Abstract:
Apparatuses for attaching tissue to bone are provided. In one exemplary embodiment, the apparatus includes an expandable body defining a bore, an expander pin having a shaft sized to be received in the bore of the expandable body, and an insertion shaft slidingly disposed in the bore of the expandable body and in a bore of the expander pin. The body is configured to expand laterally into and attach to bone when the expander pin is driven into the expandable body. The body includes a proximal main member having a distally extending threaded projection and a harder, distal tip member having a threaded recess in a proximal surface thereof such that the projection is threadedly interengageable with the recess. The expansion of the body by way of the expander pin can occur when the proximal main member and distal tip member are threadedly engaged. The insertion shaft is releasably secured to the expandable body and extends distally beyond the expandable body.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
     This is a continuation of prior U.S. patent application Ser. No. 09/714,549, filed Nov. 16, 2000 now U.S. Pat. No. 6,733,506 by Dennis McDevitt et al. for APPARATUS AND METHOD FOR ATTACHING SOFT TISSUE TO BONE. The above-identified patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to medical devices and procedures. More particularly, this invention relates to apparatus and methods for attaching soft tissue to bone. 
     BACKGROUND OF THE INVENTION 
     The complete or partial detachment of ligaments, tendons and/or other soft tissues from their associated bones within the body are relatively commonplace injuries, particularly among athletes. Such injuries are generally the result of excessive stresses being placed on these tissues. By way of example, tissue detachment may occur as the result of an accident such as a fall, over-exertion during a work-related activity, during the course of an athletic event, or in any one of many other situations and/or activities. 
     In the case of a partial detachment, the injury will frequently heal itself, if given sufficient time and if care is taken not to expose the injury to further undue stress. 
     In the case of complete detachment, however, surgery may be needed to re-attach the soft tissue to its associated bone or bones. 
     Numerous devices are currently available to re-attach soft tissue to bone. Examples of such currently-available devices include screws, staples, suture anchors and tacks. 
     In soft tissue re-attachment procedures utilizing screws, the detached soft tissue is typically moved back into its original position over the bone. Then the screw is screwed through the soft tissue and into the bone, with the shank and head of the screw holding the soft tissue to the bone. 
     Similarly, in soft tissue re-attachment procedures utilizing staples, the detached soft tissue is typically moved back into its original position over the bone. Then the staple is driven through the soft tissue and into the bone, with the legs and bridge of the staple holding the soft tissue to the bone. 
     In soft tissue re-attachment procedures utilizing suture anchors, an anchor-receiving hole is generally first drilled in the bone at the desired point of tissue re-attachment. Then a suture anchor is deployed in the hole using an appropriate installation tool. This effectively locks the suture to the bone, with the free end(s) of the suture extending out of the bone. Next, the soft tissue is moved into position over the hole containing the deployed suture anchor. As this is done, the free end(s) of the suture is (are) passed through or around the soft tissue, so that the free end(s) of the suture reside(s) on the far (i.e., non-bone) side of the soft tissue. Finally, the suture is used to tie the soft tissue securely to the bone. 
     Alternatively, in some soft tissue re-attachment procedures utilizing suture anchors of the type described above, the soft tissue may first be moved into position over the bone. Then, while the soft tissue lies in position against the bone, a single hole may be drilled through the soft tissue and into the bone. Next, a suture anchor is passed through the soft tissue and deployed in the bone using an appropriate installation tool. This results in the suture anchor being locked to the bone, with the free end(s) of the suture extending out of the bone and through the soft tissue. Finally, the suture is used to tie the soft tissue securely to the bone. 
     In some cases, the suture anchor may include drill means at its distal end, whereby the suture anchor can be drilled into the bone, or drilled through the soft tissue and into the bone, whereby the aforementioned drilling and anchor-deployment steps are effectively combined. 
     Similarly, in soft tissue re-attachment procedures utilizing tacks, the detached soft tissue is typically moved back into its original position over the bone, and then a tack-receiving hole is generally drilled through the soft tissue and into the bone. Then the tack is driven through the soft tissue and into the bone, so that the shaft and head of the tack will hold the soft tissue to the bone. 
     While systems and method based on the aforementioned screws, staples, suture anchors and tacks are generally effective, they also all suffer from one or more disadvantages. 
     OBJECTS OF THE INVENTION 
     Accordingly, one object of the present invention is to provide a novel apparatus and method for re-attaching soft tissue to bone which improves upon the prior art devices and techniques discussed above. 
     Another object of the present invention is to provide a novel apparatus and method for re-attaching soft tissue to bone which is easy to use and simple to perform. 
     And another object of the present invention is to provide a novel apparatus and method for re-attaching soft tissue to bone which expedites and facilitates the re-attachment procedure. 
     Still another object of the present invention is to provide a novel apparatus and method for re-attaching soft tissue to bone which minimizes trauma to the patient during the re-attachment procedure. 
     Yet another object of the present invention is to provide a novel apparatus and method for re-attaching soft tissue to bone which can be used in both open surgical procedures and in closed surgical procedures (e.g., arthroscopic or endoscopic surgical procedures) where access to the surgical site is provided by one or more cannulas. 
     And another object of the present invention is to provide a novel system and method for re-attaching soft tissue to bone which is also usable in the attachment of prosthetic devices, and/or grafts of natural and/or synthetic material, to bone or bone-like structures. 
     SUMMARY OF THE INVENTION 
     These and other objects of the present invention are achieved by the provision and use of a novel apparatus and method for attaching soft tissue and the like to bone. 
     In one preferred embodiment, the novel apparatus comprises an expandable body configured to expand into bone, the expandable body defining a bore; and an expander pin comprising a shaft sized to be received in the bore of the expandable body and expand the expandable body laterally when the expander pin is driven into the expandable body, and tissue attachment apparatus associated with the shaft, the expander pin defining a bore; whereby when the expander pin is driven into the expandable body, the expandable body will be attached to bone and the tissue attachment apparatus will secure tissue to the apparatus. 
     In one preferred embodiment, the novel method comprises driving an expandable fastener into a bone, the expandable fastener defining a bore and comprising tissue attachment apparatus; and fixing the expandable fastener in, and thereby securing the tissue relative to, the bone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
         FIG. 1  is a side view of a novel fastening apparatus formed in accordance with the present invention; 
         FIGS. 2-4  are perspective views of the distal end of the fastening apparatus shown in  FIG. 1 ; 
         FIG. 5  is a side view, partially in section, of the distal end of the fastening apparatus shown in  FIG. 1 ; 
         FIG. 6  is an exploded view showing the fastener, and a portion of the installation tool, of the fastening apparatus shown in  FIG. 1 ; 
         FIGS. 7 and 8  are perspective, exploded views of the elements shown in  FIG. 5 ; 
         FIGS. 9-11  show details of the distal tip member of the fastener shown in  FIG. 5 ; 
         FIGS. 12 and 13  show details of the proximal main member of the fastener shown in  FIG. 5 ; 
         FIGS. 14-16  show details of the expander pin of the fastener shown in  FIG. 5 ; 
         FIGS. 17-19  show details of the pusher member of the installation tool shown in  FIG. 5 ; 
         FIG. 20  is an exploded side view of the handle assembly of the installation tool shown in  FIG. 1 ; 
         FIGS. 21-25  show the novel fastening apparatus of the present invention being used to attach soft tissue (or the like) to bone; 
         FIGS. 26-28  illustrate one preferred form of the novel fastening apparatus of the present invention being used to attach soft tissue (or the like) to bone; 
         FIGS. 29 and 30  illustrate another preferred form of the novel fastening apparatus of the present invention being used to attach soft tissue (or the like) to bone; 
         FIG. 31  is a side view showing an alternative form of proximal main member for a fastener formed in accordance with the present invention; 
         FIG. 32  is a side view showing an alternative form of distal tip member for a fastener formed in accordance with the present invention; 
         FIGS. 33-35  show details of an alternative form of the fastener&#39;s expander pin; 
         FIGS. 36-38  show details of another alternative form of the fastener&#39;s expander pin; 
         FIGS. 39-42  show details of the construction of an alternative form of fastener also formed in accordance with the present invention; 
         FIGS. 43 and 44  show the fastener of  FIGS. 39-42  being used to attach soft tissue (or the like) to bone; 
         FIG. 45  shows details of an alternative form of expander pin for the fastener shown in  FIGS. 39-44 ; 
         FIGS. 46-49  show details of the construction of another alternative form of fastener also formed in accordance with the present invention; 
         FIGS. 50-53  show the fastener of  FIGS. 46-49  being used to attach soft tissue (or the like) to bone; 
         FIG. 54  shows details of an alternative form of expander pin for the fastener shown in  FIGS. 46-53 ; 
         FIGS. 55 and 56  show details of a removal tool for removing a fastener formed and deployed in accordance with the present invention; 
         FIG. 57  illustrates an alternative embodiment of expandable body; 
         FIG. 58  illustrates an alternative embodiment of the expander pin; and 
         FIG. 59  illustrates another alternative embodiment of the expander pin. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Looking first at  FIG. 1 , there is shown a fastening apparatus  5  for attaching soft tissue (or the like) to bone. Fastening apparatus  5  generally comprises a fastener  10  and an installation tool  15 . 
     Looking next at  FIGS. 1-8 , fastener  10  generally comprises an expandable body  100  ( FIG. 2 ) and an expander pin  200 . 
     Expandable body  100  comprises a generally frusto-conical distal end  105  ( FIG. 5 ) characterized by a frusto-conical outer surface  110  terminating in a distal end surface (or rim)  115 , and a generally cylindrical proximal end  120  terminating in a proximal end surface  125 . A central passageway  130  extends through expandable body  100 , from distal end surface  115  to proximal end surface  125 . 
     In a preferred form of the invention, central passageway  130  comprises a bore  135  opening on distal end surface  115 , a threaded section  140 , and a bore  145  opening on proximal end surface  125 . 
     Expandable body  100  preferably also comprises bone securement apparatus  150  formed on proximal end  120  for facilitating securement of fastener  10  to bone, as will hereinafter be discussed in further detail. In one preferred form of the invention, bone securement apparatus  150  comprises a plurality of frusto-conical ribs  155 . Ribs  155  are tapered, distally-to-proximally, so as to (1) facilitate insertion of expandable body  100  into bone in a distal direction, and (2) resist withdrawal of expandable body  100  from bone in a proximal direction. 
     If desired, expandable body  100  can be formed out of a single piece of material. Preferably, however, and looking now at  FIGS. 1-13 , expandable body  100  comprises a distal tip member  160  ( FIG. 9 ) and a proximal main member  165  ( FIG. 12 ). 
     Distal tip member  160  ( FIGS. 9-11 ) preferably comprises the aforementioned frusto-conical outer surface  110 , distal end surface (or rim)  115 , internal bore  135 , and threaded section  140 . Distal tip member  160  also preferably comprises a proximally-extending, threaded projection  170 . Proximally-extending threaded projection  170  serves to secure distal tip member  160  to proximal main member  165 , as will hereinafter be discussed in further detail. 
     Proximal main member  165  ( FIGS. 12 and 13 ) preferably comprises the aforementioned proximal end surface  125 , bore  145  and bone securement apparatus  150  (preferably in the form of frusto-conical ribs  155 ). Proximal main member  165  also comprises a threaded counterbore  175  at its distal end. Threaded counterbore  175  is sized and shaped so as to matingly receive proximally-extending threaded projection  170  of distal tip member  160 , whereby the two elements may be secured to one another so as to form the complete expandable body  100 . 
     Referring to  FIG. 57 , it will be seen that in an alternative embodiment proximally-extending threaded projection  170  of the distal tip member  160  is of an annular configuration and is provided with internal threads  172 . Proximal main member  165  includes a projection  176  having external threads  178  thereon for engagement with the distal tip member internal threads  172 . Threaded projection  170  is sized and shaped so as to matingly receive threaded projection  176  of main member  165 , whereby the two elements  160 ,  165  may be secured to one another so as to form the complete expandable body  100 . 
     A primary advantage of forming expandable body  100  out of two separate components (i.e., distal tip member  160  and proximal main member  165 ) is that each component can be optimized for its own function. More particularly, inasmuch as distal tip member  160  is intended to help open a passageway in bone to receive the overall fastener  10 , distal tip member  160  is preferably formed out of a relatively hard material. At the same time, however, inasmuch as proximal main member  165  is intended to expand radially outwardly during deployment of the fastener so as to fix expandable body  100  (and hence the complete fastener  10 ) to bone, proximal main member  165  is preferably formed out of a relatively soft and easily expandable material. 
     Fastener  10  also comprises the expander pin  200 . Looking next at  FIGS. 1-8  and  14 - 16 , expander pin  200  generally comprises a shaft  205  and tissue attachment apparatus  210  associated with shaft  205 . Shaft  205  is sized so that it will not normally fit within central passageway  130  ( FIG. 5 ) of expandable body  100 . However, shaft  205  is also sized so that when expander pin  200  is driven longitudinally into expandable body  100 , the expander pin will force the side walls of expandable body  100  to expand radially outwardly against adjacent bone, whereby the expandable body (and hence the entire fastener) will be secured to a host bone, as will hereinafter be discussed in further detail. 
     Preferably, shaft  205  includes fastener stabilization apparatus  215  for stabilizing the longitudinal position of expander pin  200  relative to expandable body  100 , as will hereinafter be discussed in further detail. More particularly, fastener stabilization apparatus  215  is adapted to resist withdrawal of expander pin  200  from expandable body  100  once expander pin  200  has been driven into expandable body  100 , as will hereinafter be discussed in further detail. In one preferred form of the invention, fastener stabilization apparatus  215  comprises a screw thread  220  formed on the outer surface of shaft  205 . 
     Still looking now at  FIGS. 1-8  and  14 - 16 , in one preferred form of the invention, tissue attachment apparatus  210  comprises one or more lateral projections  225  adjacent to the proximal end of the shaft. The one or more lateral projections  225  collectively form a fastener head for holding tissue to bone, as will hereinafter be discussed in further detail. Lateral projections  225  may be formed with a substantially convex configuration, as shown in  FIG. 14 ; or lateral projections  225  may be formed with a substantially planar configuration, as shown in  FIG. 58 ; or lateral projections  225  may be formed with a substantially concave configuration as shown in  FIG. 59 . Furthermore, if desired, one or more distally-projecting longitudinal projections  226  ( FIG. 14 ) may be formed on the distal side of lateral projections  225  for enhancing the engagement of lateral projections  225  with underlying tissue. 
     Expander pin  200  includes a longitudinal passageway  230  extending the length of the expander pin. 
     Fastener  10  is intended to be used in conjunction with installation tool  15 . Looking next at  FIGS. 1-8 , installation tool  15  comprises a shaft  300  ( FIG. 6 ) terminating in a tapered distal point  310 . Tapered distal point  310  is preferably formed so as to be relatively hard, whereby it can open a passageway in bone to receive the overall fastener  10 , as will hereinafter be discussed in further detail. Threads  315  are formed on shaft  300  proximal to tapered distal point  310 . Shaft  300  is sized so that it may be received in the central passageway  130  ( FIG. 5 ) of expandable body  100 , and in longitudinal passageway  230  ( FIG. 16 ) of expander pin  200 . Threads  315  of shaft  300  are sized and positioned so that when fastener  10  (i.e., expandable body  100  and expander pin  200 ) is mounted on shaft  300 , shaft threads  315  can mate with the expandable body&#39;s threads  140 , whereby expandable body  100  can be secured to the distal end of shaft  300 . In one preferred form of the invention, the shaft&#39;s tapered distal point  310  and the expandable body&#39;s frusto-conical outer surface  110  ( FIG. 9 ) are coordinated with one another so that when expandable body  100  is screwed onto shaft  300 , the expandable body&#39;s frusto-conical outer surface  110  will form, in a rough sense, a continuation, or extension, of the taper of the shaft&#39;s tapered distal point  310  ( FIG. 5 ). 
     Preferably, the installation tool&#39;s shaft  300  comprises a thinner distal section  320  ( FIG. 5 ) proximal to the shaft&#39;s tapered distal point  310  and distal to the shaft&#39;s threads  315 , and a trailing section  325  proximal to shaft threads  315 , and a thicker proximal section  330  proximal to trailing section  325 . Trailing section  325  and thicker proximal section  330  together define an annular shoulder  335  at their intersection. A rib  340  is preferably formed on trailing section  325 , distal to annular shoulder  335 . 
     A pusher  400  ( FIGS. 5 and 17 ) is preferably mounted on shaft  300 . Pusher  400  is used to help deploy fastener  10  in bone, by transferring a force applied to the proximal end of pusher  400  onto a fastener  10  located at the distal end of pusher  400 . In the process, pusher  400  acts as a sort of safeguard to prevent the proximal end of fastener  10  (i.e., the proximal end of expander pin  200 ) from being damaged during the application of such force. Pusher  400  preferably comprises a tapered distal portion  405  characterized by a tapered outer surface  410  terminating in a distal end surface  415 , and a cylindrical proximal portion  420  characterized by a cylindrical outer surface  425  terminating in a proximal end surface  427 . Pusher  400  has a central bore  430  extending therethrough. Bore  430  is sized so that it will form a close sliding fit with rib  340  ( FIG. 6 ) of shaft  300 . A lip  435  ( FIG. 17 ) protrudes into central bore  430  adjacent to the pusher&#39;s proximal end surface  427 . Lip  435  is sized so that it may not pass by rib  340  of shaft  300 . 
     In one preferred form of the invention, shaft  300  includes a plurality of ribs  345  ( FIG. 6 ) on the shaft&#39;s thicker proximal section  330 , and installation tool  15  includes a handle assembly  500  ( FIG. 20 ). Each rib  345  includes an inclined surface  345 A disposed on the proximal side of the rib ( FIG. 6 ). The distal side of each rib  345  extends substantially perpendicular to the longitudinal axis of shaft  300 . 
     Handle assembly  500  comprises a body  501  having a handle grip  502 . A trigger  505 , having a plurality of fingers  507 , is pivotally connected to body  501 . Body  501  also comprises a bore  508  opening on the body&#39;s distal end, and a counterbore  509  opening on the body&#39;s proximal end. A shoulder  509 A is formed at the intersection of bore  508  and counterbore  509 . 
     Handle assembly  500  also comprises a hollow ram  515 . Ram  515  is sized so that it can slidably accommodate shaft  300 , as will hereinafter be discussed in further detail. Ram  515  comprises a narrower distal portion  520  terminating in a distal tip  510 , and a wider proximal portion  525  including a plurality of teeth  530 . A shoulder  535  is formed at the intersection of narrower distal portion  520  and wider proximal portion  525 . A slot  540  extends through the side wall of narrower distal portion  520 . 
     Ram  515  is mounted in body  510  in the manner shown in  FIGS. 1 and 20 , i.e., so that (1) the ram&#39;s narrower distal portion  520  extends through, and protrudes from, the body&#39;s bore  508 , (2) the ram&#39;s wider proximal portion  525  is disposed in the body&#39;s counterbore  509 , and (3) the trigger&#39;s fingers  507  engage the ram&#39;s teeth  530 . As a result of this construction, moving trigger  505  will cause ram  515  to move relative to body  501 . A spring  545  is positioned in body  501 , between body shoulder  509 A and ram shoulder  535 , so as to bias ram  515  in a proximal direction. A stop pin  550  extends into counterbore  509  so as to limit proximal movement of ram  515 . 
     Handle assembly  500  also comprises a gate  555  which includes an opening  560  therein. Opening  560  defines a bottom wall  565  thereof. Gate  555  is disposed in an opening  570  formed in body  501 . A spring  575  biases gate  555  against a locking pin  580 , which extends through an oversized hole  585  formed in gate  555 . Gate  555  is disposed in body  501  so that the gate&#39;s bottom wall  565  normally protrudes, via ram slot  540 , into the interior of ram  515 ; however, pressing gate  555  downward against the power of spring  575  will permit the gate&#39;s bottom wall  565  to be removed from the interior of ram  515 . 
     In use, and as will hereinafter be discussed in further detail, handle assembly  500  is loaded over the proximal end of shaft  300 , and moved proximally down the shaft until the gate&#39;s bottom wall  565  starts to engage the ribs  345  of shaft  300 . As this occurs, the inclined proximal surfaces  345 A of ribs  345  will allow the handle assembly  500  to be moved distally along shaft  300  to the extent desired. However, since inclined surfaces  345 A are provided on only the proximal sides of ribs  345 , the geometry of the ribs will prevent handle assembly  500  from moving back proximally along the shaft, unless gate  555  is pressed downward against the power of spring  575  so as to move the gate&#39;s bottom wall  565  out of engagement with the shaft&#39;s ribs. Handle assembly  500  is moved down shaft  300  until the ram&#39;s distal end surface  510  engages, or substantially engages, the proximal end  427  of pusher  400 . Thereafter, pulling of the handle assembly&#39;s trigger  505  will cause ram  515  to move distally along shaft  300 , whereby pusher  400  can drive expander pin  200  into expandable body  100  so as to set the expandable body in bone, as will hereinafter be discussed in further detail. 
     The use of handle assembly  500  in conjunction with shaft  300  is often preferred, since it permits shaft  300  to be held in place while ram  515  is advanced down shaft  300 . More particularly, inasmuch as handle assembly  500  is releasably secured to shaft  300  via the engagement of handle gate  555  with shaft ribs  345 , handle assembly  500  can stabilize shaft  300  even as the handle&#39;s ram  515  is advancing down shaft  300 . This has been found to be advantageous in many circumstances. However, it should also be appreciated that fastener  10  can be set without using handle assembly  500 , as will hereinafter also be discussed in further detail. 
     Looking next at  FIGS. 21-25 , there is shown a general method for attaching soft tissue (or the like) to bone using the fastener of the present invention. In particular, the invention will be discussed in the context of (1) a fastener  10  comprising an expandable body  100  and an expander pin  200 ; (2) an installation tool  15  comprising a shaft  300 ; and (3) a pusher  400  mounted on shaft  300 . 
     The foregoing fastening system is prepared for use by first passing pusher  400  proximally over the distal end of shaft  300  until the pusher&#39;s proximal end surface  427  ( FIG. 17 ) engages, or approximately engages, the shaft&#39;s annular shoulder  335  ( FIG. 6 ). Then the fastener&#39;s expander pin  200  is passed proximally over the distal end of shaft  300  until the proximal end of expander pin  200  engages, or approximately engages, the pusher&#39;s distal end surface  415  ( FIG. 17 ). Next, the fastener&#39;s expandable body  100  is passed proximally over the distal end of shaft  300  until the proximal end of the expandable body&#39;s threaded section  140  ( FIG. 5 ) engages the distal end of the shaft&#39;s threads  315  ( FIG. 6 ). Then the fastener&#39;s expandable body  100  is screwed onto shaft  300 . At this point, the proximal end surface  125  ( FIG. 12 ) of expandable body  100  will engage, or approximately engage, the distal end surface of expander pin  200 . It will be appreciated that at this point, the expandable body  100 , expander pin  200  and pusher  400  will be held relatively immobile on shaft  300 , by virtue of shaft shoulder  335  ( FIG. 6 ) and shaft threads  315  and the sizing of the elements held therebetween. 
     Next, soft tissue (or the like)  600  is “stabbed” with the sharp distal point of shaft  300  and dragged to its desired position against bone  700  ( FIG. 21 ). Alternatively, soft tissue  600  may be gripped by another instrument (e.g., forceps or the like) and moved into position against bone  700 . 
     Then, with soft tissue  600  in position against bone  700 , shaft  300  is forced distally through tissue  600  ( FIG. 22 ) and into bone  700  ( FIG. 23 ). It will be appreciated that, as this occurs, expandable body  100  will be carried into the bone, due to the screw engagement established between expandable body  100  and shaft  300 . In fact, the tapered distal ends of shaft  300  and expandable body  100  will cooperate with one another so as to force an opening in the soft tissue and the bone, without any need for pre-drilling. Shaft  300  is preferably driven into bone  700  until the proximal end surface  125  of expandable body  100  is approximately even with the outer surface of bone  700  ( FIG. 23 ). If desired, markings (not shown) may be placed on the outer surface of the fastener&#39;s expander pin  200  so that, once the thickness of soft tissue  600  is known, proper depth penetration can be achieved. 
     Next, the proximal end of pusher  400  is engaged with another element (not shown in  FIGS. 21-25 , but shown in subsequent figures) so as to move the pusher distally along shaft  300 . Pusher  400  is moved distally so as to drive expander pin  200  distally, into the central passageway  130  ( FIG. 5 ) of expandable body  100 , whereby to drive the side walls of expandable body  100  radially outwardly into bone  700  and thereby secure fastener  10  to bone  700  ( FIG. 24 ). At the same time, the fastener&#39;s tissue attachment apparatus  210  will secure soft tissue  600  to the bone. More particularly, as seen in  FIG. 24 , the head of expander pin  200  (made up of one or more lateral projections  225 ) will bear distally against soft tissue  600 , whereby to keep the soft tissue fixed against bone  700 . 
     Finally, shaft  300  is unscrewed from the expandable body&#39;s threads  140  ( FIG. 5 ) and removed ( FIG. 25 ), leaving fastener  10  securing soft tissue  600  to bone  700 . 
     In the embodiment shown in  FIG. 57 , widthwise expansion of the proximal main member  165  serves to urge the external threads  178  of the projection  176  into firm engagement with the internal threads  172  of the distal tip member  160 . Thus, the distal tip member  160  is securely held in place by the expanded proximal main member  165  to permit the shaft  300  to be unscrewed from the expandable body threads  140  and removed. 
     As noted above, in one preferred form of the invention, installation tool  15  is constructed so that shaft  300  includes ribs  345  ( FIG. 6 ) adjacent its proximal end, and the installation tool includes handle assembly  500  ( FIG. 20 ).  FIGS. 26-28  illustrate how soft tissue  600  may be attached to bone  700  using such an arrangement. More particularly, after pusher  400 , expander pin  200  and expandable body  100  have been attached to shaft  300  in the manner described above with respect to  FIGS. 21-25 , and either before or after shaft  300  is driven through soft tissue  600  and into bone  700  to the point shown in  FIGS. 23 and 26 , handle assembly  500  is passed distally over the proximal end of shaft  300  until the gate  555  engages ribs  345  of shaft  300 . Handle assembly  500  is then pushed further down shaft  300  until the distal tip  510  of ram  515  engages the proximal end of pusher  400 . Then trigger  505  is activated so as to move ram  515  distally relative to pusher  400  and fastener  10 , whereby the distal tip  510  ( FIG. 20 ) of the handle assembly&#39;s ram  515  will drive distally against the proximal end of pusher  400 . This will cause pusher  400  to move expander pin  200  distally, whereby to fix fastener  10  in bone  700 , with the fastener&#39;s head fixing soft tissue  600  to bone  700  ( FIG. 27 ). Then handle assembly  500  is removed proximally off shaft  300 , i.e., by first pressing gate  555  downward against the power of spring  575  so as to move the gate&#39;s bottom wall  565  out of engagement with ribs  345 , and then pulling the handle assembly  500  proximally off the shaft. Then shaft  300  is unscrewed from the expandable body&#39;s threads  140  and removed from the surgical site ( FIG. 28 ). 
     It will be appreciated that, by virtue of the relative sizing of shaft rib  340  ( FIG. 6 ) and pusher lip  435  ( FIG. 17 ), pusher  400  will be slidably retained on the distal end of shaft  300  even after shaft  300  has been unscrewed from fastener  10 , since pusher lip  435  will be unable to move past shaft rib  340 . 
     As noted above, the use of handle assembly  500  in conjunction with shaft  300  is frequently preferred, since it permits shaft  300  to be held in place while ram  515  is advanced down shaft  300 . More particularly, inasmuch as handle assembly  500  is releasably secured to shaft  300  via the engagement of handle gate  555  with shaft ribs  345 , handle assembly  500  can stabilize shaft  300  even as the handle&#39;s ram  515  is advancing down shaft  300 . In other words, since the fastener&#39;s expandable body  100  is connected to shaft  300  by the expandable body&#39;s threaded section  140  and shaft threads  315 , and inasmuch as handle assembly  500  is releasably secured to shaft  300  via the engagement of handle gate  555  with shaft ribs  345 , the handle assembly can advance its ram  515  against the fastener&#39;s expander pin  200  even while the handle assembly is holding the shaft  300 , and hence the fastener&#39;s expandable body  100 , in place. In effect, the use of handle assembly  500  in conjunction with shaft  300  permits a proximally-directed counterforce to be applied to expandable body  100  even as a distally-directed setting force is being applied to expander pin  200 . 
     However, it should also be appreciated that fastener  10  can be set without using handle assembly  500 , as will hereinafter be discussed in further detail. 
     Thus, in another preferred form of the invention, installation tool  15  may be constructed so that shaft  300  omits ribs  345  on its proximal end, and so that the installation tool  15  does not include handle assembly  500 . In this case, pusher  400  may be moved proximally on shaft  300  by other means. 
     For example, and looking now at  FIGS. 29 and 30 , a cannulated driver  800 , such as one having a so-called “slap hammer” configuration, can be used to drive pusher  400  distally on shaft  300 , whereby to complete setting of fastener  10  in bone  700 . 
     While the “slap hammer” construction shown in  FIGS. 29 and 30  is simple and effective, it does suffer from the disadvantage that a proximally-directed counterforce is not being applied to expandable body  200  even as the distally-directed setting force is being applied to expander pin  300 , as is the case with the use of handle assembly  500  described above. 
     It should be appreciated that, if desired, the expandable body&#39;s bone securement apparatus  150  ( FIG. 12 ) may be omitted or, alternatively, replaced by a configuration different than the ribs  155  ( FIG. 12 ) previously disclosed. By way of example but not limitation, bone securement apparatus  150  may comprise screw threads  155 A shown in  FIG. 31 . 
     It should also be appreciated that, if desired, the expandable body&#39;s distal end  105  ( FIG. 5 ) may have a configuration other than the smooth, frusto-conical one disclosed above. By way of example but not limitation, expandable body  100  may have screw threads formed on its tapered distal end. See, for example,  FIG. 32 , which shows the screw threads  110 A formed on distal tip member  160 . 
       FIGS. 33-35  show an alternative form of expander pin  200 . More particularly, the expander pin  200  shown in  FIGS. 33-35  is similar to the expander pin  200  shown in  FIGS. 14-16 , except that with the expander pin of  FIGS. 33-35 , lateral projections  225 A have their outlying edges  226  rounded into an arc-like configuration. 
       FIGS. 36-38  show yet another alternative form of expander pin  200 . More particularly, the expander pin  200  shown in  FIGS. 36-38  is similar to the expander pin  200  shown in  FIGS. 14-16 , except that with the expander pin of  FIGS. 36-38 , fastener stabilization apparatus  215  comprises a plurality of frusto-conical ribs  220 A, rather than the screw thread  220  shown in  FIGS. 14-16 . 
     It is also possible to form the fastener&#39;s tissue attachment apparatus  210  with a different configuration (and with a different manner of operation) than the tissue attachment apparatus shown in  FIGS. 14-16  or  33 - 36 . 
     More particularly, with the tissue attachment apparatus  210  shown in  FIGS. 14-16  and  33 - 36 , the tissue attachment apparatus essentially comprises a head for capturing the soft tissue to bone. However, it is also contemplated that tissue attachment apparatus  210  may comprise a suture-based mechanism for capturing the soft tissue to bone. 
     More particularly, and looking now at  FIGS. 39-42 , there is shown a fastener  10  in which tissue attachment apparatus  210  comprises a plurality of transverse bores  227  formed in expander pin  200  adjacent to its proximal end. Bores  227  accommodate one or more lengths of suture  228  ( FIG. 39 ) which may be used to tie a piece of soft tissue (or the like) to bone. In one preferred form of the invention, expander pin  200  includes a cylindrical proximal end portion  229  ( FIG. 40 ) having a diameter larger than the diameter of the central passageway  130  ( FIG. 5 ) of expandable body  100 , with transverse bores  227  being formed in cylindrical proximal end portion  229 . 
     In use, the fastener is set through soft tissue  600  and into bone  700  in the normal manner ( FIGS. 43 and 44 ); however, since the fastener lacks the lateral projections  225  ( FIG. 14 ) previously disclosed, the proximal end of expander pin  200  will pass through soft tissue  600  without binding it to the bone ( FIG. 44 ). However, sutures  228  will extend out of bone  700  and through soft tissue  600 . As a result, these sutures may then be used to tie the soft tissue down to the bone. 
     If desired, the expander pin  200  shown in  FIGS. 39-44  can be modified so as to have its fastener stabilization apparatus  215  in the form of ribs  220 A ( FIG. 45 ), rather than the screw thread  220  shown in  FIG. 40 . 
     With respect to the fastener configuration shown in  FIGS. 39-45 , it should be appreciated that by positioning transverse bores  227  ( FIG. 40 ) in the diametrically-enlarged proximal end portion  229 , the transverse bores  227  will remain proximal to expandable body  100  even after setting of the fastener ( FIG. 44 ). As a result of this construction, sutures  228  will be able to slip within bores  227  even after fastener  10  has been completely deployed in bone  700 . As will be apparent to persons skilled in the art, this can be advantageous in some circumstances during tissue fixation. 
     It is also possible to fabricate a fastener  10  with a suture-based mechanism for capturing soft tissue to bone, but where the sutures are prevented from slipping relative to the fastener once the fastener has been fully deployed in the bone. 
     More particularly, and looking now at  FIGS. 46-49 , there is shown a fastener  10  which includes an expander pin  200  having a plurality of transverse bores  227  intermediate its length ( FIG. 47 ). Bores  227  accommodate the one or more lengths of suture  228  which may be used to tie a piece of soft tissue (or the like) to bone. In one preferred form of the invention, expander pin  200  includes a cylindrical intermediate portion  229 A ( FIG. 47 ) having a diameter substantially the same as the remainder of the expander pin, with transverse bores  227  being formed in the cylindrical intermediate portion  229 A. 
     Looking next at  FIGS. 50-53 , in one preferred method of use, shaft  300  and expandable body  100  are driven into bone, and then a piece of suture  228  is looped around the soft tissue  600  which is to be attached to the bone  700  ( FIG. 50 ). Then the suture  228  is pulled taut so as to bring the soft tissue into close proximity to the fastener ( FIG. 51 ). Then pusher  400  is driven distally ( FIG. 52 ) so as to completely set the fastener. At this point, since suture  228  is attached to expander pin  200  intermediate the length of the expander pin, the suture will be fixed in place relative to the deployed expander pin and, hence, will secure soft tissue  600  to bone  700 . Installation tool  15  is then removed from the surgical site by unscrewing shaft  300  from expandable body  100  ( FIG. 53 ). 
     If desired, expander pin  200  can also be formed so that its suture-receiving bores  227  are located adjacent to the distal end of the expander pin. For example, in another preferred form of the invention, expander pin  200  includes a cylindrical distal end portion  229 B ( FIG. 54 ) having a diameter substantially the same as the remainder of the expander pin, with transverse bores  227  being formed in the cylindrical distal end portion. 
     Looking next at  FIGS. 55 and 56 , there is shown a removal tool  800 . Removal tool  800  can be used to remove a previously-deployed fastener  10 , if the same should prove necessary or desirable. Removal tool  800  generally comprises a shaft  805  having a reverse thread  810  formed on its distal end and a handle  815  formed on its proximal end. The distal end of removal tool  800  is sized so as to be significantly larger than the longitudinal passageway  230  ( FIG. 16 ) formed in expander pin  200 . 
     When a previously-deployed fastener  10  is to be removed, the distal end of removal tool  800  is screwed into the proximal end of expander pin  200  using the removal tool&#39;s reverse screw thread  810 . Inasmuch as the distal end of the removal tool is significantly larger than the longitudinal passageway  230  formed in expander pin  200 , this action will cause the removal tool&#39;s distal threads  815  to force their way into the side wall of expander pin  200  and, depending on the sizing of the removal tool, possibly into the side wall of expandable body  100  as well. In any case, as the reverse thread  810  of the removal tool is screwed into the expander pin, continued reverse screwing will eventually cause the normally-threaded expander pin  200  to unscrew itself from expandable body  100 . Removal tool  800  may then be used to remove expander pin  200  from expandable body  100 . Expandable body  100  may then itself be removed from the surgical site by passing shaft  300  back into the interior of expandable body.  100 , screwing the shaft&#39;s threads  315  into the expandable body&#39;s threaded section  140 , and then removing the shaft and expandable body from the bone.