
         [0008]     Presently, most disc surgeries involve partial removal of the nucleus pulposus (nuclectomy). Or the nucleus is removed along with the entire intervertebral disc (discectomy). Standard surgical tools, such as curettes, bone nibblers or pituitary rongeurs, and a variety of techniques have been adapted for these procedures. All of these prior art tools were designed for purposes other than spinal surgery and are poorly suited to nucleus removal, especially when other tissues must be spared from injury. Generally, surgeons have experience and training only for procedures that require incremental extraction of small pieces of the nucleus (micro or partial nuclectomy). When applied to complete nuclectomy these tools lack the flexibility and control to remove all of the nucleus and invariably cause damage to the surrounding annulus fibrosus and vertebral end plates. In addition, substantial skill and dexterity is required to produce satisfactory results. Even in the hands of an experienced surgeon, nucleus extraction can be the most prolonged and difficult stage of the newer forms of spinal surgery.  
         [0009]     No devices or methods have been developed specifically to remove the entire nucleus while minimizing trauma to other tissues. Maintaining the integrity of surrounding tissue is necessary to hold the implant in place and allow proper support and separation of the surrounding vertebrae. Some the implants will function poorly or risk new herniation if 20% or even as little as 10% of the original nucleus is left behind. A clean bed, free of nuclear material in critical locations, within which to deploy or graft the implants will also be crucial to the success of surgery. As a result, special methods, tools, or procedures are needed that can cleanly remove the nucleus without damaging the fibers of the annulus.  
         [0010]     In an effort to address some of these limitations, physicians and researchers are searching for new methods of treatment for the herniated nucleus pulposus. They are looking at treatments that restore the function of the nucleus, regenerate the structure of the annulus, or are implanting artificial discs. Each of these proposed treatments introduces new difficulties and will need additional support mechanisms to prepare for the procedures. One of the most promising therapies is nucleus replacement. It is superior to traditional disc fusion because it restores movement and function to the disc space. It also promises to be superior to artificial disc implantation because much more of the original tissue is preserved, the procedure is faster, and there is less risk of malpositioning. Neither fusion nor artificial disc implantation are likely to ever be compatible with percutaneous access and thus carry a greater risk of infection and damage to other tissues or organs.  
         [0011]     Most approaches to nucleus replacement will require removing the entire nucleus. There are few methods of removing the nucleus to prepare for nucleus replacement. These include the use of manual surgical implements such as curettes, bone nibblers, and pituitary rongeurs. The procedure involves incremental extraction of small pieces of the damaged portion until a the surgeon judges that a sufficient amount has been removed.  
         [0012]     There are few companies currently looking at methods for removal of the nucleus pulposus, as nucleus replacement is a fairly new treatment modality. Clarus Medical has developed the ‘cut and suction’ method of percutaneous discectomy. Their product is the Nucleotome, a mechanical device with a blunt drill passing through a cannula that enters the disc site. It uses a rounded tip, shaped like a blunt drill to decrease the risk of cutting into the annulus. Stryker Corporation offers another rigid design, the “Dekompressor”, a percutaneous discectomy probe. It has a battery-operated disposable hand piece attached to a helical probe. The cannula allows access to the disc space, and the probe rotates and removes nucleus material through a suction mechanism. Both devices are too stiff to easily remove all of the nucleus  
         [0013]     ArthroCare Corporation, has worked on coblation technology, which involves the use of low energy radio-frequency waves. This energy creates an ionic plasma field from the sodium atoms found in the nucleus. A molecular dissociation process occurs due to this low temperature plasma field, which converts this tissue into gases that exit the treatment site. The product is named the Spine Wand. It acts as drill as it is advanced into the disc. The tissue is converted into gas that exits the disc through the cannula. An accessory to the Spinal Wand is the System 2000 Controller. This accessory uses a combination of ablation, resection, coagulation and suction. A bipolar cautery is employed. However, the insertion depth up to the annulus must be predetermined and the wand is difficult to steer to remote parts of the nucleus space.  
         [0014]     Laser discectomy employs laser energy to vaporize portions of a diseased disc. It is compatible with through minimally invasive surgery. However, laser techniques are generally useful to remove only small amounts of material because of the heat generated and other limitations. In addition, vaporized material expands to a gaseous phase and must be removed.  
         [0015]     This invention proposes devices and methods directed to improving complete removal of the disc nucleus. The new process must be a relatively quick and cost effective alternative to current procedures. In addition, the new method or device must facilitate a complete and clean removal of the disc in a safe manner that does not compromise the integrity of the annulus.  
       OBJECTS OF THE INVENTION  
       [0016]     An object of the present invention is to overcome the drawbacks described above and other limitations in existing systems by providing a surgical device to remove almost the entire nucleus from a spinal intervertebral disc.  
         [0017]     Another object of the invention is to remove nucleus material with minimal or no damage to surrounding tissues or structures such as the disc annulus, vertebral endplates, spinal nerves or blood vessels.  
         [0018]     Another object of the invention is to be minimally invasive and carry a low risk of infection or discomfort to the patient.  
         [0019]     Another object of the invention is to provide a system and method that removes the nucleus rapidly.  
         [0020]     Another object of the invention is to provide a system and method that allows a surgeon to remove the nucleus without prolonged training, practice or skill.  
         [0021]     Another object of the invention is to provide a system and method that removes the nucleus while allowing the surgeon fine control of the procedure.  
         [0022]     These and other objects of the invention are accomplished according to various embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]      FIG. 1  is a frontal-lateral view of the anatomy of a section of the human lumbar spine.  
         [0024]      FIG. 2  is a superior view cross section of the anatomy of a human lumbar intervertebral disc.  
         [0025]      FIG. 3  is a superior view in cross section of a herniated human intervertebral disc.  
         [0026]      FIG. 4  is a side view representation of the human spine in the vicinity of a herniated disc.  
         [0027]      FIG. 5  is a component view of the present invention.  
         [0028]      FIG. 6   a  is close up view of the shearing type embodiment. This figure shows the present invention in the open position.  
         [0029]      FIG. 6   b  is a view of the shear type embodiment in the closed position.  
         [0030]      FIG. 6   c  is a side view of the shear type embodiment detailing cutting edge angles.  
         [0031]      FIG. 7   a  is a close up view of twist type distal tip. This figure shows the present invention in the open position.  
         [0032]      FIG. 7   b  is a view of the twist type distal tip in the closed position.  
         [0033]      FIG. 7   c  is a side view of the twist type embodiment detailing cutting edge angles.  
         [0034]      FIG. 8  is an isometric view of a shear type embodiment with a distal tip extension.  
         [0035]      FIG. 9  is an isometric view of a punch type embodiment.  
         [0036]      FIG. 10  is an isometric view of a reciprocating cutting loop embodiment of the present invention.  
         [0037]      FIG. 11  is an isometric view of a reciprocating disk embodiment of the present invention.  
         [0038]      FIG. 12  is an isometric view of a reciprocating bilobed cutting loop embodiment of the present invention.  
         [0039]      FIGS. 13   a  and  13   b  are isometric views of a rotational cutting loop embodiment of the present invention.  
         [0040]      FIG. 13   c  is a phantom isometric view of the rotational cutting loop embodiment of the present invention comprising an auger.  
         [0041]      FIGS. 14   a  to  14   c  are isometric views of a rotational cutting vane embodiment of the present invention.  
         [0042]      FIG. 15  is an isometric view of another rotational cutting vane embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0043]     This invention overcomes various limitations of prior art means to remove nucleus pulposus from spinal intervertebral discs.  FIG. 1  shows a section of the lumbar spine with major anatomic features labeled. Vertebrae are the bones that provide essential strength and stiffness to the spine and afford protection to the spinal cord, spinal nerve roots and major blood vessels (the blood vessels are not shown but are located opposite the spinal cord). The discs located between vertebra provide the spine with the ability to articulate by lubricating and separating the vertebrae.  
         [0044]      FIG. 2  is a superior sectional view through an intervertebral disc  24  of the lumbar spine, the front of the body is upward in this view. Spinal nerves  22  radiate from the spinal cord  23 , located posterior to the spine, to provide control and sensation to various segments and organs of the body. The disc  24  is roughly kidney shaped and defined by the annulus fibrosus  21 . The annulus is composed of concentric layers of fibrous tissue that seal the space between vertebra located above and below the disc (not shown). Each layer of annulus  21  connective tissue is comprised of type I collagen oriented at approximately 30°. Successive annulus  21  layers alternate the 30° angle to provide substantial resistance to pressure from inside the disc  24 . Within the space defined by the annulus  21  is the nucleus pulposus  20 . The nucleus is avascular and comprised of hydrated mucoprotein gel and type II collagen fibers.  
         [0045]     The intervertebral disc functions somewhat like a water bed to allow articulation of the spine. When a person is upright substantial hydrostatic pressure is developed within the disc  24  and this pressure increases at lower portions of the spine, particularly the lumbar and sacral region. The annulus  21  serves to contain nucleus  20  that is under pressures in the range of 690 to 2000 kPa (100 to 300 psi). Articulation of the spine is accommodated by displacement of nucleus material from one side of the nucleus space to another. In a normal, healthy spine the vertebrae are prevented from contacting each other even at maximal angles of articulation.  
         [0046]     In young adults the intervertebral disc  24  is approximately 7 to 9 mm thick. With age and disease the hydration level of the nucleus  20  decreases. This thickens the nucleus from a soft gel-like consistency to become relatively stiff. Further degeneration with age and disease can occur to both the nucleus  20  and the annulus  21 . This may allow the thickness of the disc  24  to decrease until, in the final stages, the vertebrae are in contact during some or all postures and movement. Contact between vertebrae damages these bony structures and generates substantial pain. Disc thickness greater than approximately 4 mm is presently considered suitable for nucleus replacement therapy. At lesser thickness treatment will usually involve removal of the disc  24  for spinal fusion or implantation of an artificial disc.  
         [0047]     Because the nucleus  20  is avascular there are no living cells and exchange of fluids is through the cartilaginous endplates (not shown) covering the vertebral body. The endplates are a thin layer of primarily hyaline cartilage. The endplates are important to proper function of the intervertebral disc. In traditional therapies of fusion and disc replacement the endplates are not preserved so surgical techniques generally disregarded protection of the endplates. With motion restoration implantation of nucleus replacements the endplates must be protected from damage.  
         [0048]     Similarly, with age and disease the annulus  21  may become weakened. This is a frequent cause of herniation, as illustrated in  FIG. 3 . As shown, the annulus  21  has weakened under pressure exerted by the nucleus  20  (in response to compression from the vertebrae) and compresses spinal nerve root  22 .  FIG. 4  is lateral view of a disc  41  herniation impacting spinal nerve  42  caused by annular failure  30 . Similarly, the annulus  21  can fail such that nucleus material  20  exits the annulus and causes a direct effect on the nerve. In addition to being one of the major causes of disc therapy, degeneration of the annulus makes it vulnerable to damage during nucleus removal. The various embodiments of the present invention provide means of protecting the annulus from penetration or disruption.  
         [0049]     A first embodiment  50  of the present invention is illustrated in  FIG. 5 . It comprises a hand control  52 , vacuum source  51  connected via flexible tubing  55  to a nucleus collection container  56  which in turn provides vacuum to the hollow lumen of the nucleus collection tube  54 , and cutting tube  53 . The cutting tube  53  has an inner diameter larger than the outer diameter of the collection tube  54  and is arranged to slide over the collection tube  54 . The distal portions of the cutting  53  and collection  54  tubes (away from the vacuum source) are intended to be operated within the intervertebral disc  24  to remove nucleus material  20 . The diameters of the distal portions of the tubes  53  and  54  are smaller than the height of intervertebral disc defined by the separation of the vertebrae forming the disc. These diameters are preferably less than 4 mm to allow insertion through a minimally invasive surgery guiding device and to fit within diseased or compressed intervertebral discs.  
         [0050]     To aid in accessing and navigating the annulus space of the intervertebral disc the tubes  53  and  54  of the invention  50  may be formed of a partially elastic material that can bend through an angle up to approximately 20 degrees in the range of force that may be conveniently be applied by hand. Further, the most distal portion (e.g., a tip) of the collection tube  54  preferably comprises a material with a hardness in the same range as annulus  21 , or softer. It may also be formed with a rounded or blunted surface. These will aid in protecting the annulus and vertebral surfaces from iatrogenic damage. The length of the tubes  53  and  54  is chosen to allow for use in less invasive or minimally invasive surgery. The tubes  53  and  54  are preferably manufactured of material with relatively high strength, such as stainless steel braid or polycarbonate, that resists fracture when manipulated by the operator. One or both of the tubes  53  and  54  may be formed of transparent material, depending on operator preference to observe the removal of nucleus material  20 .  
         [0051]     The collection container  56  is also preferably formed of transparent material and is sealed except for the outlet and inlet ports connected respectively to the vacuum source  51  and collection tube  53 . The container  56  preferably is formed of two or more pieces or an access port that may be used to remove and preserve collected nucleus material  20 ; and markings or other means to allow estimation of the volume of nucleus material collected in the container. The container  56  also serves to prevent nucleus material  20  and other tissue from contaminating the vacuum source  51 .  
         [0052]     The two-piece hand control  52  is comprised of two arms  52   a  and  52   b  able to pivot at a pin joint  57 . The shorter portion of the distal hand control arm  52   a  is attached to the cutting tube  53  while the proximal arm  52   b  is attached to the collection tube  54 . Operating the hand control to bring the long portions of the arms together causes the cutting tube to move so that it substantially covers the distal portion of the collecting tube. The handle may further comprise a spring mechanism (not shown) that separates the arms once a force applied to bring the arms together is removed. Alternatively, the hand control may be arranged and connected to the tubes  53  and  54  so that bringing the longer portion of the arms together causes the cutting tube  53  to move proximally. Optionally, the tubes  53  and  54  may be manipulated directly or with gripping regions (not shown) without the aid of the hand control.  
         [0053]      FIG. 6   a  is an expanded view of one embodiment of the distal portion of the invention  50 . The collection tube  54  comprises a side opening  60  defined by edges  64  and end cap  62 . The cutting tube  53  slides over the collection tube  54 , as described above, and substantially or completely covers the side opening, as shown in  FIG. 6   b  illustrating the closed position. The distal edge  63  of the cutting tube  53  may be thin or sharpened to be capable of penetrating and separating nucleus material  20 . When the cutting tube  53  is made of a polymer or other flexible material the edge may be formed of a harder material, such as metal, attached to cutting tube by means known in the art.  
         [0054]     The distal edge of the cutting tube  53  in the embodiment of  FIG. 6   a  has an angle between 90 and 20 degrees, and preferably 75 to 30 degrees from the long axis of the tube. This angle preferably matches, within 10 degrees, the slope of the distal portion of edge  64  formed around opening  60  in collection tube  54 . The purpose of these angles is to enhance the shearing action of the cutting tube  53  relative to the collection tube  54  in disrupting nucleus material  20 . The end cap  62  of the collection tube  54  is preferably formed at an angle between 90 degrees and the angle of the cutting tube edge  63 .  
         [0055]     To remove nucleus material  20  from the intervertebral disc space  24  the distal end of collection tube  54  is inserted through an opening formed in the annulus  21 . Once inside the annulus the opening  60  collection tube  54  is pushed into the nucleus material  20  so that material enters the opening  60 . The cutting tube  53  is then moved forward, slicing through the nucleus material  20  and entraining a discreet quantity of nucleus material within the collection tube  54 . Suction provided from the vacuum source through a lumen in the collection tube causes the entrained nucleus material to be pulled proximally and into the collection container  56 . The cutting tube may be returned to a distal position immediately to re-expose opening  60  in the collection tube  54  and the collection tube repositioned to ‘pack’ more nucleus material  20  into the collection tube  54 . This may aid in forming a plug of nucleus material across the entire cross-section of the lumen in the collection tube  54  so that maximum suction pressure may be developed to move the nucleus material proximally to the collection container  56 . A further technique to aid in mobilizing nucleus material  20  proximally involves manipulating the cutting tube  53  across the opening  60  in the collection tube  54  to occlude air passages that may exist proximally of the nucleus material. The steps of engaging, cutting and removing nucleus material by positioning the invention  50  and moving the cutting tube  53  relative to the collection tube  54  are repeated until the desired amount of nucleus material is removed.  
         [0056]     The operator may remove the invention from the intervertebral disc as needed to permit visualization of the annular space and then reinserted to continue the procedure. Alternatively, one or more optical fibers may be incorporated into the invention to permit visualization during nucleus removal and to aid in positioning the collection tube opening  60  for the most efficient and complete removal of nucleus material  20 .  
         [0057]      FIG. 7   a  shows another embodiment of the present invention wherein the cutting tube  53  is rotated around collection tube  54  to sever and entrain nucleus material  20  within opening  60 .  
         [0058]      FIG. 7   b  shows this embodiment with the tubes  53  and  54  in a configuration forming the closed position. The angle  72  forming the end of the cutting tube  53  is preferably 10 to 40 degrees. This smaller angle permits a larger opening  60  and a longer shearing edge. A further embodiment may combine these two modes of operation between the tubes  53  and  54 : distal/proximal translation and rotation.  
         [0059]      FIG. 8  illustrates a modified version of the embodiment of the invention presented in  FIG. 6   a . Relatively soft (compliant) material forms an extension  82  of the end cap  62  at the end of the collection tube  54 . The stiffness of the extension is set sufficiently low, in the range of Shore A hardness less than 80, to protect the annulus  21  and vertebral surfaces from injury. The compliant extension comprises a long dimension, preferably at least 1.25 times the outer diameter of the collection tube  54 , oriented in the same direction as the opening  60  in the collection tube  54 . The width of the protruding material is approximates the outer diameter of the collection tube  54 . The extension aids in disrupting or dislodging nucleus material  20  located at periphery of the annulus space of the intervertebral disc  24  and bringing the nucleus material into approximation of the opening  60 .  
         [0060]      FIG. 9  shows yet another modification of the present invention. The distal cap  62  attached to the collection tube  54  incorporates an extension  92  beyond the diameter of the collection tube to approximately the outer diameter of the cutting tube  53 . This embodiment permits entrained nucleus material  20  to be severed from remaining nucleus material in the fashion of a punch. The distal edge  63  of the cutting tube  53  would have the same angle  65  as the angle of the distal cap  62  and extension  92 . The distal edge  63  would preferably be thin or sharpened around the entire circumference of cutting tube  53  to aid in cutting nucleus material  20 . The sharpened distal edge  63  of the cutting tube  53  pressed sufficiently tightly against the extension  92  to completely sever the entrained nucleus material  20 .  
         [0061]     All of the preceding embodiments of the invention rely on force developed by suction pressure to pull entrained nucleus material  20  to the proximal end of the collection tube  54  and into the collection container  56 . As described above, nucleus material becomes stiffer and is composed of increasing quantities of discreet, rigid components with age or the progress of disease. Consequently, additional features may be needed to disrupt the nucleus material and bring it out of the disc space and toward the collection container  56 .  
         [0062]      FIG. 10  illustrates an embodiment  100  of the present invention that incorporates a loop  101  attached at an angle of approximately 90 degrees to the end of a control rod  102 . The loop  101  has a major diameter substantially equal to or greater than the inner diameter of the distal collection tube  54  and opening  60 . The loop  101  may protrude beyond the opening  60  in the collection tube  54  and be sufficiently hard and stiff to disrupt nucleus material  20  as it is moved longitudinally within the opening  60 . Preferably, the loop  101  is also sufficiently flexible to be captured entirely within the collection tube  54  without exceeding its yield stress. With the loop  101  positioned within the collection tube a cutting tube  53  (not shown) may be deployed to completely entrain nucleus material  20  within the opening  60 .  
         [0063]     The control rod  102  is manipulated by an operator from outside the intervertebral disc  24  to move the loop  101 . The control rod  102  may pass through a second lumen of the collection tube  54  or a lumen  103  within a capture tube  105  located within the collection tube. Alternatively, the control rod may move freely within the main lumen of the collection tube  54 . In this latter configuration the loop  101  may be withdrawn through the lumen of the collection tube  54  to assist in bringing nucleus material proximally through the collection tube. The loop  101  is used in the configuration with the capture tube  105  to bring nucleus material into the distal opening of the capture tube so that suction pressure will draw the nucleus material to the container  56  which is connected in this configuration to the capture tube instead of the collection tube  54 . Alternatively, the loop  101  can trap a quantity of nucleus material  20  against the capture tube  105  and the combination withdrawn through the collection tube  54 .  
         [0064]      FIG. 11  shows is an alternative embodiment  110  of the invention where a solid or mesh disc  111  is attached to the end of the control rod  102 . This embodiment is preferred for trapping nucleus material  20  against or within the capture tube  105 .  
         [0065]     The embodiment of the present invention  120  shown in  FIG. 12  comprises a plurality of control rods  122  that pass through separate lumens of the capture tube  105 . Also illustrated is a loop  121  formed in a bilobed shape. One lobe of loop  121  essentially conforms to the inside diameter of the collection tube  54 . The other lobe is shaped to engage more nucleus material  20  beyond the collection tube  54 . Utilizing more than one control rod permits greater control of the loop  121  with less difficulty preventing unwanted rotation or bending of the loop. Functions of embodiments  110  and  100  are retained in embodiment  120 .  
         [0066]      FIG. 13   a  shows an embodiment of the present invention comprising a loop  131  formed on the end of a rotational control rod and located in the opening  60  of the collection tube  54 . The control rod passes through a lumen of the collection tube  54  near the center line of the opening  60 . Alternatively, the lumen  103  guiding the control rod may be within the wall of a capture tube  105  located within the collection tube  54 , as illustrated in  FIG. 13   b . The proximal end of the control rod is turned by the operator to cause rotation of the loop  131 . This rotation disrupts portions of nucleus material that are carried into the opening  60 . Suction applied to the lumen of the collection tube  54  or, if present, capture tube  105  carries nucleus material proximally in the fashion described above.  FIG. 13   b  also illustrates a pivot extension  132  of the loop  131  that helps to stabilize the loop so that it remains within the opening  60  and does not bend when encountering stiffer nucleus material  20 .  
         [0067]      FIG. 13   c  shows an auger  106  located within a lumen of capture tube  105 . The auger comprises and central rod and one or more flutes or vanes  107  that serve to move stiffened and granular nucleus material  20  proximally for removal. Similar auger features may be incorporated within the collection tube  54  and in any of the embodiments of the invention described herein.  
         [0068]      FIGS. 14   a ,  14   b  and  14   c  illustrate an embodiment of the present invention  140  with vanes  141  formed on the a rotatable control rod  142 . The control rod passes through a lumen  103  formed in the wall of collection tube  54 . When rotated, the vanes serve to disrupt or sever nucleus material  20  that enters an opening at the end of the collection tube  54 . The length of the vanes is preferably selected to be able to substantially or completely occlude the opening in the collection tube through rotation and an opening  144  that approximates the cross section of the opening to permit the maximum amount of nucleus material  20  to enter the opening. As shown in  FIG. 14   c  the vanes may comprise sharpened edge  143  to improve the ability to sever stiffened or granular nucleus material. The vanes may be rotated either in a single direction as circular motion or through 180 degrees and then returned to a starting position. Suction and/or an auger, as described above, serve to move entrained nucleus material proximally.