Abstract:
Spinal fusion appliances, delivery devices and methods of using the same are provided. In various embodiments, the appliances include a housing and a flexible tape with opposite ends that are optionally adjustable using an actuator within the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/618,234, filed Mar. 30, 2012 by Geisert entitled “ALIF Spinal Implant.” The entire disclosure of this application is hereby incorporated by reference for all purposes. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The technology disclosed herein relates, in general, to medical implants and, more specifically, to methods and devices for intervertebral fixation. 
       BACKGROUND 
       [0003]    Back pain, particularly lower back pain, is the fifth most common reason for all physician visits in the United States. (See Roger Chou et al.  Diagnosis and Treatment of Low Back Pain: A Joint Clinical Practice Guideline from the American College of Physicians and the American Pain Society.  147 Annals of Internal Medicine pp. 478-491 (Oct. 2, 2007)) While back pain may be managed in some patients with conservative treatments such as exercise, acupuncture, massage or steroid injection, other patients&#39; pain may be caused by disk conditions such as disk herniation or degeneration, or vertebral conditions such as fracture and spondylolisthesis, which require more invasive treatments such as spinal fusion and fixation. 
         [0004]    Spinal fusion is a surgical procedure in which two or more vertebrae are fused to prevent or decrease movement at or around a site of back pain. The fusion of vertebrae is augmented by the use of rigid implantable fixation devices such as bone screws or plates, which limit the movement of vertebrae relative to one another. These devices may be implanted between individual vertebrae in the space usually occupied by the spinal disk, in what is termed “interbody fixation.” Many interbody fixation devices, such as screws and plates, are fully rigid, and prevent movement between fused vertebrae, which may result in decreased patient mobility after the procedure. Other interbody fixation devices incorporate a hinge or a surface that permits limited movement of fused vertebrae relative to one another, but these devices generally apply outward pressure on the fused vertebrae, which may propagate through the spine. 
         [0005]    Interbody fixation implants are typically implanted using anterior or posterior approaches. In a posterior approach (a “posterior lumbar interbody fixation” or “PLIF”) the spine is accessed via a posterior incision which is relatively straightforward for the surgeon, but which may result in pain for the patient. In an anterior approach (“ALIF”), the approach is through an abdominal incision, which is more complicated for the surgeon but which may be less painful. Other approaches, such as transforaminal (TLIF) and “extreme lateral” (XLIF) utilize a lateral or posterolateral access. 
         [0006]    Interbody fixation implants typically include screws or other means by which they are secured to vertebrae. These means may be angled relative to the central axis of the implant, necessitating the use of a wider surgical access and potentially resulting in increased pain and recovery time for patients. Given the fact that the average cost of operating room time in the US is $15-$25 per minute, there is a constant need in the art to minimize the complexity, and therefore the time required, to perform a surgical interbody fixation procedure. (Stahl, J et al, Reorganizing patient care and workflow in the operating room: a cost-effectiveness study, Surgery, 139:717-728, 2006.) 
       SUMMARY OF THE INVENTION 
       [0007]    The current invention, in its various embodiments, addresses needs in the art by providing systems and methods for simplified vertebral fixation employing ALIF, PLIF, TLIF and/or XLIF approaches utilizing a narrow surgical access. In one aspect, the invention relates to a medical device that includes a housing, a flexible tape with first and second ends passing through the housing, and an actuator that contacts the flexible tape and adjusts tension on the flexible tape to urge the first and second ends toward one another. The actuator may be a cylindrical body with an aperture through which the tape passes, and the cylindrical body may rotate within the housing, and can include a portion that can be mated with a tool so a user can rotate the actuator within the housing. The medical device can include portions that anchor the first and second ends of the tape within the bone, which portions are optionally planar and include one or more perforations, bumps, or ridges. In addition, the housing can include one or more flanged extensions that are connectable to a bone cage, and flexible tape can include a strengthening element to prevent deformation. 
         [0008]    In another aspect, the invention relates to a system for treating a patient that includes a medical device as described above, along with a delivery device that includes multiple bone chisels that define a space sized and/or shaped to fit the medical device. The space in the delivery device may separate the first and second ends by a distance sufficient to permit their being anchored in the cancellous bone of adjacent vertebrae while the housing rests between the vertebrae. 
         [0009]    In still another aspect, the invention relates to a delivery device for a spinal fusion appliance that includes multiple bone chisels that, together, define a space sized and/or shaped to accommodate the spinal fusion appliance. The space is optionally shaped so that, when the device is used, each of the first and second ends can be anchored within the cancellous bone of a first vertebra and a second vertebra while the the housing rests between the first and second vertebra 
         [0010]    In yet another aspect, the invention relates to a method of treating a patient needing interbody fixation that includes providing a medical device that includes a housing, a flexible tape with first and second ends passing through the housing, and an actuator that contacts the flexible tape and adjusts tension on the flexible tape to urge the first and second ends toward one another, positioning the medical device in relation to two vertebrae so that the first and second ends of the tape are positioned in the cancellous bone of one vertebra or the other while the housing is positioned between the vertebrae, and moving the actuator to urge the first and second ends of the tape toward one another, thereby urging the two vertebrae toward the housing. 
     
    
     
       DRAWINGS 
         [0011]    In the drawings, like reference characters refer to like features throughout the different views. The drawings are not necessarily to scale, with emphasis being placed on illustration of the principles of the invention 
           [0012]      FIG. 1  shows multiple schematic perspective and exploded views of an exemplary interbody fixation appliance according to the invention. 
           [0013]      FIG. 2  shows a schematic side view of a portion of an exemplary interbody fixation appliance including a view of the rotating coupling including the central rotating members, the flexible tape, and the vertebral securement features. 
           [0014]      FIG. 3  shows multiple schematic perspective views of an exemplary interbody fixation appliance including x-ray views showing the rotating coupling. 
           [0015]      FIG. 4  shows a schematic ventral x-ray view of an exemplary interbody fixation appliance deployed between vertebrae, including the positioning of the vertebral securement features and the flexible tape within the vertebrae. 
           [0016]      FIG. 5  shows a schematic ventral view as in  FIG. 4 . 
           [0017]      FIG. 6  shows schematic ventral and lateral X-ray views of a spinal column, the lateral view including an exemplary interbody fixation appliance. 
           [0018]      FIG. 7  shows a schematic X-ray view of a spinal column. 
           [0019]      FIG. 8  shows a schematic lateral X-ray view of adjacent vertebrae with an exemplary interbody fixation appliance disposed therebetween. 
           [0020]      FIG. 9  shows a schematic oblique view of an exemplary interbody fixation appliance. 
           [0021]      FIG. 10  includes schematic lateral and oblique views of an exemplary interbody fixation appliance including a vertebra into which a vertebral securement feature and a portion of a flexible tape are positioned. 
           [0022]      FIG. 11  shows a schematic oblique view of an interbody fixation appliance disposed within two adjacent vertebrae. 
           [0023]      FIG. 12  shows multiple views of a delivery device for an interbody fixation appliance, including a close-up view of a head of the delivery device containing an interbody fixation appliance, and a driver for rotating the rotating member, thereby retracting and/or tensioning the flexible member. 
           [0024]      FIG. 13  shows schematic views of the positioning of an interbody fixation appliance in TLIF and XLIF procedures. 
           [0025]      FIG. 14  shows schematic x-ray oblique views of an interbody fixation appliance in use, illustrating the shortening of portion of the flexible tape extending from either side of the appliance to urge the vertebrae to be fused toward one another. 
           [0026]      FIG. 15  shows schematic cutaway views of an exemplary interbody fixation appliance at various stages of retraction of the flexible tape. 
           [0027]      FIG. 16  shows a schematic exploded view of an interbody fixation appliance including multiple bone cage portions that can be attached to the main housing. 
           [0028]      FIG. 17  shows schematic views of exemplary interbody fixation appliances having curved edges, tapes, and surfaces to better fit in spaces between vertebrae while minimizing trauma. 
           [0029]      FIG. 18  shows schematic views of another exemplary interbody fixation appliance for lateral interbody fusion procedures including bone cage portions having curved surfaces. 
           [0030]      FIG. 19  shows a schematic x-ray view of a laterial interbody fixation appliance according to  FIG. 18  when deployed. It will be appreciated that the drive portion of the central rotating member faces laterally, rather than anteriorly or posteriorly. 
           [0031]      FIG. 20  shows multiple schematic views of a locking plate for locking the central rotating member, and the flexible tape, in position. 
           [0032]      FIG. 21  shows multiple schematic views of belt fixing systems utilizing ratchet and pawl mechanisms. 
           [0033]      FIG. 22  shows an exemplary interbody fusion appliance for use in ALIF procedures, which includes a cam-lobe tensioning system and which utilizes rigid arms rather than a flexible tape. 
           [0034]      FIG. 23  shows the multiple schematic views of an interbody fusion appliance as in  FIG. 22  as the rigid arms are retracted. 
           [0035]      FIG. 24  shows an exemplary interbody fusion appliance that includes a flexible tape comprising a woven textile belt. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    With reference to  FIGS. 1-3 , an exemplary Interbody fixation appliance according to the invention includes, in some embodiments, an interbody fixation appliance  100  having a central rotating member  105  with a slit  107  therethrough and a flexible tape  110  extending through the slit. The central rotating member  105  is rotatably disposed within a housing  115  that is sized to fit within a space between vertebrae. The housing  115  may include one or more ratcheting features to facilitate the incremental rotation of the rotating member in one or more directions. The housing may also include tabbed projections  116  permitting the permanent or reversible attachment of one or more cages  120 , which cages may also be sized to fit within a space between vertebrae and which may include features that promote bone ingrowth such as cavities, pores, holes, and bioactive materials disposed within or coating the cages. The tape  110  has two termini, and vertebral securement features  125  are disposed at the termini. The vertebral securement features  125 , in various embodiments, extend away from the tape at an angle, to apply pressure over an area of the vertebrae when tension is applied to the tape and to prevent slippage of the tape. While the figures depict the vertebral securement features  125  extending substantially perpendicularly from the tape, the members may extend away at any suitable angle, including, without limitation, 15°, 30°, 45°, 60°, etc. The vertebral securement features  125  may also include features to promote bone ingrowth such as those listed above.  FIG. 17-20  show a vertebral securement feature  125  that includes irregular cut-out portions. Not wishing to be bound to any particular theory, it is believed that by providing voids or other features into which cells can migrate, tissue ingrowth into the vertebral securement features is improved, which in turn improves the quality of fusion achieved by the Interbody fixation appliance. 
         [0037]    The central rotating element  105 , in some embodiments, includes a drive  106  sized to accommodate the tip  305  of a driver  300 . The drive may have any suitable shape, including a slot, Philips head, square, hexagonal, octagonal, star, etc. to engage the driver  300 . The driver  300 , in turn, includes a tip  305  having a shape complementary to the drive  106 , so that the driver  300  can be coupled to the drive  106  and used to rotate the central rotating element  105 . An exemplary driver is shown in  FIG. 12   
         [0038]    The tape  110  may be made of any suitable material, including metal, plastic, polymer, textile, mesh, etc., and may include features to promote bone ingrowth such as those listed above. A depiction of an exemplary Interbody fixation appliance  100  that includes a textile tape  110  is shown in  FIG. 24 . The textile tape includes multiple woven fibers, which define surfaces and voids that promote tissue ingrowth, thereby improving the quality of fusion achieved by the Interbody fixation appliance. 
         [0039]    In use, the housing  115  and one or more cages  120  attached thereto are positioned between adjacent vertebrae, as shown in  FIGS. 4-8 . The tape  110  is fully extended, and the vertebral securement features are disposed on or in the vertebrae. The central rotating member  105  is rotated, applying tension to the tape and urging its termini and the vertebral securement features  125  together. 
         [0040]    As shown in  FIG. 9 , the interbody fixation appliance  100  may have any suitable shape, and may incorporate curved features such as housing  115 , vertebral securement features  125 , and tape  110 . 
         [0041]      FIG. 11  shows an interbody fixation appliance  100  according to an embodiment of the invention which is adapted for use in ALIF procedures. In an ALIF procedure, the housing  115  and the cage(s)  120  are shaped to be inserted between vertebrae such that the drive  106  of the central rotating member  105  faces the abdomen. In other embodiments, the appliance  100  can be sized for use in PLIF, TLIF or XLIF procedures, as shown in  FIGS. 17-19 . 
         [0042]      FIG. 12  shows a delivery device (top and inset, left) that may be used to position the interbody fixation appliance  100 . The delivery device  200  includes a shaft  205  and an appliance engagement portion  210  sized to engage the interbody fixation appliance  100  with the tape  110  at least partially extended and the vertebral securement features  125  disposed at a distance from the housing  115 . The appliance engagement portion  210  includes two chisel portions  215 , which include a central recess sized to accommodate an end of the tape  110  and the vertebral securement feature  125 . Prior to use, the appliance engagement portion  210  of the delivery device  200  is optionally loaded with an interbody fixation appliance  100 ; alternatively, the appliance engagement portion  210  is left empty, so that it can create a space or void for subsequent insertion of an appliance  100 . In use, the engagement portion  210  is inserted through a surgical access and placed in contact with the anterior surfaces of the vertebrae adjacent to the site at which the appliance  100  will be implanted (in an ALIF procedure). A user applies force along the shaft  205 , urging the engagement portion toward the vertebrae of the patient, so that the chisel portions  215  penetrate the vertebrae, positioning appliance  100  such that the housing  115  rests between the vertebrae and the vertebral securement features  125  and tape  110  lie within the vertebrae; alternatively, if the delivery device  200  is not pre-loaded with an appliance  100 , use of the delivery device  200  creates a space into which the appliance  100  can be inserted, as above. After the appliance  100  is positioned, the delivery device  200  is removed, and the central rotating member  105  is rotated using a driver  300  having a tip complementary to the drive  106  of the central rotating member  105 , thereby spooling the tape  110  about the central rotating member  105  and, consequently, urging the vertebral securement features  125  toward one another, as illustrated in  FIG. 14 . Spooling of the tape  110  about the central rotating member  105  is further illustrated in the cutaway views of  FIG. 15 . Those skilled in the art will appreciate that the delivery device  200  and the procedure described above can be adapted for TLIF, XLIF and PLIF procedures, and that the appliance  100  is capable of functioning in different orientations, as shown in  FIGS. 13   a - b.    
         [0043]      FIG. 16  depicts an appliance  100  having an extended tape  110  in relation to a pair of cages  120  that are attachable to the housing  115  by means of complementary tabbed projections  116  on the housing  115  and holes  121  sized to fit the tabbed projections, thereby achieving a mechanical fit. Appliances according to  FIG. 16  which include simple mechanical means for attaching a cage  120  to the housing advantageously permit the cages  120  to be attached to the housing  115  by untrained users without the need for specialized tools or adhesive means, permitting the cages to be attached, for example, en suite immediately prior to implantation of the appliance  100  within a spine or even after the appliance  100  has been implanted. In other embodiments, cages  120  are secured to the housing  115  using means generally known in the art, including adhesive means, heat welding, sonic welding, friction fit, etc. 
         [0044]    Voids within the cages  120  provide spaces into which fillers such as bone putty, bone paste, bone cement, grafted bone, mesenchymal stem cells, osteoblasts, depot-release drug or biopharmaceutical formulations (including, without limitation, bone morphogenic protein  2 ), can be placed. Alternatively, the voids which can remain open to permit tissue ingrowth. Other portions of the apparatus  100 , particularly the vertebral securement features  125  as shown in  FIGS. 17-18 , can include voids either for the addition of materials such as those set forth above, or to permit tissue ingrowth. 
         [0045]    The housing  115  optionally includes a feature to lock the central rotating member  105  in position, such as a locking plate as shown in  FIG. 20 . Alternatively, the drive  106  can include a multi-toothed ring and one or more pawls  117 , as shown in  FIG. 21 . While embodiments of the invention have been described with an emphasis on a single central rotating member  105  and a tape  110 , other suitable arrangements will occur to those skilled in the art, such as the cam-lobe arrangement shown in  FIGS. 22-23 , as well as arrangements utilizing multiple rotating members, which may optionally be coupled to one another, etc. 
         [0046]    Bioactive materials, including without limitation Bone Morphogenetic proteins such as BMP7, may be incorporated within or applied to surfaces of the appliance  100 , for example to promote bone growth. 
         [0047]    The termini of the tape  110  may be either flexible or rigid, and may incorporate strengthening elements that prevent deformation of the termini of the tape  110  and the vertebral securement features  125 . 
         [0048]    As used in this specification, the term “substantially” or “approximately” means plus or minus 10% (e.g., by weight or by volume), and in some embodiments, plus or minus 5%. Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology. 
         [0049]    The phrase “and/or,” as used herein should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
         [0050]    The term “bioactive material” as used herein should be understood to mean any substance that has a biological effect, including without limitation proteins and peptides, nucleic acids, lipids, carbohydrates, drugs, etc. 
         [0051]    The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive.