Patent Publication Number: US-10765465-B2

Title: Tensioning instrument

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/837,615, filed Mar. 15, 2013, which claims the benefit of U.S. Patent Application No. 61/728,930 filed Nov. 21, 2012, which are both hereby incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a bone plate system and, more particularly, to a bone plate system for securing and stabilizing a plurality of bones. 
     BACKGROUND OF THE INVENTION 
     There are presently many different types of plate and fixture systems for securing bones so that the secured bones may fuse or heal. As used herein, the term bone may refer to a bone or a portion of a bone. One application for plate and fixture systems is in the field of cardiovascular surgery, where access to a patient&#39;s heart may be obtained by cutting the sternum of the patient longitudinally from the manubrium through the xiphoid process. Cutting the sternum longitudinally creates halves of the sternum that may be separated to provide access to the chest cavity. After the patient&#39;s heart is operated upon, the sternal halves are brought back together and secured to one another. One approach for securing the sternal halves involves looping a metal wire around the sternal halves and twisting ends of the wire to secure the wire in tight engagement extending about the cut sternum bone halves. This process is repeated at several longitudinally spaced positions along the cut sternum in order to restrict separation and shifting of the sternal halves post-surgery. However, the twisted wires may loosen over time and permit relative movement of the sternal halves which adversely affects post-operative fusion of the sternal halves. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect, a bone plate system is provided for securing and stabilizing portions of one or more bones, such as halves of a sternum after the sternum has been cut longitudinally to provide access to an underlying chest cavity. The bone plate system includes a bone plate, a cable configured to be looped around the portions of the one or more bones and connected to the bone plate, and opposite halves of the bone plate that are laterally spaced apart from each other and which are configured for engaging a bone portion on either side of an incision that separates the bone portions. The bone plate has a locking device that interconnects and extends laterally between the spaced bone plate halves and resists relative movement therebetween. The locking device has an unlocked configuration that allows the cable to be shifted relative to the bone plate as tension is applied to the cable. Tensioning the cable tightly wraps the cable about the bone portions, approximates the bone portions together, and draws the bone plate tightly against the approximated bone portions to rapidly and efficiently produce a construct of the bone plate, cable, and approximated bone portions. 
     Once the cable has been tightened to a desired tension, the locking device of the bone plate may be reconfigured to a locked configuration which rigidly fixes the cable to the bone plate and secures the bone plate and cable about the bones. The bone plate halves include a plurality of throughbores for receiving bone anchors for anchoring the bone plate halves in engagement with the bone portions. In this manner, the bone plate system utilizes both the high tensile strength of the cable and the rigid fixation of the bone anchors to the bone plate to provide two load bearing mechanisms which resist separation and movement of the bone portions. 
     In accordance with another aspect, a method of securing and stabilizing a plurality of bone portions is provided. The method includes connecting a trailing end portion of a cable to a bone plate, positioning the bone plate adjacent the bone portions, advancing a leading end portion of the cable around the bones to form a loop of the cable around the bone portions, and connecting the leading end portion of the cable to the bone plate. In one form, connecting the cable to the bone plate includes advancing the leading end portion of the cable through an aperture of the bone plate sized so that there is a slip fit between the cable and the bone plate. The method further includes tightening the loop of cable around the bone portions to seat the bone plate against the bone portions. In one approach, tightening the loop of cable around the bone portions includes pulling the leading end portion of the cable away from the bone plate and urging the bone portions together. As the cable loop is tightened around the bone portions, the tension force acting along the surgical cable substantially simultaneously urges the bone portions together (if they are separated), draws the bone plate against the bone portions, and firmly seats the bone plate against the bone portions. The method further includes reconfiguring a locking device associated with the bone plate to a locked configuration to fix the locking device to the cable and secure the bone plate, cable, and bone portions to one another. In this manner, the method provides a rapid and straightforward approach for urging a plurality of bone portions together, seating a bone plate against the bone portions, and securing the bone plate, cable, and bone portions to one another. 
     The method further includes driving bone anchors through openings in the bone plate and into the bone portions to rigidly fix the bone plate to the bone portions. One advantage of using the cable to draw the bone plate against the bone portions and seat the bone plate against the bone portions is that the bone plate can be secured against the bone portions using the cable before the bone anchors are used to provide additional fixation of the bone plate to the bone portions. This may reduce shifting of the bone plate on the bone portions while driving the bone anchors through the openings in the bone plate. Another advantage of using the cable to draw the bone plate against the bone portions and seat the bone plate against the bone portions is that the bone plate may be firmly seated against the bone portions even if the bone portions are weakened, such as bones having a thin cortical section and/or voids between cortical sections. This approach stands in contrast to some prior fixation systems that exclusively utilize bone screws to seat a plate member against bones. If the bones are weakened, the bone screws of these prior fixation systems may not have sufficient purchase with the bones to draw the bone plate against the bones and fully seat the bone plate. 
     In another aspect, a bone plate system is provided for stabilizing portions of one or more bones that provides an easier-to-use approach for stabilizing the bone portions. The bone plate system includes a bone plate and a connector device having a flexible portion for being looped around the bone portions and secured to the bone plate. The bone plate has a deformable member with a throughbore configured to receive the connector device extending therethrough. The deformable member has exposed opposing crimp portions disposed across the throughbore from one another with the opposed crimp portions being configured to be deformed toward each other to fix the connector device to the bone plate. The exposed opposing crimp portions may thereby provide more secure and durable locking of the connector device to the bone plate than some conventional approaches that utilize a single stud to pinch a wire or cable against a channel wall. 
     The deformable member may be a cylindrical, tubular member and the crimp portions may be diametrically opposed from one another across the throughbore. The tubular member presents a less obtrusive profile than some prior approaches that utilize outwardly projecting locking members. This reduces the likelihood of tissues becoming pinched by or otherwise entangled with the features of the locking device. 
     In one form, the bone plate includes a pair of tool-receiving through openings on opposite sides of the deformable member. The tool-receiving through openings are sized to accommodate a user positioning a tool in the through openings, such as advancing jaws of a crimping tool into the through openings. One of the opposing crimp portions of the deformable member extend along one of the pair of bone plate through openings and the other crimp portion extends along the other of the pair of through openings. In this manner, the crimp portions of the deformable member are readily accessible to a tool advanced into the bone plate through openings so that the tool may be used to deform the deformable portions. 
     In another form, the bone plate includes a pair of elongated, spaced tool alignment members connected to the deformable member and extending generally parallel to one another on opposite sides of the deformable member. The tool alignment members define at least a portion of a tool-receiving through opening of the bone plate. The tool alignment members may be separated by a predetermined distance that is slightly larger than a width of a jaw of a crimping tool to provide the jaw with clearance to be inserted into the tool-receiving through opening. This cooperating configuration also aligns the jaws of the crimping tool with the crimp portions along the deformable member and ensures that the jaws of the crimping tool engage the crimp portions of the deformable member. 
     The bone plate system is especially advantageous for emergency reentry situations wherein the chest cavity must be accessed after utilizing the bone plate system to secure halves of a cut sternum together. Emergent reentry situations may include situations where the patient suffers a heart attack after installation of the bone plate system. Because the cable is disposed within the throughbore of the bone plate deformable member, cutting the deformable member cuts the deformable member and the cable in one step. This is especially advantageous when compared to prior systems with separate approximating wires and bone plates disposed along the cut sternum which may require separate tools for cutting the approximating wires and the bone plates. Separately cutting the approximating wires and the bone plates of these prior systems may increase the time it takes to gain access to the chest cavity of the patient in an emergent reentry situation. 
     In accordance with another aspect, an instrument for tensioning a surgical cable is provided. The tensioning device has a rotary tensioning device configured to have a cable wound thereon and a ratchet assembly that permits turning of the rotary tensioning device in a wind up direction and selectively resists turning of the rotary tensioning device in a pay out direction. By wrapping the surgical cable about the rotary tensioning device, the tensioning device can take up and tension a relatively long section of surgical cable. This approach stands in contrast to some prior surgical cable tensioning instruments that, in order to tension a cable, utilize a cable tensioning mechanism which linearly translates a cable locking mechanism secured to the cable. With these devices, the overall length of the device is directly proportional to the length of linear travel of the tensioning mechanism such that tensioning larger sections of cable requires a proportionally larger tensioning device. 
     The rotary tensioning device has gripping portions configured to shift relative to each other with turning of the rotary tensioning device. Specifically, turning the rotary tensioning device in the wind up direction shifts the rotary tensioning device form a pass through configuration that permits the cable to be drawn through the gripping portions to a gripped configuration that fixes the cable relative to the shifted gripping portions. In this manner, tension can be applied to the fixed cable by simply turning the rotary tensioning device in the wind up direction. Thus, the tensioning instrument provides an improvement over some conventional tensioning instruments that require a user to perform separate manual operations of locking the tensioning instrument to the cable and then applying tension to the cable, such as by using different handles of the instrument to perform the locking and tensioning operations. 
     In one form, the ratchet assembly has a tensioning configuration that permits a surgeon to incrementally rotate the rotary tensioning device in a wind up direction, wrap the cable about the rotary tensioning device, and apply tension to the cable. By permitting incremental tensioning of the cable, the surgeon receives tactile feedback as the cable is tensioned and may stop rotating the rotary tensioning device once the desired tension has been reached. At this point, the cable may be secured, for example, in a looped configuration around a pair of bone portions using a locking device of a bone plate as described in greater detail below. With the cable secured, the ratchet assembly may be reconfigured to a release configuration to permit the rotary tensioning device to rotate in the pay out direction and allow the tensioning device to be removed from the surgical cable. 
     The ratchet assembly may include a drive for turning the rotary tensioning device and a release mechanism having a release configuration that disengages the drive from the rotary tensioning device and a tensioning configuration that engages the drive to the rotary tensioning device. With the release mechanism in the engaged configuration, the drive is connected to the rotary drive device such that turning of the drive produces turning of the rotary tensioning device. With the release mechanism in the disengaged configuration, the rotary tensioning device can turn relative to the drive which allows the tensioning instrument to be removed from the cable, such as by pulling the tensioning instrument off of the surgical cable. Pulling the tensioning instrument off of the surgical cable turns the rotary tensioning device and causes the cable to be unwound from the rotary tensioning device. Further, because the drive is disengaged from the rotary tensioning device, turning of the rotary tensioning device due to unwinding of the cable therefrom generally does not produce movement of the drive which makes the tensioning instrument easier to handle as it is removed from the cable. 
     In another aspect, a method is provided for approximating and securing a plurality of bone portions using a cable and a tensioning instrument that is configured to quickly and easily tension the cable around the bone portions. The method includes positioning a trailing end portion of the cable and a locking device connected thereto adjacent one or more of the plurality of bone portions and advancing a leading end portion of the cable around the plurality of bone portions and into the locking device to form a loop of the cable around the bone portions. The method includes feeding the leading end portion of the cable through a distal end of the tensioning instrument, advancing the cable between gripping portions of a rotary tensioning device of the tensioning instrument, and outward though a proximal end of the tensioning instrument. Next, the tensioning instrument is shifted downward along the cable until the distal end of the tensioning instrument abuts the locking device. The leading end portion of the cable is then pulled away from the locking device to draw slack out of the cable. 
     The method further includes turning the rotary tensioning device to substantially simultaneously lock the rotary tensioning device to the cable and tension the cable. Turning the rotary tensioning device locks the cable to the rotary tensioning device by reconfiguring the gripping portions of the rotary tensioning device from a pass-through configuration that permits the cable to be advanced through the gripping portions to a gripped configuration which fixes the cable relative to the shifted gripping portions. Further, turning the rotary tensioning device tensions the cable by drawing a portion of the cable on a distal side of the rotary tensioning device onto the rotary tensioning device while the distal end of the tensioning instrument remains abutting the locking device. If the bone portions are separated, turning of the rotary tensioning device tensions the looped cable around the bone portions and approximates the bone portions together. The method further includes selectively locking the rotary position of the rotary tensioning device once the cable has been sufficiently tensioned in order to maintain the cable at the desired tension. The locking device of the cable may then be reconfigured to a locked configuration to secure the tightened loop of cable around the bone portions. In one form, turning the rotary tensioning device also draws a portion of the cable onto the rotary tensioning device from a proximal side of the rotary tensioning device. The tensioning device preferably has an interior cavity sized to accommodate relatively long lengths of cable being drawn onto the rotary tensioning device from both the distal and proximal sides of the rotary tensioning device. The method thereby provides a quick and elegant approach to tensioning and securing a cable around a plurality of bone portions and, in some applications, approximating the bone portions while tensioning the cable. 
     In accordance with another aspect, an instrument for tensioning a surgical cable is provided. The instrument includes a rotary tensioner operable to have a surgical cable wound up thereon and a ratchet assembly that permits turning of the rotary tensioner in a wind up direction. The ratchet assembly, however, resists turning of the rotary tensioner in a pay out direction. The instrument further includes a drive operably connected to the rotary tensioner and having a handle configured to be turned in a first rotary direction to cause the drive to turn the rotary tensioner in the wind up direction and wind cable onto the rotary tensioner. The handle is configured to be turned in a reverse, second rotary direction to operatively disengage the drive from the ratchet assembly and permit the rotary tensioner to turn in the pay out direction. In this manner, the handle of the instrument is turned in the first rotary direction to apply a desired tension to the surgical cable and, after the cable has been crimped or otherwise secured, the handle is turned in the opposite, second rotary direction to pay out the surgical cable from the rotary tensioner and allow the instrument to be removed from the surgical cable. The instrument thereby allows a surgeon to quickly apply tension to a cable, crimp or otherwise secure the tensioned cable, and remove the instrument from the cable. Further, because the handle is turned in the second rotary direction to pay out the surgical cable, the instrument is more reliable and can overcome friction caused by the cable being wrapped on itself. The handle may be sized to provide a desired amount of leverage to overcome friction in the cable and make paying out the cable easier. 
     In yet another aspect of the present invention, an instrument for tensioning a surgical cable is provided that includes a drive shaft assembly connecting a handle and a rotary tensioner. The instrument has a ratchet assembly that is operatively engageable with the drive shaft assembly and permits turning of the drive shaft assembly in a first rotary direction and resists turning of the drive shaft assembly in a second rotary direction. The drive shaft assembly includes a pair of shaft members configured to turn relative to each other with turning of the handle in the second rotary direction which operatively disengages the drive shaft assembly from the ratchet assembly and permits the drive shaft assembly to turn in the second rotary direction. The drive shaft assembly further includes a biasing member that resists relative turning of the shaft members and urges the shaft assembly back into operative engagement with the ratchet assembly. Because turning the handle in the first rotary direction causes the rotary tensioner to turn in a wind up direction and turning the handle in the second rotary direction causes relative turning of the shaft members, the handle thereby controls both applying tension to a surgical cable and operatively disengaging the drive shaft from the ratchet assembly to remove the instrument from the surgical cable after tensioning. This makes the instrument easier to use since the surgeon has to interface with only one handle to control both cable tensioning and instrument removal operations. Further, the biasing member automatically returns the shaft assembly back into operative engagement with the ratchet assembly which simplifies use of the instrument. 
     In accordance with another aspect, an instrument for tensioning a surgical cable is provided that includes a rotary tensioner, a drive shaft connected to the rotary tensioner, and a ratchet assembly having a pawl and a ratchet gear. The instrument includes at least one release member having a drive position wherein turning of the drive shaft in a first rotary direction causes the rotary tensioner to turn in the wind up direction for winding up surgical cable on the rotary tensioner. The at least one release member also has a release position wherein the rotary tensioner is permitted to turn in a pay out direction for unwinding the surgical cable from the rotary tensioner. The instrument further includes a first actuator that is operable to shift the at least one release member between the drive position and the release position without disengaging the pawl from the ratchet gear. In this manner, the at least one release member may be shifted between the drive and release positions to permit the rotary tensioner to turn in the pay out direction without having to overcome a force maintaining the pawl and ratchet gear in engagement. Further, by separating the release and ratchet operations, the at least one release member may be shifted from the release position to the drive position without having to suddenly re-engage the pawl and ratchet gear which reduces wear on the pawl and ratchet gear. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a bone plate system in accordance with the present invention positioned on a sternum that has been cut longitudinally; 
         FIG. 2  is a perspective view of the bone plate system of  FIG. 1  showing surgical cables of the bone plate system having opposite ends of the surgical cables connected to a plate member of the bone plate system; 
         FIG. 3  is a perspective view of the bone plate of the bone plate system of  FIG. 1  showing laterally spaced halves of the bone plate with throughbores therein for receiving bone anchors; 
         FIG. 4  is a cross sectional view taken across line  4 - 4  in  FIG. 3  showing through apertures of the bone plate at one end thereof; 
         FIG. 5  is an enlarged elevational view of the bone plate member of  FIG. 1  showing the through apertures of the bone plate shown in  FIG. 4 ; 
         FIG. 6  is a perspective view of the surgical cables of the bone plate system of  FIG. 1  showing plugs of the surgical cables that abut surfaces of the through apertures of the bone plate and restrict the surgical cables from passing through the apertures; 
         FIG. 7  is a cross sectional view taken across line  7 - 7  in  FIG. 4  showing threads of the throughbores disposed between the upper and lower surfaces of the bone plate; 
         FIG. 8  is a side elevational view of the bone plate of  FIG. 1  showing generally flat upper and lower surfaces of the bone plate; 
         FIGS. 9-16  illustrate a method of using the bone plate system of  FIG. 1  to secure the halves of the cut sternum; 
         FIGS. 16A-16D  illustrate an alternative approach of using the bone plate system of  FIG. 1  to secure the halves of the cut sternum; 
         FIG. 17  is an elevational view of one of the bone screws of the bone plate system of  FIG. 1  showing threads on both the head and shank of the bone screw; 
         FIG. 18  is a perspective view of the bone screw of  FIG. 17  showing radially extending undercuts in the head of the bone screw for engaging a retention mechanism of a driver tool; 
         FIG. 18A  is a perspective view of a driver tool showing a centering pin projecting from a distal end of the tool for centering the tool on a screw head; 
         FIG. 19  is a perspective view of another bone plate member having a general curvature of the bone plate along its length; 
         FIGS. 20 and 21  are elevational views of the bone plate of  FIG. 19  showing a generally convex upper surface of the bone plate and a generally concave lower surface of the bone plate; 
         FIG. 22  is a perspective view of another plate member having a single locking device for locking a surgical cable to the bone plate; 
         FIG. 23  is a plan view of the bone plate of  FIG. 22  with a surgical cable having one end connected to the bone plate and an opposite end with a hook disposed thereon for advancing around bones; 
         FIG. 24  is an enlarged perspective view of the bone plate and surgical cable of  FIG. 23  showing the end of the surgical cable connected to the bone plate; 
         FIG. 25  is a cross sectional view taken across line  25 - 25  in  FIG. 22  showing through apertures of the bone plate for receiving the surgical cable; 
         FIGS. 26 and 27  are elevational views of the bone plate of  FIG. 22  showing a generally convex upper surface and a generally concave lower surface of the bone plate; 
         FIG. 28  is a perspective view of another plate member showing a single locking device of the bone plate disposed at one end of the bone plate; 
         FIGS. 29-32  are views of another bone plate and screws for use therewith; 
         FIG. 33  is an elevational view of the bone plate of  FIG. 29  showing a generally convex upper surface and a generally concave lower surface of the bone plate; 
         FIG. 34  is a perspective view of an alternative screw showing upstanding features of the screw head for engaging a retention feature of a driver tool; 
         FIG. 35  is a plan view of another plate member having a single locking device for locking a surgical cable to the bone plate 
         FIG. 36  is a perspective view of the bone plate of  FIG. 35 ; 
         FIGS. 37 and 38  are elevational views of the bone plate of  FIG. 36  showing a generally convex upper surface of the bone plate and a generally concave lower surface of the bone plate; 
         FIGS. 39 and 40  are perspective views of another cable tensioning instrument showing a distal end into which a surgical cable may be advanced and a proximal end with an outlet opening through which the surgical cable is pulled outward therefrom; 
         FIG. 41  is an exploded perspective view of the tensioning device of  FIG. 39 ; 
         FIG. 41A  is an enlarged end elevational view of a drive shaft of the tensioning instrument of  FIG. 39 ; 
         FIG. 42  is a front perspective view of a tension drive of the tensioning instrument of  FIG. 39  showing a drive socket of the tension drive; 
         FIG. 43  is a rear perspective view of the tension drive of  FIG. 42  showing a recess for receiving a pin connected to a tension ring of the tensioning device of  FIG. 39 ; 
         FIG. 44  is a perspective view of the tension ring of the tensioning instrument of  FIG. 39  showing a central opening of the tension ring which receives the tension drive; 
         FIG. 45  is an elevational view of the tensioning instrument of  FIG. 39  showing an outer profile of a body of the tensioning device; 
         FIG. 46  is a cross sectional view taken across line A-A in  FIG. 45  showing a distal end of the tensioning instrument abutting a locking device and a simplified surgical cable extending through the tensioning instrument to illustrate a path of the surgical cable from the locking device through the tensioning instrument; 
         FIG. 47  is a cross sectional view similar to  FIG. 46  showing the surgical cable locked to a rotary tensioning device of the tensioning instrument after a handle of the tensioning instrument has been turned ninety degrees; 
         FIG. 48  is an elevational view of the tensioning instrument of  FIG. 39  showing a cap welded to the body of the tensioning instrument to secure components of the tensioning instrument within the body; 
         FIG. 49  is a cross-sectional view taken across line B-B in  FIG. 48  showing a portion of the drive shaft received in the drive socket of the tension drive so that the drive shaft is in operative engagement with the tension drive; 
         FIG. 50  is a cross sectional view similar to  FIG. 49  showing the tension drive and the tension ring rotated after the handle connected to the drive has been turned ninety degrees; 
         FIG. 51  is a cross sectional view similar to  FIG. 50  showing a release button of the handle pressed and a button shaft connected to the release button disengaging the socket of the tension drive from the drive shaft; 
         FIG. 52  is a top plan view of the tensioning device showing openings of the tension drive and the tension ring aligned with the outlet opening of the body of the tensioning device when the handle is aligned with a surgical cable path through the tensioning device; 
         FIG. 53  is a perspective view of another cable tensioning instrument; 
         FIG. 54  is an exploded perspective view of the tensioning instrument of  FIG. 53 ; 
         FIG. 55  is a fragmentary view of components of the cable tensioning instrument of  FIG. 53  including a drive shaft and a ratchet assembly; 
         FIG. 56  is a partial cross-sectional view of a release shaft of the tensioning instrument disposed in the drive shaft; 
         FIG. 57  is a perspective view of a tension drive of the tensioning instrument of  FIG. 53  showing a socket that receives a drive portion of the drive shaft; 
         FIG. 58  is an elevational view of the tension drive of  FIG. 57  showing a longitudinal groove formed in a face of the tension drive; 
         FIG. 59  is a plan view of the tension drive of  FIG. 57  showing end plates of the tension drive that define a recess therebetween; 
         FIG. 60  is a perspective view of a clamp member that is received in the recess of the tension drive,  FIG. 60  showing a face of the clamp member and a groove formed therein; 
         FIG. 61  is a cross-sectional view taken across line  61 - 61  in  FIG. 53  showing the drive shaft connected to the socket of the tension drive and a head of the release shaft aligned with ball bearings in the drive shaft drive portion; 
         FIG. 62  is a cross-sectional view similar to  FIG. 61  showing the release shaft head shifted out of alignment with the ball bearings which permits the ball bearings to shift inwardly and disengage the drive shaft from the tension drive; 
         FIG. 63  is a cross-sectional view taken across line  63 - 63  in  FIG. 53  and shows a through passage of a body of the tensioning instrument that is aligned with a through opening formed between the tension drive and the clamp member; 
         FIG. 64  is an enlarged cross-sectional view similar to  FIG. 63  showing a protrusion of the clamp member disposed in a complementary recess of the instrument body; 
         FIG. 65  is a cross-sectional view similar to  FIG. 64  showing a handle of the instrument having been turned which moves the clamp member protrusion out of the body recess and into engagement with an inner surface of the body; 
         FIG. 66  is a perspective view of a bone anchor having a generally cross-shaped drive recess; 
         FIG. 67  is a plan view of the bone anchor of  FIG. 66  showing features of the drive recess; 
         FIG. 68  is a perspective view of a distal end portion of a driver tool for use with the bone anchor of  FIG. 66 ; and 
         FIG. 69  is an elevational view of the distal end portion of the driver tool of  FIG. 68  showing a distal tapered post of the driver tool. 
         FIG. 70  is a perspective view of another cable tensioning instrument; 
         FIG. 71  is an exploded view of the cable tensioning instrument of  FIG. 70  showing a drive shaft assembly of the instrument which includes a handle shaft, a torsion spring, and a tensioner shaft; 
         FIG. 72  is a cross-sectional view taken across line  72 - 72  in  FIG. 70  showing the handle shaft extending within the tensioner shaft and the torsion spring extending within the handle shaft; 
         FIG. 73A  is a side elevational view of a portion of the tensioning instrument of  FIG. 70  showing a ratchet gear carried on the tensioner shaft and a pawl engaged with the ratchet gear; 
         FIG. 73B  is a top plan view of the portion of  FIG. 73A  with a handle of the tensioning instrument removed to show a pin extending through an elongated slot of the tensioner shaft and abutting an end of the elongated slot; 
         FIG. 73C  is a top plan view similar to  FIG. 73B  showing the handle shaft having been turned to abut the pin against an opposite end of the elongated slot of the tensioner shaft; 
         FIG. 74  is an exploded view of the tensioner shaft, a tension drive formed integrally with the tensioner shaft, the ratchet gear, and balls operable to engage the tensioner shaft and the tension drive relative to the ratchet gear; 
         FIG. 75  is a cross-sectional view taken across line  75 - 75  in  FIG. 72  showing the handle shaft maintaining the balls in a radially outward position which operatively engages the tensioner shaft and the ratchet gear; 
         FIG. 76  is a cross-sectional view similar to  FIG. 75  showing the handle shaft turned counter-clockwise and the balls shifted radially inward to disengage the tensioner shaft from the ratchet gear and permit the tension drive to turn in a pay out direction; 
         FIG. 77  is an end elevational view of the handle shaft showing an angled slot within the handle shaft that receives one end of the torsion spring; 
         FIG. 78  is an elevational view of the tensioner shaft and tension drive showing a vertical slot of the tensioner shaft that receives an opposite end of the torsion spring; 
         FIG. 79  is a cross-sectional view taken across line  79 - 79  in  FIG. 72  showing a protrusion of a clamp member of the rotary tensioner disposed in a complimentary recess of a body of the tensioning instrument; and 
         FIG. 80  is a cross-sectional view similar to  FIG. 79  showing the handle of the tensioning instrument having been turned which moves the clamp member protrusion out of the body recess and into engagement with an inner surface of the body. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , there is provided a bone plate system  10  for securing portions of one or more bones. In one approach, the bone plate system  10  is used to secure a sternum  12  that has been cut  14  into halves  16 ,  18  with the cut  14  extending longitudinally along the sternum  12 . The bone plate system  10  includes a bone plate, such as plate member  20 , and surgical cables  22 ,  24  configured to be advanced around the sternal halves  16 ,  18  and form loops  23 ,  25  (see  FIG. 2 ) about the sternal halves  16 ,  18 . Each surgical cable  22 ,  24  has a trailing end portion  26  connected to the bone plate  20  and a leading end portion  28  configured to be advanced around the sternal halves  16 ,  18  and into openings  30 ,  32  of the bone plate  20 . The openings  30 ,  32  are sized to form a slip fit between the bone plate  20  and the surgical cables  22 ,  24 . To tighten the loops of the cables  22 ,  24  about the sternal halves  16 ,  18 , the bone plate  20  is held adjacent the sternal halves  16 ,  18  and the leading end portions  28  of the surgical cables  22 ,  24  are advanced in directions  33 ,  35 . As the surgical cables  22 ,  24  tighten around the sternal halves  16 ,  18 , the tension forces in the surgical cables  22 ,  24  urge the sternal halves  16 ,  18  together, draw the bone plate  20  against the sternal halves  16 ,  18 , and firmly seat the bone plate  20  against the sternal halves  16 ,  18 . The bone plate system  10  thereby allows rapid and substantially simultaneous approximation of the sternal halves  16 ,  18 , drawing of the bone plate  20  toward the sternal halves  16 ,  18 , and seating the bone plate  20  against the sternal halves  16 ,  18  as the surgical cables  22 ,  24  are tensioned about the sternal halves  16 ,  18 . 
     The bone plate system  10  has a pair of locking devices  40 ,  41  disposed at opposite ends of the bone plate  20  for fixing the bone plate  20  to the surgical cables  22 ,  24 . As discussed in greater detail below, after the leading end portions  28  of the surgical cables  22 ,  24  have been advanced through openings  30 ,  32  of the bone plate  20  and properly tensioned, the locking devices  40 ,  41  are reconfigured to a locked configuration to fix the bone plate  20  to the surgical cables  22 ,  24 . The surgical cables  22 ,  24  have high tensile strength and, once looped around the sternal halves  16 ,  18  and fixed to the bone plate  20 , serve as a primary load bearing mechanism that resists separation and relative movement of the sternal halves  16 ,  18 . Thus, the bone plate system  10  provides a straightforward and easy-to-use apparatus for forming a secure construct of the sternal halves  16 ,  18 , bone plate member  20 , and surgical cables  22 ,  24 . 
     The bone plate  20  has a body  42  extending along the length of the bone plate  20  between the locking devices  40 ,  41  that includes a plurality of throughbores  44  for receiving bone anchors, such as bone screws  46 . The bone screws  46  are driven into the throughbores  44  and sternum  12  to fix the bone plate  20  to both halves  16 ,  18  of the sternum  12 . With the bone screws  46  fully driven into the sternal halves  16 ,  18 , the bone screws  46  provide anchor points to transmit loading from the sternal halves  16 ,  18  to the bone plate  20  and reinforce the sternum  12 . In this manner, the bone plate system  10  utilizes the high tensile strength of the surgical cables  22 ,  24  extending tightly about the bone plate  20  as a primary load bearing mechanism and the rigid engagement between the screws  46  and the bone plate  20  as a secondary load bearing mechanism to resist to relative movement of the sternal halves  16 ,  18 . By utilizing both load bearing mechanisms, the bone plate system  10  provides for load bearing between the primary load bearing cables  22 ,  24  and the secondary load bearing screws  46  with greater post-operative stability and fixation of the sternal halves  16 ,  18  than either load bearing mechanism on its own. As will be apparent, the bone plate system  10  may be used to secure and stabilize many different types of bones, bone fragments, and portions of bones. The bone plate system  10  may also be used to hold one or more medical implant devices, such as a splint, rod, graft, or the like, against one or more bones. 
     With respect to  FIG. 2 , the bone plate  20  has a pair of tool alignment members, such as longitudinal members  50 ,  52 , positioned on opposite side of the cut  14  (see  FIG. 1 ) that extend along the length of the bone plate  20 . Transverse supports  54 ,  56 ,  58  extend across the cut  14  between the longitudinal members  50 ,  52  and serve to interconnect and brace the longitudinal members  50 ,  52 . The transverse supports  54 ,  56 ,  58  rigidly restrict lateral, rostral caudal, and anterior posterior movement of the longitudinal members  50 ,  52  and the sternal halves  16 ,  18  secured thereto. 
     With reference to the longitudinal member  50  as shown in  FIG. 3 , each of the longitudinal members  50 ,  52  have portions  49 A,  49 B projecting beyond the transverse supports  54 ,  58  and along the sternal half  16  to increase the contact area between the bone plate  20  and the sternal half  16  along the cut  14  and further secure the bone plate  20  to the sternal half  16 . The projecting portions  49 A,  49 B also serve to guide one of the jaws  152 ,  153  of a crimping tool  150  (see  FIG. 14B ) into an aligned position with the locking devices  40 ,  41 , as will be discussed in greater detail below. Extending inward toward the center of the bone plate  20  are inner guide portions  51 A,  51 B of the longitudinal members  50 ,  52 . The inner guide portions  51 A,  51 B serve to guide the other one of the jaws  152 ,  153  of the crimping tool  150  into an aligned position on the opposite side of the locking devices  40 ,  41 . The longitudinal members  50 ,  52  further have angled portions  53 A,  53 B that bow outward from the inner guide portions  51 A,  51 B to laterally space halves of the bone plate  20 , such as generally triangular lobes  55 , outward from a central, longitudinal axis  106  of the bone plate  50 . The lobes  55  have throughbores  44  formed therein such that positioning the lobes  55  outward from the longitudinal axis  106  positions longitudinal axes  57  (see  FIG. 17 ) of the bone screws  46  away from the cut  14 . This improves the engagement between the bone screws  46  and the sternal half  16  by keeping the bone screws  46  from splintering the bone adjacent the cut  14 . 
     With reference to  FIGS. 2-4 , the bone plate system  10  includes connections  64 ,  66  between the trailing ends  26  of the surgical cables  22 ,  24  and the bone plate  20 . The connections  64 ,  66  are similar and, as shown with respect to connection  66  and cable  24 , each have a stop aperture  70  of the bone plate  20  sized to permit the leading end portion  28  of the surgical cable  24  to be advanced therethrough until an end plug  72  (see  FIG. 6 ) of the trailing end portion  26  of the cable  24  enters the stop aperture  70  and abuts against an interior shoulder or annular surface  74  of the bone plate  20 . As shown in  FIG. 4 , the stop aperture  70  includes a larger diameter portion  76  sized to permit the surgical cable  24  and the end plug  72  thereof to travel through the larger diameter portion  76  and abut the annular surface  74 . The stop aperture  70  also has a smaller diameter portion  78  that includes the annular surface  74  and is configured to restrict the end plug  72  from advancing out of the stop aperture  70  in direction  62 . The end plug  72  may be swedged onto the braided multi-stranded wires of the cable  24  or secured using, for example, welding. In an alternative form, the connections  64 ,  66  may have, for example, a press fit or weld between the trailing end portions  26  of the surgical cables  24 ,  26  and the bone plate  20 . 
     As shown in  FIGS. 4 and 5 , the annular surface  74  of the stop aperture  70  narrows the stop aperture  70  to block the movement of end plug  72  beyond the annular surface  74 . At this point, the trailing end  26  of the surgical cable  24  can no longer be moved in direction  62  beyond the stop surface  74 . Utilizing the abutting contact between the end plug  72  and the annular surface  74  provides an easy to use approach for connecting the trailing end  26  of the surgical cable  24  to the bone plate  20 . The bone plate  20  and surgical cables  22 ,  24  may be assembled in an operating room by first selecting surgical cables  22 ,  24  suitable for a particular patient anatomy and then advancing the leading end portions  28  of the selected surgical cables  22 ,  24  through the stop aperture  70  of the bone plate  20 . In another approach, the bone plate  20  and preselected surgical cables  22 ,  24  may be packaged in a preassembled configuration to save assembly time in the operating room. 
     In one form, the transverse support  58  has a tubular wall  82  with an inner surface  84  thereof defining a locking aperture  80  as shown in  FIG. 4 . The tubular wall  82  includes exposed crimp portions  85 ,  85  on opposite sides of the aperture  80  configured to be deformed toward each other and fix the cable  28  to the bone plate  20 . The locking aperture  80  extends between opposite lateral surfaces  86 ,  88  of the bone plate  20  and is configured to receive the leading end portion  28  of the surgical cable  24 . To increase the ease with which the leading end portion  28  of the surgical cable  24  may be advanced into the locking aperture  80 , the bone plate  20  may include a chamfered surface  90  adjacent the openings of the aperture  70 . Further, the tubular wall  82  may have a generally constant diameter along its length. In one form, the tubular wall  82  is free of any openings in communication with the locking aperture  84  which reduces the likelihood of tissues entering the aperture  84 . This may also increase the strength of the tubular wall  82 . Still further, the locking devices  40 ,  41  may be integral with the bone plate  20  and have a portion of the transverse supports  54 ,  58 . 
     The locking aperture  80  is preferably sized with a diameter slightly larger than the surgical cable  24  such that the inner surface  84  of the tubular wall  82  is initially in a slip fit configuration with the surgical cable  24 . The locking aperture  80  is also sized to provide a compression fit between the inner surface  84  of the tubular wall  82  and the surgical cable  24  to maintain the positioning of the tubular wall  84  along the surgical cable  24  once the tubular wall  82  has been crimped. Using a surgical cable  24  having a diameter of about 0.049 inches as an example, the outer diameter of the tubular wall  82  is initially about 0.096 inches and the diameter of the locking aperture  80  may be about 0.055 inches. Crimping the tubular wall  82  against the surgical cable  24  flattens out the tubular wall  82 , decreases the diameter of the locking aperture  80  by about 0.01 inches, and forms a compression fit between the inner surface  84  of the tubular wall  82  and the surgical cable  24 . 
     Rather than utilizing stop apertures  70  to connect one end of the surgical cables  22 ,  24  to the bone plate  20  and a locking aperture  80  to connect the other end of the surgical cables  22 ,  24  to the bone plate  20 , the locking devices  40 ,  41  may have multiple lumen crimps with a separate lumen for crimping each end of the cables  22 ,  24 . In other forms, the locking devices  40 ,  41  may be separate from the bone plate  20 . For example, the bone plate  20  may have apertures for receiving the surgical cables  22 ,  24  but a separate and distinct crimp may be applied to each of the surgical cables  22 ,  24  to fix the cables  22 ,  24  in the closed loop configuration about the sternal halves  16 ,  18  after the surgical cables  22 ,  24  have been advanced through the apertures of the bone plate. Examples of separate and distinct crimps that could be used with such a plate member include the multiple lumen crimps disclosed in U.S. Pat. Nos. 6,832,532 and 6,629,975. 
     With reference to  FIG. 7 , the throughbores  44  of the bone plate  20  have retention devices, such as threads  100 , configured for engaging threads  184  on the heads  181  of the bone screws  46  (see  FIG. 17 ) and resisting back-out of the screws  46  from the throughbores  44 . The threads  100  of each throughbore  44  are spaced inward from the upper and lower surfaces  102 ,  104  of the bone plate  20  along a bore axis  108  by equal distances. With reference to  FIG. 8 , the upper and lower surfaces  102 ,  104  of the bone plate  20  are generally straight and permit either the upper and lower surface  102 ,  104  to be placed against sternal halves  16 ,  18 . By positioning the threads  100  inward from the upper and lower surfaces  102 ,  104  equal distances, the threads  184  of the bone screw  46  can engage the threads  100  of the aperture  44  regardless of whether the upper surface  102  or the lower surface  104  is facing the sternal halves  16 ,  18 . 
     The threads  100  include a plurality of leads adjacent the upper and lower surfaces  102 ,  103  of the bone plate  20 , such as leads  105 ,  107  adjacent the upper surface  102  and leads  109 ,  111  adjacent the lower surface  104 . The head  181  of the bone screw  46  has threads  184  with a matching number of leads  186 ,  188  (see  FIG. 17 ) that are adapted to mate with the leads  105 ,  107  or  109 ,  111  of the throughbore  44  depending on which direction the bone screw  46  is driven into the throughbore  44 . For example, with reference to  FIG. 7 , with the lower surface  104  of the bone plate  20  positioned against the sternal halves  16 ,  18 , a surgeon can drive the bone screw  46  from above the upper surface  102  into one of the throughbores  44  until the head  181  of the bone screw  46  is proximal the threads  100  of the throughbore  44 . Rotation of the bone screw  46  brings the leads  186 ,  188  of the head  181  into engagement with the leads  105 ,  107  of the throughbore  44 . Conversely, if the upper surface  102  of the bone plate  20  is positioned against the sternal halves  16 ,  18 , the bone screw  46  would be driven from above the lower surface  104  into the throughbore  44  and the leads  186 ,  188  of the head  181  would engage the leads  109 ,  111  of the throughbore  44 . In this manner, the bone screws  46  can be driven into the throughbores  44  and rotated to bring the leads  186 ,  188  into engagement with either of the leads  105 ,  107  or  109 ,  111  of the throughbore  44  regardless of whether the upper surface  102  or the lower surface  104  of the bone plate  20  is positioned against the sternal halves  16 ,  18 . Although only two leads (either  105 ,  107  or  109 ,  111  depending on the orientation of the bone plate  20 ) are identified as engaging the leads  186 ,  188  of the screw head  181 , the threads  100  of the throughbore  44  and the threads  184  of the head  181  each have four leads configured so that the threads  184  engage the threads  100  with a quarter-turn or less of the screw  46 . Preferably, the number of leads of the throughbore threads  100  and the number of leads of the screw head threads  184  match so that all of the leads of the throughbore threads  100  engage all of the leads of the screw head threads  184  as the bone screw  46  is driven into the throughbore  44 . 
     With respect to  FIGS. 9-16 , a method is disclosed for utilizing the bone plate system  10  to secure the halves  16 ,  18  of a cut sternum  12 . The trailing end  26  of each cable  22 ,  24  may be connected to the bone plate  20  as discussed above and the bone plate  20  may be positioned above the sternal halves  16 ,  18 . The leading end portion  28  of each cable  22 ,  24  is advanced around the sternal halves  16 ,  18  and into the locking aperture  80  adjacent lateral surface  86  (see  FIG. 4 ). The leading end portion  28  is advanced outward from the locking aperture  80  adjacent the opposite lateral surface  88  in direction  120 , as shown in  FIG. 10 . 
     With the leading end  28  of each surgical cable  22 ,  24  extending beyond the lateral surface  88  of the bone plate  20 , the bone plate  20  is held against the sternal halves  16 ,  18  and a tensioning instrument  122  (see  FIG. 11 ) is used to apply tension to the surgical cables  22 ,  24  and draw the bone plate  20  against the sternal halves  16 ,  18 . More specifically, the leading end portion  28  of the surgical cable  24  is advanced through a distal end  124  of the tensioning instrument  122  until the leading end  28  advances outward from a proximal end  126  of the tensioning instrument  122 , as shown in  FIG. 12 . The leading end  28  of the surgical cable  24  may be grasped and pulled in direction  130  and the tensioning instrument  122  slid downward along the surgical cable  24  in direction  132  until the distal end  124  thereof abuts the lateral surface  88  of the bone plate. The handle  136  of the tensioning instrument  122  is rotated in direction  138  which causes a rotary tensioning device  139  of the tensioning instrument  122  to lock onto the surgical cable  24  and shift the surgical cable  24  in direction  130 . A ratchet assembly  140  of the tensioning instrument  122  restricts return of the surgical cable  24  in direction  142  once tension has been applied to the surgical cable  24  by way of rotation of the handle  136 . Continued rotation of the handle  136  advances the surgical cable  28  in direction  130 , tightens the surgical cable  24  around the sternal halves  16 ,  18 , and compresses the sternal halves  16 ,  18  together. Further, tensioning the surgical cable  24  draws the bone plate  20  downward against the sternal halves  16 ,  18  and seats the bone plate  20  securely against the compressed sternal halves  16 ,  18 . In one approach, forceps are used in conjunction with tensioning of the surgical cable  24  to bring the sternal halves  16 ,  18  together. 
     Once the desired amount of tension has been applied to the surgical cable  24 , the crimping tool  150  is used to clamp the tubular wall  82  of transverse support  58  to the surgical cable  24 . The crimping tool  150  has jaws  152 ,  153  for being positioned on opposite sides of the tubular wall  82  with jaw surfaces  157 ,  159  positioned adjacent crimp portions of the tubular wall  82 , such as the portions  161 ,  163  shown in dashed lines in  FIG. 14B . To permit access to the crimp portions  161 ,  163 , the bone plate  20  has access openings, such as through openings  143 ,  145 , sized to permit the jaws  152 ,  153  to be inserted therein. The through openings  143 ,  145  have alignment walls, such as walls  147 A,  147 B and  149 A,  149 B extending away from the tubular wall  82  on opposite sides of the through openings  143 ,  145 . The jaws  152 ,  153  have a width  154  sized to fit snugly between the walls  147 A,  147 B and  149 A,  149 B and into position on opposite sides of the tubular wall  82 . More specifically, the width  154  of the jaws  152 ,  153  is less than a distance  156 A between the walls  147 A,  147 B and a distance  156 B between the walls  149 A,  149 . The close tolerances between the jaws  152 ,  153  and the walls  147 A,  147 B and  149 A,  149 B ensures that the jaw surfaces  157 ,  159  are aligned with the crimp portions  161 ,  163  before the crimping tool  150  crimps the tubular wall  82 . For example, the distances  156 A,  156 B are about 0.21 inches, the width  154  of the jaws  152 ,  153  are about 0.2 inches, and the crimp portions  161 ,  163  extend along the tubular member  82  a distance  165  of about 0.140 inches. 
     Next, handles  160 ,  162  of the crimping tool  150  are squeezed together to shift the jaws  152 ,  153  against the crimp portions  161 ,  163 , deform the crimp portions  161 ,  163  toward each other, and crimp the tubular wall  82  to the surgical cable  24 . Once the tubular wall  82  has been crimped onto the surgical cable  24 , the crimping tool  150  can be removed and the tensioning instrument  122  may be removed by depressing a ratchet release button  164  thereof and sliding the tensioning tool  122  along the surgical cable  24  in direction  166  (see  FIG. 14 ). Using a cable cutter  170 , the leading end portion  28  is then cut flush with the lateral surface  88  of the bone plate  20 . The process of tensioning and crimping is repeated with the surgical cable  22 . In some applications, the crimping tool  150  may be configured to require a particular amount of travel of the jaws  152 ,  153  towards one another before the crimping tool  150  may be disengaged from the tubular wall  82 . This configuration ensures that the tubular wall  82  has deformed a predetermined distance into engagement with the surgical cable  24  and achieved a sufficient crimp strength therewith before the surgeon can remove the crimping tool  150 . 
     With the surgical cables  22 ,  24  tensioned and crimped to the bone plate  20 , the bone screws  46  may be connected to a driver tool  180  (see  FIG. 18A ) and driven into throughbores  44  of the bone plate  20  to secure the bone plate  20  to the sternal halves  16 ,  18 , as shown in  FIG. 16 . 
     In an alternative approach shown in  FIGS. 16A-D , the bone screws  46  may be used to secure the bone plate  20  to one of the sternal halves  16 ,  18 , such as sternal half  18  as shown in  FIG. 16A . Next, the sternal halves  16 ,  18  are approximated together using forceps, wire, or another approach, as shown in  FIG. 16B . With the sternal halves  16 ,  18  approximated, bone screws  46  are driven into the throughbores  44  of the bone plate  20  disposed above sternal half  16 , as shown in  FIG. 16C . Next, the distal end portions  26  of the surgical cables  22 ,  24  are connected to the bone plate  20  and the leading end portions  28  of the surgical cables  22 ,  24  are looped around the sternal halves  16 ,  18  and into openings  30 ,  32  of the bone plate  20 , as shown in  FIG. 16D . The surgical cables  22 ,  24  are then tensioned and locked to the bone plate as described above. Although the surgical cables  22 ,  24  are connected to the bone plate  20  after the bone screws  46  have secured the bone plate  20  to the sternal halves  16 ,  18 , the surgical cables  22 ,  24  may still act as a primary load bearing mechanism to resist movement of the sternal halves  16 ,  18 . 
     In yet another approach, the sternal halves  16 ,  18  may be approximated together using forceps, wires, or another approach before placing the bone plate  20  on the approximated sternal halves  16 ,  18 , looping the surgical cables  22 ,  24  around the sternal halves  16 ,  18 , tensioning the surgical cables  22 ,  24 , locking the bone plate  20  to the surgical cables  22 ,  24 , and driving the bone screws  46  into the throughbores  44  of the bone plate  20  to fix the bone plate  20  to the sternal halves  16 ,  18 . This approach is similar to the method described above with respect to  FIGS. 9-16 , with the exception that the forceps or wires are used to approximate the sternal halves rather than the surgical cables  22 ,  24 . 
     With reference to  FIGS. 17 and 18 , an elevational view of one of the bone screws  46  is shown. The bone screw  46  has a head  181  having drive structures  182  for receiving a distal end of the driving tool  180 . The drive structures  182  have undercuts  192  and radially extending members  194  for engaging corresponding a screw retention feature on the driving tool  180 , such as a centering pin  198  of the driving tool  180 . Advancing the centering pin  198  into a blind bore  196  of the screw head  181  centers the distal end of the driving tool  180  on the screw head  181  and causes the centering pin  198  to resiliently deflect the radially extending members  194  downward. This produces a friction fit between the centering pin  198  and the radially extending members  194  which keeps the screw  46  retained on the distal end of the driving tool  180  before driving the screw  46  into bone. 
     The head  181  also includes threads  184  that include multiple leads  186 ,  188  for engaging the multiple lead threads  100  of the throughbore  44 . The threads  184  provide tactile feedback to the surgeon driving the bone screw  46  into bone that the head  181  is engaged with the bone plate  20 . Further, the threads  184  provide resistance to the bone screw  46  backing out of the throughbore  44  of the bone plate  20 . As shown in  FIG. 17 , the screw  46  has an elongate shank  190  with threads  192  thereon that may have a different pitch, size, and number of leads than the threads  184  of the head  181 . In one form, the shank  190  is configured to be self-drilling and self-tapping. 
     The surgical cables  22 ,  24  are made of surgical grade braided multi-stranded stainless steel cable. Other materials such as titanium alloy, cobalt chromium alloy, polymers, or other biocompatible materials may also be used. The braided surgical cables  22 ,  24  have a significantly higher tensile strength than surgical wires and provide better resistance to separation and relative movement of the sternal halves  16 ,  18 . In one form, the cables  22 ,  24  have a diameter in the range of about 0.8 mm to about 2.4 mm, and more preferably about 1.3 mm. The cables  22 ,  24  may be swedged to reduce surface roughness and may have a high flexibility which may provide a tighter loop yet avoid damage to surrounding tissue. The bone plate  20  may be fabricated from a surgical grade stainless steel, titanium, titanium alloy, cobalt chromium alloy, nitinol, polyether ether ketone, or other biocompatible materials. Likewise, the bone screws  46  may be made of, for example, stainless steel, titanium, titanium alloy, or cobalt chromium alloy. The components of the cable tensioner  122  may be made of metals or alloys including stainless steel. 
     Referring now to  FIGS. 19-21 , there is illustrated another embodiment of a plate member  200  in accordance with the present invention. The bone plate  200  is generally the same as plate member  20  described above with respect to  FIGS. 1-8 , with the exception of a curvature of the bone plate about at longitudinal axis  202  thereof. 
     More particularly, the bone plate  200  has a central portion  204  aligned along the longitudinal axis  202  and locking devices  206 ,  208  also aligned along the longitudinal axis  202  on opposite sides of the central portion  204 . The bone plate  200  has curved plate halves  210 ,  212  that are shaped to conform to bones having either a convex or concave outer surface. More specifically, if the bones (such as sternal halves  16 ,  18 ) have a convex outer surface, a concave lower surface  214  (see  FIG. 21 ) of the bone plate  200  would be positioned against the outer surfaces of the bones. However, if the bones had a concave outer surface, a convex upper surface  216  of the bone plate  200  would be positioned against the bones. In this manner, the bone plate  200  can be flipped to position either the concave lower surface  214  or the convex upper surface  216  against the bones to be secured depending on the anatomy of the patient. This provides greater flexibility and the ability to utilize a single plate member  200  for two different anatomies. 
     With reference to  FIGS. 22-27 , another embodiment of a plate member  300  is shown. The bone plate  300  is similar to the bone plates  20 ,  200  except that the bone plate  300  has a single locking device disposed on a central portion  304  of the bone plate  300 . Further, like the bone plate  200 , the bone plate  300  has a curvature about a longitudinal axis  306  thereof such that the bone plate  300  has a convex upper surface  307  and a concave lower surface  309 , as shown in  FIGS. 26 and 27 . 
     Like the locking devices  40 ,  41  of the bone plate  20 , the locking device  302  includes a stop aperture  310 , a locking aperture  312 , a transverse support  314 , and a tubular wall  316 . The stop aperture  310  is sized to permit a surgical cable  320  (see  FIG. 23 ) to be advanced therethrough and form a connection  322  between and annular stop surface  324  of the stop aperture  310  and a plug  326  of the cable  320  (see  FIG. 24 ). With reference to  FIG. 23 , the surgical cable  320  may include a hardened integrated lead  330  and a hook  332  releasably connected thereto. The hook  332  may be used for advancing a leading end  319  of the surgical cable  320  around bones, such as the sternal halves  16 ,  18  of the sternum  12 . Once the leading end  319  has been advanced around the bones, the hook  332  may be pulled off of the integrated lead  330  and then the integrated lead  330  may be advanced through the locking aperture  312 . The locking device  302  of the bone plate  300  may then be reconfigured to a locked configuration as explained above with respect to locking device  40 . 
     Referring now to  FIGS. 28 and 29 , there is illustrated another embodiment of a plate member  400 . The bone plate  400  is similar to the bone plates discussed above, except that the bone plate  400  has a single locking device  402  positioned at one end  404  of the bone plate  400  opposite a transverse support portion  406  of the bone plate  400  along a longitudinal axis  407  of the bone plate  400 . The bone plate  400  allows a surgical cable, such as surgical cable  24 , to be offset from lobes  408  of the bone plate  400 . 
     With respect to  FIGS. 29-33 , another bone plate system  500  is shown. The bone plate system  500  is similar in a number of ways to the foregoing bone plate systems in that the bone plate system  500  includes a plate member  502  having throughbores  504  therein for receiving bone anchors, such as bone screws  506 , to secure the bone plate  502  to one or more bones. Further, the bone plate  502  may have a convex upper surface  508  and a concave lower surface  510  that conform to the outer surfaces of the one or more bones. Further, the bone plate throughbore  504  has threads  512  including multiple leads  514  for engaging similar threads on a head  516  of the bone anchor  506 . The bone plate system  500  is different from the bone plate system  10  in that the bone plate system  500  lacks a locking device for securing a surgical cable to the bone plate  500 . However, the bone plate system  500  may be used in conjunction with a surgical wire, locking device, and/or the other bone plate systems discussed above. 
     An alternative embodiment of a bone screw head  600  is illustrated in  FIG. 34 . The head  600  includes upstanding, resilient members  602  that deform radially outward with connection of a driver tool to the head  600 . For example, advancing the centering pin  198  of the driving tool  180  into a blind bore  604  of the screw head  600  causes the centering pin  198  to deflect the upstanding members  602  radially outward. Deforming the upstanding members  602  radially outward causes the upstanding members  602  to bias against the centering pin  198  and form a friction fit therewith which retains the head  600  on the driving tool. 
     Referring now to  FIGS. 36-38 , there is illustrated another embodiment of a plate member  700 . The bone plate  700  is similar to the bone plate  300  and includes only one locking device  702  disposed at a mid-point of the bone plate  700  along longitudinal axis  704 . The bone plate  700  is also similar to the bone plate  300  in that the bone plate  700  is curved slightly about the longitudinal axis  704  such that the bone plate  700  has a convex upper surface  710  and a concave lower surface  712  which permit the bone plate  700  to be flipped to position either the upper surface  710  or the lower surface  712  against the bones depending on whether the bones have a concave or convex outer surface. The bone plate  700  differs from the bone plate  300  in that the bone plate  700  has a substantially rectangular configuration with only one lobe  706  disposed at each of the outermost corners of the bone plate  700  and transverse supports  708  extending across the axis  704  which connect the lobes  706 . The more rectangular configuration of the bone plate  700  may be preferred when a plate member having a more compact footprint is desired due to patient anatomy. 
     Turning to  FIGS. 39-51 , a tensioning instrument  800  is shown that is similar to the tensioning instrument  122  and may be operated in a manner similar to the approach described above with respect to  FIGS. 11-14 . More specifically, the tensioning instrument  800  has a distal end  802  with an inlet opening  804  sized to permit a surgical cable  805  to be advanced through the inlet opening  804 , into a body  808  of the tensioning instrument  800 , and through a through opening  807  of a rotary tensioning device  824  within the body  808 , as shown in  FIG. 46 . The surgical cable  805  is advanced in direction  806  until the surgical cable  805  exits the tensioning instrument  800  through an outlet opening  810  at a proximal end  812  of the tensioning instrument  800 . With the surgical cable  805  extending outward from the outlet opening  810 , a surgeon may move the tensioning instrument  800  along the surgical cable  805  toward the bone plate  20  with one hand and pull any slack out of the surgical cable  805  with the other hand (see  FIGS. 12, 13, and 39 ). The tensioning instrument  800  has a drive  823  including a handle  820  that is configured to be turned in a wind up direction  970  to rotate the rotary tensioning device  824  within the body  808  and cause the surgical cable  805  to be wound up onto the rotary tensioning device  824 , as shown in  FIG. 47 . The tensioning instrument  800  also has a ratchet assembly  826  that selectively restricts rotation of the rotary tensioning device  824  in a pay out direction while permitting a user to incrementally wind the surgical cable  805  onto the rotary tensioning device  824  in the wind up direction  970  (see  FIGS. 39 and 46 ). 
     Once a desired amount of tension has been applied to the surgical cable by rotating the drive  823  and the rotary tensioning device  824  connected thereto, a release button  840  of a release mechanism  842  is pressed to disengage the ratchet assembly  826 , permit the rotary tensioning device  824  to turn freely in the pay out direction, and allow the tensioning instrument  800  to be pulled off of the surgical cable  805  (see  FIGS. 39, 50 , and  51 ). Disengaging the ratchet assembly  826  disconnects the rotary tensioning device  824  from the drive  823  and allows the surgical cable  805  to be unwound from the rotary tensioning device  824 , such as by pulling the surgical cable  805  outward from the distal end  802 , without rotating the handle  820 . In this manner, the tensioning instrument  800  can be removed from the surgical cable  805  without the handle  820  spinning or otherwise interfering with surgery. 
     With reference to  FIG. 41 , the drive  823  includes a drive shaft  850  having a hex drive  852  for non-rotatably mating with a hex recess  854  of the handle  820  and threads  856  for engaging a shaft nut  858  which fixes the drive shaft  850  to the handle  820 . The tensioning instrument  800  has a rotary tensioning device  824  with gripping portions, such as tension drive  872  and tensioning ring  932 , which are configured to shift relative to each other and fix a cable to the rotary tensioning device  824 . With the drive shaft  850  operatively engaged with a tension drive  872  of the rotary tensioning device  824 , turning the handle  820  turns the drive shaft  850  and the tension drive  872  connected thereto, reconfigures the tension drive  872  and the tension ring  932  from a pass-through configuration to a gripping configuration, and draws the surgical cable  805  onto the tension ring  932  carried on the tension drive  872 . The direct mechanical connection between the handle  820 , the drive shaft  850 , and the tension drive  872  provides direct tactile feedback of the tension being applied to the surgical cable  805 . Further, the handle  820  has an overall length  851  that is twice a cable-receiving diameter  853  of the tension ring  932 , as shown in  FIG. 49 . This two-to-one relationship balances the ease of turning the handle  820  with providing sufficient tactile feedback regarding the tension in the surgical cable  805 , which are both important considerations when tensioning a surgical cable to a particular tension. Although a two-to-one relationship is ideal for many applications, it will be appreciated that ½ to 1, 3 to 1, or other relationships may be desired for other applications. The tensioning instrument  800  also has a sleeve bearing  862  that supports the drive shaft  850  and handle  820  as the handle  820  is turned. 
     The tensioning instrument  800  includes structures that align through apertures of the internal components of the tensioning instrument  800  and increase the ease with which the surgical cable  805  can be advanced through the tensioning instrument  800  when the handle  820  is generally aligned with the path of the surgical cable  805  through the body  808  of the tensioning instrument  800 , as shown in  FIG. 46 . More specifically, the through opening  807  of the rotary tensioning device  824  includes a pair of apertures  1014 ,  1016  of the tension ring  932  and a through opening  1018  of the tension drive  872  that are aligned when the tension ring  932  and the tension drive  872  are in the pass-through configuration, as shown in  FIGS. 42, 44, and 46 . To ensure that the tension drive through opening  1018  is oriented to permit the surgical cable  805  to be advanced therethrough, the drive shaft  850  has a generally rectangular oblong key  870  at one end thereof for engaging the tension drive  872 , as shown in  FIGS. 41 and 41A . The tension drive  872  has a complementary generally rectangular oblong drive socket  874  (see  FIG. 42 ) for transmitting torque from the handle  820  and drive shaft  850  to the tension drive  872  and the tension ring  932  carried thereon. The oblong drive socket  874  includes spaced, generally flat sidewalls  876 ,  878  in a vertical orientation (as shown in  FIG. 42 ) parallel with a through opening  1018  of the tension drive  874  through which the surgical cable  805  is advanced. The socket  874  also has shorter sidewalls  879 ,  891  in a horizontal orientation perpendicular to the through opening  1018 . Because the key  870  and the socket  874  are both oblong, the key  870  and the socket  874  fit together in only two orientations that are 180° apart from each other. In either orientation, the handle  820  is aligned with the through opening  1018  of the tension drive  872  when the drive shaft key  870  is engaged with the tension drive socket  874 . Thus, when the drive shaft  850  is engaged with the tension drive  872  and the handle  820  is in a vertical orientation (see  FIG. 46 ), the through opening  1018  of the tension drive  872  will be aligned with the path of the surgical cable  805  through the body  808 . As discussed in greater detail below, the tensioning instrument  800  has a bias assembly  946  that maintains the tension ring  932  in a pass-through position about the tension drive  872  where the tension ring apertures  1014 ,  1016  are aligned with the tension drive through opening  1018 . In this manner, the surgical cable  805  can be quickly and easily advanced through the tension ring apertures  1014 ,  1016  and the tension drive through opening  1018  when the handle  820  is aligned with the path of the surgical cable  805  through the tensioning instrument  800 . 
     The drive shaft  850  also has a ratchet portion  882  with ratchet teeth configured to engage a pawl  884  and restrict rotation of the drive shaft  850  in a pay out direction, as shown in  FIGS. 41 and 49 . The pawl  884  is disposed within an opening  892  of the body  808  and is aligned with the ratchet portion  882  of the drive shaft  850  when the drive shaft  850  has been inserted into a cavity  886  of the body and secured to the handle  820 . With reference to  FIG. 41 , the tensioning instrument  800  includes a plug  890  welded or otherwise secured to the body  808  to close the opening  892  and restrict removal of the pawl  884  from within the opening  892 . The opening  892  is sized to permit up and down movement of the pawl  884  and a spring  894  is positioned between the plug  890  and the pawl  884  to bias the pawl  884  downwardly into engagement with the teeth of the ratchet portion  882  of the drive shaft  850 . The pawl  884  has a tooth  898  at a leading end thereof for engaging and restricting rotation of the teeth of the ratchet portion  882  when the drive shaft  850  is rotated in a pay out direction  971  and permitting rotation of the teeth of the ratchet portion  882  when the drive shaft  850  is rotated in the wind up direction  970  (see  FIG. 47 ). In one form, the plug  890  has an downwardly extending fin that engages a slot on a trailing end  896  of the pawl  884 . The fin restricts rotation of the pawl  884  relative to the plug  890  and keeps the tooth  898  of the pawl  884  aligned with the teeth of the ratchet portion  882 . 
     To disengage the tension drive  872  from the drive shaft  850 , the tensioning instrument  800  has a release shaft  900  with a button end  902  connected to the button  840  and a plunger end  904  configured to abut a receiving surface  906  of the drive socket  874 , as shown in  FIGS. 41 and 42 . The release shaft  900  is slidably received with a throughbore  908  of the drive shaft  850  and is biased in direction  909  by a spring  980 , as shown in  FIG. 50 . Pressing the button  840  in direction  910  shifts the release shaft  900 , tension drive  872 , and the tension ring  932  in direction  910 , as shown in  FIG. 51 . The plunger end  904  has a circular, flat pusher surface  911  with a diameter thereacross that is less than a width  913  of the drive socket  874  between sidewalls  876 ,  878  but larger than an opening  915  in the receiving surface  906 , as shown in  FIGS. 41 and 42 . The clearance between the plunger end  904  and the socket sidewalls  876 ,  878 ,  879 ,  881  and the sliding contact between the pusher surface  911  and the receiving surface  906  allows the tension drive  872 , and the tension ring  932  carried thereon, to rotate about the plunger end  904  once the release shaft  900  has shifted the tension drive  872  out of engagement with the drive shaft  850 , as shown in  FIG. 51 . The tension drive  872  and the tension ring  932  may then be rotated by the tension in the surgical cable  805  as the tension is released after disengagement of the drive shaft  850  and the tension drive  872 . 
     The tensioning instrument  800  includes a cable gripping mechanism  930  that locks onto the surgical cable  805  with rotation of the handle  820 , as shown in  FIGS. 41, 46 , and  47 . In one form, the cable gripping mechanism  930  includes the tension drive  872  and the tension ring  932  disposed coaxially thereon. When the tension drive  872  is rotated by turning the handle  820 , the tension drive  872  shifts rotationally within a central opening  940  of the tension ring  932  and causes a circular outer surface  942  of the tension drive  872  to slide along an annular inner surface  944  of the tension ring  932 , as shown in  FIGS. 42, 44, 46, and 47 . Shifting the tension ring  932  about the tension drive  872  causes the tension drive  872  and the tension ring  932  to fix the tension drive  872  and the tension ring  932  to the surgical cable  805 , as discussed in greater detail below. With the tension drive  872  and the tension ring  932  fixed to the surgical cable  805 , continued turning of the handle  820  continues to turn the tension drive  872  and the tension ring  932 , further winds the surgical cable  805  onto the tension ring  932 , and further tensions the surgical cable  805 . 
     The cable gripping mechanism  930  also includes the bias assembly  946  configured to limit relative rotation between the tension drive  872  and the tension ring  932  and return the tension ring  932  to the pass through orientation about the tension drive  872 . The bias assembly  946  has a tension pin  948  sized to fit within a pin aperture  950  of the tension ring  932  and a base  954  secured to the tension ring  932  to fix the tension pin  948  to the tension ring  932 , as shown in  FIGS. 41, 44, and 46 . The base  954  is preferably welded or otherwise secured to the tension ring  932  after the tension drive  872  has been positioned within the central opening  940  of the tension ring  932 . Further, the tension pin  948  may extend radially inward from the tension ring  932  with a tension ring tooth  952  disposed within a pin slot  960  in an outer wall  962  of the tension drive  872  (see  FIGS. 42, 43, and 46 ). The engagement between the tension pin  948  and the pin slot  960  captures the tension drive  872  within the central opening  940  of the tension ring  932  while permitting a predetermined amount of relative rotary motion therebetween. 
     With reference to  FIGS. 43 and 46 , the bias assembly  946  further includes a spring  964  having an end  966  for engaging a spring seat  968  of the tension drive  872  and an opposite end  969  abutting the tooth  952  of the tension pin  948 . The pin slot  960  extends along a circumference of the outer wall  962  a distance that is longer than a diameter of the tension pin  948  to permit the tension pin  948  to slide within the slot  960  as the tension drive  872  moves rotationally relative to the tension ring  932 . More specifically, movement of the tension drive  872  in direction  970  brings spring seat  968  toward the tooth  952  of the tension pin  948  and compresses the spring  964 , as shown in  FIG. 47 . The compressed spring  964  provides a restoring force that tends to shift the tension ring  932  in direction  970  and re-align apertures  1014 ,  1016  of the tension ring  932  with the through opening  1018  of the tension drive  872  once tension has been released from the surgical cable  805 , such as after a locking device  809  has been crimped to secure the surgical cable  805  around bones and the drive shaft  850  has been disengaged from the tension drive  872 . In this manner, the cable gripping mechanism  930  may automatically release the surgical cable  805  and permit the surgical cable  805  to be withdrawn from the tensioning instrument  800  after tension has been released in the surgical cable  805 . 
     The release mechanism  842  includes the spring  980  having one end  982  abutting a cap  984  welded to the body  808  at points  986 , as shown in  FIG. 48 , and an opposite end  988  abutting a washer  981  for biasing the tension drive  872  in direction  982 , as shown in  FIG. 49 . The spring  980  biases the washer  981  against the tension drive  872  and maintains the tension drive socket  874  firmly engaged with the drive shaft key  870 . To overcome the bias force of the spring  980  and disengage the tension drive socket  874  from the drive shaft key  870 , the release button  840  is pressed to shift the release shaft  900  in direction  910  which moves the tension drive  872  in direction  910 , as discussed in greater detail above and shown in  FIGS. 50 and 51 . 
     The operation of the tensioning instrument  800  is substantially identical to the operation of the tensioning instrument  122  such that the following description of the operation of the tensioning instrument  800  will begin at the point where the surgical cable  805  has been advanced through the distal end  802  of the tensioning instrument  800 , out from the proximal end  812 , and pulled tightly to remove slack from the surgical cable, as shown in  FIG. 46 . More specifically, with the handle  820  in the vertical orientation and the tension drive  872  and the tension ring  932  in the pass through configuration shown in  FIG. 46 , the surgical cable  805  may be readily advanced through the opening  807  of the rotary tensioning device  824  and out the outlet opening  810 . The surgical cable  805  extends through a guide tube  1009  of the distal end  802 , upward beyond an aperture  1010  in the body  808 , through the opening  807  of the rotary tensioning device  824 , and outward through the outlet opening  810 , as shown in  FIG. 46 . The aperture  1010  allows a surgeon to view the surgical cable  805  within the body  808  which may be useful when advancing the surgical cable  805  into the through opening  807  of the rotary tensioning device  824 . 
     The handle  820  is then turned in the wind up direction  970  to substantially simultaneously fix the cable gripping mechanism  930  to the surgical cable  805  at two positions along the surgical cable  805  as well as tension the surgical cable  805  by winding the surgical cable  805  onto the rotary tensioning device  824 . The handle  820  is shown in  FIG. 47  as having been rotated a quarter turn in the wind up direction  970  to illustrate the operation of the internal components of the tensioning instrument  800 . It will be appreciated that the handle  820  may be turned farther to continue to take up the surgical cable  805  onto the tension ring  932 . Further, the cavity  886  of the body  808  includes gaps  1013 ,  1015  disposed radially between the tension ring  932  and the body  808  that are sized to provide clearance between coils of the surgical cable  805  and the body  808  as the surgical cable  805  is drawn onto the tension ring  932 , as shown in  FIG. 49 . These gaps  1013 ,  1015  permit relatively long sections of the surgical cable  805  to be wound around the tension ring  932  with continued turning of the handle  824 . 
     Turning the handle  820  in the wind up direction  970  rotates the tension drive  872  in direction  970  and causes a surgical cable distal section  1030  to be drawn onto a lower portion  1032  of the tension ring  932  and a surgical cable proximal section  1034  to be drawn onto an upper portion  1036  of the tension ring  932 . Drawing the surgical cable distal section  1030  onto the tension ring  932  tensions the surgical cable  28  between the tension ring  932  and the distal end  802  of the tensioning tool  800  which is positioned against the locking device  809 . The tension in the surgical cable  805  shifts the tension ring  932  in direction  971  relative to the tension drive  872  and causes the tension ring  932  to pinch the surgical cable  805  at intersections  1042 ,  1044  between the apertures  1014 ,  1016  of the tension ring  932  and the central through opening  1018  of the tension drive  872 , as shown in  FIG. 47 . Further, shifting of the tension ring  932  about the tension drive  872  moves the spring seat  968  toward the tension pin  952  and compresses the spring  964 . 
     Once a desired amount of tension has been applied to the surgical cable  805 , and the pawl  884  resisting turning of the drive shaft  850  in the pay out direction  971 , the surgical cable  805  is secured in position such as by crimping the locking device  809 . Next, the release button  840  is pressed in direction  910  to shift the release shaft  900  in direction  910 , as shown in  FIGS. 50 and 51 . The plunger end  940  presses against the receiving surface  906  (see  FIG. 42 ) of the drive socket  874 , shifts the tension drive  872  and the tension ring  932  in direction  910 , and shifts the tension drive socket  874  out of engagement with the drive shaft key  870 . In this position, the tension drive  872  and the tension ring  932  may rotate in the pay out direction  971  relative to the drive shaft  850  so that any tension previously applied to the surgical cable  805  by turning of the handle  820  is released from the surgical cable  805 . Further, with the release button  840  depressed, the surgical cable  805  can be withdrawn in direction  1060  from the distal end  802  of the tensioning instrument  800 , as shown in  FIG. 51 . Because the tension drive  872  and tension ring  932  are disconnected from the drive shaft key  870 , pulling the surgical cable  805  in direction  1060  off of the tension ring  932  causes the tension drive  872  and the tension ring  932  to rotate about the plunger end  940  in pay out direction  971  and permits the surgical cable  805  to be paid out from the tension ring  932 . Once the surgical cable  805  has been withdrawn from the tensioning instrument  800 , the tensioning instrument  800  can be removed from the surgical site and the surgical cable  805  cut to length as desired. 
     With reference to  FIGS. 53-65 , a cable tensioning instrument  1500  is shown that permits rapid and easy-to-use tensioning of surgical cable  24 . The tensioning instrument  1500  has a body  1502  with a scalloped profile  1504  and a rotary tensioning device  1510  with a tension drive  1572  that is partially visible from outside of the body  1502 , as shown in  FIG. 53 . The instrument  1500  has a drive  1512  including a handle  1513  coupled to the rotary tensioning device  1510  so that turning of the handle  1513  produces associated turning of the rotary tension device  1510  (and tension drive  1572  with etch mark  1573  thereon). With reference to  FIGS. 53 and 63 , the body  1502  has a distal end  1520  with an inlet opening  1522 , a proximal outlet opening  1524 , a passage  1823  (see  FIG. 63 ) extending therebetween, and a through opening  1811  of the rotary tensioning device  1510 . In a manner similar to the use of the tensioning instrument  122  discussed above with reference to  FIGS. 10-13 , the leading end portion  28  of the cable  24  is inserted into the inlet opening  1522 , along the passage  1823  and through the opening  1811 , and outward from the body outlet opening  1522  in order to initially connect the tensioning instrument  1500  to the cable  24 . 
     With the cable  24  extending through the tensioning instrument  1500 , a surgeon may move the tensioning instrument  1500  along the surgical cable  24  toward the bone plate  20  with one hand and pull any slack out of the surgical cable  24  with the other hand, as discussed above with respect to tensioning instruments  122  and  800 . Next, the handle  1513  is turned to turn the rotary tensioning device  1510  and wrap cable  24  onto the rotary tensioning device  1510 . Turning the rotary tensioning device  1510  within the body  1502  reconfigures the grip device  1514  from a pass-through configuration where the cable  24  may be advanced through the rotary tensioning device opening  1811  between the tension drive  1572  and the clamp body  1800  (see  FIGS. 63 and 64 ), to a gripping configuration where the tension drive  1572  and clamp body  1800  are shifted together and clamp the cable  24  (see  FIG. 65 ). Continued turning of the handle  1513  continues to wrap cable onto the rotary tensioning device  1510  while the tension drive  1572  and clamp body  1800  fix the cable  24  to the rotary tensioning device  1510 . This turning of the rotary tensioning device  1510  while maintaining the  1572  and clamp body  1800  fixed on the cable  24  applies tension to the cable  24 . 
     It will be appreciated that the tensioning instrument  1500  is similar in many respects to the structure and operation of the tensioning instruments  122 ,  800  discussed above such that the following discussion will highlight differences between the instrument  1500  and the instruments  122 ,  800 . For example, the rotary tensioning device  1510  has a grip device  1514  (see  FIG. 54 ) that clamps the cable  24  between faces  1820  (see  FIG. 58 ),  1870  (see  FIG. 60 ) of the tension drive  1572  and a clamp body  1800  rather than clamping a cable between the portions of tension ring  932  and tension drive  872  as in the instrument  800  (see  FIGS. 46 and 47 ). 
     With reference to  FIG. 54 , the tensioning instrument  1500  includes a ratchet assembly  1530  configured to selectively permit turning of the rotary tensioning device  1510 . The ratchet assembly  1530  includes a pawl assembly  1532  having a pawl  1534  with a split tooth  1536 , the pawl  1534  being slidably received within a pawl sleeve  1540 . The pawl  1534  is longitudinally movable within the pawl sleeve  1540  and is biased by a spring  1542  into engagement with a drive shaft  1550  (which is secured at its other end to the handle  1513 ). The pawl tooth  1536  engages teeth  1664  on a ratchet portion  1560  of the drive shaft  1550 , as shown in  FIG. 54 . As will be discussed in greater detail below, the ratchet assembly  1530  has a different configuration than the ratchet assembly  826  in order to provide different assembly and disassembly of the instrument  1500 . 
     The tensioning instrument  1500  also has a different connection between the drive shaft  1550  and the rotary tension device  1510  than the components of the tensioning instrument  800 . In particular, the drive shaft  1550  has a drive portion  1570  that is selectively engaged via ball bearings  1586  with the tension drive  1572  of the rotary tension device  1510 . With reference to  FIGS. 54 and 56 , the drive shaft  1550  has an inner throughbore  1580  with a release shaft  1582  slidably disposed therein. The drive shaft drive portion  1570  includes radially outwardly extending openings  1584  (see  FIG. 56 ) that receive the ball bearings  1586  and are sized to permit the ball bearings  1586  to shift inwardly and outwardly within the openings  1584  based upon the position of the release shaft  1582 . As shown in  FIG. 56 , the release shaft  1582  has an enlarged collar  1590 , a neck  1592 , and an enlarged head  1594  at a distal end thereof. The head portion  1594  has an outer diameter sized to fill substantially the entire throughbore  1580  and shift a portion of each of the ball bearings  1586  outwardly into pockets  1600  (see  FIG. 57  and  FIG. 61 ). 
     With the drive shaft drive portion  1570  engaged in the socket  1576  and the ball bearings  1586  shifted outward by the release shaft head  1590  into engagement with the pockets  1600 , turning of the drive shaft  1550  produces turning of the tension drive  1572 , as shown in  FIG. 61 . For example, if the handle  1513  is turned in a wind up direction  1650  to apply tension to the cable  24  once the cable  24  has been advanced through the instrument  1500  (see  FIG. 53 ), the drive shaft  1550  will turn in the wind up direction  1650  while the cable  24  will resist the tensioning and tend to turn the tension drive  1572  in a pay out direction  1652 . However, a section of each ball bearing  1586  is disposed in the drive shaft openings  1584  while the remaining section extends outward into the tension drive pockets  1600 . The ball bearings  1586  are thereby engaged with both the drive shaft drive portion  1570  and the tension drive socket  1576  and inhibit relative movement between the drive shaft  1550  and the tension drive  1572 . Thus, turning the handle  1512  and drive shaft  1550  in the wind up direction  1650  with sufficient torque produces turning of the tension drive  1572  (and clamp body  1800  connected thereto) and applies tension to the cable  24 . It will be appreciated that the ball bearings  1586  are preferably made of a sufficiently hard material to resist the shearing loads applied to the ball bearings  1586  by the tension drive  1572  and the drive shaft  1550 . 
     To disengage the drive shaft  1550  from the tension drive  1572 , a button  1610  connected to the release shaft  1582  is pressed to shift the release shaft  1582  in direction  1612  toward a release position, as shown in  FIG. 61 . This aligns the neck  1592  of the release shaft  1582  with the radially extending openings  1584  of the drive shaft drive portion  1570 , as shown in  FIG. 62 . Moving the neck  1592  into alignment with the openings  1584  moves a gap  1612  between the drive shaft  1550  and the release shaft  1582  into communication with the openings  1584  which permits the ball bearings  1586  to shift inwardly. To aid the ball bearings  1586  in shifting inwardly, the pockets  1600  of the tension drive  1572  have curved inner surfaces  1620  (see  FIG. 57 ) that engage outer surfaces  1622  (see  FIG. 55 ) of the ball bearings  1586  and cam the ball bearings  1586  radially inward upon turning of the now-disengaged tension drive  1572  about the drive shaft drive portion  1570 . For example, once the button  1610  has been pressed in direction  1612  and the shaft  1582  shifted to its release position, tension in the cable  24  may turn the tension drive  1572  in the pay out direction  1652  because the ball bearings  1586  are no longer held in the outwardly biased position by the release shaft  1582 . The resulting turning of the now-disengaged tension drive  1572  about the drive shaft drive portion  1570  causes the pocket surfaces  1620  to cam the bearings  1586  radially inward into the gap  1612  to provide clearance for the tension drive  1572  about the drive shaft drive end  1570 . 
     The ratchet assembly  1530  includes a spring  1630  that biases against the button  1610  and shifts the release shaft  1582  backward in direction  1632 , as shown in  FIG. 62 . Shifting the release shaft  1582  backward returns the release shaft  1582  to its engaging position and re-aligns the release shaft head  1594  with the ball bearings  1586  to shift the ball bearings  1586  back into engagement with the tension drive socket pockets  1600 . With reference to  FIG. 56 , the release shaft  1582  has a tapered cam surface  1634  extending outwardly from the neck  1592  toward the enlarged head  1594 . The cam surface  1634  is configured to engage the ball bearings  1586  and cam the ball bearings  1586  radially outward within the openings  1584  upon return of the release shaft  1582  in direction  1632 . This aids in returning the ball bearings  1586  to their engaged position within the drive shaft socket pockets  1600 . With the release shaft  1582  returned to its engaged position, as shown in  FIG. 61 , turning of the handle  1513  in the wind up direction  1650  will again produce corresponding turning of the tension drive  1572  and the clamp body  1800  in the wind up direction  1650  and apply tension to the cable  24  if the cable  24  is present in the instrument  1500 . 
     The pawl  1534  of the tensioning instrument  1500  is different than the pawl  884  discussed above because the pawl  1534  is slidably mounted within the pawl sleeve  1540 , as shown in  FIGS. 54 and 55 . Further, the pawl  1534  has a split tooth  1536  with portions disposed on opposite sides of a central fin  1660  of the pawl sleeve  1540  once the pawl  1534  has been positioned within the pawl sleeve  1540 , as shown in  FIGS. 55 and 61 . The fin  1660  fits into a channel  1662  disposed between sets of the teeth  1664  of the drive shaft ratchet portion  1560 , as shown in  FIG. 55 . The engagement of the fin  1660  in the channel  1662  restricts axial movement of the drive shaft  1550  in direction  1612  and maintains the drive shaft  1550  mounted in the body  1502  against a bearing  1663 , as shown in  FIG. 54 . On the other side of the body  1502  from the bearing  1663 , the instrument has a nut  1677  that threadingly engages the drive shaft  1550  and further secures the drive shaft  1550  in position on the body  1502 . 
     With reference to  FIGS. 55 and 61 , the pawl assembly  1532  includes a disassembly button  1666  and a pin  1668  that connects the disassembly button  1666  to the pawl  1534 . The pin  1668  extends through a slot  1672  in the body  1502  and through a slot  1670  in the pawl sleeve  1540 , as shown in  FIG. 61 . The body slot  1672  restricts the pin  1668  and pawl  1534  to axial movement up and down within a cavity  1669  of the body  1502  and the engagement of the pin  1668  within the pawl sleeve slot  1670  restricts turning of the sleeve  1540  about the pawl  1534 . Thus, both the pawl  1534  and pawl sleeve  1540  are generally restricted to axial, up-and-down movement within the body cavity  1669 . 
     To disassemble the instrument  1500 , a user presses the button  1666  in direction  1673  to shift the pin  1668  and pawl  1534  connected thereto in direction  1673  and disengage the pawl tooth  1536  from the drive shaft ratchet teeth  1664 . Continued movement of the button  1666  in direction  1673  contacts the pin  1668  against a lower end of the slot  1670  of the pawl sleeve  1540  and shifts the pawl sleeve  1540  in direction  1673  as well. Movement of the pawl sleeve  1540  disengages the fin  1660  from the drive shaft channel  1662  such that both the pawl  1534  and the pawl sleeve  1540  are disengaged from the drive shaft  1550 . The handle  1513  can then be moved in direction  1612  (see  FIG. 61 ) to shift the tension drive  1572 , clamp body  1800 , and drive shaft drive portion  1580  outward from a cavity  1675  of the body  1502 , as shown in  FIG. 54 . In one form, the button  1610  is laser welded to the release shaft  1582  such that the drive shaft  1550  is restricted from being completely removed from the body  1502 . In another form, the button  1610  is connected with threads to the release shaft  1582 , such that the button  1610  and the nut  1677  can be unthreaded from the release shaft  1610  and the drive shaft  1550 , respectively, to permit the drive shaft  1550  and release shaft  1610  to be fully removed from the body  1502 , as shown in  FIG. 54 . 
     Another advantage of the pawl assembly  1532  is that the pawl  1534  and pawl sleeve  1540  are separate components that independently perform different functions. More specifically, the pawl sleeve  1540  and fin  1660  thereof engage the drive shaft  1550  to restrict axial movement of the drive shaft  1550 . The pawl  1534  operates in an orthogonal direction with the pawl tooth  1536  moving up and down as the pawl tooth  1536  travels up and down along the drive shaft ratchet teeth  1664 . Thus, the pawl assembly  1532  uses the pawl  1534  and the pawl sleeve  1534  to provide two different functions in a compact package within the instrument  1500 . 
     More specifically, frictional engagement between the pawl sleeve fin  1660  and sidewalls  1676  of the ratchet teeth  1664  (see  FIG. 55 ) may cause the pawl sleeve  1540  to travel axially downward within the cavity  1669  (see  FIG. 61 ) with turning of the drive shaft  1550  in the wind up direction  1650 . However, this axial movement of the pawl sleeve  1540  generally does not produce axial movement of the pawl  1534  and disengagement of the pawl tooth  1536  from the drive shaft ratchet teeth  1664 . Instead, the pawl sleeve  1540  shifts downwardly along the outer surface of the pawl tooth  1536  toward the distal end  1520  of the instrument  1500 . The spring  1542 , however, continues to bias the pawl  1534  and tooth  1536  in an opposite direction toward the drive shaft  1550  and into engagement with the drive shaft ratchet teeth  1664  thereof despite any slight axial movements of the pawl sleeve  1540 . Thus, the pawl assembly  1532  reduces the likelihood of unintentional disengagement of the pawl  1534  from the drive shaft drive portion  1570 . 
     With reference to  FIGS. 57-59 , the tension drive  1572  has structures that guide and engage the clamp body  1800  during turning of the rotary tensioning device  1510  and reconfiguring of the grip device  1514  from the pass-through configuration to the gripped configuration. In particular, the tension drive  1572  has a drive plate  1810  and an exterior plate  1812  that define a recess  1814  therebetween sized to receive the clamp body  1800  therein, as shown in  FIG. 57 . The drive plate  1810  has the drive socket  1576  formed therein and the external plate  1812  forms an outer wall of the tensioning instrument  1500  that is visible from the exterior of the tensioning instrument  1500 , as shown in  FIG. 53 . The etch mark  1573  is generally parallel to a groove  1822  of the tension drive  1572  such that the etch mark  1573  is aligned with a through opening  1811  of the grip device  1514  formed by the groove  1822  of the tension drive  1572  and a groove  1824  of the clamp body  1800 , as shown in  FIGS. 57, 60, and 63 . By turning the handle  1513  to align the etch mark  1573  with an etch mark  1813  (see  FIG. 53 ) on the body  1502 , the surgeon can visually confirm that the opening  1811  is aligned with a through passage  1823  of the body  1502 , as shown in  FIG. 63 . The cable  24  can then easily be passed into the inlet opening  1522 , through the body passage  1823 , through the rotary tensioning instrument opening  1811 , and outward from the outlet opening  1524 . 
     With reference to  FIG. 59 , the plates  1810 ,  1812  may extend from a face  1820  of the tension drive  1572  on opposite sides of the recess  1814 . The face  1820  has the cable-receiving groove  1822  formed therein that cooperates with the groove  1824  (see  FIG. 60 ) of the clamp member  1800  to define the through opening  1811  of the grip device  1514 , as will be discussed in greater detail below. With reference to  FIGS. 54 and 58 , the tension drive face  1820  has a pair of blind bores  1830  that receive sliding pins  1832 . The pins  1832  have support ends  1834  (see  FIG. 54 ) that are fixed within the blind bores  1830  and free ends  1836  (see  FIG. 55 ) extending outward from the tension drive face  1820  into sliding engagement with a circumferential retention groove  1840  of the drive shaft drive portion  1570 , as shown in  FIG. 55 . The sliding pin free ends  1836  extend generally perpendicular to the length of the drive shaft  1550  and are oriented to fit into the groove  1840  on opposite sides of the drive shaft  1550 . With reference to  FIG. 60 , the clamp member has a recess  1850  that provides clearance for the sliding pin free ends  1836 . This clearance permits the clamp member  1800  to move relative to the tension drive  1572  without contacting or interfering with the engagement of the sliding pin  1832  with the drive shaft retention groove  1840 . Similarly, the tension drive  1572  has a relatively large opening  1835  that receives a portion of a pin  1837  which extends outward from the clamp body  800 . Because the opening  1835  is larger than the pin  1837 , the opening  1835  retains the pin  1837  therein while permits the clamp body  1800  to move relative to the tension drive  1572  between the pass through and gripped configurations. 
     With reference to  FIGS. 55 and 58 , the tension drive face  1820  also includes blind bores  1860  that receive springs  1862  and clamp plungers  1864  therein. The clamp plungers  1864  can slide in a piston-like manner within the blind bores  1860  with distal ends  1866  of the clamp plungers  1864  biased by the springs  1862  into engagement with a face  1870  of the clamp body  1800 , as shown in  FIG. 55 . Clamp plungers  1864  operate to separate the clamp body  1800  from the tension drive  1572  once the tension drive  1572  and clamp body  1800  have been turned to a pass through configuration where the tension drive  1572  and clamp body  1800  can move apart, as shown in  FIG. 64 . During assembly, the clamp plungers  1864  are inserted into the bores  1860  after the springs  1862  and a portion of the tension drive  1572  surrounding the opening of the bores  1860  can be deformed to capture the plungers  1864  and springs  1862  in the bores  1860 . 
     With reference to  FIG. 60 , the clamp body  1800  has a pair of end walls  1872 ,  1874  on opposite sides of a curved winding portion  1876 . The winding portion  1876  forms a partially discontinuous spool in combination with a winding portion  1880  of the tension drive  1572  (see  FIG. 59 ). The end walls  1872 ,  1874  of the clamp body  1800  each include a protrusion  1890  having an engagement surface, such as outer curved surface  1892 , which is configured to engage a locking surface of the body  1502 , such as curved inner surface  1900  of the cavity  1675 , as shown in  FIG. 63 . With the tension drive  1572  and the clamp body  1800  in the pass-through configuration (see  FIG. 63 ), the clamp end wall protrusions  1890  are positioned within a complementary recess  1904  of the body cavity  1902 , as shown in  FIG. 64 . In this orientation, the clamp plungers  1864  can press against the clamp body  1800  and separate the clamp body  1800  from the tension drive  1572  as discussed above. The biasing force of the plungers  1864  against the clamp body  1800  positions the tension drive  1572  and clamp body  1800  so that the rotary tensioning device through opening  1811  has a release or pass-through diameter  1910 . As shown in  FIG. 64 , there is a gap  1912  between the faces  1820 ,  1870  of the tension drive  1572  and the clamp member  1800  when the tension drive  1572  and the clamp body  1800  are in the pass-through configuration. 
     Turning the handle  1513  in the wind up direction  1650  brings the protrusion outer surface  1892  into camming engagement with the body inner surface  1900  which shifts the clamp member  1800  toward the face  1820  of the tension drive  1572 , as shown in  FIG. 65 . Thus, turning the handle  1513  in the wind up direction  1650  reconfigures the tension drive  1572  and the clamp body  1800  from the pass-through configuration to the gripped configuration. With reference to  FIG. 65 , the rotary tensioning device through opening  1811  has an engagement diameter  1920  that is smaller than the pass-through diameter  1910  once the tension drive  1572  and clamp body  1800  have been shifted to the gripped configuration. In particular, the faces  1820 ,  1870  are brought into engagement with one another and the grooves  1822 ,  1824  compress the cable  24  therebetween. This fixes the locking clamp member  1800  and tension drive  1572  onto the cable  24 . It will be appreciated that the grooves  1822 ,  1824  may have surface treatments or structures that increase the frictional engagement of the tension drive  1572  and clamp body  1800  with the cable  24 . 
     To release the grip device  1514  from the cable  24 , the button  1610  is pressed to shift the release shaft  1582  in direction  1612  (see  FIG. 61 ) and disengage the tension drive  1572  from the drive shaft  1550 , as discussed above. The tension in the cable  24  will then turn the tension drive  1572  and the clamp member  1800  back in the pay out direction  1652  which pays out the cable  24  from the winding portions  1876 ,  1880  of the tension drive  1572  and the clamp member  1800 . 
     With reference to  FIGS. 66-69 , a bone anchor  2000  and a driver tool distal end  2002  are shown. The bone anchor  2000  and driver tool distal end  2002  are substantially similar to the bone screw  46  and driver  180  discussed above such that the differences from the bone screw  46  and driver  180  will be highlighted. The bone anchor  2000  has a head portion  2004  with a substantially cross-shaped drive recess  2006  with axially extending walls  2008  that extend to a floor  2010  of the recess  2006 . The floor  2010  has a blind bore  2012  formed therein. The anchor  2000  has a shank  2005  depending from the head portion  2004 . The shank  2005  may be threaded in a complimentary manner to threads  2007  on the head portion  2004 . 
     With reference to  FIG. 68 , the driver distal end  2002  has cross-shaped drives  2020  configured to engage the walls of the drive recess  2006 . The distal end  2002  also has a retention device  2022  including a tapered post  2024  which forms a press fit engagement with the blind bore  2012  of the bone anchor  2000 . 
     With reference to  FIG. 70 , another table tensioning instrument  2100  is provided that is similar in many respects to the cable tensioning instruments  800 ,  1500  discussed above such that primarily only the differences between the instruments will be highlighted. The tensioning instrument  2100  includes a body  2102  and a rotary tensioner  2104 . The rotary tensioner  2104  is similar to the examples of rotary tensioners discussed above including rotary tensioning devices  824 ,  1510 . The rotary tensioner  2104  is rotatably supported in the body  2102  and the tensioning instrument  2100  includes a drive  2106  for turning the rotary tensioner  2104 . 
     The body  2102  includes a distal end  2108  with an inlet opening  2110  through which a cable  2111  (see  FIG. 79 ) may be inserted in direction  2112 . To apply tension to the cable  2111 , the cable  2111  is advanced through a passage  2114  of the body  2102 , through a passage  2116  of the rotary tensioner  2104 , and outward in direction  2118  from a proximal opening  2120  of the body  2102  as shown in  FIG. 79 . The instrument  2100  is then slid down along the cable  2111  until the distal end  2108  abuts a device for securing the cable  2111 , such the bone plate  20  or a crimp. The drive  2106  includes a first actuator, such as a handle  2122 , and a shaft assembly  2124  which are turned in a first rotary direction  2126  to apply tension to the cable  2111  once the distal end  2108  abuts the bone plate  20  or crimp. This causes a grip device  2130  (see  FIG. 71 ) of the rotary tensioner  2104  to grab onto the cable  2111 , wind the cable  2111  onto the rotary tensioner  2104 , and tension the cable  2111  as shown in  FIGS. 79 and 80 . The instrument  2100  provides a rigid, mechanical connection between the handle  2122  and the rotary tensioner  2104  when the handle  2122  is turned in the first rotary direction  2126  such that the handle  2122  provides direct tactile feedback to the surgeon of the tension being applied to the cable  2111 . The surgeon uses this tactile feedback to determine when a desired tension has been reached. Once the desired tension has been applied to the cable  2111 , the cable  2111  is secured using the bone plate  20  or crimp. To remove the tensioning instrument  2100  from the cable  2111 , the surgeon turns the handle  2122  in a second rotary direction  2170  which disengages the shaft assembly  2124  from a ratchet assembly  2171  of the tensioning instrument  2100 . Turning the handle  2122  in the second rotary direction  2170  also causes the rotary tensioner  2104  to turn in a pay out direction  2170 A (see  FIG. 71 ) which, in turn, pays the cable  2111  off from the rotary tensioner  2104 . To assist with removal of the rotary tensioner  2104  from the cable  2111 , the surgeon may move the tensioning instrument  2100  away from the bone plate  20  or the crimp simultaneously with turning the handle  2122  in the second rotary direction  2170 . 
     With reference to  FIGS. 70 and 71 , the body  2102  includes an upper body portion  2132 , a lower body portion  2136 , and a rotatable connection  2137  that permits the upper body portion  2132  to be turned in directions  2138 ,  2140  about axis  2139  relative to the lower body portion  2136 . The ability of the upper body  2137  to turn relative to the lower body  2136  permits the surgeon to turn the upper body  2137  and position the handle  2122  where it is easiest to turn for the surgeon. This improves the ease with which the tensioning instrument  2100  can be used in confined environments, such as where patient anatomy or other instruments interfere with placement of the tensioning instrument  2100 . 
     With reference to  FIG. 71 , the upper body portion  2132  has a cavity  2134  that receives the rotary tensioner  2104 . The drive shaft assembly  2124  connects the handle  2122  to the rotary tensioner  2104  and includes a handle shaft  2150 , a tensioner shaft  2152 , and a biasing member, such as a torsion spring  2154 . The handle shaft  2150  is sized to fit within an inner bore  2156  (see  FIGS. 72 and 74 ) of the tensioner shaft  2152 . With reference to  FIG. 74 , the rotary tensioner  2104  includes a tension drive  2153  that, in one form, is formed integrally with the tensioner shaft  2152 . As other examples, the tension drive  2153  and the tension shaft  2152  may be secured together using welds or fasteners. The tension drive  2153  has a drive plate  2157  secured to the tensioner shaft  2152  and an exterior plate  2159  visible from the exterior of the tensioning instrument  2100 . The grip device  2130  is similar to the devices discussed above and includes the tension drive  2153 , a clamp body  2161 , and a pin  2163  (see  FIG. 71 ) pivotally connecting the clamp body  2161  to the tension drive  2153 . 
     The shaft assembly  2124  includes a pair of hard stops between the handle shaft  2150  and tensioner shaft  2152  to transfer turning of the handle  2122  in the first and second rotary directions  2126 ,  2170  into turning of the tensioner shaft  2152  in the first and second directions  2126 ,  2170 . With respect to  FIGS. 73B and 73C , the shaft assembly  2124  has also has a rotary slide connection  2149  that includes a pin  2160  and diametrically opposed, elongated slots  2166  of the tensioner shaft  2152 . The rotary slide connection  2149  permits the handle shaft  2150  to turn a predetermined rotary distance in the second rotary direction  2170  between the hard stops without causing turning of the tensioner shaft  2152 . Turning of the handle shaft  2150  in direction  2170  relative to the tensioner shaft  2152  causes the drive shaft  2124  to disengage from the ratchet assembly  2171  and permits the handle shaft  2150 , tensioner shaft  2152 , and rotary tensioner  2104  to turn in a pay out direction  2170 A and pay out the cable  2111  from the rotary tensioner  2104  as discussed in greater detail below. 
     With reference to  FIGS. 71 and 72 , the handle shaft  2150  and the pin  2160  are fixed relative to the handle  2122 . More specifically, a ring  2164  extends circumferentially around the tension shaft  2152  and the handle shaft  2150  therein and receives ends of the pin  2160 . The ring  2164  shifts circumferentially around an outer surface of the tensioner shaft  2152  and guides the pin  2160  with turning of the handle shaft  2150  relative to the tensioner shaft  2152 . The handle  2122  has a countersunk bore  2165  that receives the ring  2164  and resists movement of the pin  2160  radially outward from the handle shaft  2150 . The handle shaft  2150  and the pin  2160  are fixed relative to the handle  2122  by way of a hex drive end  2174  of the handle shaft  2150  being matingly engaged with a hex socket  2176  of the handle  2122 . To keep the hex drive end  2174  engaged with the hex socket  2176 , a pan head screw  2178  has a shank  2180  inserted from an opposite side of the handle  2122  and into engagement with threads  2175  of an inner bore of the hex drive end  2174 . Additionally, these components can be disassembled by removing the pan head screw  2178 , withdrawing the hex drive end  2174  from the hex socket  2176 , shifting the pin  2160  radially outward from the handle shaft  2150 , tensioner shaft  2152 , and ring  2164  and removing the ring  2164  from the tensioner shaft  2152 . 
     With respect to  FIGS. 72 and 73B , the pin  2160  extends through apertures  2162  of the ring  2164 , through the elongated slots  2166  on opposite sides of the tensioner shaft  2152 , and through an aperture  2168  of the handle shaft  2150 . The aperture  2168  of the handle shaft  2150  is circular and closely sized to a diameter of the pin  2160  to limit movement between the pin  2160  and the handle shaft  2150 . In other words, the annular wall of the handle shaft  2150  confines the pin  2160  within the aperture  2168 . With reference to  FIG. 73B , the elongated slots  2166  of the tensioner shaft  2152  each have an obround shape and are elongated in a circumferential direction around the circumference of the tensioner shaft  2152 . 
     With reference to  FIG. 73B , the handle  2122  is removed to show the pin  2160  extending through one of the elongated slots  2166  of the tensioner shaft  2152 . The torsion spring  2154  biases the handle shaft  2150  in direction  2126  relative to the tensioner shaft  2152  to hold the pin  2160  in its initial position wherein the pin  2160  is in abutment with an end  2167  of each of the slots  2166  prior to a surgeon manipulating the handle  2122 . The abutting contact of the pin  2160  against the end  2167  of each of the slots  2166  forms one of the hard stops of the drive shaft assembly  2124 . 
     When the handle  2122  is turned in the first rotary direction  2126  against the bias force of the torsion spring  2154 , the pin  2160 , ring  2164 , and handle shaft  2150  turn together in the first rotary direction  2126  due to the fixed relation between these components. This presses the pin  2160  against the end  2167  of each of the slots  2160  causing the pin  2160  to turn the tensioner shaft  2152  in the first rotary direction  2126  which, in turn, causes the rotary tensioner  2104  to turn in the wind up direction  2126 A. Conversely, when the handle  2122  is turned in the second rotary direction  2170  against the bias force provided by the spring member  2154 , the pin  2160 , ring  2164 , and handle shaft  2150  turn together in the second rotary direction  2170 . The pin  2160  slides circumferentially along the elongated slots  2166  and may abut against an opposite end  2169  of each of the elongated slots  2166 , which forms the other hard stop of the drive shaft assembly  2124 . 
     As the pin  2160  slides from the end  2167  to the end  2169  of the slots  2166  in the second rotary direction  2170 , the handle shaft  2150  turns in the second rotary direction  2170  within the inner bore  2156  of the tensioner shaft  2152 . Because the pin  2160  is sliding between the slot ends  2167 ,  2169 , the pin  2160  slides relative to the tensioner shaft  2152  without causing turning of the tensioner shaft  2152 . This relative rotary movement of the handle shaft  2150  and tensioner shaft  2152  disengages the shaft assembly  2124  from the ratchet assembly  2171 . 
     More specifically, the handle shaft  2150  and the tensioner shaft  2152  have a driving rotary orientation relative to each other (see  FIG. 75 ) which permits turning of the handle  2122  in the first rotary direction  2126  to produce turning of the rotary tensioner  2104  in the wind up direction  2126 A. The handle shaft  2150  includes ribs  2310  that are configured to maintain at least one detent member, such as balls  2252 , in radially outward, drive positions when the handle shaft  2150  and tensioner shaft  2152  are in the drive rotary orientation thereof. In this regard, the ribs  2310  project radially outward from the handle shaft  2150 , and with the pin  2160  biased to its initial position, the ribs  2310  will be aligned with corresponding ones of the balls  2252  to shift the balls  2252  to radially outward drive positions. Further, the pin  2160  abuts the ends  2167  of the elongate slots  2166  (see  FIG. 73B ) when the handle shaft  2150  and the tensioner shaft  2152  are in the drive rotary orientation. 
     The handle shaft  2150  and the tensioner shaft  2152  also have a release rotary orientation relative to each other (see  FIG. 76 ) that disengages the tensioner shaft  2152  from the ratchet assembly  2171  and permits turning of the handle  2126  in the second rotary direction  2170  to produce turning of the rotary tensioner  2104  in the pay out direction  2170 A. In the release orientation, the ribs  2310  are no longer aligned with the balls  2252  permitting the balls  2252  to shift radially inward into gaps  2311  between the ribs  2310 . Further, the pin  2160  abuts against the ends  2169  of the elongated slots  2166  when the handle shaft  2150  and the tensioner shaft  2152  are in the release rotary orientation. 
     In one form, the tensioning instrument  2100  automatically maintains the handle shaft  2150  and the tensioner shaft  2152  in the driving rotary orientation when the handle  2122  is not being manipulated. In this manner, the pin  2160  is abutting against the ends  2167  of the slots  2166  so that turning the handle  2122  in direction  2126  causes immediate turning of the rotary tensioner  2104  in wind up direction  2126 A without any take-up turning required. This provides immediate tactile feedback to the surgeon of the tension being applied to the cable  2111  with turning of the handle  2122  and makes the tensioning instrument  2100  more intuitive to use. 
     With reference to  FIGS. 71 and 72 , the handle shaft  2150  includes an inner bore  2182  that receives the torsion spring  2154 . The torsion spring  2154  in one form is a straight, bar-like member with opposite end portions  2190 ,  2192 . The end portion  2190  is received in an angled slot  2186  of the handle shaft  2150  as shown in  FIG. 77 . The angled slot  2186  is angled relative to vertical as shown in  FIG. 77 . With reference to  FIGS. 72, 76 and 78 , the inner bore  2156  of the tensioner shaft  2152  receives the handle shaft  2150  and the torsion spring  2154  therein. The torsion spring  2154  extends axially beyond the end of the handle shaft  2150  to position the end portion  2192  of the torsion spring  2154  in a vertical slot  2194  of the tensioner shaft  2152 . The vertical slot  2194  is vertical as shown in  FIG. 78 . The angled slot  2186  and the vertical slot  2194  extend transverse to each other to generate preload in the torsion spring  2154  as discussed below. 
     To maintain the driving rotary orientation (see  FIG. 75 ), the angled slot  2186  imparts a helical twist to the torsion spring  2154 . In this manner, the torsion spring  2159  is preloaded urging the handle shaft  2150  in direction  2126  relative to the tensioner shaft  2152 . This keeps ribs  2310  of the handle shaft  2150  radially aligned with the balls  2252  to shift the balls  2252  radially outwardly. Further, once the surgeon releases the handle  2122  after turning the handle in the second rotary direction  2170  (see  FIG. 76 ), the torsion spring  2154  resiliently urges the handle shaft  2150  in direction  2126  relative to the tensioner shaft  2152  and automatically returns the handle shaft  2150  and tensioner shaft  2152  to the drive rotary orientation (see  FIG. 75 ). 
     Because the torsion spring end portion  2190  is secured to the handle shaft  2150  and the torsion spring end portion  2192  is secured to the tensioner shaft  2152 , the torsion spring  2154  is progressively loaded by turning of the handle shaft  2150  in the second rotary direction  2170  relative to the tensioner shaft  2152 . In this manner, turning of the handle  2122  in the second rotary direction  2170  requires overcoming the bias force from the torsion spring  2154  to reconfigure the handle shaft  2150  and the tensioner shaft  2152  from the drive rotary orientation to the release rotary orientation. 
     Returning to  FIGS. 72 and 73A , the ratchet assembly  2171  includes a ratchet gear  2200  that is selectively fixed against rotary movement relative to the tensioner shaft  2152 . The ratchet assembly  2171  further includes a pawl  2202  with a tooth  2204  that engages against teeth  2206  of the ratchet gear  2200 . Like the gears  82  and  1560  discussed above, the teeth  2206  are shaped to interact with the pawl tooth  2204  and form a hard stop against turning of the ratchet gear  2200  in one direction relative to the pawl  2202 . The teeth  2206  are different than a typical gear tooth because the teeth  2206  are configured to abut the pawl  2200  and resist turning of the ratchet gear  2200  in one rotary direction rather than transferring mechanical power to another gear. 
     The ratchet assembly  2171  includes a spring  2208 , a pin  2212  and a second actuator, such as disassembly button  2214 , as shown in  FIG. 73A . The spring  2208  urges the pawl  2202  upward in direction  2210  to position the pawl tooth  2204  in overlapping relation with one of the teeth  2206  of the ratchet gear  2200  and thus the circumferential path of the teeth  2206  as the ratchet gear  2200  is turned. The ratchet assembly  2171  may also include a pawl sleeve  2222  positioned concentric with the pawl  2202 . The pawl sleeve  2222  has an elongated opening  2224  (see  FIG. 72 ) that provides clearance for the pin  2212  to move relative to the pawl sleeve  2222 . The pawl sleeve  2222  includes a lip  2226  that fits into a channel  2228  between a flange  2230  of the ratchet gear  2200  and the drive plate  2157  of the tension drive  2153 . The lip  2226  of the pawl sleeve  2222  resists axial movement of the gear  2200  and tensioner shaft  2152  in axial directions  2234 ,  2235 . Further, because the pawl sleeve  2222  can move vertically relative to the pawl  2202 , the pawl  2202  remains engaged with the ratchet gear  2202  even if friction between the lip  2226  and the flange  2230  were to shift the pawl sleeve  2222  downwardly in a manner similar to the pawl  1534  and pawl sleeve  1540  discussed above. 
     To disassemble the instrument  2100 , a user may press downward in direction  2216  on the disassembly button  2214  to disengage the pawl  2202  from the ratchet gear  2200 . With reference to  FIG. 72 , once the disassembly button  2214  and pawl  2202  have been shifted downwardly far enough, and the handle  2122  disassembled from the handle shaft  2150  as discussed above, the tensioner shaft  2152  may be shifted in direction  2220  to shift the handle shaft  2150 , tensioner shaft  2152 , ratchet gear  2200 , balls  2252 , and rotary tensioner  2104  outward from the cavity  2134  of the upper body portion  2132 . 
     With respect to  FIG. 72 , the instrument  2100  includes a release mechanism  2250  that is operated by the handle  2122  to disengage the tensioner shaft  2152  from the ratchet gear  2200  after a desired tension has been applied to the cable  2111  and the cable has been crimped or otherwise secured. In one form, the ratchet assembly  2171  includes at least one release member, such as the balls  2252 . The balls  2252  are similar to the other examples of release members discussed above, including release shaft  900  and ball bearings  1586  which are shifted to permit turning of the associated rotary tensioner in a pay out rotary direction. The balls  2252  have a radially outward, drive position wherein the balls  2252  resist rotary movement of the tensioner shaft  2152  relative to the ratchet gear  2200  so that the tensioner shaft  2152  and the ratchet gear  2200  rotate together, and a radially inward, release position wherein the balls  2252  are in clearance with the ratchet gear  2200  and permit rotary movement of the tensioner shaft  2152  relative to the ratchet gear  2200 . 
     With reference to  FIG. 74 , the tensioner shaft  2152  includes a drive portion  2256  with radially extending openings  2258  sized to receive the balls  2252 . The ratchet gear  2200  has an annular configuration to extend about an opening  2260  that is sized to allow the gear  2200  to be fit over the tensioner shaft  2152  and permit the ratchet gear  2200  to be slid onto the tensioner shaft  2152  in direction  2262 . The ratchet gear  2200  includes recessed openings or pockets  2266  at circumferentially spaced positions around an inner surface  2268  of the ratchet gear  2200 . Each of the pockets  2262  includes a concave curved surface  2270  configured to cam the ball bearing  2252  received in the pocket  2262  radially inward farther into the openings  2258  and out from the pocket  2262  once the handle  2122  has been turned in the second rotary direction  2170  as discussed in greater detail below. 
     As shown in  FIGS. 71 and 77 , the handle shaft  2150  has a shift portion  2300  that includes the ribs  2310 . In one form, the shift portion  2300  has a continuous undulating outer surface  2302  formed at least in part by the ribs  2310  which cams the balls  2252  radially outward with turning of the handle shaft  2150  in the first rotary direction  2126  and provides clearance for the balls  2252  to shift radially inward with turning of the handle shaft  2150  in the second rotary direction  2170 . 
     With reference to  FIG. 75 , the handle shaft  2150  and the tensioner shaft  2152  are shown in the driving rotary orientation wherein turning of the handle  2122  in the first rotary direction  2126  causes turning of the handle shaft  2150 , presses the pin  2160  against the ends  2167  of the slots  2166  (see  FIG. 73B ), and turns the tensioner shaft  2152  and the tension drive  2153  in the first rotary direction  2126 . With the handle shaft  2150  and the tensioner shaft  2152  in the driving rotary orientation, tip portions  2312  of the ribs  2310  engage and hold the balls  2252  in the radially outward, driving position thereof in direction  2304 . The balls  2252  have radially inner portions  2322  supported in the openings  2258  of the tensioner shaft  2152  by the rib tips  2312  and radially outer portions  2324  extending into the pockets  2266  of the ratchet gear  2200 . Further, although the curved surfaces  2270  of the pockets  2266  are shaped to cam the balls  2252  inwardly, the presence of the ribs  2310  prevents radially inward movement of the balls  2252  in direction  2306 . Because the balls  2252  extend in both the openings  2258  and the pockets  2266 , the balls  2252  operate as a catch between the tensioner shaft  2152  and the ratchet gear  2200  and thereby operatively engage the tensioner shaft  2152  to the ratchet gear  2200  so that the tensioner shaft  2152  and the ratchet gear  2200  rotate together. In other words by operatively engage, it is intended to mean that the tensioner shaft  2152  is held against rotational movement relative to the ratchet gear  2200 . In one form, the balls  2252  are of a metallic material such as stainless steel to resist the shear forces applied to the balls  2252  by the tensioner shaft  2152  and the ratchet gear  2200 . 
     With reference to  FIG. 76 , once a desired amount of tension has been applied to the cable  2111 , the surgeon turns the handle  2111  in second rotary direction  2170  to reconfigure the handle shaft  2150  and the tensioner shaft  2152  to the release rotary orientation and disengage the tensioner shaft  2152  from the ratchet gear  2200 . More specifically, when the handle  2122  is turned in the second rotary direction  2170 , the fixed connection between the handle  2122  and the handle shaft  2150  causes the handle shaft  2150  to also turn in the second rotary direction  2170 . The inter-engagement of the pawl  2202 , ratchet gear  2200 , and balls  2252  initially resists rotary movement of the tensioner shaft  2152  in the second rotary direction  2170  so that the handle shaft  2150  turns in the second rotary direction  2170  relative to the tensioner shaft  2152 . The torsion spring  2154  also resists turning of the handle shaft  2150  relative to the tensioner shaft  2152 , such that the user turns the handle  2122  in the second rotary direction  2170  against the bias of the torsion spring  2154 . 
     The surgeon continues to turn the handle shaft  2150  in direction  2170  which causes the ribs  2310  to rotate out of radial alignment with the balls  2252  and causes the gaps  2311  between the ribs  2310  to rotate into radial alignment with the balls  2252  as shown in  FIG. 76 . Turning the handle  2122  and the handle shaft  2150  in the second rotary direction  2170  also slides the pin  2160  along the elongated slots  2166  from ends  2167  toward ends  2169 . Continued turning of the handle  2122  in the second rotary direction  2170  causes turning of the tensioner shaft  2152  in the second rotary direction  2170 . As the tensioner shaft  2152  turns in the second rotary direction  2170 , the curved surfaces  2270  of the ratchet gear pockets  2266  cammingly engage the spherical outer surfaces of the balls  2252  and urge the balls  2252  radially inward in direction  2306 . This shifts the balls  2252  radially inward into the release position thereof where the balls  2252  extend into the gaps  2311  of the handle shaft  2150 . When the balls  2252  are in the release positions thereof, the radially outer portions  2324  of the balls  2252  no longer extend into the pockets  2266  of the ratchet gear  2200 . In this manner, the tensioner shaft  2152  is operatively disengaged from the ratchet gear  2200 . It will be appreciated that the balls  2252  may still contact and roll relative to the ratchet gear  2200  when the balls  2252  are in the release position thereof. But the balls  2252  no longer operate as a catch and now permit the tensioner shaft  2152  to rotate relative to the ratchet gear  2200 . 
     With reference to  FIG. 76 , the surgeon continues to turn the handle  2122  in the second rotary direction  2170  after the balls  2252  have shifted radially inwardly to the release positions thereof to pay out the cable  2111  from the tension drive  2153 . The pin  2160  abutting the ends  2169  of the elongated slots  2152  (see  FIG. 73C ) transfers turning of the handle  2122  in the second rotary direction  2170  into turning of the tensioner shaft  2152  and the tension drive  2153  in the second rotary direction  2170 . The cable  2111  is paid out from the tension drive  2153  by the portions  2480 ,  2484  unwinding from the tension drive  2153  in directions  2483 ,  2487  as shown in  FIG. 80 . The user may continue turning the handle  2122  in direction  2170  until the cable  2111  has been fully unwound from the rotary tensioner  2104 . 
     Alternatively, the torsion spring  2154  may turn the tensioner shaft  2152  and the tensioner drive  2153  in the second rotary direction  2170  before the pin  2160  abuts the ends  2169  of the elongated slots  2152 . Because the torsion spring  2154  is causing the turning of the tensioner shaft  2152 , there may be intermittent engagement of the balls  2252  in the recesses  2266  of the ratchet gear  2200  which may slow or stop pay out of the cable  2111 . More specifically, once the tensioner shaft  2152  has been turned in the second rotary direction  2170  sufficiently far that the openings  2258  are near the pockets  2266  of the ratchet gear  2200 , the torsion spring  2154  may turn the tensioner shaft  2152  in the first rotary direction  2126  relative to the handle shaft  2152  to release some of the load in the torsion spring  2154 . This turning of the tensioner shaft  2152  in the first rotary direction  2126  relative to the handle shaft  2152  causes cam surfaces  2330  (see  FIG. 75 ) of the ribs  2310  to shift the balls  2252  radially outward in direction  2304  and snap into the pockets  2226 . 
     To continue paying out of the cable  2111 , the surgeon turns the handle  2122  farther in the second rotary direction  2170  to reconfigure the handle shaft  2150  and the tensioner shaft  2152  to the release rotary orientation and disengage the balls  2252  from the pockets  2266  of the ratchet gear  2200 . The snapping of the balls  2252  into and out of engagement with the ratchet gear  2200  allows the surgeon to incrementally pay out the cable  2111  if he stops turning the handle  2122  each time the balls  2252  engage the ratchet gear  2200  or continuously pay out the cable  2111  if the surgeon continuously turns the handle  2122  in the second rotary direction  2170 . 
     To improve the ease of removing the tensioning instrument  2100  from the cable  2111 , the surgeon may move the tensioning instrument  2100  away from the plate member  30  or crimp as the handle  2122  is turned in the second rotary direction  2170 . 
     The tensioning instrument  2100  also provides flexibility in determining the tension to be applied to the cable  2111 . For example, the surgeon may desire to release a small amount of tension from the cable  2111  without fully unwinding the cable  2111  from the rotary tensioner  2104 . In this case, after the surgeon has turned the handle  2122  in the first rotary direction  2126  to apply tension to the cable  2111 , the surgeon may turn the handle  2122  in the second rotary direction  2170  to cause the rotary tensioner  2104  to turn in the pay out direction  2170 A, and release tension in the cable  2111 . The release of tension in the cable  2111  may create tactile feedback to the surgeon via the handle  2122 . Once the desired amount of tension has been released from the cable  2111 , the surgeon can release the handle  2122  and the torsion spring  2154  will bias the handle shaft  2150  in direction  2126  (see  FIG. 75 ) and return the handle shaft  2150  and the tensioner shaft  2152  to the driving rotary orientation thereof to lock the tension in the cable  2111  at the lowered amount thereof. The ribs  2310  have cam surfaces  2330  configured to contact the outer surfaces of the balls  2252  and shift the balls  2252  radially outward in direction  2304  to the driving position thereof as the torsion spring  2154  turns the handle shaft  2150  in the first rotary direction  2126  relative to the tensioner shaft  2152 . With the balls  2252  in the driving position and extending into the pockets  2266  of the ratchet gear  2200 , the tensioner shaft  2152  is fixed to the ratchet gear  2200 . In this manner, the torsion spring  2154  automatically returns the handle shaft  2150  and the tensioner shaft  2152  back to the driving rotary orientation, shifts the ball bearings  2252  to the radially outward, driving position, and operatively engages the tensioner shaft  2152  and the ratchet gear  2200 . The ratchet assembly  2171  resists further turning of the tensioner shaft  2152  in the second rotary direction  2170  and maintains the desired, lower tension in the cable  2111 . The surgeon can then crimp or otherwise secure the bone plate  20  or crimp to secure the cable  2111  with the desired, lower tension. 
     With reference to  FIG. 79 , the rotatable connection  2137  between the upper body portion  2132  and the lower body portion  2136  includes a bore  2400  of the lower body portion  2136  and a projection  2402  of the upper body portion  2132 . The projection  2402  includes a shoulder  2404 , a neck  2406 , and a head  2408 . The lower body portion  2136  includes a pin  2410  (see  FIG. 71 ) extending through a hole  2412  in the lower body portion  2136  and tangentially through an annular channel  2414  of the neck  2406 . The projection  2402  has a generally cylindrical shape and the bore  2400  has a mating, generally cylindrical shape. In this manner, the pin  2410  can slide tangentially relative to the neck  2406  via the channel  2414  as the upper body portion  2132  is in turned in directions  2138 ,  2140  as shown in  FIG. 70  above. Returning to  FIG. 79 , in one approach, the rotatable connection  2137  includes a bearing, such as a quad ring  2420 , between the upper body portion  2132  and the lower body portion  2136  such as between the end of the projection  2402  and a bottom  2401  of the bore  2400  to increase the ease with which the upper body portion  2132  can be turned especially when the cable  2111  is under tension. 
     With reference to  FIG. 79 , a method of tensioning the cable  2111  is shown. Initially, an end of the cable  2111  advanced in direction  2111  through the passage  2114  of the body  2102  and through the passage  2116  of the rotary tensioner  2104 . The rotary tensioner  2104  is shown in a pass-through configuration which permits the cable  2111  to be advanced between the tension drive  2153  and the clamp body  2161 . When the rotary tension  2104  is in the pass-through configuration, the clamp body  2161  has protrusions  2452  that are aligned with a cavity  2454  of the upper body portion  2132 . 
     The tensioning instrument  2100  is then slid along the cable  2111  until the distal end  2108  abuts the bone plate  20  or crimp. Next, the surgeon turns the handle  2122  in the first rotary direction  2126 . As shown in  FIG. 80 , turning the handle  2122  in the first rotary direction  2126  causes the rotary tensioner  2104  to turn in the wind up direction  2126 A and causes a camming engagement of the protrusions  2452  of the clamp body  2161  against a curved inner surface  2470  of the upper body portion  2132 . The camming engagement pivots the clamp body  2161  toward a confronting, adjacent face  2472  of the tension drive  2153  to clamp the cable  2111  between the clamp body  2161  and the face  2472  of the tension drive  2153 . 
     Continued turning of the handle  2122  in the first rotary direction  2126  draws a portion  2480  of the cable  2111  upward in direction  2482  onto the rotary tensioner  2104  and a portion  2484  of the cable  2111  downward in direction  2486  onto the rotary tensioner  2104 . With reference to  FIG. 74 , the cable  2111  is wound upon an outer curved winding portion  2456  of the clamp body  2161  and an outer curved winding portion  2458  of the tension drive  2153 . The winding of the cable  2111  onto the rotary tensioner  2104  applies tension to the cable  2111 . 
     In one form, the torsion spring  2154  has the shape of a strip and is approximately 0.083 inches thick, approximately 0.13 inches tall, and approximately 1 inch long. The torsion spring  2154  may be machined from superelastic nitinol or spring steel. The upper body portion  2132  and lower body portion  2136  may be made from stainless steel. The handle  2122  may be made from aluminum. The handle shaft  2150  and the tensioner shaft  2152  may be made from 465 stainless steel and may be coated with cobalt chrome. The balls  2252  may be made from stainless steel and the quad ring  2420  may be made from rubber. 
     While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention.