Abstract:
An articulated delivery instrument for the proper positioning and placements of inserts, for example, an insert such as a lumbar interbody fusion device (“LIF”). The instrument may comprise a body and a first member slidingly coupled to the body. A rotating member for releasably retaining an insert may be pivotally coupled to a distal end of the body and the first member. A first actuator may function to translate the first member relative to the body. Translation of the first member relative to the body may rotate the rotating member relative to the instrument. A second actuator may function to transition the rotating member between release and retention of the insert.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application relates to, and claims the benefit of the filing date of, U.S. provisional patent application Ser. No. 60/752,544 entitled “RETICULATED DELIVERY INSTRUMENT” filed Dec. 21, 2005, the entire contents of which are incorporated herein by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This disclosure relates to systems and methods for stabilization of human spines, and, more particularly, to instruments for inserting spinal implants for lumbar interbody fusion devices. 
     2. Description of the Related Art 
     The human spine is a complex structure designed to achieve a myriad of tasks, many of them of a complex kinematic nature. The spinal vertebrae allow the spine to flex in three axes of movement relative to the portion of the spine in motion. These axes include the horizontal (bending either forward/anterior or aft/posterior), roll (lateral bending to either left or right side) and rotation (twisting of the shoulders relative to the pelvis). 
     The intervertebral spacing (between neighboring vertebrae) in a healthy spine is maintained by a compressible and somewhat elastic disc. The disc serves to allow the spine to move about the various axes of rotation and through the various arcs and movements required for normal mobility. The elasticity of the disc maintains spacing between the vertebrae, allowing room or clearance for compression of neighboring vertebrae, during flexion and lateral bending of the spine. In addition, the disc allows relative rotation about the vertical axis of neighboring vertebrae, allowing the twisting of the shoulders relative to the hips and pelvis. Clearance between neighboring vertebrae maintained by a healthy disc is also important to allow nerves from the spinal chord to extend out of the spine, between neighboring vertebrae, without being squeezed or impinged by the vertebrae. 
     In situations (based upon injury or otherwise) where a disc is not functioning properly, the inter-vertebral disc tends to compress, and in doing so pressure is exerted on nerves extending from the spinal cord by this reduced inter-vertebral spacing. Various other types of nerve problems may be experienced in the spine, such as exiting nerve root compression in neural foramen, passing nerve root compression, and enervated annulus (where nerves grow into a cracked/compromised annulus, causing pain every time the disc/annulus is compressed), as examples. Many medical procedures have been devised to alleviate such nerve compression and the pain that results from nerve pressure. Many of these procedures revolve around attempts to prevent the vertebrae from moving too close to each other by surgically removing an improperly functioning disc and replacing it with a lumbar interbody fusion device (“LIF”). Although prior interbody devices, including LIF cage devices, can be effective at improving patient condition, the vertebrae of the spine, body organs, the spinal cord, other nerves, and other adjacent bodily structures make it difficult to obtain surgical access to the location between the vertebrae where the LIF cage is to be installed. 
     Generally speaking, using a less invasive surgical technique for a spinal surgical procedure will minimize trauma to the surrounding bone, tissues and muscle and improve patient condition after the surgery. However, the size of the LIF cage itself often dictates a relatively large size for the required surgical opening. Accordingly, it would be desirable to reduce the size of the LIF cage to minimize the size for the required surgical opening for installation of the LIF cage, while maintaining high strength, durability and reliability of the LIF cage device. Furthermore, it would also be desirable to design instruments for delivering these types of spinal implants. Instruments that can minimize trauma to the patient and can deliver these spinal implants accurately and precisely will be desirable. 
     SUMMARY OF THE INVENTION 
     An embodiment of the present invention provides an instrument for delivering an insert. The instrument may comprise a body, a first member translatingly coupled to the body, and a rotating member pivotally connected to a distal end of the body and the first member. The rotating member may be configured to releasably retain the insert. The instrument may further comprise a first actuator coupled to the body and the first member. The first actuator may be configured to translate the first member with respect to the body. Additionally, the instrument may comprise a second actuator coupled to the rotating member. The second actuator may be configured to transition the rotating member between release and retention of the insert. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Detailed Description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1A  is a sagittal view of an embodiment of a delivery instrument designed to insert a LIF cage into the intervertebral space; 
         FIG. 1B  is a bottom view of an embodiment of the delivery instrument of  FIG. 1A ; 
         FIG. 1C  is a detail view of an articulated joint of the delivery instrument shown in  FIG. 1B ; 
         FIG. 1D  is a sectional detail of the articulated joint shown in  FIG. 1C ; 
         FIGS. 2A-2B  are sectional views illustrating operation of the delivery instrument; 
         FIG. 3A-3D  are perspective views illustrating operation of the articulated joint. 
     
    
    
     DETAILED DESCRIPTION 
     The entire contents of Provisional Patent Application Ser. No. 60/752,544 entitled “RETICULATED DELIVERY INSTRUMENT” filed Dec. 21, 2005, are incorporated herein by reference for all purposes. In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without such specific details. 
       FIG. 1A  is a sagittal view of an illustrative embodiment of a delivery instrument  100  designed to insert a LIF cage into an intervertebral space.  FIG. 1B  depicts the delivery instrument  100  and illustrates another view of the articulated joint  114  and the internal actuator rod  104 .  FIG. 1C  is a detail of the articulated joint  114 .  FIG. 1A  depicts a main body portion  102 , and a sliding actuator portion or actuator portion  106  slidably coupled to the main body portion  102 . An embodiment of a first actuator or actuator mechanism, such as a threaded knob  112  rotatably mounted on a proximal end of the delivery instrument  100 , may couple the sliding actuator  106  to the main body portion  102 . A second actuator , such as a handle  108 , may be pivotally coupled to the main body portion  102  and, by way of a link member  110 , the handle  108  may be further coupled to an internal actuator rod  104 . At a distal end of the delivery instrument  100 , an articulated joint  114  of certain embodiments may comprise a pair of grasping plates, or first and second grasping or fastening members,  118 A and  118 B, rotatably mounted on a pin  124 . The distal ends of grasping plates  118  may be configured to support an intervertebral implant device, such as an LIF cage, one embodiment of which is shown here as an implant device  120 , releaseably grasped by the grasping plates  118 . 
     As shown in  FIG. 1D , each of the grasping plates  118  may be configured to have a circular portion  116 , a thumb portion  117 , and an extended finger portion  119 . Thumb portions  117  may be rotatably coupled to the proximal end of sliding actuator portion  106  by a pin  121 . Extended finger portions  119  may rigidly and removably grasp the implant device  120 . As shown in  FIG. 3D , protrusions  119 A and  119 B of the extended finger portions  119  may be securely fitted within corresponding recesses located within the implant device  120 . Therefore, when the implant device  120  is attached to an end of the delivery instrument  100 , the implant device  120  may be restrained from translating or rotating relative to the extended finger portions  119 . As shown in  FIG. 1D , some illustrative embodiments of the extended finger portions  119  may comprise a rectangularly shaped protrusion, for example, for insertion within a similarly shaped slot located in an implant device  120 . Further details of an embodiment of grasping plates  118  grasping the implant device  120  are depicted in  FIGS. 3A-3D . 
       FIGS. 2A-2B  are sectional views of an embodiment of the delivery instrument  100 , illustrating an operation of an embodiment of the articulated joint  114 . The threaded knob  112  may be rotatably mounted on a proximal end of the delivery instrument  100 , coupling the main body portion  102  to the sliding actuator portion  106 . In an illustrative embodiment of the threaded knob  112 , internal threads may be formed within the knob  112  to mate with external threads formed on a proximal end of main body portion  102 . A pin  113  disposed within the sliding actuator  106  may couple the knob  112  to the sliding actuator  106  via an internal groove located within the knob  112 . As the knob  112  is rotated, the threaded coupling advances or retracts the sliding actuator  106  via the pin  113  moving through the groove. This may cause the articulated joint  114  to rotate about an axis through a pivot pin or central pivot  124 , which axis is nominally perpendicular to a vertebral endplate. As the knob  112  is rotated in one direction, the threaded coupling between the knob  112  and the main body portion  102  may advance the sliding actuator  106  forward with respect to the main body  102 . Advancement of the sliding actuator  106  may pivot the articulated joint  114  about an attachment point  124  and arcuately move the implant device  120  through an arc “B.” 
     To release the implant device  120 , a trigger  108  in certain embodiments may be pressed against the main body portion  102 , thereby advancing an internal actuator rod  104  by way of a coupling established through link member  110 , between the trigger  108  and the actuator rod  104 . As shown in  FIGS. 3C-3D , a wedge portion  126  formed at the distal end of the actuator rod  104  is thereby forced between the inner surfaces  116 A and  116 B of each of the grasping plates  118 , forcing the grasping plates  118 A and  118 B apart. Grasping plate  118 A is separated far enough from grasping plate  118 B so that the protrusions at the ends of each finger  119  may be removed from their corresponding recesses in the implant device  120 . At this point, the implant may be released from the implant device  120 . 
     A surgeon may use the delivery instrument  100  to appropriately position and release the implant device within an intervertebral space in vivo. The surgeon may reset the instrument  100  to an initial configuration, comprising open grasping plates  118 A and  118 B and a relatively coincident articulated joint  114 . The implant device  120  may be placed between the open grasping plates  118 A and  118 B and secured by moving the trigger  108  away from the main body portion  102 , in some embodiments. 
     The implant device  120 , secured to the delivery instrument  100 , is then inserted in vivo. The surgeon may place the implant device  120  proximal to the intervertebral space. In some cases, the surgeon may have to strike the proximate end of the delivery instrument  100  in order to drive the implant device  120  into the intervertebral space. Once within the intervertebral space, the implant device  120  may be further positioned and rotated into an appropriate configuration. 
     Removing the delivery instrument  100  initially requires opening the grasping plates  118 A and  118 B by moving the trigger  108  closer to the main body portion  102 , in some embodiments. The delivery instrument  100  may then be moved so as to clear the end of the implant device  120 . Once clear, the articulated joint  114  may then be rotated to be relatively coincident with the main body portion  102 . The delivery instrument  100  may then be removed from in vivo. 
     Having thus described the present invention by reference to certain of exemplary embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure. In some instances, some features of an embodiment of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of illustrative embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.