Abstract:
A method for correcting an angular deformity in a bone includes inserting a guide wire within a physis of a bone having an angular deformity, the physis extending between a first side the bone on which the guide wire is inserted and an opposing second side of the bone. The guide wire is used to guide a link to the physis. The link is then secured to the first side of the bone so that the link spans across the physis and restricts the growth of the physeal tissue of the physis on the first side of the bone. The physis is then allowed to generate more physeal tissue on the second side of the bone than on the first side of the bone so that the angular deformity of the bone is reduced.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 10/310,720, filed Dec. 4, 2002, which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to the design and method of use for an implant to help realign angular and rotational deformities in long bones in patients with active growth plates. 
     2. Related Technology 
     As a result of congenital deformation, traumatic injury or other causes, long bones such as the femur, tibia and humerus may grow out of alignment, causing deformity of the limb and biomechanical abnormalities. While some deformities are asymptomatic or may resolve spontaneously, it is often necessary to intervene surgically to realign these limbs. For the patients requiring surgical intervention, both osteotomy with realignment of the bone and epiphyseal stapling are currently accepted methods of treatment. 
     One common method of surgical bone realignment is by means of an osteotomy, or cutting of the bone, followed by realignment of the bone. In some procedures the bone is cut laterally, transverse to the longitudinal axis of the bone. Then the bone is realigned. A bone graft is then placed in the resulting wedge space. The bone and the bone graft are stabilized by orthopedic fragment fixation implants such as screws and bone plates. In an alternative osteotomy procedure, a bone wedge is removed. The bone is realigned, and similar implants are used to secure the bone. A third method of deformity correction via osteotomy is to first cut the bone, then apply an external frame attached to pins drilled through the skin and into the bone. By adjusting the frame, either intraoperatively or postoperatively, the bone is straightened. 
     Because osteotomy methods require a relatively large incision to create bone cuts, they are relatively invasive; they disrupt the adjacent musculature and may pose a risk to the neurovascular structures. An additional disadvantage of these procedures is the potential risk of damage to the growth plate, resulting in the disruption of healthy limb growth. Consequently, this procedure may be reserved for bone alignment in skeletally mature patients in whom the growth plates are no longer active. 
     One less invasive method of bone alignment involves the placement of constraining implants such as staples around the growth plate of the bone to restrict bone growth at the implant site and allow the bone to grow on the opposite side. First conceived in 1945 by Dr. Walter Blount, this method is known as epiphyseal stapling. Typically epiphyseal stapling is more applicable in young pediatric patients and adolescents with active growth plates. A staple is placed on the convex side of an angular deformity. Since the bone is free to grow on the concave side of the deformity, the bone tends to grow on the unstapled side, causing the bone to realign over time. Once the bone is aligned, the constraining implants are typically removed. 
     As long as the growth plate is not disturbed, this type of intervention is generally successful. However, the procedure must be done during the time that the bone is still growing, and the physiodynamics of the physis (growth plate) must not be disturbed. With proper preoperative planning and placement of the implants, the surgeon can use the implants to slowly guide the bone back into alignment. 
     The implants currently used in epiphyseal stapling procedures are generally U-shaped, rigid staples. The general design has essentially remained the same as those devised by Blount in the 1940&#39;s. Since these implants are rigid, they act as three-dimensional constraints prohibiting expansion of the growth plate. They are not designed to allow flexibility or rotation of the staple legs with the bone sections as the bone is realigned. Due to the constraints of these staple implants, the planning associated with the placement of the implants is overly complicated. Consequently, the surgeon must not only determine where to position the implant across the physis, but also must account for the added variables of implant stiffness, implant strength and bone-implant interface rupture. 
     The force associated with bone growth causes bending of these implants proportionate to their stiffness. Depending on the strength of the implant, these loads could eventually cause the implants to fracture under the force of bone realignment. This can make them difficult or impossible to remove. These same forces can also cause the implants to deform, weakening the bone-to-implant interface. This weakening may result in migration of the implant out of the bone, risking damage to the adjacent soft tissues and failure of the procedure. 
     SUMMARY OF THE INVENTION 
     The invention relates to an orthopedic bone alignment implant system that includes a guide wire, a link and bone fasteners. The guide wire serves to locate the growth plate under fluoroscopic guidance. The bone fasteners and the link function together as a tether between bone segments on opposite sides of the physis. As the bone physis generates new physeal tissue, the bone alignment implant tethers between engagers on the bone segments. This tethering principle guides the alignment of the bone as it grows. 
     Although applicable in various orthopedic procedures involving fracture fixation, the bone alignment implant is also applicable to the correction of angular deformities in long bones in which the physis is still active. 
     The distal end of the guide wire is used to locate the physis. Once its tip is placed in the physis, it is driven partly into the physis to function as a temporary guide for the link. The delivery of the implant over the guide wire assures that the link is properly placed with the bone fasteners on opposite sides of the physis. This will minimize the chance of damaging the physis throughout bone realignment. The link is then placed over the guide wire and oriented such that openings through the link for the bone fasteners are on either side of the physis. For pure angular correction, these openings would be collinear with the long axis of the bone; for rotational correction, they would be oblique to its axis. 
     The bone fasteners are then placed through the openings in the link and into the bone, connecting the sections of bone on opposite sides of the physis with the implant. Alternatively, guide pins can be used to help align canullated fasteners. 
     The implant is designed such that it partially constrains the volume of the bone growth on the side of the physis that it is placed. The implant guides the growth of new bone at the physis such that the growth direction and resulting alignment is controlled. The implant limits the semi-longitudinal translation of the bone fasteners yet allows for the bone fasteners to freely rotate with the bone segments as the angular or torsional deformity is straightened. 
     In some embodiments of this invention, both the link and the fasteners are rigid, but the connection between them allows for relative movement of the fasteners. In other embodiments the link is flexible allowing the fasteners to move with the bone sections. In other embodiments, the fasteners have flexible shafts allowing only the bone engager of the fasteners to move with the bone sections. In still other embodiments, both the link and the shafts of the fasteners are flexible, allowing movement of the bone sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present invention will now be discussed with reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. 
         FIG. 1  is an anterior view of the knee showing a genu valgum deformity (knee knocking) in the femur and the insertion of a guide wire approximately parallel to the physis; 
         FIG. 2  is a sagittal view of that described in  FIG. 1  showing the placement of the guide wire in the physis; 
         FIG. 3  is an anterior view of the knee showing the placement of a link and drill guide over the guide wire and the use of the guide to place two guide pins for fasteners on opposite sides of the physis; 
         FIG. 4  is a sagittal view of the placement of the link described in  FIG. 3  showing the position of the two guide pins on opposite sides of the physis; 
         FIG. 5  is an alternative method of applying the link over the guide wire in which the link is placed first, then the fasteners are placed through the openings in the link; 
         FIG. 6  is a sagittal view of the link placement also shown in  FIG. 5 ; 
         FIG. 6A  is a top plan view of the link shown in  FIG. 6 ; 
         FIG. 7  is an anterior view showing an alternative method of drilling of holes in the bone over the guide pins to prepare the bone for the fasteners; 
         FIG. 8  is an anterior view of the link showing the placement of the fasteners through the link and into the bone segments; 
         FIG. 9  is a sagittal view of the fasteners and link described in  FIG. 8 ; 
         FIG. 10  is an anterior view as seen after the physeal tissue has grown and the bone alignment implant assembly has been reoriented as the bone is realigned; 
         FIG. 11  is a sagittal view of the bone alignment implant placed on a rotational deformity; 
         FIG. 12  is the same sagittal view described in  FIG. 12  after the rotational deformity has been corrected; 
         FIG. 13  is a perspective view of a threaded fastener; 
         FIG. 14  is a perspective view of a barbed fastener; 
         FIG. 15  is a perspective view of an alternative embodiment of the bone alignment implant with rigid link and fasteners, with joints allowing restricted movement between them; 
         FIG. 16  is a perspective view of an alternative embodiment of the bone alignment implant showing a flexible midsection of the link with rigid material surrounding the openings; 
         FIG. 17  is a perspective view of an alternative embodiment of the bone alignment implant showing a flexible midsection of the link made from a separate flexible member with rigid material surrounding the openings; 
         FIG. 18  is a perspective view of an alternative embodiment of the bone alignment implant showing flexible woven material throughout the body of the link with reinforcement grommets surrounding the openings; 
         FIG. 19  is a perspective view of an alternative embodiment of the bone alignment implant showing the link made from a flexible band of material; 
         FIG. 20  is a perspective view of an alternative embodiment of the bone alignment implant showing the link made from a flexible ring of braided material that is joined in the midsection, forming two openings; 
         FIG. 21  is a side view of an alternative embodiment of the bone alignment implant showing bone fasteners that have flexible shaft sections; 
         FIG. 22  is a side view of an alternative embodiment of the bone alignment implant showing two barbed bone fasteners attached to a flexible link; and 
         FIG. 23  is a side view of an alternative embodiment of the bone alignment implant showing one barbed bone fastener and one threaded bone fastener connected to a flexible link. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a schematic anterior view of the human knee joint is depicted in which a distal femur  10  is proximal to a proximal tibia  5  and a proximal fibula  6 . A distal femoral physis  1 , or growth plate, separates a distal epiphyseal section  3  from a proximal metaphyseal section  2  of the distal femur  10 . Likewise a proximal tibial physis  1 ′ separates a proximal epiphyseal section  3 ′ from a metaphyseal section  2 ′ of the proximal tibia  5  and a proximal fibula physis  1 ″ separates a proximal epiphyseal section  3 ″ of a proximal fibula  6  from a metaphyseal section  2 ″ of the proximal fibula  6 . Although the invention described herein is adaptable to nearly all of the long bones in the body, only the example of correcting one type of an angular deformity in the distal femur will be described in detail. The principles described herein can be adapted to other deformities and other bones such as the tibia, fibula, humerus, radius and ulna. 
     By example, an angular deformity  4  in the femur  10  known as genu valgum or knock-knee is shown in  FIG. 1 . The angular deformity  4  is the angle between a pretreatment longitudinal axis  12  of the femur  10  and a post treatment projected longitudinal axis  13  of the femur  10 . A bone alignment implant will be placed on the medial side of the femur  10 . In this case, the medial side of the femur  10  is curved in a convex arc. Hence, this side of the deformity is called a convex side  16  because the angular deformity  4  bends the femur  10  in a curve that is angled away from or convex with respect to the medial side. A concave side  17  is on the opposite side of the femur  10 . Likewise, the angular deformity  4  is angled towards the concave side  17 . 
     A guide wire  8 , as shown in  FIG. 1 , is used to locate the physis and guide the bone alignment implant to the surgical site. The guide wire  8  comprises a long axis  11 , a distal section  9  that is shaped to fit into the physeal tissue, and a periphery  14  that is typically a constant size and shape. In this case, the shape of the guide wire  8  along the long axis  11  is essentially cylindrical so the shape of the periphery  14  is round and does not change except for in the distal section  9 . However, the periphery  14  can be a variable cross-section that changes shape or size along the length of the long axis  11 . 
     In this example, the long axis  11  of the guide wire  8  is placed into and approximately parallel with the physis  1  and is aligned approximately in the same plane as the angular deformity  4 . As shown in  FIG. 1 , the distal section  9  of the guide wire  8  is partly inserted into the physis  1 . Since the cartilaginous physis  1  is of less density than the surrounding bone, the surgeon can either poke the distal section of the guide wire  8  into the bone until the physis  1  is located, or the surgeon can use fluoroscopic x-ray (not shown) or other bone density detection means (not shown) to determine the location of the physis  1  relative to the distal section of the guide wire  8  to place the guide wire  8  in a direction that is approximately parallel with the physis  1 . 
       FIG. 2  is a sagittal view approximately perpendicular to the anterior view described in  FIG. 1 . For reference, a patella  7  is shown on the anterior side of the femur  10  and tibia  5 . For clarity, in this example the guide wire  8  is straight and has a constant round outer periphery  14 . Consequently, only the outer periphery  14  of the guide wire  8  is shown and appears as a circle in  FIG. 2 .  FIG. 2  shows the placement of the guide wire  8  in the physis between the femoral metaphyseal section  2  and the distal femoral epiphyseal section  3 . This is the preferred placement of the guide wire  8 . The guidewire  8  is used to locate an area in the physis that will eventually be bridged by the bone alignment implant  9  that will tether between two sections of the bone. In  FIG. 2 , the two sections of bone that will be tethered by the bone alignment implant  9  are the distal femoral proximal epiphyseal section  3  and the femoral metaphyseal section  2 . 
       FIG. 3  is an anterior view of the knee showing the placement of a link  30  and a guide  20  over the guide wire  8 . The guide  20  is used to place a first guide pin  40  and a second guide pin  50  on opposite sides of the physis  1 . The link  30  has an outer periphery  34  that defines the outer material bounds of the link  30 , a bone side  37  that is the side of the link that is placed against the bone, a first opening  31  and a second opening  32 . 
     First, the guide  20  and link  30  are placed over the guide wire  8  by guiding the guide wire  8  over a guide opening  33  in the link  30  and the guide hole  23  in the guide  20 . Then the first guide pin  40  is driven through a first hole  21  in the guide  20  and through the first opening  31  in the link  30  into the metaphyseal bone  2 , and the second guide pin  50  is driven through a second hole  22  in the guide  20  and the second opening  32  in the link  30  into the distal epiphyseal section  3 . Once the first guide pin  40  and the second guide pin  50  are placed, the guide  20  is removed. 
       FIG. 4  is a sagittal view of the placement of the link  30  described in  FIG. 3 . The position of the first guide pin  40  is through the first opening  31  in the link  30 . The position of the second guide pin  50  is through the second opening  32  in the link  30 . The guide pin  40  and guide pin  50  are on opposite sides of physis  1 . Likewise, the first opening  31  and the second opening  32  are on opposite sides of the physis  1 . 
       FIG. 5  is an anterior view showing an alternative embodiment of the link  30  placed on the medial femur  10 . In this embodiment, a first set of spikes  35  and a second set of spikes  36  on the bone side  37  of the link  30  help to keep the link  30  in place prior to the placement of a first bone fastener  70  and a second bone fastener  80 . The first set of spikes  35  is positioned near the first opening  31  and the second set of spikes  36  is positioned near the second opening  32  in the link  30 . Hence, as the link  30  is placed across the physis  1 , the first set of spikes  35  contacts the metaphyseal section  2  and the second set of spikes  36  contacts the epiphyseal section  3 . In this embodiment, the first bone fastener  70  is placed though the first opening  31  in the link  30  then into the metaphyseal section  2  and the second bone fastener  80  is placed through the second opening  32  in the link  30  then into the epiphyseal section  3 . 
       FIG. 6  is a sagittal view of the link  30  on the femur  10  showing the location of the first set of spikes  35  near the first opening  31  on the metaphyseal section  2  side of the physis  1  and the location of the second set of spikes  36  near the second opening  32  on the epiphyseal section  3  side of the physis  1 . 
     As shown in  FIG. 6A , link  30  can further be defined as having a top surface  150  that is opposite the bottom surface  37 . Bottom surface  37  was also previously referenced as bone side  37  in  FIG. 3 . Both bottom surface  37  and top surface  150  extend between a first side edge  152  and an opposing second side edge  154 . Likewise, both bottom surface  37  and top surface  150  longitudinally extend between a first end  156  and an opposing second end  158 . A first recess  162  is centrally formed on first side edge  152  while a second recess  164  is centrally formed on second side edge  154 . 
     In the embodiment depicted, guide opening  33  is centrally disposed between first opening  31  and second opening  32  with guide opening  33  being smaller than openings  31  and  32 . Each of openings  31 ,  32 , and  33  are aligned along a central longitudinal axis  160  that extends between first end  156  and second end  158 . Recesses  162  and  164  can be positioned on opposing sides of guide opening  33  such that a linear line  166  extending between recesses  162  and  164  intersect guide opening  33 . The length of linear line  166  extending between recesses  162  and  164  is a first width of link  30 . Linear line  166  is shown in the present embodiment as extending orthogonal to longitudinal axis  160 . 
     Link  30  can also be formed so that a linear line  168  can extend between side edges  152  and  154  so as to intersect with first opening  31 . Line  168  is shown extending orthogonal to longitudinal axis  160  and measures a second width of link  30 . Because of recesses  162  and  164 , the first width is smaller than the second width. A linear line  170  can similarly extend between side edges  152  and  154  so as to intersect with second opening  32 . Line  170  is shown extending orthogonal to longitudinal axis  160  and measures a third width of link  30 . The first width of link  30  is smaller than the third width. 
       FIG. 7  is an anterior view of the placement of the link  30 , first guide pin  40 , and second guide pin  50  as previously described in the sagittal view shown in  FIG. 4 .  FIG. 7  also shows a bone preparation tool  60  that can be used to prepare a bore  28  in the bone prior to the first fastener  70  or second fastener  80  placements. The bone preparation tool  60  can be a drill, tap, rasp, reamer, awl or any tool used to prepare a bore in bone tissue for a fastener. The bone preparation tool  60  is used to prepare a bore  28  on the bone near the second opening in the epiphyseal section  3  for the second fastener  80 . A bone preparation tool  60  can also be used to prepare the bone in the metaphyseal section  2  for the first fastener  70 . In the case of the example shown in  FIG. 7 , the bone preparation tool  60  is placed over the second guide pin  50 , through the second opening  32 , and into the epiphyseal section  3 . However, the bone preparation tool  60  can also be placed directly through the second opening  32  without the guidance of the second guide pin  50 . The bone preparation tool  60  is used if needed to prepare the bone to receive the first fastener  70  and second fastener  80 . Once the bone is prepared, the bone preparation tool  60  is removed from the surgical site. 
     The first fastener  70  is then placed over the first guide pin  40 , through the first opening  31 , and into the metaphyseal section  2 . The second fastener  80  is placed over the second guide pin  50 , through the second opening  32  and into the epiphyseal section  3 . If the first guide pin  40  and second guide pin  50  are not used, the first fastener  70  is simply driven through the first opening  31  and the second fastener  80  is simply driven though the second opening  32  without the aid of the guide pins  40  and  50 . 
       FIG. 8  is an anterior view showing the position of a bone alignment implant  15  on the convex side  16  of the angular deformity  4 . The bone alignment implant  15  comprises the link  30 , the first fastener  70 , and the second fastener  80 . The bone alignment implant  15  functions as a tether connecting the metaphyseal section  2  and the epiphyseal section  3 . The first fastener  70  and the second fastener  80  are placed on opposite sides of the physis  1 . As the physis  1  generates new physeal tissue  90 , the physeal tissue  90  will fill in between the metaphyseal section  2  and the epiphyseal section  3  in the space subjected to the least resistance. The bone alignment implant  15  restricts the longitudinal movement between the epiphyseal section  3  and the metaphyseal section  2  on the convex side  16  of the angular deformity  4 . 
       FIG. 9  shows the sagittal view of that described for  FIG. 8 . The bone alignment implant  15  functioning as a tether restricting the longitudinal movement between the epiphyseal section  3  and the metaphyseal section  2 . 
     As shown in  FIG. 10 , in a patient with an active physis, the newly generated physeal tissue  90  fills in more on the side of the bone that is not tethered by the bone alignment implant  15 . Hence, a net gain  95  of physeal tissue  90  forces the bone to align in the direction of an angular correction  97 . 
     Select embodiments of the bone alignment implant  15  comprise the first fastener  70  having a first engager  75 , the second fastener  80  having a second engager  85  and the link  30 . The link  30 , the first fastener  70  and the second fastener  80  function together as tethers between a first engager  75  on the first fastener  70  and a second engager  85  on the second fastener  80 , guiding movement between the epiphyseal section  3  and metaphyseal section  2  of bone. 
       FIG. 11  and  FIG. 12  show an example of using the bone alignment implant to correct a torsional abnormality between the metaphyseal section  2  and the epiphyseal section  3 . The link  30  is placed across the physis  1  at an angle  18  that is related to the amount of torsional deformity between the bone sections  2  and  3 . As the physis  1  generates new physeal tissue  90 , the bone alignment implant  15  guides the direction of growth of the bone to allow a torsional correction  98  of the bone alignment. 
     Different fastening devices designs that are well known in the art can be functional as fasteners  70  and  80 . The basic common elements of the fasteners  70  and  80  are seen in the example of a threaded fastener  100  in shown in  FIG. 13  and a barred fastener  120  shown in  FIG. 14 . 
     The threaded fastener  100 , and the barbed fastener  120  both have a head  73  comprising a head diameter  74 , a drive feature  72  and a head underside  71 . The drive feature in the threaded fastener  100  is an internal female hex drive feature  102 . The drive feature in the barbed fastener  120  is an external male drive feature  122 . The shape of the underside  71  of the barbed fastener  120  is a chamfer cut  124  and the underside of the threaded fastener  100  is a rounded cut  104 . The underside  71  shape of both the threaded fastener  100  and the barbed fastener  120  examples are dimensioned to mate with shapes of the first opening  31  and the second opening  32  in the link  30 . 
     Directly adjacent to the head  72  on both threaded fastener  100  and the barbed fastener  120  is a fastener shaft  79  with a shaft diameter  76 . Protruding from the shaft  79  is the aforementioned engager  75  with a fixation outer diameter  77 . This fixation diameter varies depending on the bone that is being treated and the size of the patient. Typically this diameter is from 1 mm to 10 mm. The shaft diameter  76  can be an undercut shaft  125 , as shown in the barbed fastener  120 , with a diameter  76  smaller than the fixation outer diameter  77 . The shaft diameter can also be a run out shaft  105  as shown in the threaded fastener  100  with a diameter  76  larger than or equal to the fixation diameter  77 . In either case, the shaft diameter  76  is smaller than the head diameter  74 . This allows fasteners  70  and  80  to be captured and not pass completely through the openings  31  and  32  in the link  30 . 
     In the case of the threaded fastener  100 , the engager  75  comprises at least one helical thread form  103 . Although the example of a unitary continuous helical thread  103  is shown, it is understood that multiple lead helical threads, discontinuous helical threads, variable pitch helical threads, variable outside diameter helical threads, thread-forming self-tapping, thread-cutting self-tapping, and variable root diameter helical threads can be interchanged and combined to form an optimized engager  75  on the threaded fastener  100 . The engager  75  on the barbed fastener  120  is shown as a uniform pattern of connected truncated conical sections  123 . However, it is understood that different barbed fastener designs known in the art such as superelastic wire arcs, deformable barbs, radially expandable barbs, and barbs with non-circular cross-sections can be interchanged and combined to form an optimized engager  75  on the barbed fastener  120 . 
     Protruding from the engager  75  at the distal end of both the threaded fastener  100  and the barbed fastener  120  is a fastener tip  78 . The fastener tip  78  can either be a smooth conical tip  126  as shown in the barbed fastener  120 , or a cutting tip  106  as shown on the threaded fastener  100 . Although a cutting flute tip is shown as the cutting tip  106  on the threaded fastener, other cutting tips designs including gimble and spade tip can be used. 
     In the example of the barbed fastener  120 , a canulation bore  128  passes though the head  73 , the shaft  79 , the engager  75 , and the tip  78 . This canulation bore  128  allows placement of the fasters  70  and  80  over the guide pins  40  and  50 . Although not shown on the example of the threaded fastener  100  in  FIG. 13 , it is understood that the fasteners  70  and  80 , regardless of their other features, can either be of the cannulatted design shown in the barbed fastener  120  example or a non-cannulatted design as shown in the threaded fastener  100  example. 
     Fasteners  70  and  80  can be made in a variety of different ways using a variety of one or more different materials. By way of example and not by limitation, fasteners  70  and  80  can be made from medical grade biodegradable or non-biodegradable materials. Examples of biodegradable materials include biodegradable ceramics, biological materials, such as bone or collagen, and homopolymers and copolymers of lactide, glycolide, trimethylene carbonate, caprolactone, and p-dioxanone and blends or other combinations thereof and equivalents thereof. Examples of non-biodegradable materials include metals such as stainless steel, titanium, Nitinol, cobalt, alloys thereof, and equivalents thereof and polymeric materials such as non-biodegradable polyesters, polyamides, polyolefins, polyurethanes, and polyacetals and equivalents thereof 
     All the design elements of the threaded fastener  100  and barbed fastener  120  are interchangeable. Hence either of the fasteners  70  and  80  can comprise of any combination of the design elements described for the threaded fastener  100  and the barbed fastener  120 . By way of one example, the first fastener  70  can be made from a bioabsorbable copolymer of lactide and glycolide and structurally comprise an external male drive feature  122 , a run out shaft  105 , a multiple-lead, non-continuous helically threaded engager  75 , with a cutting flute tip  106  and a continuous canulation  128 . Likewise the second fastener  80  can be made from a different combination of the features used to describe the threaded fastener  100  and the barbed fastener  120 . 
     Although the examples of barbed connected truncated conical sections  123  and helical thread forms  103  are shown by example to represent the bone engager  75 , it is understood that other means of engaging bone can be used for the engager  75 . These means include nails, radially expanding anchors, pressfits, tapers, hooks, surfaces textured for biological ingrowth, adhesives, glues, cements, hydroxyapatite coated engagers, calcium phosphate coated engagers, and engagers with tissue engineered biological interfaces. Such means are known in the art and can be used as alternative bone engagement means for the first bone engager  75  on the first fastener  70  or the second bone engager  85  on the second fastener  80 . 
     Different embodiments of the bone alignment implant  15  invention allow for different means of relative movement between the two bone sections  2  and  3 . Nine embodiments of the bone alignment implant  15  are shown in  FIG. 15  through  FIG. 23 . These embodiments are labeled  15 A through  15 I. 
     In a rigid-bodies embodiment  15 A shown in  FIG. 15 , both the link  30  and the fasteners  70  and  80  are rigid, but a first connection  131  and a second connection  132  between each of them allows for relative movement between the link  30  and the fasteners  70  and  80  resulting in relative movement between the bone sections  2  and  3 . In embodiments  15 B,  15 C, and  15 D of this invention shown in  FIG. 16 ,  FIG. 17  and  FIG. 18 , the link  30  is deformable allowing the fasteners  70  and  80  to move with the bone sections  2  and  3 . In embodiments  15 E and  15 F shown in  FIG. 19  and  FIG. 20 , the connections between the link  30  and the fasteners  70  and  80  along with the deformable link  30  allow the fasteners  70  and  80  to move with the bone sections  2  and  3 . In an embodiment  15 G shown in  FIG. 21 , the fasteners  70  and  80  are deformable allowing movement of the bone sections  2  and  3 . In embodiments  15 H and  15 I shown in  FIG. 22  and  FIG. 23 , the fasteners  70  and  80  are fixed to a flexible link  30 . 
     A rigid-bodies embodiment  15 A of the bone alignment implant  15  is shown in  FIG. 15 . In the rigid-bodies embodiment  15 A, the link  30  is a rigid link  130 . In the rigid bodies embodiment  15 A, the first fastener  70  is free to rotate about its axis or tilt in a first tilt direction  60  or a second tilt direction  61  and is partially constrained to move in a longitudinal direction  62  by the confines of the size of the first opening  31  and the first shaft diameter  77 , and partially constrained to move in the axial direction by the confines of the size of the first opening and the diameter  74  of the head  73  of the first fastener  70 . The first opening  31  is larger in the longitudinal direction  62  than is the shaft diameter  77  of the first fastener  70 . This allows for relative movement at the first joint  131  in a combination of tilt in the first direction  60 , tilt in the second direction  61 , and translation in the axial direction  63 . 
     Similar tilt and translation is achieved between the second fastener  80  and the link  30  at the second joint  132 . The second fastener  80  is also free to rotate or tilt in a first tilt direction  60 ′ or a second tilt direction  61 ′ and is partially constrained to move in a longitudinal direction  62 ′ by the confines of the size of the second opening  32  and the shaft diameter of the second fastener  80 . The second opening  31  is larger in the longitudinal direction  62 ′ than is the shaft diameter of the second fastener  80 . This allows for relative movement at the second joint  132  in a combination of tilt in the first direction  60 ′ and tilt in the second direction  61 ′ and limited translation in the axial direction  63 ′. 
     The combination of relative movement between the first joint and the second joint allows for relative movement between the bone sections  2  and  3  when the rigid bodies embodiment  15 A of the bone alignment implant  15  is clinically applied across an active physis  1 . 
     A flexible link embodiment  15 B of the bone alignment implant  15  is shown in  FIG. 16 . In the deformable link embodiment  15 B, the link  30  is represented by a deformable link  230  that allows deformation of the sections  2  and  4  as the physis  1  grows in a first bending direction  64  and a second bending direction  65 . However, the maximum length between the first opening  31  and the second opening  32  of the deformable link  230  limits the longitudinal displacement  62  between the head  73  of the first fastener  70  and the longitudinal displacement  62 ′ between the head  83  of the second fastener  80 . Since the heads  73  and  83  are coupled to the respective bone engagers  75  and  85 , and the bone engagers  75  and  85  are implanted into the respective bone segments  2  and  3 , the maximum longitudinal displacement of the bone segments  2  and  3  is limited by the deformed length between the first opening  31  and second opening  32  of the link  30 , and the flexibility and length of the fasteners  70  and  80 . 
     Also shown in  FIG. 16  is a material differential area  38  on the link  30 . The material differential area  38  is an area on the link  30  where material is either added to the link  30  or removed from the link  30  in relationship to the desired mechanical properties of a central section  39  of the link  30 . The central section  39  is made stiffer by adding material to the material differential area  38 . 
     The central section  39  is made more flexible by removing material from the material differential area  38 . Similarly the central section  39  is made stiffer by holding all other variables constant and decreasing the size of the guide opening  33 . The central section  39  is made more flexible by increasing the size of the guide opening  33 . Hence the desired stiffness or flexibility of the link  30  is regulated by the relative size of the material removed or added at the material differential areas  37  and  38  and the relative size of the guide opening  33  with respect to the outer periphery  34  in the central section  39  of the link  30 . 
     It is also understood that the relative stiffness and strength of the link  30  and structural elements such as the central section  39  is dependent on the material from which it is made. The link  30  and structural elements such as the central section  39  therein can be made in a variety of different ways using one or more of a variety of different materials. By way of example and not by limitation, the central section  39  can be made from medical grade biodegradable or non-biodegradable materials. Examples of biodegradable materials include biodegradable ceramics, biological materials, such as bone or collagen, and homopolymers and copolymers of lactide, glycolide, trimethylene carbonate, caprolactone, and p-dioxanone and blends or other combinations thereof and equivalents thereof. Examples of non-biodegradable materials include metals such as titanium alloys, zirconium alloys, cobalt chromium alloys, stainless steel alloys, Nitinol alloys, or combinations thereof, and equivalents thereof and polymeric materials such as non-biodegradable polyesters, polyamides, polyolefins, polyurethanes, and polyacetals and equivalents thereof. 
       FIG. 17  shows a flexible cable embodiment  15 C of the bone alignment implant  15 . The flexible cable embodiment  15 C comprises a flexible cable link  330  joined to the first fastener  70  by a first eyelet  306  on the first side  310  and joined to the second fastener  80  by a second eyelet  307  on the second side  311 . The first eyelet  306  has a first opening  331  through which the first fastener  70  passes. The second eyelet  307  has a second opening  332  through which the second fastener  80  passes. A flexible member  339  connects the first eyelet  306  to the second eyelet  307 . The flexible member  339  allows relative movement between the first eyelet  306  and the second eyelet  307 , except the longitudinal displacement  62  and  62 ′ is limited by the length between the first opening  331  and the second opening  332 . This is proportional to the length of the flexible member  339 . 
     The flexible member  339  is connected to the first eyelet  306  and the second eyelet  307  by means of joined connections  318  and  319 . These joined connections  318  and  319  are shown as crimped connections in this example. However, the flexible member  339  can be joined to the link  30  by other means such as insert molding, welding, soldering, penning, pressfitting, cementing, threading, or gluing them together. 
       FIG. 18  shows a flexible fabric embodiment  15 D of the bone alignment implant  15 . The flexible fabric embodiment  15 D comprises a flexible fabric link  430  joined to the first fastener  70  and the second fastener  80 . The flexible fabric link  430  comprises a first grommet  406  on a first side  410  and joined to the second fastener  80  by a second grommet  407  on a second side  411 . The first grommet  406  has a first opening  431  through which the first fastener  70  passes. The second grommet  407  has a second opening  432  through which the second fastener  80  passes. A flexible fabric  439  connects the first grommet  406  to the second grommet  407 . The flexible fabric  439  allows relative movement between the first grommet  406  and the second grommet  407 , except the longitudinal displacement  62  is limited by the length between the first opening  431  and the second opening  432 . A guide hole grommet  433  may be employed to reinforce the guide pin opening  33 . 
     The grommets function as reinforcement structures that prevent the flexible fabric from being damaged by the fasteners  70  and  80 . The grommets can be made from medical grade biodegradable or non-biodegradable materials. Examples of materials from which the grommet can be made are similar to those bioabsorbable and non-biodegradable materials listed as possible materials for the fasteners  70  and  80 . 
     The flexible fabric  439  comprises woven or matted fibers of spun medical grade biodegradable or non-biodegradable materials. A wide variety of materials may be used to make the flexible fabric  439 . For example, wire, fibers, filaments and yarns made therefrom may be woven, knitted or matted into fabrics. In addition, even non-woven structures, such as felts or similar materials, may be employed. Thus, for instance, nonabsorbable fabric made from synthetic biocompatible nonabsorbable polymer yarns, made from polytetrafluorethylenes, polyesters, nylons, polyamides, polyolefins, polyurethanes, polyacetals and acrylic yarns, may be conveniently employed. Similarly absorbable fabric made from absorbable polymers such as homopolymers and copolymers of lactide, glycolide, trimethylene carbonate, caprolactone, and p-dioxanone and blends or other combinations thereof and equivalents thereof may be employed. Examples of non-biodegradable non-polymeric materials from which the flexible fabric can be made include metals such as stainless steel, titanium, Nitinol, cobalt, alloys thereof, and equivalents thereof. 
     A band embodiment  15 E is shown in  FIG. 19  in which a band  530  that is a continuous loop or band of material that functions as the link  30 . The band embodiment  15 E allows both movement at the first joint  131  and second joint  132  and allows deformation within the link  30 . The shafts  79  of the first fastener  70  and second fastener  80  are both positioned in the inside  531  of the band  530 . The band can be either a fabric band made from the same materials described for the flexible fabric  439  of the flexible fabric embodiment  15 D, or the band  530  can be a unitary, continuous loop of a given biocompatible material such as a bioabsorbable polymer, non-biodegradable polymer, metal, ceramic, composite, glass, or biologic material. 
     In the band embodiment  15 E, the band  530  tethers between the head  73  of the first fastener  70  and the head  83  of the second fastener  80  as the physeal tissue  90  generates and the bone is aligned. One advantage of the band embodiment  15 E is that after the desired alignment is obtained, the band  530  can be cut and removed without removing the fasteners  70  and  80 . Furthermore, as with all of the embodiments of the bone alignment device  15 A,  15 B,  15 C,  15 D,  15 F,  15 G,  15 H and  151 , the fasteners  70  and  80  can be made from a biodegradable material and left in place to degrade. 
     A crimped band embodiment  15 F of the bone alignment device  15  is shown in  FIG. 20 . The crimped band embodiment  15 F is similar to the band embodiment  15 E in that it allows both movement at the first joint  131  and second joint  132 . The crimped band embodiment  15 F comprises a crimped band link  630  that comprises a band  632  that loops around the head  73  of the first fastener  70  and the head  83  of the second fastener  80 . However, the link  30  in the crimped band embodiment  15 F has an additional ferrule feature  631  comprising a loop of deformable material that brings a first side  634  and a second side  635  of the band together forming the first opening  31  and the second opening  32 . A bore  633  in the midsection of the ferrule  631  passes through the crimped band link  630  to form the aforementioned guide pin hole  33 . 
     As with the band embodiment  15 E, an advantage of the crimped band embodiment  15 F is that after the desired alignment is obtained, the band  632  can be severed across the boundaries of the first opening  31  and the boundaries of the second opening  32 . This provides a means for the crimped band link  630  to be removed without removing the fasteners  70  and  80 . 
     A deformable fastener embodiment  15 G is shown in  FIG. 21 . The deformable fastener embodiment  15 G comprises a first deformable fastener  770  with a deformable shaft  776 , a link  30  and a second fastener  780 . The second fastener  780  may also have a deformable shaft  786  as shown in the deformable fastener embodiment  15 G. However, it may also have a nondeformable shaft. The second fastener  780  may also be in the design or material of any of the combinations of aforementioned threaded fasters  100  or barbed fasteners  120 . Likewise, the second fastener  780  can have a flexible shaft  786 , as shown in the example of the deformable fastener embodiment  15 G in  FIG. 21 , and the first fastener  770  can be in the design or material of any of the combinations of aforementioned threaded fasters  100  or barbed fasteners  120 . 
     The flexibility of the flexible shafts  776  and  786  of the fasteners  770  and  780  can be simply a result of the material selection of the flexible shaft  776  and  786 , or can be the result of a design that allows for flexibility of the shaft. For example, the flexible shaft  776  and  786  can be manufactured from a material such as the aforementioned biocompatible polymeric materials or superelastic metallic materials such as Nitinol that would deform under the loads associated with bone alignment. The flexible shafts  776  and  786  could also be manufactured from biocompatible materials typically not considered to be highly elastic such as stainless steel, titanium, zirconium, cobalt chrome and associated alloys thereof, and shaped in the form of a flexible member such as cable, suture, mesh, fabric, braided multifilament strand, circumferentially grooved flexible shaft, filament, and yarn. 
     Connections  778  and  788  between the flexible shafts  776  and  786  and the associated engagers  775  and  785  of the fasteners  770  and  780  can be unitary and continuous, as is typically the case for fasteners  770  and  780  made entirely from the aforementioned biocompatible polymeric materials and superelastic metallic materials. The connections  778  and  788  can also be joined connections as is the case for flexible shafts  776  and  786  made from flexible members. Although the example of a pressfit connection is shown as the means of the connections  778  and  788  in the deformable fastener embodiment  15 G shown in  FIG. 21 , these joined connections  778  and  788  can be crimped, welded, insert molded, soldered, penned, pressfit, cemented, threaded, or glued together. 
     Heads  773  and  783  are connected to the respective flexible shafts  776  and  786  by respective head connections  779  and  789 . These head connections  779  and  789  can also be unitary and continuous, as again is typically the case of fasteners  70  and  80  made entirely from the aforementioned biocompatible polymeric materials and superelastic metallic materials. The head connections  779  and  789  can also be joined connections, as is the case for flexible shafts  776  and  786  made from flexible members. Although the example of a pressfit connection is the means of the connections  779  and  789  in the deformable fastener embodiment  15 G shown in  FIG. 21 , these joined connections  779  and  789  can also be crimped, insert molded, welded, soldered, penned, pressfit, cemented, threaded, or glued together. 
     Embodiments of the bone alignment implant  15  are shown in  FIGS. 22 and 23  in which the first fastener  70  and second fastener  80  are fixedly joined to the link  30  that is flexible. 
     A paired fastener embodiment  15 H is shown in  FIG. 22  in which similar designs of paired fasteners  870  and  880  are fixedly joined to a flexible link  830  by means of joined connections  831  and  832 . These joined connections  831  and  832  are shown as insert molded connections in this example in which the link is formed within the fastener by means of molding the molded fasteners  870  and  880  around the flexible link  830 . However, the paired fasteners  870  and  880  can be joined to the link  830  by other means such as crimping, welding, soldering, penning, pressfitting, cementing, threading, or gluing. 
     In the paired fastener embodiment  15 H, the first paired fastener  870  and the second paired fastener  880  are shown in  FIG. 22  as barbed style fasteners similar to the aforementioned barbed fastener  120 . However, the paired fasteners  870  and  880  can also be similar to the aforementioned threaded fastener  100  or can comprise of any combination of the design elements described for the threaded fastener  100  and the barbed fastener  120 . 
     A non-paired fastener embodiment  15 I is shown in  FIG. 23  in which different designs of fasteners  970  and  980  are fixedly joined to a flexible link  930  by means of joined connections  931  and  932 . These joined connections  931  and  932  are shown as insert molded connections in this example in which the link is formed within the fastener by means of molding the molded fasteners  970  and  980  around the flexible link  930 . However, the fasteners  970  and  980  can be joined to the link by other means such as crimping, welding, soldering, penning, pressfitting, cementing, threading, or gluing. 
     While the present invention has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. No single feature, function, element or property of the disclosed embodiments is essential. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. The following claims define certain combinations and subcombinations that are regarded as novel and non-obvious. Other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such claims, whether they are broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of applicant&#39;s invention. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.