Abstract:
An apparatus for repairing a tear in an annulus fibrosus of a spinal disc includes a hollow, helically-shaped suturing needle and a retriever. The needle is used to insert a suture along a helical pathway bridging the tear. The retriever is used to retrieve one end of the suture from the inside of the annulus and bring it close the other end of the suture outside the annulus, where the suture can be tensioned and tied to fixate the tear. In other embodiments, multiple sutures are placed with helically-shaped needles of differing dimensions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from U.S. Provisional Patent Application No. 60/601,800, filed on Aug. 16, 2004, entitled “Helical Suturing Device”, which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention is related to medical devices for suturing. More particularly, it relates to devices for repairing a tear in the annulus fibrosus of a spinal disc.  
       BACKGROUND  
       [0003]     The intervertebral discs are ligaments that connect the vertebrae of the spine together. They provide structural support for the spine and distribute forces exerted on the spinal column. An intervertebral disc consists of three major components: cartilage endplates, nucleus pulposus, and annulus fibrosus. The central portion, nucleus pulposus, is relatively soft and gelatinous, having a consistency similar to that of crabmeat. Surrounding the nucleus is the annulus fibrosus, which has a more rigid consistency and is largely comprised of concentric layers of fibrous tissue. The annular portion serves to provide peripheral mechanical support to the disc, afford torsional resistance, and contain the softer nuclear portion and resist its hydrostatic pressure.  
         [0004]     Unfortunately, intervertebral discs are susceptible to injury. Disc herniation occurs when the nucleus begins to extrude through an opening in the annulus, often to the extent that the herniated material impinges on nerve roots in the spine, resulting in pain. One way to address such pain is remove the bulging disk material surgically through a nucleotomy and/or anulotomy, thus relieving pressure on the nerve roots. Further treatment might include the use of intervertebral spacers to reduce the pressure exerted on the disc by the spine. However, very few products are currently available that address the repair of the annulus fibrosus per se. This is true whether the annular tissue has been damaged by herination, or by the creation of surgical access ports in the course of disc repair.  
         [0005]     There exists a need for methods and instruments for repair of the annulus fibrosus. Any such methods that are simple and compatible with minimally-invasive surgical techniques would be particularly desirable.  
       SUMMARY  
       [0006]     The present invention, according to one embodiment, is a system for repairing a tear in an annulus fibrosus of a spine. The system includes a substantially helically-shaped suturing needle, a length of suture, and a retriever. The suturing needle is configured to deliver the suture in a helically-shaped path bridging the tear. The retriever is configured to retrieve one end of the suture from the inside of the annulus to the outside, where the two ends of the suture can be tensioned and tied. In other embodiments, multiple systems are used to place multiple sutures.  
         [0007]     This summary is not intended to describe each embodiment or every implementation of the present invention. A more complete understanding of the invention will become apparent upon review of the detailed description and listing of embodiments in conjunction with the accompanying drawings. As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is an illustration of a representative section of human spine having two vertebrae and a disc with a set of tools for suturing the disc according to one embodiment of the present invention.  
         [0009]      FIG. 2  is a perspective detail view of the helically-shaped suturing needle and needle handle shown in  FIG. 1 .  
         [0010]      FIG. 3  is a detailed view of the the distal end of the helically-shaped suturing needle shown in  FIG. 1  and  2 .  
         [0011]      FIG. 4  is a flowchart describing a method of repairing an annulus fibrosus according to one embodiment of the present invention.  
         [0012]      FIG. 5  illustrates a helically-shaped needle, needle handle, and retriever in relation to each other and a representative disc undergoing repair.  
         [0013]      FIG. 6  is a detailed view of the distal ends of the helically-shaped needle and retriever illustrated in  FIGS. 1-4 .  
         [0014]      FIG. 7  is a set of detailed views of an alternate distal end for the retriever. 
     
    
     DETAILED DESCRIPTION  
       [0015]     The present invention, in one embodiment, is directed to the repair of tears, cuts, voids, or like tissue damage in discs of the spine.  FIG. 1  illustrates a simplified representation of a section of spine including two vertebrae  10  between which is seen an annulus fibrosus  12  of a spinal disc. Major components of an apparatus  13  for repairing an annulus  12  are also shown. A needle handle  14  manipulates a helical suturing needle  16  engaged with the annulus  12 . A suture retriever  18  is shown above the needle handle  14 . The suture retriever  18  has a flat  19  to indicate its rotational orientation.  
         [0016]      FIG. 2  is a perspective view of a distal end  20  of the needle handle  14  attached to a helical suturing needle  16 . The helical needle  16  can be characterized by a longitudinal depth  22 , a diameter  24 , and a pitch  26 . In one embodiment, the needle  14  is hollow, having a central lumen that communicates with three bores in the needle, a first bore (not shown) at a proximal end (not shown; located in the needle handle  14 ) of the needle, a second bore  30  at a distal end  32 , and a third bore  34  near the distal end. (See  FIG. 3  for an enlarged view of the bores  30 ,  34 .) The needle handle  14  also features a retriever guide  36  that facilitates use of the suture retriever  18 .  
         [0017]     The chosen values of the depth  22 , diameter  24 , and pitch  26  of a helical suturing needle  16  will vary with the particular injury to be repaired, the location of the disc along the spine, and the particularities of the individual patient. According to one embodiment, the depth  22  of the needle  16  will have a value ranging from about 3 mm to about 25 mm, the diameter  24  will have a value ranging from about 2 mm to about 13 mm, or, alternatively, from about 2 mm to about 19 mm, and the pitch  26  will have a value ranging from about 2 mm per turn to about 7 mm per turn. According to another embodiment, the needle  16  has a depth  22  of about 11 mm and a diameter  24  of about 7 mm. According to still another embodiment, the needle  16  has a depth  22  of about 5 mm and a diameter  24  of about 3 mm.  
         [0018]      FIG. 3  is an enlarged perspective view of the distal end  32  of the helical needle  16 . Prior to use, a length of suture  38  is loaded in the helical needle  16  such that it runs from the first bore (not shown) up the needle to the second bore  30 , exits the needle there and reenters the needle at the third bore  34 , whereupon it runs down the needle back to the first bore. The suture  38  may be loaded during the manufacturing of the helical needle  16  or may be inserted by the surgeon using a push rod (now shown) or some other method of passing the suture  38  through the helical needle  16 . In this configuration, both a first end  40  and a second end  42  of the suture  38  extend out of the first bore of the helical needle near the distal end  20  of the needle handle  14 , where they can be manipulated by a surgeon (see  FIG. 2 ). The second  30  and third  34  bores of the helical needle hold the suture  38  such that a capturable segment  44  of the suture is formed.  
         [0019]     A method  50  for using the present invention according to one embodiment to repair an annulus fibrosus  12  is summarized in the flowchart of  FIG. 4 . The method may be better understood by referring also to  FIG. 5 , which illustrates the situation mid-way through the procedure at block  56 , and  FIG. 6 , an enlarged view of the distal ends ( 32 ,  46 ) of the helical needle  16  and suture retriever  18 , along with this description.  
         [0020]     Standard surgical techniques are used to gain access to the annulus fibrosus  12 , and if necessary, a nucleotomy and/or an anulotomy are performed to remove bulging disc tissue (block  52 ). Any appropriate conventional or otherwise known techniques can be used for these purposes. A surgeon inserts a helical suturing needle  16 , preloaded with suture  38 , along a tear (not shown for clarity) in the manner of a corkscrew by rotating the needle handle  14  such that the helix is centered on the tear and the needle penetrates tissue along opposing sides of the tear (block  54 ). The insertion is continued until the distal end  32  of the needle  16  reaches an interior region  70  of the annulus fibrosus  12 .  
         [0021]     After the insertion of the needle  16 , the suture retriever  18  is advanced into the annulus  12  (block  56 ), guided by the retriever guide  36  of the needle handle  14 . During this step, the surgeon holds the first  40  and second  42  ends of the suture  38  taut to maintain the capturable segment  44  in a well-defined position relative to the needle  16  and handle  14 . The retriever  18  and guide  36  are tightly toleranced such that the distal end  46  of the suture retriever  18  is reliably brought to the capturable segment  44 . A hook  48  at the distal end  46  of the retriever  18  captures the capturable segment  44  (block  58 ).  
         [0022]     To aid in this capture process, in some embodiments, the retriever  18  and guide  36  include corresponding structures to stop the motion of the retriever in the distal direction once the distal end  46  of the retriever reaches the capturable segment  44 . Also in some embodiments, the retriever  18  and guide  36  include corresponding structures to restrict the rotational orientation of the retriever relative to the needle handle  14  and helical suturing needle  16 .  
         [0023]     In another embodiment of the present invention, illustrated in  FIG. 7 , a suture retriever  18 ′ has double opposing hooks  74  for capturing the suture at its distal end  46 ′. In this version, the retriever  18 ′ is advanced so that the suture  38  fully enters the slot  72 . The surgeon then rotates the retriever  18 ′ about 90 degrees and withdraws it. The hooks  74  ensure that the suture  38  remains captured during the withdrawal.  
         [0024]     Following capture of the suture  38 , the surgeon releases the first end  40  of the suture while maintaining a grip on the second end  42 . Then he or she withdraws the retriever  18 , which pulls the first end  40  of the suture  38  out of the annulus fibrosus  12  along the interior of the helical pathway defined by the suturing needle  16  (block  60 ). The surgeon then grips the first end  40 , releases the second end  42 , and retracts the helical suturing needle  16  in a reverse screwing motion, leaving suture  38  along its path (block  62 ).  
         [0025]     With the helical needle  16  completely removed from the annulus fibrosus  12 , the suture  38  remaining in the needle is freed by further withdrawal of the needle, or alternately the suture is simply cut between the needle and the annulus. The surgeon starts tying the suture  38  with an overhand knot, carefully applies tension to draw the tear of the annulus  12  together, completes the knot as per standard surgical technique, and cuts off the excess suture (block  64 ).  
         [0026]     While the preceding method describes repair of a tear in an annulus fibrosus oriented in a predominantly radial direction, the present invention may also be used to repair tears with other orientations, such as parallel to the outer surface of an annulus. Furthermore, the present invention may be usefully employed in other anatomies as well.  
         [0027]     The present invention leaves only suture as the final implanted material. Suture is equally distributed over the entire depth of the tear, and acts to close the tear from all directions. The present invention offers improved resistance to recurrence of herniation over prior suturing methods.  
         [0028]     In other embodiments of the present invention, the above described procedure is performed more than once on the same tissue, with different helical suture needles  16 , and hence, different paths for the sutures  38 , potentially resulting in more secure fixation. For example, two sutures  38  may be concentrically placed with two diameters  24  of needles  16 . Alternately, two sutures  38  may be placed with two needles  16  of identical dimensions  22 ,  24 ,  26  but having differing right- and left-handed helical shapes. In these embodiments, associated sets of sutures  38  and tools  14 ,  18  may be given corresponding visual appearances (e.g., colors) to assist surgeons with identification.  
         [0029]     In yet other embodiments of the present invention, the suture material includes a bioactive material. The bioactive material may be used to deliver a drug therapy. It may include antibiotic and/or antiviral medications. It may include drugs that promote regenerative growth of the tissues of the annulus fibrosus or other tissues. It may include cultured cells to enhance the healing process.  
         [0030]     Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the disclosure, together with all equivalents thereof.