Abstract:
An implant insertion device is adapted for use with a shape memory implant. The shape memory implant includes a bridge interconnecting first, second, and third legs. The shape memory implant is movable between a first shape in which at least the first leg is substantially non-parallel and a second shape in which at least the first leg is substantially parallel. The implant insertion device engages the shape memory implant to maintain the shape memory implant in its second shape until the delivery of the shape memory implant into tissue or bone.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to an implantation device and, more particularly, but not way of limitation, to an implantation device designed for loading with a surgical implant and for subsequent delivery of the surgical implant. The implantation device uses jaws and a slider to secure a surgical implant and allow implantation into a patient. 
         [0003]    2. Description of the Related Art 
         [0004]    Shape memory implants are commonly used in surgical procedures that require the reattachment or fusing of tissue or bone. Shape memory implants can be composed of shape memory material such as Nitinol that allows the shape memory implants to have a first final shape and the ability to transform into a second shape. A shape memory implant can be either thermally activated, in which an external heating source or body temperature would be required to activate the implant, or mechanically activated, in which a constraining instrument would be required. A shape memory implant that requires mechanical constraint stores mechanical energy due to elastic (recoverable) deformation, and then releases the stored mechanical energy when the constraint is removed. In these types of implants, the implants are mechanically deformed into their second shape and maintained in their second shape by instrumentation such that, upon release from the instrumentation, the implants elastically deform from their second shape into their first final shape. 
         [0005]    In surgical procedures, the elastic property of constrained shape memory implants is used as follows. Bones that require fixating are aligned, and the shape memory implant, which has been mechanically deformed to its second shape, is maintained in instrumentation and inserted between the bones. In the second shape, the legs of the implant are generally parallel. After insertion, the shape memory implant is released from the instrumentation, whereupon the shape memory implant elastically returns to its first final shape such that the shape memory implant maintains the bones fixated together. In the first final shape, the legs of the implant are converging at the tips. Because the shape memory implant stores mechanical energy, it continuously applies force to the fixated bones as the shape memory implant transitions from the second shape to the first final shape, which aids in the healing process. 
         [0006]    Various types of instrumentation can be used for either maintaining the shape memory implants in their second shape or moving an implant from its first final shape to a temporary second shape. Some companies used metal forceps to open and insert the shape memory implant. These forceps have to be sterilized by a hospital, and then a shape memory implant can be placed on the forceps, opened to a desired position, and used for inserting the implant. Although potentially effective, forceps require the implant to be loaded into the forceps during surgery, which might be cumbersome and time consuming. In addition, forceps might be large which could hinder implantation of the shape memory implant into a patient during surgery. It is also possible that a physician using the forceps might damage the shape memory implant in various ways, such as stretching the implant beyond the second shape, fatiguing the implant, or causing metal-on-metal scraping of the implant with the instrument. Furthermore, forceps can be expensive instruments that require cleaning and sterilization after each surgery. 
         [0007]    Other companies use plastic and disposable tools to maintain a shape memory implant in the second shape. This type of instrumentation can be preloaded and sterilized with the implant already in the second shape, and the implant can be pre-activated so that it does not require heating with an external heater or body temperature after use. One type of plastic and disposable instrument operates by having the implant fit inside a passage that is substantially the same diameter as the shape memory implant. By using this method, the implant insertion device allows the shape memory implant to be preloaded prior to surgery. However, using an implant insertion device that substantially conforms to the profile of the shape memory implant can create several problems for a surgeon. First, this type of implant insertion device often makes disengagement of the shape memory staple after implantation problematic. In particular, the shape memory implant sticks to the implant insertion device due to the frictional engagement between the shape memory implant, which is trying to compress, and the passage of the implant insertion device, resulting in a more difficult surgical procedure and the potential for a less than satisfactory fixation of tissue or bone. Second, this type of implant insertion device results in an abrupt and sudden release of stored mechanical energy as the implant is removed from the device. This type of implant insertion device provides no method by which to slowly transition the stored energy in the implant from the implant insertion device to the bones that are being fixated. Finally, this type of implant insertion device can result in entanglement during release, in which the implant legs begin to compress upon release and make extraction of this type of insertion device more difficult. 
         [0008]    Accordingly, an instrument that constrains a shape memory implant in its second shape, allows the shape memory implant to be preloaded and sterilized prior to surgery, simplifies removal of the shape memory implant after partial implantation, and controls the rate of release of tension would be beneficial. 
       SUMMARY OF THE INVENTION 
       [0009]    In accordance with the present invention, an implant insertion system includes a shape memory implant and an implant insertion device adapted for use with the shape memory implant. The shape memory implant includes a bridge interconnecting first, second, and third legs. The shape memory implant is movable between a first shape in which at least the first leg is substantially non-parallel and a second shape in which at least the first leg is substantially parallel. The implant insertion device engages the shape memory implant to maintain the shape memory implant in its second shape until the delivery of the shape memory implant into tissue or bone. 
         [0010]    The implant insertion device includes a first insertion tool piece and a second insertion tool piece. The first insertion tool piece includes a slider slot. The first insertion tool piece terminates in a first jaw including a first tool slot adapted to receive therein a portion of the bridge of the shape memory implant. The second insertion tool piece includes a slider slot. The second insertion tool piece terminates in a second jaw including a second tool slot adapted to receive therein a portion of the bridge of the shape memory implant. The second insertion tool piece hingedly connects with the first insertion tool piece such that the first and second insertion tool pieces reside in an opposed relationship with their slider slots aligned. 
         [0011]    The implant insertion device further includes a slider disposed in the slider slots of the first and second insertion tool pieces. The slider includes a separator disposed between the first and second insertion tool pieces. The slider moves such that the separator separates the first and second insertion tool pieces to release the shape memory implant from the first and second insertion tool pieces. The slider further moves such that the separator permits closure of the first and second insertion tool pieces. When the first and second insertion tool pieces are closed, the first and second tool slots each receive therein a portion of the bridge of the shape memory implant to maintain the shape memory implant in its second shape, the first jaw engages the first and second legs to maintain the shape memory implant in its second shape, and the second jaw engages at least the third leg to maintain the shape memory implant in its second shape. The second jaw may engage the first leg to maintain the shape memory implant in its second shape. 
         [0012]    The first jaw includes a projection that engages the first leg to maintain the first leg substantially parallel such that the shape memory implant resides in its second shape. The first jaw further includes a projection that engages the second leg to maintain the second leg substantially parallel such that the shape memory implant resides in its second shape. The second jaw includes a projection that engages the third leg to maintain the third leg substantially parallel such that the shape memory implant resides in its second shape. The second jaw may include a projection that engages the first leg to maintain the first leg substantially parallel such that the shape memory implant resides in its second shape. 
         [0013]    The first insertion tool piece includes a first insertion tool piece ramp, and the second insertion tool piece includes a second insertion tool piece ramp. The hinged connection between the first insertion tool piece and the second insertion tool piece places the first and second insertion tool piece ramps interior to the first and second insertion tool pieces and in an opposed relationship. When disposed in the slider slots of the first and second insertion tool pieces, the slider positions the separator between the first and second insertion tool piece ramps. The slider moves such that the separator engages the first and second insertion tool piece ramps to separate the first and second insertion tool pieces and release the shape memory implant from the first and second insertion tool pieces. The slider further moves such that the separator disengages from the first and second insertion tool piece ramps to permit closure of the first and second insertion tool pieces. 
         [0014]    The first insertion tool piece includes a first insertion tool piece slider slot lock, and the second insertion tool piece includes a second insertion tool piece slider slot lock. The hinged connection of the first insertion tool piece with the second insertion tool piece places the first insertion tool piece slider slot lock in opposed relationship with the second insertion tool piece slider slot lock. Once the first and second insertion tool pieces are closed, the slider moves such that a slot in the slider engages the first and second insertion tool piece slider slot locks thereby locking the first insertion tool piece with the second insertion tool piece. The slider further moves such that the slot in the slider disengages from the first and second insertion tool piece slider slot locks to permit separating of the first and second insertion tool pieces. 
         [0015]    In a method of holding a shape memory implant until the delivery of the shape memory implant into tissue or bone, a shape memory implant is provided. The shape memory implant includes a bridge interconnecting first, second, and third legs. The shape memory implant is movable between a first shape wherein the first leg is non-parallel and a second shape wherein the first leg is substantially parallel. A slider of an implant insertion device inserts between a first insertion tool piece hingedly connected to a second insertion tool piece. Responsive thereto, the first and second insertion tool pieces separate thereby opening the implant insertion device to receive the shape memory implant therein. The shape memory implant is moved into its second shape wherein the first leg is substantially parallel and placed between a first jaw of the first insertion tool piece and a second jaw of the second insertion tool piece. The slider of the implant insertion device is moved to permit closure of the first and second jaws of the first and second insertion tool pieces. When the first and second jaws are closed, a first tool slot in the first jaw and a second tool slot in the second jaw each receive therein a portion of the bridge of the shape memory implant, the first jaw engages the first and second legs to maintain the shape memory implant into its second shape wherein the first leg is substantially parallel, and the second jaw engages at least the third leg. The slider of the implant insertion device then is moved to engage the first and second insertion tool pieces to lock the first and second jaws closed about the shape memory implant into its second shape. 
         [0016]    Once the first and second jaws are locked about the shape memory implant into its second shape, the implant insertion device is used to deliver the shape memory implant into tissue or bone. After delivering the shape memory implant into tissue or bone, the slider of the implant insertion device is moved such that the slider disengages from the first and second insertion tool pieces to unlock the first and second jaws. The slider of the implant insertion device then is moved to insert between the first and second insertion tool pieces such that the first and second insertion tool pieces separate thereby releasing the shape memory implant from the first and second jaws. Upon the release of the shape memory implant from the first and second jaws, the shape memory implant moves from its second shape wherein the first leg is substantially parallel to its first shape wherein the first leg is non-parallel. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a side view of a first embodiment of an implant in a first position. 
           [0018]      FIG. 2  is a perspective view illustrating the first embodiment of the implant in the first position. 
           [0019]      FIG. 3  is a side view of the first embodiment of the implant in a second position. 
           [0020]      FIG. 4  is a perspective view illustrating the first embodiment of the implant in the second position. 
           [0021]      FIG. 5  is a side view of a second embodiment of the implant in a second position. 
           [0022]      FIG. 6  is a perspective view illustrating the second embodiment of the implant in the second position. 
           [0023]      FIG. 7  is a perspective view of an insertion tool slider. 
           [0024]      FIG. 8  is an outside view of a right insertion tool piece. 
           [0025]      FIG. 9  is an inside view of the right insertion tool piece. 
           [0026]      FIG. 10  is an outside view of a left insertion tool piece. 
           [0027]      FIG. 11  is an inside view of the left insertion tool piece. 
           [0028]      FIG. 12  is a perspective view illustrating the insertion tool assembly after release of the implant. 
           [0029]      FIG. 13  is a perspective view illustrating the insertion tool assembly after unlocking the implant. 
           [0030]      FIG. 14  is a perspective view illustrating the insertion tool assembly with the implant in a locked position. 
           [0031]      FIG. 15  is a side view of the insertion tool assembly after release of the implant. 
           [0032]      FIG. 16A  is a section view taken along line A-A of  FIG. 16B  illustrating the insertion tool assembly after release of the implant. 
           [0033]      FIG. 16B  is a side view illustrating the insertion tool assembly after release of the implant. 
           [0034]      FIG. 17A  is a section view taken along line B-B of  FIG. 17B  illustrating the insertion tool assembly after unlocking the implant. 
           [0035]      FIG. 17B  is a side view illustrating the insertion tool assembly after unlocking the implant. 
           [0036]      FIG. 18A  is a section view taken along line C-C of  FIG. 18B  illustrating the insertion tool in the locked position. 
           [0037]      FIG. 18B  is a side view illustrating the insertion tool assembly in the locked position. 
           [0038]      FIG. 19  is a bottom view of the insertion tool assembly after release of the implant. 
           [0039]      FIG. 20  is a bottom view of the insertion tool assembly with the implant in the locked position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0040]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Figures are not necessarily to scale, and some features may be exaggerated to show details of particular components or steps. 
         [0041]      FIGS. 1 and 2  respectively display an orthopedic implant  1  in a first position  100 . Implant  1  consists of two or more legs, such as the three legs  5 ,  6 , and  7  shown in this embodiment. Although the three legs in this embodiment form an isosceles triangle, any number of other multi-legged designs exist. Each leg is capable of penetrating into bone to anchor implant  1 . Barbs on each leg, such as representative barb  13 , provide resistance to movement when the implant is inserted into bone. Any number of barbs can be on each leg. Leg tip  14 , which is on leg  5 , but is representative of the leg tips on each leg, can be blunt or pointed for insertion into bone. Bridge  20  connects the two or more legs of implant  1 . Corners  10 ,  11 , and  12  represent the location where legs  5 ,  6 , and  7  attach to bridge  20 . Corners  10 ,  11 , and  12  can be of any radius such that implant  1  conforms to bone when implanted. Bridge  20  is mostly flat when viewed in  FIG. 1  when it is first position  100 . However, there is any number of shapes for bridge  20  that will attach legs  5 ,  6 , and  7  and conform to bone after implantation. 
         [0042]    Implant  1  is made of an elastic material suitable for orthopedic use, such as a shape memory material. In first position  100 , the legs  5 ,  6 , and  7  of implant  1  are mostly parallel to each other, such that implant  1  can be easily inserted into holes drilled in bone. However first position  100  is not the natural shape of implant  1 , and thus legs  5 ,  6 , and  7  must be constrained either mechanically, or by chilling implant  1  until it is in the martensitic state such the legs naturally remain in first position  100 . 
         [0043]      FIGS. 3 and 4  illustrate the first embodiment of an orthopedic implant in a second position  101 . Implant  1  is now in a second position in which leg  5  has moved inward due to the shape memory or superelastic property of the material near corner  10 . Leg  5  is no longer parallel to legs  6  and  7 . This has occurred either because a mechanical constraint of leg  5  has been removed, allowing it to swing inward, or because leg  5  was previously chilled in a deformed martensite state and now has transitioned to its natural shape in the austenite phase. Furthermore, bridge  20  has now arched due to the same reasons, so as to bring leg  5  closer to legs  6  and  7 . In these two ways, implant  1  creates compression force between leg  5  and legs  6  and  7 . In addition to this motion, a person familiar with the art could design implant  1  to have any number of legs, or any combination of movements. Although stationary in this embodiment, in an alternative embodiment legs  6  and  7  could move towards leg  5  or towards each other. 
         [0044]      FIGS. 5 and 6  illustrate a second embodiment of an orthopedic implant in a second position  102 . In this second embodiment, implant  1  has the same features as the first embodiment, except that legs  5 ,  6 , and  7  all move under the action of shape memory or superelasticity to non-parallel positions. The material in corners  10 ,  11 , and  12  has now caused legs  5 ,  6 , and  7  to move to the compressed and non-parallel positions, either due to release of a mechanical constraint on the legs or due to a phase change from chilled martensite to the austenite phase. In this way, additional compressive force is created by the legs of implant  1 . 
         [0045]      FIG. 7  is an isometric view of an insertion tool slider. Insertion tool slider  200  consists of a separator  206  defining ramps  210  and  211 , finger grips  220  and  221 , and slot  205 . Insertion tool slider  200  can be made of any material. The purpose of insertion tool slider  200  will be more apparent in the paragraphs below, however it&#39;s general purpose is allow a physician to release a shape memory implant from an insertion tool instrument. The finger grips  220  and  221  are contoured to allow easy grasping and leverage for moving insertion tool slider  200 . Slot  205  is designed to fit over mating parts that will be evident in later drawings. Ramps  210  and  211  are designed to provide separator  206  with a wedge shape that can be used to wedge two opposing pieces apart in subsequent paragraphs. 
         [0046]      FIGS. 8 and 9  illustrate a right insertion tool piece. Right insertion tool piece  300  can be made of any material. Right insertion tool piece  300  consists of body  315 , slider slot  305 , slider slot lock  306 , hinge  310 , and additional features described below. Slider slot  305  is a window or hole in right insertion tool piece  300  that fits the dimensions of insertion tool slider  200 . Slider slot lock  306  is a recessed area in right insertion tool piece  300  that also fits the dimensions of insertion tool slider  200 , but in addition will allow slot  205  of insertion tool slider  200  to lock in place. This will be evident in subsequent drawings. Hinge  310  is configured to mate with a corresponding hinge on a left insertion tool piece  400 , described in a subsequent drawing. Body  315  is designed to provide structural rigidity as well as ergonomic shape for a physician to hold. Right insertion tool piece  300  includes jaw  350  that is adapted to interface with an implant  1  at bridge  20  and legs  5  and  6 . In particular, jaw  350  includes projections  320  and  321  that contact implant  1  at legs  5  and  6 , respectively. Jaw  350  includes right insertion tool slot  325 , which is only visible in  FIG. 9  (inside view of the right insertion tool piece). Right insertion tool slot  325  is designed to match the shape of bridge  20  when implant  1  resides in its first position  100 . Right insertion tool ramp  307 , which is also only visible in  FIG. 9 , is a ramped section of piece  300  that will be shown later to interface with the insertion tool slider  200 . Finally, right insertion tool surface  330  is a surface that can mate with a second half of an insertion tool when it is in its assembled position. 
         [0047]      FIGS. 10 and 11  illustrate a left insertion tool piece. In this embodiment, left insertion tool piece  400  is a mirror image of right insertion tool piece  300 . Features on left insertion tool piece  400  are equivalent in function to  300 . Left insertion tool piece  400  consists of body  415 , slider slot  405 , slider slot lock  406 , hinge  410 , and additional features described below. Slider slot  405  is a window or hole in left insertion tool piece  400  that fits the dimensions of insertion tool slider  200 . Slider slot lock  406  is a recessed area in left insertion tool piece  400  that also fits the dimensions of insertion tool slider  200 , but in addition will allow slot  205  of insertion tool slider  200  to lock in place. This will be evident in subsequent drawings. Hinge  410  is configured to mate with a corresponding hinge on a right insertion tool piece  300 , described in a previous drawing. Body  415  is designed to provide structural rigidity as well as ergonomic shape for a physician to hold. Left insertion tool piece  400  includes jaw  450  that is adapted to interface with an implant  1  at bridge  20  and legs  5  and  7 . In particular, jaw  450  includes projections  420  and  421  that contact implant  1  at legs  5  and  7 , respectively. Jaw  450  includes left insertion tool slot  425 , which is only visible in  FIG. 11  (inside view of the left insertion tool piece). Left insertion tool slot  425  is designed to match the shape of bridge  20  when implant  1  resides in its first position  100 . Left insertion tool ramp  407 , which is also only visible in  FIG. 11 , is a ramped section of piece  400  that will be shown later to interface with the insertion tool slider  200 . Finally, left insertion tool surface  430  is a surface that can mate with a second half of an insertion tool when it is in its assembled position. 
         [0048]      FIGS. 12 through 14  illustrate how the insertion tool and implant can be used by a physician.  FIG. 12  illustrates an insertion tool assembly in final shape  250 .  FIG. 12  illustrates the implant  1  of a second embodiment in a second position  102 . Implant  1  is in the position of being released from insertion tool assembly  500 . Shape  250  corresponds to the position of insertion tool assembly  500  just as it releases implant  1  after insertion into bone. Insertion tool assembly  500  consists of right insertion tool piece  300 , left insertion tool piece  400 , and insertion tool slider  200 . Hinges  310  and  410  on right and left insertion tool pieces  300  and  400  interfaces with each other so that insertion tool assembly  500  stays together as one unit. Insertion tool slider  200  fits in between insertion tool pieces  300  and  400 , with separator  206  and ramps  210  and  211  pointing upwards towards hinges  310  and  410 , and slot  205  pointing downwards towards implant  1 . Finger grips  220  and  221  project out through slider slots  305  and  405 . In shape  250 , finger grips  220  and  221  have been used by a physician to pull up on insertion tool slider  200 , which causes the ramps  210  and  211  of insertion tool slider  200  to engage ramps  307  and  407  of right insertion tool piece  300  and left insertion tool piece  400 , such that insertion tool slider  200  acts as a wedge that forces right and left insertion tool pieces  300  and  400  apart at the bottom while they remain connected by hinges  310  and  410 . In shape  250 , it is seen that finger grips  200  and  221  are near the top of slider slots  305  and  405 . Also, in shape  250 , jaws  350  and  450  are open such that implant  1  is not disposed in slots  325  and  425 , projections  320  and  420  are separated and not engaged with implant  1 , and projections  321  and  421  do not engage with implant  1 , thus allowing insertion tool assembly  500  to be removed from implant  1  after implant  1  is in bone. 
         [0049]      FIG. 13  illustrates the insertion tool assembly in intermediate shape  251 .  FIG. 13  shows implant  1  in a first position  100 , with legs  5 ,  6 , and  7  parallel to each other. In shape  251 , implant  1  is in the position of being on the verge of release from insertion tool assembly  500 . Shape  251  corresponds to the position of insertion tool assembly  500  before it releases implant  1  after insertion into bone. In shape  251 , finger grips  220  and  221  have been used by a physician to partially pull up on insertion tool slider  200 , such that slot  205  no longer engages slider slot locks  306  and  406 , however, separator  206  and ramps  210  and  211  have not yet forced insertion tool pieces  300  and  400  to separate. Insertion tool  500  in shape  251  is thus in an intermediate position where the physician has unlocked the two halves of the insertion tool pieces but not yet separated them. In shape  251 , it is seen that finger grips  200  and  221  are near the middle of slider slots  305  and  405 . Also in shape  251 , jaws  350  and  450  are closed to engage with implant  1  in its first position  100 . In particular, slots  325  and  425  receive therein the bridge  20  of the implant  1 , projections  320  and  420  come together and engage leg  5  to mechanically constrain leg  5  in the parallel position, and projections  321  and  421  engage a respective leg  6  and  7  to mechanically constrain legs  6  and  7  in the parallel position. 
         [0050]      FIG. 14  illustrates the insertion tool assembly in initial shape  252 .  FIG. 14  shows implant  1  in a first position  100 , with legs  5 ,  6 , and  7  parallel to each other. In shape  252 , implant  1  is firmly held and locked by insertion tool assembly  500  with legs  5 ,  6 , and  7  parallel. Shape  252  corresponds to the position of insertion tool assembly  500  when a physician is preparing to use implant  1 , but it has not yet been placed into bone. In shape  252 , finger grips  220  and  221  have not yet been used by a physician, and slot  205  engages slider slot locks  306  and  406 , keeping slider slot locks  306  and  406  together and thus keeping insertion tool pieces  300  and  400  together. Insertion tool  500  in shape  252  is thus the initial position where the physician has not yet unlocked or separated the two halves of the insertion tool pieces. In shape  252 , it is seen that finger grips  200  and  221  are near the bottom of slider slots  305  and  405 . Also, in shape  252 , jaws  350  and  450  are closed to engage with implant  1  in its first position  100 . In particular, slots  325  and  425  receive therein the bridge  20  of the implant  1 , projections  320  and  420  come together and engage leg  5  to mechanically constrain leg  5  in the parallel position, and projections  321  and  421  engage a respective leg  6  and  7  to mechanically constrain legs  6  and  7  in the parallel position. While the preferred embodiment discloses jaw  350  including projection  320  and jaw  450  including projection  420 , one of ordinary skill in the art will recognize that a single projection on either jaw  350  or  450  may be used. 
         [0051]      FIG. 15  illustrates the insertion tool assembly after release of an orthopedic implant. Insertion tool assembly  500  is in its final shape  250  with right and left insertion tool pieces  300  and  400  separated at the bottom with jaws  350  and  450  in their open position, but still held together by hinges  310  and  410  at the top. In this view, it can be seen that insertion tool assembly  500  is free to be removed from implant  1  because jaws  350  and  450  are no longer engaging implant  1 . In addition, slot  205  can be seen to no longer be engaged with slot locks  306  and  406 , which is what permits insertion tool pieces  300  and  400  to separate from each other. What cannot be seen in this figure, but is occurring nonetheless, is that a physician has pulled up on finger grips  220  and  221 , causing ramps  210  and  211  to engage corresponding ramps  307  and  407  on right and left insertion tool pieces  300  and  400 , and ramps  210  and  211  have then acted as a wedge to force the two insertion tool pieces apart. 
         [0052]      FIGS. 16A and 16B  illustrate the insertion tool assembly components after release of an orthopedic implant. This corresponds to final shape  250  of insertion tool  500 . In  FIG. 16A , the functioning of insertion tool slider  200  are apparent. Finger grips  220  and  221  have been used by the physician to pull up on slider  200 , which releases slot  205  from restraining locks  306  and  406 . In addition, pulling upon slider  200  has caused ramps  210  and  211  on slider  200  to engage ramps  307  and  407  on insertion tool pieces  300  and  400 , wedging the two pieces apart at the bottom such that jaws  350  and  450  are in their open position. This action causes slots  325  and  425  to release implant  1  so that its legs  5 ,  6 , and  7  can create compression in bone, and insertion tool assembly  500  can be lifted away from implant  1 . 
         [0053]    Similarly,  FIGS. 17A and 17B  illustrate the insertion tool assembly components after unlocking an orthopedic implant but before separating the two halves of insertion tool assembly  500 . This corresponds to shape  251  for insertion tool  500 . The function of insertion tool slider  200  is apparent in  FIG. 17A . A physician has partially raised finger grips  220  and  221 , such that slot  205  no longer engages slider lock slots  306  and  406 . However, ramps  210  and  211  are not yet wedging the two halves of insertion tool assembly  500  apart. This leaves insertion tool assembly  500  in an intermediate shape where the jaws  350  and  450  are closed to constrain implant  1 , but it is on the verge of releasing implant  1 . Projections  320 ,  321 ,  430 , and  421  contact respective legs  5 ,  6 , and  7  of implant  1  such that legs  5 ,  6 , and  7  are still parallel and implant  1  is in first position  100 . 
         [0054]      FIGS. 18A and 18B  illustrate the orthopedic implant  1  in the locked position held by insertion tool assembly. Implant  1  is in first position  100 , and insertion tool  500  is in shape  252 . Slider  200  has not been used by a physician, and therefore is in its locked downward position. Slot  205  constrains slider lock slots  306  and  406 . Right and left insertion tool slots  325  and  425  include bridge  20  received therein and projections  320 ,  321 ,  430 , and  421  contact respective legs  5 ,  6 , and  7  to constrain legs  5 ,  6 , and  7  of implant  1  in the parallel position. Right insertion tool surface  330  and left insertion tool surface  430  are touching in these figures. 
         [0055]      FIG. 19  illustrates the insertion tool assembly after release of the orthopedic implant. This corresponds to implant  1  in second position  102 , and insertion tool assembly  500  in final shape  250 . Note that slots  325  and  425  on right and left insertion tool pieces are not engaging implant  1 , and thus projections  320 ,  321 ,  430 , and  421  are not constraining legs  5 ,  6 , and  7  in their parallel positions. 
         [0056]      FIG. 20  illustrates the orthopedic implant in the locked position. This corresponds to implant  1  in first position  100 , and insertion tool assembly  500  in initial shape  252 . Surfaces  330  and  430  are touching, and slots  325  and  425  engage bridge  20  of implant  1  and projections  320 ,  321 ,  430 , and  421  constrain legs  5 ,  6 , and  7  in their parallel positions. 
         [0057]    It can also be seen that the foregoing steps represent a method for inserting an orthopedic implant. In particular, an insertion tool assembly  500  holds and constrains an orthopedic implant  1  in an insertion shape, such that the legs of implant  1  can be inserted into drill holes in bone. A physician drills holes in bone at the proper distance from each other. The physician inserts the implant legs into bone by holding the insertion tool assembly. At the desired time, the physician pulls up on the insertion tool assembly slider, which unlocks the two halves of the insertion tool assembly. Continuing to pull up on the slider causes the two halves to separate due to the wedge action of the slider, and thus releases the implant. 
         [0058]    Although the present invention has been described in terms of the foregoing preferred embodiments, including the insertion instrument and its components, the method of use of the insertion instrument and its various components, the method of controllably releasing the implant, the combination of the implant and its interaction with the insertion instrument, and other ideas presented herein, such description has been for exemplary purposes only and, as will be apparent to those of ordinary skill in the art, many alternatives, equivalents, and variations of varying degrees will fall within the scope of the present invention. That scope, accordingly, is not to be limited in any respect by the foregoing detailed description; rather, it is defined only by the claims that follow.