Abstract:
An implant for fracture fixation in which a wire element has one end installed in bone and an opposite end fixed externally to the bone to apply compression across the fracture wherein a guide system is provided for guiding a tip of the one end of the wire element into a pilot hole in the bone prior to producing compression across the fracture.

Description:
CROSS RELATED APPLICATION 
     This application is a C-I-P of application Ser. No. 11/377,605 filed Mar. 16, 2006 which in turn is a C-I-P of application Ser. No. 10/073,826 filed Feb. 11, 2002 (now U.S. Pat. No. 7,037,308) which claims the priority of Provisional Application Ser. No. 60/268,099 filed Feb. 12, 2001. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to an implant device for applying compression across a fracture site in a bone and more particularly to a guide means and associated method for installing the implant device in bone. 
     BACKGROUND AND PRIOR ART 
     By way of example, fractures of the olecranon (upper end of the ulna at the level of the elbow), fractures of the medial malleolus (ankle), and fractures of the patella (kneecap) are fractures that involve an articular surface. Restoration of the joint surface to anatomic alignment is the accepted method of fixation. 
     Both the olecranon and patella are loaded during joint flexion. The deep articular surface is loaded in longitudinal compression by the reactive forces across the articular surface; the superficial bone surface is loaded in tension by the pull of a strong muscular insertion (the triceps in the case of the olecranon, and the quadriceps tendon in the case of the patella). As a result, these bones normally have a compressive side (deep surface) and a tension side (superficial surface). 
     A well accepted method of fixation of both olecranon fractures and patella fractures is a technique known as  FIG. 8  tension band wiring.  FIGS. 1 and 2  show an example of the known technique. Referring to these figures, two stiff stainless steel pins A are driven longitudinally into bone B across the fracture site C. Instead of pins, screws can be utilized. A flexible wire D is passed through a drill hole E on one side of the fracture site C and the two ends of the wire are crossed over the fracture site to the opposite side. One wire is then passed under the ends F of the two pins A, and the wire twisted and tightened at G to the other end to develop tension in the wire to produce compression across the fracture site. 
     The tension band technique holds the tension side of the bone in apposition. Since the deep surface is under load from the articular surface, the technique results in production of compressive force across the fracture site, resulting in secure fixation, promoting early union of the fracture and early motion of the joint. 
     One problem with this standard  FIG. 8  tension band wiring occurs because standard large pins A are used which protrude from the end of the bone at F at the location where a major tendon inserts. Because of this, the ends F of the pins frequently cause irritation of the soft tissues and require removal. 
     A minor technical problem with the standard  FIG. 8  tension band wiring is that the passage of the wire through drill hole D and through the tendon and under the pins can be cumbersome. 
     SUMMARY OF THE INVENTION 
     The invention provides an implant for fracture fixation in which a wire element has one end installed in bone and an opposite end fixed externally to the bone to apply compression across the fracture wherein a guide means is provided for guiding a tip of said one end of the wire element into a pilot hole in the bone. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING 
         FIG. 1  is a side view of a conventional fixation device. 
         FIG. 2  is a plan view, from below at the posterior side in  FIG. 1 . 
         FIG. 3  is a side view of the fixation device of the invention implanted in a bone. 
         FIG. 4  is a perspective view of one embodiment of the fixation device. 
         FIG. 4A  is a perspective view of another embodiment of the fixation device. 
         FIG. 5  is a plan view of the fixation device at the posterior side. 
         FIG. 6  shows the device of  FIG. 5  with a tensioning device prior to application of tension force. 
         FIG. 7  shows application of tension force by the tensioning device. 
         FIG. 8  is a side view of a modified embodiment of the fixation device in which the wires are crossed at the upper or superior surface of the bone. 
         FIG. 9  is a top plan view of the device in  FIG. 8 . 
         FIG. 10  is an end view of the device in  FIG. 8 . 
         FIG. 11  is an elevational view of a different embodiment of the tensioning device in a relaxed state. 
         FIG. 12  shows the tensioning device of  FIG. 11  in an active state in which tension is applied to the fixation device. 
         FIG. 13  is a sectional view taken along line  13 - 13  in  FIG. 11 . 
         FIG. 14  is a sectional view taken along line  14 - 14  in  FIG. 12 . 
         FIG. 15  is a plan view illustrating a further embodiment of the invention. 
         FIG. 15A  is a plan view of a modification of the embodiment illustrated in  FIG. 15 . 
         FIG. 16  is a side elevational view of the embodiment illustrated in  FIG. 15 . 
         FIG. 17  is a top plan view showing the embodiment of  FIG. 15  installed in the bone. 
         FIG. 17A  is similar to  FIG. 17  but illustrates the modification in  FIG. 15A . 
         FIG. 18  is a side elevational view showing the embodiment of  FIG. 15  installed in the bone. 
         FIG. 19  is a top plan view of a further embodiment of the invention. 
         FIG. 20  is a side elevational view of the embodiment in  FIG. 19 . 
         FIG. 21  is an end view as seen in the direction of arrow X in  FIG. 19 . 
         FIG. 22  is a sectional view taking on line  22 - 22  in  FIG. 20 . 
         FIG. 23  is a side elevational view showing the embodiment of  FIG. 19  installed in the bone. 
         FIG. 24  is a top plan view of  FIG. 23 . 
         FIG. 25  is a sectional view taking along line  25 - 25  in  FIG. 23 . 
         FIG. 26  is a plan view of a further embodiment according to the invention. 
         FIG. 27  is a side elevational view of the embodiment shown in  FIG. 26 . 
         FIG. 28  is a plan view of a further embodiment according to the invention. 
         FIG. 29  is a side elevational view of the embodiment illustrated in  FIG. 28 . 
         FIG. 30  is a plan view of a further embodiment of the invention shown installed in the bone. 
         FIG. 31  is an elevational view of  FIG. 30 . 
         FIG. 32  shows a further embodiment of the invention installed in the bone. 
         FIG. 33  is an elevational view of  FIG. 32 . 
         FIG. 34  shows a further embodiment installed in the bone. 
         FIG. 35  is a plan view showing a further embodiment installed in the bone. 
         FIG. 36  is a top plan view of another embodiment of a fixation device according to the invention. 
         FIG. 37  is a side elevational view thereof. 
         FIGS. 38 and 39  illustrate successive stages of installation of the fixation device of  FIG. 36 . 
         FIG. 40  shows the installation of the fixation device in top plan view. 
         FIG. 41  shows the installation of the fixation device in side elevation view. 
         FIG. 42  is a diagrammatic sectional view on enlarged scale illustrating a guide means for installing the ends of legs of the implant device into pilot holes in bone. 
     
    
    
     DETAILED DESCRIPTION 
     The drawings illustrate a fracture fixation implant device  1  for applying compression across a fracture  2  in a bone B. The bone B, for example, may be the olecranon or the patella that involve an articular surface. 
     The implant device  1  comprises a continuous wire element  3  formed with two spaced longitudinally extending legs  4  which are adapted to be driven into the bone B across the fracture  2 . The term “wire” or “wire element” is an art recognized term and covers elements having circular or rectangular cross-sections and commonly referred to as pins, wires or bars. The legs  4  form a first portion  5  of the wire element and the legs  4  extend at their ends remote from free ends  6  thereof to bend portions  7  extending outside the bone. Integrally connected to bend portions  7  is a second portion  8  extending backwardly from the bend portions  7  in juxtaposition with the legs  4  of the first portion  5 . The second portion  8  includes legs  9  continuous with respective bend portions  7  and crossing one another at an intersection  10  which is located approximately at the fracture  2 . The legs  9  extend to a connecting portion  11  in the form of a U-shaped bend to complete the continuity of the wire element  3 . In  FIG. 3  the wire element  3  is illustrated in an embedded condition in the bone so that the second portion  8  extends on a lower or posterior surface  12  of the bone. 
       FIG. 4A  illustrates a modified embodiment of the wire element in which the same numerals are used to designate the same parts and primes are used for modified parts. In  FIG. 4A , the wire element  3 ′ has legs  9 ′ of the second portion  8 ′ which do not cross one another as in  FIG. 4  but are spaced from one another. In other respects, the wire element  3 ′ is the same as wire element  3  in  FIG. 4 . 
     Hereafter, the invention will be described with reference to the wire element  3  of  FIG. 4 , but it is to be understood that the wire element  3 ′ could also be used. 
     A washer  15  is secured at the posterior surface  12  of the bone by a bone screw  16 . The legs  9  are loosely disposed below the washer  15 . A tensioning device  20  is then installed between the washer  15  and the bend portion  11  of the wire element  3 . The tensioning device  20  includes a rotatable cam  21  temporarily installed in the bone. In the position shown in  FIG. 6 , the cam does not apply any tension to the wire element  3 . When the cam is turned from the position shown in  FIG. 6 , a force is applied to the U-shaped bend  11  which develops tension in the wire element and causes the bend portions  7  to bear tightly against the distal end of the bone and produce compression across the fracture  2 . In the ninety degree position shown in  FIG. 7  of the cam  21 , a maximum compression is developed across the fracture  2 . When the proper tension has been developed in the wire element, the washer which has been loosely seated by the bone screw  16  is then fully seated by tightening the bone screw  16 . Thereby, the tension in the wire element is maintained. The cam  21  which has been temporarily installed in the bone is then removed. 
       FIGS. 8-10  are similar to the embodiment of  FIGS. 3-7  except that the second portion  8  with the legs  9  or  9 ′ is adapted to extend on the upper or anterior surface of the bone and tensioning of the wire element takes place at the upper surface. In practice, the legs  9  or  9 ′ can be positioned on any superficial surface of the bone. 
     The installation of the implant is carried out as follows. 
     Two holes are drilled at the end of the bone at a spacing corresponding to the width of the implant as measured by the spacing of the legs  4  of the implant device thereof. The legs  4  of the implant device are impacted longitudinally into the drilled holes entering and aligning to the medullary canal. The fracture site is closed and the implant device is firmly seated and secured with the bone screw and washer to the bone at one end of the implant device. Compression at the fracture is achieved by turning the cam between the washer and the U-shaped bend of the implant device to effect further compression whereafter the screw is fully tightened and the washer is seated and then the cam is removed. In lieu of the cam, the tension force in the wire element can be produced by the surgeon applying pressure to the U-shaped bend portion  11  and then tightening the bone screw  16  while the wire is under tension. 
     Implant devices having wire elements of different diameter are suited for different bone fractures. For example, a 0.062 inch diameter wire can be used for olecranon fractures whereas a larger diameter wire would be used for patella fractures and a smaller diameter wire element may be used for transverse lateral or medial malleolar fractures. 
     In accordance with a particular feature of the invention, the diameter of the wire of the continuous wire element need not be uniform along its length and it is particularly advantageous if the legs  4  of the wire element are of greater diameter than the remainder of the wire element in the legs  9  or  9 ′ and U-shaped bend  11  of the second portion  8  or  8 ′. In this way, absolute reliability of the embedded legs  4  of the first portion is obtained while flexibility of the wire element of the second portion can be obtained to achieve development of adequate tension in the wire element and resulting compression across the fracture. In addition, having a smaller diameter wire on the surface of the bone is less prominent and less likely to result in soft tissue irritation or inflammation. 
       FIGS. 11-14  show another embodiment of the tensioning device designated generally by numeral  30 . The tensioning device  30  comprises lever arms  31  and  32  connected together by a hinge  33 . The arms  31  and  32  have respective hand-engaging gripper ends  34  and  35  above the hinge  33  and actuator arms  36  and  37  below hinge  33 . The arm  36  supports an actuating jaw  38  at its lower end and the arm  37  supports a counter-bearing jaw  39  at its lower end. The jaws  38  and  39  are slidable with respect to one another and jaw  38  can be moved from an inactive state, as shown in  FIG. 11  in which the wire element is not subjected to tensile stress by the tensioning device, to active state as shown in  FIG. 12  in which the jaw  38  has been displaced to apply tension to the wire element. The jaw  39  is connected by a strut  40  to an actuator plate  41  and the jaw  38  is connected by struts  42  to a counter-bearing plate  43 . The counter-bearing plate  43  can be secured by a temporary pin  44  which is placed in a drill hole in the bone. The U-shaped bend  11  of the second portion  8  of the wire element, passes around a back surface of the actuator plate  41 . When the lever arms  34  and  35  are brought together as shown in  FIG. 12 , the actuator plate  41  is displaced away from the counter-bearing plate  43  to produce tension in the wire element. When the desired degree of tension has been achieved, the bone screw  16  is fully tightened, the pin  44  is extracted and the tensioning device is removed. 
     Although the prior figures have depicted an implant with two separate legs for both the first portion  5  and the second portion  8 , either the first portion  5  or the second portion  8  or both may consist of one leg or more than two legs 
     Referring to  FIGS. 15 and 16 , therein is shown a further embodiment of a fixation device  103  according to the invention in which the first portion consists of a single leg. The fixation device  103  has a leg  104  adapted for insertion into the bone and the leg  104  extends to a bend  107  connected to one leg  109  of the second portion  108  of the device. A U-shaped bend  111  connects leg  109  with a second leg  109  of the second portion  108 .  FIGS. 17 and 18  illustrate the installation of the fixation device  103  in bone B. As seen therein, the leg  104  is driven into the bone and extends across the fracture  102  and the second portion  108  consisting of legs  109  extends on an outer surface of the bone. The legs  109  of the second portion are secured to the bone by a bone screw  116  installed in a washer  115 , following the development of tension in the device in a manner previously explained. 
       FIGS. 15A and 17A  illustrate a modification of the embodiment illustrated in  FIGS. 15 and 17 . Herein, the fixation device is comprised of two parts  63  each having a leg  64  adapted to be implanted into the bone to form fixation portion  65 . The leg  64  is connected by a bend  67  to second leg  69  of second portion  68  which extends backwardly and is juxtaposed with leg  64 . The second legs  69  of the two parts  63  can be pulled to fix the fracture and develop tension in parts  63  and apply compression across the fracture. Washer  75  is secured to the bone by bone screw  76  to connect the second legs  69  together and maintain the tension developed in the two parts  63  via the second legs  69 . 
       FIGS. 19 through 25  illustrate another embodiment of the fixation device according to the invention which is particularly applicable to the fixation of a fracture of the olecranon. This embodiment is distinguished from the earlier described embodiments in that the second portion  208  is non-planar but is bent in more than one plane to match the contour of the bone as shown with particularity in  FIG. 25 . In particular, the fixation device comprises two legs  204  which are driven into the intramedullary canal across the fracture  202 . The legs  204  extend to the bend portions  207  which extend out of the bone to the second portion  208  which comprises the crossed legs  209  connected together by the U-shaped bend  211 . It is noted that the U-shaped bend  211  is not composed only of curved portions but includes a straight portion with end radii connecting the U-shaped bend  211  to the legs  209  of the second portion  208 . When reference is made in this disclosure to the U-shaped bend, this not only includes curved portions but portions which can be straight and includes such configurations as V-shaped bends and the like. The legs  209  of the second portion  208  have a transition region  220  in which the legs are bent out of plane and pass in opposition at the sides of the bone as shown in  FIG. 25 . The U-shaped bend  211  extends out of plane and connects the ends of the legs  209  as shown in  FIGS. 22 and 25 . The legs  204  are formed with a larger diameter than the legs  209  and there is a gradual taper in diameter between the legs at the bend portions  207 . As evident from  FIG. 25 , the U-shaped bend  211  which is curved in two planes engages the surface of the bone B and forms a stabilized engagement therewith. 
       FIGS. 26 and 27  show another embodiment of the fixation device designated  303  which is similar to the embodiment shown in  FIG. 4A . The same reference numerals will be used to designate the same parts. The fixation device  303  is particularly applicable for fractures at the distal end of the ulna which is often fractured in addition to fractures of the distal radius. In this embodiment, the diameter of the wire elements is constant throughout and the characterizing feature is that the legs  4 A which are inserted into the bone (the ulna) are not linear but have a curved or bent shape to produce a resilient effect when inserted into the intramedullary canal to produce greater fixation of the bone from the interior and help prevent the device from rotating due to resilient engagement of the legs  4 A within the intramedullary canal. In use, the free ends of the legs  4 A of the fixation device  303  are inserted into the intramedullary canal and squeezed together so that upon further insertion the more widely spaced bend portions of the legs  4 A are squeeze more tightly and secure the fixation device with resilient pressure against the inner wall of the intramedullary canal. 
       FIGS. 28 and 29  show another embodiment  403  of the fixation device which is similar to the embodiment in  FIG. 4A  and the embodiment in  FIGS. 26 and 27 . The fixation embodiment  403  in  FIGS. 28 and 29  is particularly adapted to fractures of the patella. The fixation device  403  differs from that in  FIG. 4A  in that bend portions  411  connecting the legs  4  and  9 ′ are not in the same plane as the legs  9 ′ so that the spacing between the opposite legs  9 ′ is less than that between the opposite legs  4  as evident from  FIG. 28 . Additionally, the diameter of the legs  4  is greater than the diameter of the legs  9 ′ and the change in diameter takes place gradually through the bend portions  411 . Referring to  FIGS. 30 and 31 , therein the fixation device  403  is shown implanted in the patellar bone  2  across the fracture  2  in which two washers  15  and two bone screws  16  are employed. 
       FIGS. 32 and 33  show another embodiment of the invention similar to the embodiment in  FIG. 4  but modified to provide fixation for fractures of the proximal humerus, the distal humerus, the lateral humerus, the lateral malleolus and medial malleolus. The embodiment illustrated in  FIGS. 32 and 33  and designated  504  differs from the earlier described embodiment of  FIG. 4  in that legs  504  of the fixation device are not straight but are formed with straight portions  504 A and diverging non-symmetrical portions  504 B. The implant thereby is adapted to the configuration of the particular bone and the relatively wide aspect or spacing of the bend portions  511  as shown in  FIG. 32 . In this embodiment, two washers  15  and the bone screws  16  are utilized as in previous embodiments. 
       FIG. 34  shows a variation of the embodiment in  FIG. 32  adapted for being implanted in the medial malleolus. In this embodiment instead of the legs of the implanted first portion  5  being non-parallel, the legs  604  are parallel and the legs of the second portion are bent and widen from the bend portions  611  to form diverging leg portions  608 A which merge with parallel leg portions  608 B. 
     In a modification shown in  FIG. 35 , the legs of the first portion include diverging portions  704 A which then converge to portions  704 B which are joined to bend portions  711  connected to the crossing legs of the second portion of the fixation device. 
       FIGS. 36 and 37  show another embodiment of a fixation device  703  having a single straight leg  704  forming the first portion  705  of the fixation device connected by a bend portion  711  to a single leg  709  forming the second portion  708  of the fixation device. At the end of leg  709 , a 90° bend is formed to define a hook  710 . 
     In  FIG. 38 , the leg  704  of the fixation device is impacted into the intramedullary canal of the bone B across the fracture  2 . An anchoring hole  712  is drilled in the bone B and is engaged by one arm  713  of a tensioning instrument  714 . The other arm  715  engages the hook  710  at the end of leg  708 . The tensioning instrument is then closed as shown in  FIG. 39  to close and compress the fracture. A guide hole  715  is drilled in the bone B tensioning instrument  714  is then removed and hook  710  is impacted into the guide hole  715 . A bone screw  716  and washer  717  is then installed to hold end of the leg  709  in place. 
     The embodiment shown in  FIGS. 36-41  differs from the previously described embodiments in that instead of fixedly securing the end of leg  708  by the washer and bone screw, the hook which is impacted into the bone serves for anchoring the leg  708  and the bone screw and washer only serve for preventing the end of the leg from coming out of the bone. In the previously described embodiments the bone screw has to be tightened with substantial force to prevent the leg under the washer from sliding on the bone. 
     There will now be explained how the legs  4  are installed into bone B. 
     Referring to  FIG. 3  and the description thereof, in order to install the legs  4  into bone B, two pilot holes  1000  ( FIG. 42 ) are first drilled into the bone B. The depth and diameter of the pilot holes  1000  are a function of the structure of the particular bone which is fractured and its quality (strength, hardness, elasticity etc.). In a first case, the pilot holes  1000  are approximately equal in diameter to the diameter of the legs  4  so that the legs  4  can be engaged in and supported by the pilot holes, preferably, with a frictional fit. The pilot holes  1000  are drilled to a depth that equals or exceeds the length of legs  4  and serve as a channel for insertion and support of the legs therein to enable tension to be developed in the wire element and compression to be applied across the fracture. Alternatively, the pilot holes may be drilled less than the length of legs  4  to serve as guide holes for entry of the legs into bone B after which the legs  4  are driven or impacted over the remaining distance into the bone much as a nail is driven into a piece of wood. In either case, feature of the invention is the manner in-which the legs  4  are inserted into the pilot holes  1000 . 
     The insertion of the legs  4  into the pilot holes may be difficult under operating conditions and require some “hunting” on the part of the surgeon to insert the legs  4  into the guide holes, particularly when soft tissue and tendons obscure the small guide holes. 
     In order to facilitate installation of legs  4  into the pilot holes  1000  in bone B the invention provides a guide means GM connected between the bone B and legs  4  for guidable insertion of legs  4  into the pilot holes  1000 . 
     The guide means GM is constituted by a guide wire in the form of a guide pin  1001  and a bore  1002  in the distal end of leg  4 . In one embodiment, the bore  1002  is axially aligned with the predominant longitudinal axis of the leg and extends, from the tip of leg  4  along the length of leg  4  and exits in a region proximate to bend  7 . In another preferred embodiment, the bore is directed at a specified angle to the predominant longitudinal axis of leg  4 . Typical diameters for the guide pin  1001  range from 0.8 mm to 3 mm. 
     The bore  1002  is located proximate to the center of the tip of leg  4  to form an inlet end for guide pin  1001  and the bore  1002  extends obliquely downwards at an angle to exit at a bottom surface of leg  4  to form an outlet for guide pin  1001  (as explained later). In the preferred embodiment, the bore  1002  is angulated instead of extending longitudinally through leg  4  in order not to weaken the leg. The bore  1002  is slightly larger in diameter than the guide pin  1001  to allow the guide pin to be slidable in the bore  1002 . 
     The operation of installing the legs  4  into the bone B is as follows. 
     The guide pins  1001  are drilled into bone B at the locations where legs  4  are to be installed in the bone. The pilot holes  1000  are then over drilled on the guide pins  1001  by a cannulated drill leaving the guide pins in the bone and extending from the pilot holes  1000 . The guide pins  1001  are then inserted into bores  1002  in legs  4  and the free ends of guide pins  1001  extend out of the outlet ends of the bores  1002 . The implant device is then slid along the guide pins until the tips of legs  4  enter the holes  1000  and the legs  4  are seated in the pilot holes  1000 . The guide pins  1001  are then removed by pulling on the free ends of the guide pins extending out of legs  4 . If the legs  4  are not fully seated in the pilot holes  1000  the legs  4  are then impacted into the bone B. 
     The guide pins thus serve as guides for insertion of the tips of legs  4  into the pilot holes  1000  in the bone and save a lot of time and frustration in hunting for the small holes  1000  in the bone during the operation, especially when the holes become covered by the somewhat elastic soft tissue after the pilot holes have been drilled. 
     Although the invention is disclosed with reference to particular embodiments thereof, it will become apparent to those skilled in the art that numerous modifications and variations can be made which will fall within the scope and spirit of the invention as defined by the attached claims.