Abstract:
An inserter for implanting a spinal implant such as an intervertebral spacer into a spinal disc space is disclosed. The inserter comprises a jaw assembly connected to a shaft assembly that is connected to a handle assembly. The shaft assembly includes an angled portion in which the distal end of the instrument is displaced from the proximal end of the instrument affording the clinician a more unobstructed view of the operative site. The user operates the handle assembly at the proximal end to open and close the jaw assembly to thereby connect to and release from the intervertebral spacer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 60/934,104 entitled “Inserter for intervertebral spacer” filed on Jun. 11, 2007 which is incorporated herein by reference in its entirety. This application also claims priority to and is a continuation-in-part of U.S. patent application Ser. No. 12/156,857 entitled “Inserter for a spinal implant” filed on Jun. 4, 2008 which claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 60/933,538 filed on Jun. 7, 2007, all of which are hereby incorporated by reference in their entireties. 
     
    
     FIELD 
       [0002]    The present invention generally relates to medical devices, and in particular, the present invention relates to a surgical instrument for introducing spinal implants such as an intervertebral spacer into a disc space between adjacent vertebral bodies. 
       BACKGROUND 
       [0003]    Deterioration or dislocation of a spinal disc located between two adjacent vertebral bodies often results in the two adjacent vertebral bodies coming closer together. The reduced disc space height typically results in instability of the spine, decreased mobility and pain and discomfort for the patient. A common treatment is to surgically restore the proper disc space height to thereby alleviate the neurologic impact of the collapsed disc space. Typically, most surgical corrections of a disc space include at least a partial discectomy which is followed by restoration of normal disc space height and, in some instances, fusion of the adjacent vertebral bodies. Restoration of normal disc space height generally involves the implantation of a spacer and fusion typically involves inclusion of bone graft or bone graft substitute material into the intervertebral disc space to create bony fusion. Fusion rods may also be employed. Some implants further provide artificial dynamics to the spine. Such techniques for achieving interbody fusion or for providing artificial disc functions are well-known in the art. 
         [0004]    One problem, among others, with inserting an implant, for example, is associated with patient anatomy. Inserting and positioning the implant in the space between adjacent vertebrae can be difficult or time consuming if the bony portions are spaced too close together, or if the adjacent tissue, nerves or vasculature impedes access to or placement of the implant in the space between the bony portions. Furthermore, maintenance of distraction of the space during insertion of the implant requires additional instruments in the operative space which can make the procedure more invasive and impede access and visibility during implant insertion and thereby make the procedure more difficult. 
         [0005]    Another difficulty of implant insertion is related to the point of access to the damaged disc space which may be accomplished from several approaches to the spine with each approach having different associated difficulties. One approach is to gain access to the anterior portion of the spine through a patient&#39;s abdomen. For an anterior approach, extensive vessel retraction is often required and many vertebral levels are not readily accessible from this approach. Another approach is a posterior approach. This approach typically requires that both sides of the disc space on either side of the spinal cord be surgically exposed, which may require a substantial incision or multiple access locations, as well as extensive retraction of the spinal cord. Yet another approach is a postero-lateral approach to the disc space. The posterior-lateral approach is employed in a posterior lumbar interbody fusion (PLIF) or transforaminal lumber interbody fusion (TLIF) procedure which may be performed as an open technique which requires making a larger incision along the middle of the back. Through this incision, the surgeon then cuts away, or retracts, spinal muscles and tissue to access the vertebrae and disc space. The TLIF procedure may also be performed as a minimally invasive or as an extreme lateral interbody fusion (XLIF) procedure that involves a retroperitoneal transpoas approach to the lumbar spine as an alternative to “open” fusion surgery. In the minimally invasive procedure, the surgeon employs much smaller incisions, avoids disrupting major muscles and tissues in the back and reduces the amount of muscle and tissue that is cut or retracted. As a result, blood loss is dramatically reduced and these minimally invasive benefits also lead to shorter hospital stays and quicker patient recovery times. The aforementioned and various other difficulties associated with the point of access to the damaged disc space and the need to navigate an implant insertion instrument through the point of access further place demands on insertion instrument design. Therefore, there remains a need for improved insertion instruments, implants and techniques for use in any one or more types of approaches to the disc space that facilitate and provide for effective insertion while saving time, minimizing the degree of invasiveness for the patient and complementing surgeon skill demands. 
       SUMMARY 
       [0006]    According to one aspect of the invention, an inserter for implanting a spinal implant is disclosed. The instrument includes a shaft assembly connected to a jaw assembly at one end and to a handle assembly at the other end. The shaft assembly has an angled portion and includes an inner shaft and an outer shaft. The handle assembly is connected to the shaft assembly such that the handle assembly is operable to open and close the jaw assembly to thereby connect to and release the spinal implant. 
         [0007]    According to another aspect of the invention, an inserter for a spinal implant is provided. The instrument includes a jaw assembly, a shaft assembly and a handle assembly. The shaft assembly is connected to the jaw assembly. The shaft assembly includes an inner shaft and a distal shaft. The inner shaft has a distal end configured to engage the jaw assembly. The inner shaft is located in the outer shaft such that the inner shaft is movable with respect to the outer shaft. The distal end of the outer shaft is connected to the jaw assembly such that the jaw assembly is movable with respect to the outer shaft. The handle assembly is connected to the shaft assembly. The handle assembly includes a first portion connected to the second portion such that the second portion is movable with respect to the first portion. The first portion is connected to the proximal end of the outer shaft and the second portion is connected to the proximal end of the inner shaft. The inner shaft is operable via the second portion to open and close the jaw assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0008]    The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. 
           [0009]    On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. 
           [0010]      FIG. 1   a  illustrates a top view of an inserter according to the present invention. 
           [0011]      FIG. 1   b  illustrates a cross-sectional view of the inserter of  FIG. 1  according to the present invention. 
           [0012]      FIG. 2   a  illustrates a perspective view of a jaw piece of a jaw assembly of an inserter according to the present invention. 
           [0013]      FIG. 2   b  illustrates a top cross-sectional view of the jaw piece of  FIG. 2   a  of an inserter according to the present invention. 
           [0014]      FIG. 3   a  illustrates a perspective view of an outer shaft of a shaft assembly of an inserter according to the present invention. 
           [0015]      FIG. 3   b  illustrates a top view of the outer shaft of  FIG. 3   a  according to the present invention. 
           [0016]      FIG. 3   c  illustrates a side view of the outer shaft of  FIG. 3   a  according to the present invention. 
           [0017]      FIG. 4  illustrates a top view of an inner shaft of a shaft assembly of an inserter according to the present invention. 
           [0018]      FIG. 5  illustrates a cross-sectional view of a handle of a handle assembly of an inserter according to the present invention. 
           [0019]      FIG. 6  illustrates a cross-sectional view of a knob of a handle assembly according to the present invention. 
           [0020]      FIG. 7   a  illustrates a top and cross-sectional view of a spacer in juxtaposition with an inserter according to the present invention. 
           [0021]      FIG. 7   b  illustrates a top cross-sectional view of a spacer connected to an inserter according to the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0022]    Before the subject devices, systems and methods are described, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. 
         [0023]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. 
         [0024]    It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a spinal segment” may include a plurality of such spinal segments and reference to “the screw” includes reference to one or more screws and equivalents thereof known to those skilled in the art, and so forth. 
         [0025]    All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed. 
         [0026]    The present invention is described in the accompanying figures and text as understood by a person having ordinary skill in the field of spinal implants and related instrumentation. 
         [0027]    Referring now to  FIGS. 1   a  and  1   b , there are shown top and cross-sectional views, respectively, of an inserter  10  for inserting an intervertebral spacer into a disc space between two adjacent vertebral bodies. The inserter  10  includes a jaw assembly  12 , a shaft assembly  14  and a handle assembly  16 . The shaft assembly  14  is connected to the jaw assembly  12  and the handle assembly  16 . Turning now to  FIGS. 2   a  and  2   b , there are shown perspective and cross-sectional views, respectively, of the jaw assembly  12  according to the present invention. The jaw assembly  12  includes a two jaw pieces  18  (one jaw piece is shown in  FIGS. 2   a  and  2   b ), and two fasteners  20  (shown in  FIG. 1   b ). Each jaw piece  18  includes a jaw pin receiving portion  22 , a bore  24  for receiving a fastener  20  and spacer engaging features  26 . The spacer engaging features  26  are extending features configured to engage the interbody spacer (not shown). In one variation, the features  26  are projections configured to be inserted into complementary shaped apertures in the interbody spacer. The jaw pin receiving portion  22  includes a first receiving portion  28  and a scalloped portion  30 . 
         [0028]    Referring back to  FIG. 1   b , the shaft assembly  14  includes an outer shaft  32  and an inner shaft  34 . The inner shaft  34  is disposed inside the outer shaft  32 . The outer shaft  32  will now be discussed in reference to  FIGS. 3   a ,  3   b  and  3   c.    
         [0029]    Turning now to  FIGS. 3   a ,  3   b  and  3   c , there are shown perspective, top and side views, respectively, of the outer shaft  32  according to the present invention. The outer shaft  32  includes a distal end  36  and a proximal end  38 . The outer shaft  32  is configured as a tube having a central bore  40  opening at and extending between the distal and proximal ends  36 ,  38 . In one variation, the outer shaft  32  includes an angled portion  42  imparting the outer shaft  32  with a curve, bend or bayonet-like appearance. The bayonet shape permits the working distal end  36  to be displaced from the proximal handling end  38 . The displacement of the working distal end  36  from the proximal handling end  38  by a distance eases installation of the implant and helps keep the working distal end  36  substantially unobstructed by the instrument&#39;s proximal end when viewed from the proximal end  38  along the longitudinal axis of the distal end  36 . In another variation, the outer shaft  32  is not angled and is a substantially straight tube. In one variation, the outer shaft  32  includes an open portion  44  that opens to and extends from the proximal end  38  towards the distal end  36 . The open portion  44  comprises a section of the outer shaft  32  in which the at least a portion of the wall is removed. 
         [0030]    Still referencing  FIGS. 3   a ,  3   b  and  3   c , the distal end  36  of the outer shaft  32  includes a jaw assembly receiving portion  46  configured to receive and connect to the jaw assembly  12 . The jaw assembly receiving portion  46  includes a slot  48  and two substantially flattened portions  50  in substantial parallel orientation with respect to one another. Each flattened portion  50  includes two aligned bores  52  for receiving fasteners  20 . 
         [0031]    Turning now to  FIG. 4 , there is shown an inner shaft  34  according to the present invention. The inner shaft  34  includes a distal end  54  and a proximal end  56 . 
         [0032]    The inner shaft  34  is configured to be substantially cylindrical in shape. In one variation, the inner shaft  34  includes an angled portion  58  imparting the inner shaft  34  with a curve, bend or bayonet-like appearance. The angled portion  58  of the inner shaft  34  is configured to conform to the shape of an angled outer shaft  32  such that the angled inner shaft  34  fits inside an angled outer shaft  32 . In another variation, the inner shaft  34  is not angled and is substantially straight and configured to fit within an outer shaft  32  that is also substantially straight. The inner shaft  34  includes a pin  60  at the distal end  54  configured to engage the jaw assembly  12  and to be received in the pin receiving portions  22  of each jaw piece  18 . The pin  60  has a bulbous head or spherically-shaped head connected to a neck portion as shown in  FIG. 4 . Other suitable and functional shapes for the pin  60  are within the scope of the present invention and include any polyhedron or partial polyhedron, cube or partial cube, sphere or partial sphere, cylinder or partial cylinder, a prism or partial prism, cylinder or partial cylinder, and any shape with an angled surface or any shape having a surface angled with respect to the inner shaft. The proximal end  56  of the inner shaft  34  includes a threaded portion  62  configured for threaded engagement with the handle assembly  16 . The shaft assembly  14  is assembled by inserted the inner shaft  34  into the outer shaft  32 . 
         [0033]    Turning briefly back to  FIG. 1   b , the handle assembly  16  includes a handle  64  and a knob  66 . The handle  64  will now be discussed in reference to  FIG. 5 . 
         [0034]    Referring now to  FIG. 5 , there is shown a cross-sectional view of the handle  64  of the handle assembly  16 . The handle  64  includes a proximal end  68  and a distal end  70 . The handle  64  has an outer gripping surface and is substantially cylindrical in shape. The handle  64  includes a shaft assembly receiving portion  74  at the distal end  70  configured to connect with at least a portion of the shaft assembly  14 . The handle also includes a knob receiving portion  76  at the proximal end  68  configured to connect to the knob  66 . In one variation, the shaft assembly receiving portion  74  and the knob receiving portion  76  form a central bore  72  of varied diameter opening to and extending between the proximal and distal ends  68 ,  70  as shown in  FIG. 5 . The handle  64  also includes at least one pin slot  77  for the insertion of pins (not shown) to securely connect the handle  64  to the outer shaft  32 . 
         [0035]    Referring now to  FIG. 6 , there is shown a cross-sectional view of the knob  66  of the handle assembly  16 . The knob  66  has a distal end  78  and a proximal end  80 . 
         [0036]    The distal end  78  includes an engaging portion  82  configured to connect with the handle  64  and with the inner shaft  34 . The engaging portion  82  includes a male member having an interior threaded bore  84  for connecting with the threaded portion  62  of the inner shaft  34 . The interior threaded bore  84  opens at the distal end  84  and extends inwardly towards the proximal end  80 . The outer surface of the male member engaging portion  82  is sized to be received in the knob receiving portion  76  of the handle  64  and includes recesses  88  for receiving locking pins for connecting the knob  66  to the handle  64 . The proximal end  80  of the knob  66  has a larger cross-section and includes an interior threaded bore  86  opening at the proximal end  80  and extending inwardly towards the distal end  78 . The threaded bore  86  serves as a connection point for a slap hammer attachment (not shown) permitting use of a slap hammer to aid in removing the inserter  10  from tight intervertebral spaces. 
         [0037]    The assembly of the inserter  10  will now be discussed. The inner shaft  34  is inserted into the outer shaft  32 . Pins  60  of the inner shaft  34  are located in the pin receiving portions  22  of each jaw piece  18 . Fasteners  20  are inserted into the aligned bores  52  of the outer shaft and bores  24  of the jaw pieces  18  and swaged thereto to secure the jaw pieces  18  to the outer shaft  32  capturing the pin  60  of the inner shaft  34  in between the jaw pieces  18  such that the jaw pieces  18  are capable of movement with respect to the outer shaft  32  and about fasteners  20 . At the proximal end, the threaded portion  62  of the inner shaft  34  is threadingly engaged inside bore  84 . The outer and inner shafts  32 ,  34  are passed into the central bore  72  of the handle  64 . Pins are passed into apertures  77  of the handle  64  to secure the handle  64  and outer shaft  32  together such that the inner shaft  34  is permitted to move with respect to the outer shaft  32 . Other pins are passed into apertures  77  to engage recesses  88  to prevent the knob  66  from falling out yet permitting it to rotate with respect to the handle  64 . 
         [0038]    Operation of the inserter instrument  10  will now be discussed with initial reference to  FIGS. 7   a  and  7   b . Referring firstly to  FIG. 7   a , an interbody spacer  90  having engaging apertures  92  is shown in juxtaposition with the inserter  10  with the jaw assembly  12  in an open position in which the jaw pieces  18  are spread apart, pivoted about their respective connecting fasteners  20 . The typical spacer  90  includes a body formed by a wall extending about a central cavity. The cavity extends between and opens at an upper bearing surface and a lower bearing surface. The upper and lower bearing surfaces contact the adjacent vertebral endplates to support the adjacent vertebrae when the spacer is implanted into the spinal disc space. The bearing surfaces include grooves formed to facilitate engagement with the vertebral endplates and resist the spacer from migrating within the disc space. The spacer includes a convexly curved anterior wall and an opposite concavely curved posterior wall. These wall portions are connected by a convexly curved leading end wall and a convexly curved trailing end. The overall shape provides a banana or kidney type shape for the spacer. 
         [0039]    The spacer  90  includes spacer engaging apertures  92  that are shown in  FIG. 7   a  to be aligned with the spacer engaging features  26  of the jaw assembly  12 . The handle knob  66  is rotated such that the threaded engagement with the inner shaft  34  draws the inner shaft  34  proximally with respect to the handle  64  and outer shaft  32  moving the integral jaw pin  60  along with it, thereby angulating the jaws  18  about fasteners  20  into a closed position as shown in  FIG. 7   b . In the closed position, the spacer engaging features  26  are clamped to the spacer  90  as shown in  FIG. 7   b . Turning the knob  66  in reverse releases the spacer  90 . Hence, the spacer  90  is released and recaptured as desired. The open portion  44  of the outer shaft  32  allows the inner shaft  34  to pass therethrough as it moves proximally and distally with respect to the outer shaft  32  as the knob  66  is turned. 
         [0040]    The preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims.