Abstract:
An implant holder and driver for use in implanting orthopedic implants is disclosed. The instrument includes a distal retaining member that affirmatively holds the orthopedic implant and allows significant force to be applied by the driver without dislodging the engagement. An actuation mechanism is provided to move the retaining member between the open and closed positions. The actuation mechanism utilized in one aspect of the present invention may be operated in an ergonomic and efficient fashion.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to instruments used to manipulate orthopedic implants. More particularly, the present invention relates to the manipulation of bone anchoring elements positioned in the spine that may be connected to longitudinal members extending along the length of the spine. While the invention is particularly useful in spinal surgery, it may find use in other areas of medicine as well. 
       BACKGROUND OF THE INVENTION 
       [0002]    In many applications, particularly those related to spinal correction techniques, it is desirable to place a series of implants in a patient&#39;s spine prior to inserting a longitudinal member (a rod or a plate) along the spine to interconnect the previously placed implants. Placement of the bone anchoring elements can be a challenging surgical procedure as the surgical access to the spinal column is limited and there is a need for very precise placement. 
         [0003]    As a result of the demands of the surgical procedure, there remains a need for improvements to surgical instruments that can hold and push orthopedic implants. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect of the present invention, there is provided a surgical instrument for placement of orthopedic implants. The surgical instrument comprises a shaft having a distal portion, an opposite proximal portion and a longitudinal axis. The surgical instrument includes a driving surface associated with an implant receiving area extending distally from the shoulder. A retaining member extends distally from the implant receiving area and is adapted to be moveable to hold an implant to the surgical instrument. 
         [0005]    In another aspect of the present invention, there is provided a combination orthopedic implant and surgical instrument for holding and driving the implant. This combination comprises a surgical instrument with a driving area and retaining member operable on the distal portion of the implant between a locked retaining position and a released open position. 
         [0006]    In yet a further aspect of the present invention, there is provided a method for implanting an orthopedic implant. The surgical method comprises providing a surgical instrument having a driving surface and a distally extending retaining member. An implant is positioned adjacent the driving surface and the retaining member is moved to engage the implant and retain it adjacent the driving surface. The implant is positioned in a patient&#39;s body, the retaining member is moved to a spaced relation away from the implant, and the surgical instrument is removed. 
         [0007]    Related objects and advantages of the present invention will be apparent from the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a surgical instrument in accordance with one aspect of the present invention. 
           [0009]      FIG. 2  is an enlarged partial perspective view of the implant driver portion of the surgical instrument of  FIG. 1 . 
           [0010]      FIG. 3  is an enlarged partial cross-sectional view of the actuation mechanism of the surgical instrument of  FIG. 1 . 
           [0011]      FIG. 4  is a perspective view of a portion of the surgical instrument of  FIG. 1  engaged with an orthopedic implant. 
           [0012]      FIG. 5  is a top view of the surgical instrument of  FIG. 4 . 
           [0013]      FIG. 6  is a side view of the surgical instrument of  FIG. 4  and the orthopedic implant being implanted in a spinal segment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such applications of the principles of the invention as illustrated herein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0015]    Referring now to  FIG. 1 , an implant holder  10  according to the present invention is illustrated. Implant holder  10  includes a handle  12  adjacent to the proximal end  14 . Extending towards distal end  15  and away from the handle  12 , implant holder  10  narrows to shaft  16  which includes a thumb actuator  18  extending out of aperture  19 . The shaft includes taper  20  extending to distal, hollow shaft  22  which includes a bend  24  and an implant driver assembly  30 . Implant holder  10  includes a longitudinal axis L 1  extending along a substantial portion of handle  12  and shaft  16 . It will be appreciated that implant driver assembly  30  extends at an oblique angle with respect to the longitudinal axis L 1 . 
         [0016]    Referring now to  FIG. 2 , there is shown an enlarged view of the implant driver assembly  30  of  FIG. 1 . Implant driver assembly  30  includes an enlarged flange  28  having a distal implant driving surface  32 . Continuing distally toward distal end  15 , driving assembly  30  includes implant receiving area  34  which has a pair of intermediate protrusions  36  extending outwardly from the longitudinal axis L 2  that extends along a substantial portion of implant driving assembly  30 . At the distal most portion of driving assembly  30 , the device includes a retaining member  40 . Retaining member  40  has a pair of proximal projections  42  and  44  (see also  FIG. 5 ). Additionally, retaining member  40  includes an implant engaging surface disposed on its proximal portion configured and adapted for engaging an orthopedic implant. Retaining member  40  is attached to driving assembly  30  via a cable  50  (see  FIG. 3 ) that engages retaining member  40  at attachment  52 . Retaining member  40  is configured and adapted to be moveable in the direction of arrow A proximally and distally along longitudinal axis L 2 . Retaining member  40  can be moved distally along longitudinal axis L 2  into a released position, as shown in  FIG. 2 , adapted for receiving an implant or releasing a previously engaged implant. Similarly, movement of retaining member  40  proximally along longitudinal axis L 2  moves the retaining member  40  to a retaining position, as shown in  FIG. 6 , for holding an implant on the implant receiving area  34 . 
         [0017]    Referring now to  FIG. 3 , there is shown an enlarged partial cross-sectional view of the actuation mechanism for implant holder  10  and the associated implant driver assembly  30 . The actuation mechanism includes a thumb actuator  18  joined to shaft  16  via pivot pin  54  to create a freely moveable actuator arm  56  opposite thumb actuator  18 . Actuator arm  56  is joined to cable  50  (shown in dashed lines) which extends along the length of the device inside shaft  22  between the actuator  18  and retaining member  40 . In one aspect of the present invention, a biasing member such as spring  58  is disposed about cable  50  and engages actuator arm  56  to urge the actuation mechanism into the locked position. It will be appreciated that spring  58  applies a force on cable  50  that has a tendency to pull retaining member  40  proximally towards driving surface  32 . 
         [0018]    Referring now to  FIGS. 4-6 , the implant holder  10  will now be described in use with an orthopedic implant. Specifically, implant holder  10  will be disclosed and described for use with placement of a spinal hook  80 . Spinal hook  80  includes a bone engagement area  82  and external surface  84 . Disposed within the external surface along its distal end are a pair of receiving recesses  86  and  88 . Further, as known in the art, hook  80  has an internal cavity  90  adapted to receive a longitudinal spinal rod and a retaining member (not shown) to join hook  80  to the rod. 
         [0019]    In use, driving assembly  30  is positioned and aligned above internal cavity  90  with the implant mating area  34  positioned such that protrusions  36  substantially match and align with the internal contours of cavity  90 . The implant is then moved transverse to longitudinal axis L 2  to seat implant mating area  34  within internal cavity  90 . In the illustrated embodiment, this movement is conducted with one hand positioned on handle  12  and the thumb of the same hand depressing actuator  18  such that retaining member  40  is in the released position. As will be understood, it is possible that the operator may use the opposing hand to hold the spinal implant before insertion into the implant holder  10 . In the alternative, spinal hook  80  may be positioned in a hook holder or otherwise in a tray such that it may be picked up by implant holder  10  using only the single hand positioned on the instrument. It will be appreciated that in one aspect, although not required for all aspects, the present invention provides an instrument for gripping and driving an implant that is operable for these functions with only one hand of the user. After implant mating area  34  is positioned within internal cavity  90  the operator may release thumb actuator  18 . Biasing member  58  will then apply tension on cable  50  to urge retaining member  40  against the exterior surface  84  of the implant. In the illustrated embodiment, the proximal surface of retaining member  40  includes projections  42  and  44  that may be received within receiving cavities  86  and  88  on the implant, respectively. It will be appreciated that while projections  42  and  44  are disposed within recesses  86  and  88 , respectively, the implant  80  cannot be removed from the implant mating area  34 . 
         [0020]    In one aspect, implant mating area  34  is sized and configured to have a slightly smaller external dimension than the internal dimension of internal cavity  90  to permit the implant to move proximally in response to force applied by the retaining member  40  on the distal exterior surface of the implant. In this manner, the retaining member  40  urges the proximal outer surface  87  on the proximal portion of hook  80  against driving surface  32  of flange  28 . As a result, implant  80  is squeezed between the implant engaging surface of the retaining member  40  and the driving surface  32 . Further, when it is necessary to apply a driving force on implant  80  the force is transmitted from driving surface  32  to the exterior surface  87  of the implant. In the illustrated aspect, implant receiving area  34  and retaining member  40  can be formed in a less robust form permitting a lower profile since they do not need to be constructed to transmit a driving force to the implant  80 . Moreover, the protrusions  36  on implant mating area  34  inhibit rotation of implant  80  with respect to implant holder  10 . As a result, the hook  80  is firmly attached to implant holder  10  and may be driven with significant force into position. 
         [0021]    In an alternative configuration, the flange  28  and associated driving surface  32  may be greatly diminished or omitted. In this configuration, implant receiving area  34  is configured with a driving surface to engage the interior surface of the cavity of the implant. It will be understood that at least a portion of the implant receiving area  34  will be configured for engagement with the implant to transmit impaction forces to the implant. 
         [0022]    As will be appreciated from  FIG. 5 , retaining member  40  has a constant width from the lateral side adjacent projection  42  to the opposite lateral side adjacent projection  44  regardless of whether it is positioned in the retaining position or the releasing position. In the illustrated embodiment, the width of the retaining member  40  is less than the width of the implant  80 . Further, the distal most portion of the retaining member  40  (see  FIG. 6 ) remains proximal of the greatest distal projection of implant  80  when held by the implant holder  10 . As such, the retaining member  40  can be moved between the retaining position and the releasing position without increasing the total length or width of the combination of the implant holder  10  and the implant  80 . 
         [0023]    As shown in  FIG. 6 , hook  80  has been positioned adjacent the lamina of a spinal segment. If needed, a mallet (not shown) can be used to impact on proximal portion  14  adjacent handle  12  to drive the hook into position and firmly engage it in the spine. Further use and description of spinal hooks is not described herein, however U.S. Pat. Nos. 5,910,141 and 5,246,442 are incorporated by reference herein in their entirety. 
         [0024]    The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.