Patent Publication Number: US-2009234356-A1

Title: Method and apparatus for fracture fixation

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
     This patent application claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 61/001,599, filed Nov. 2, 2007 by Barry T. Bickley for METHOD AND APPARATUS FOR FRACTURE FIXATION (Attorney&#39;s Docket No. SIM-4 PROV), which patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to surgical methods and apparatus in general, and more particularly to methods and apparatus for fracture fixation. 
     BACKGROUND OF THE INVENTION 
     Bone fractures are a relatively common physical malady. Bone fractures are typically the result of a traumatic injury, e.g., a fall, an automobile accident, etc. Bone fractures can also be brought on by certain medical conditions which significantly weaken bones, e.g, osteoporosis, cancer, etc. 
     When a bone is fractured, it is common to temporarily stabilize the bone with a stabilization apparatus while healing occurs. This process is commonly referred to as fracture fixation. The stabilization apparatus may comprise external devices (e.g., casts, support frames, etc.) and/or internal devices (e.g., plates and screws, intramedullary rods and screws, cerclage wires, etc.). 
     One common type of fracture occurs at the base of the tibia. More particularly, and looking now at  FIG. 1 , there is shown a tibia  5 . Tibia  5  is characterized by, among other things, a distal end  10  having a lateral protusion (medically referred to as “the lateral malleolus”)  15 . Distal end  10  of tibia  5  terminates in a bearing surface  20  which slidably engages the talus bone (not shown) so as to form the ankle joint. In many cases, the tibia may be fractured at the point where lateral malleolus  15  meets the remainder of the tibia, e.g., such as at the fracture line  25 . In this case, it is frequently necessary to stabilize lateral malleolus  15  at fracture line  25  while healing occurs. 
     In this respect it should be appreciated that, while fracture fixation is commonly employed for many different types of bone fractures, it is particularly important in the case of a fracture of the lateral malleolus. This is because the ankle&#39;s bearing surface  20  extends along a portion of the lateral malleolus and, as a result, it is critical that the lateral malleolus be properly stabilized during healing if the patient is to fully recover from the fracture. 
     Currently, a fracture of the lateral malleolus is typically stabilized by passing one or more screws through the lateral malleolus and into the distal end of the tibia. See, for example,  FIG. 2 , where a screw  30  is shown extending through lateral malleolus  15  and into distal end  10  of tibia  5 . However, this stabilization technique is hampered by the fact that the integrity of the repair is entirely dependent upon (i) maintaining proper alignment of the lateral malleolus while installing the screw, through the lateral malleolus and into the tibia, and (ii) the quality of the bone at the distal end of the tibia. In point of fact, many surgeons have difficulty maintaining proper bone alignment while setting the screw. Perhaps even more importantly, many patients (particularly older patients) have relatively poor bone quality at the distal end of the tibia, and the threads of the screw cannot gain sufficient purchase with the surrounding tibia to effect a reliable fracture fixation. 
     Thus there is a need for a new and improved approach for stabilizing the lateral malleolus while healing occurs. 
     There is also a need for a new and improved approach for stabilizing other fractures while healing occurs. 
     SUMMARY OF THE INVENTION 
     These and other objects of the present invention are addressed by the provision and use of a new and improved fracture fixation system. 
     In one form of the invention, there is provided a method for securing a first bone segment to a second bone segment, the method comprising the steps of: 
     positioning the first bone segment against the second bone segment, forming a first bore through the first bone segment and into the second bone segment, and forming a second bore into the second bone segment so that the second bore intersects the first bore; 
     positioning a locking member within the second bore so that an opening in the locking member is aligned with the first bore; and 
     positioning an interlocking screw within the first bore so that the interlocking screw passes through the opening in the locking member and makes a locking engagement therewith, whereby to lock the interlocking screw with the locking member and thereby secure the first bone segment to the second bone segment. 
     In another form of the invention, there is provided a system for securing a first bone segment to a second bone segment, wherein a first bore is formed through the first bone segment and into the second bone segment, and a second bore is formed into the second bone segment so that the second bore intersects the first bore of the first bone segment, the system comprising: 
     a locking member for positioning within the second bore so that an opening in the locking member is aligned with the first bore; and 
     an interlocking screw for positioning within the first bore so that the interlocking screw may be passed through the opening in the locking member and make a locking engagement therewith, whereby to lock the interlocking screw with the locking member and thereby secure the first bone segment to the second bone segment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be more fully disclosed in, or rendered obvious by, the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein: 
         FIG. 1  is a schematic view of a tibia with a fractured lateral malleolus; 
         FIG. 2  is a schematic view of an X-ray showing a prior art repair for a fractured lateral malleolus; 
         FIGS. 3-7  are schematic views showing a fracture fixation system formed in accordance with the present invention, including its various components and their features, and their manner of assembly; 
         FIGS. 8-29  are schematic views showing the repair for a fractured lateral malleolus using the present invention; 
         FIG. 30  is a schematic view of showing the repair of an olecranon fracture of the ulna; and 
         FIGS. 31-37  show alternative constructions for the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     Looking now at  FIG. 3 , the present invention comprises the provision and use of a new facture fixation system  100 . Fracture fixation system  100  generally comprises an interlocking screw  101 , an arm  102 , a pivot block  103 , an anchoring screw  104 , a locking member  105 , an upper tube pusher  106 , a clevis pin  107 , lower ratchet tubes  108 , a spring plunger  109 , a lower tube cannula  110  and an upper tube cannula  111 . As seen in  FIG. 3 , and as will hereinafter be described, pivot block  103  is rotatably pinned to arm  102 , and lower ratchet tubes  108  are slidably connected to arm  102 . 
       FIGS. 4-7  show further details with respect to fracture fixation system  100 , its various components and their features, and their manner of assembly, all of which will be discussed hereinafter. 
       FIGS. 8-29  illustrate how fracture fixation system  100  may be utilized to stabilize a fracture of the lateral malleolus while healing occurs. 
     More particularly, as shown in  FIGS. 8 and 9 , fracture fixation system  100  is secured to tibia  5  by passing the anchoring screw  104  through pivot block  103  and into tibia  5 . 
     Then, as shown in  FIGS. 10 and 11 , lower ratchet tubes  108  are first brought into alignment with lateral malleolus  15  by rotating the system about clevis pin  107  ( FIG. 10 ), and then brought into engagement with lateral malleolus  15  by longitudinally advancing lower ratchet tubes  108  against the force of spring plunger  109 . At this point, the distal tip A of the lower ratchet tubes will compressibly hold the lateral malleolus in position against the remainder of the tibia. 
     Looking next at  FIGS. 12-16 , lower tube cannula  110  is next inserted into one of the bores of lower ratchet tubes  108  ( FIG. 12 ), a drill  112  is passed down lower tube cannula  110 , through the lateral malleolus and into the distal end of the tibia ( FIGS. 13 and 14 ), and then withdrawn ( FIG. 15 ), and then lower tube cannula  110  is withdrawn from the bore of lower ratchet tubes  108  ( FIG. 16 ), leaving a bore  113  extending through lateral malleolus  15  and into distal end  10  of tibia  5 . Then this process is repeated for the other of the bores of lower ratchet tubes  108  (not shown). At this point, two holes will have been drilled through the lateral malleolus and into the distal end of the tibia. At the same time, the lateral malleolus will be held in position against the distal end of the tibia by virtue of the compressive engagement of lower ratchet tubes  108 . 
     Looking now at  FIGS. 17-20 , upper tube cannula  111  is then inserted into one of the bores of arm  102  ( FIG. 17 ), a drill  114  is passed down upper tube cannula  111  and into tibia  5  ( FIGS. 17 and 18 ), and then drill  114  is withdrawn ( FIG. 19 ), leaving a bore  115  extending through distal end  10  of tibia  5 . Next, upper tube cannula  111  is withdrawn ( FIG. 20 ). Then this process is repeated for the other of the bores of the upper ratchet tubes  111  (not shown). At this point, two holes will have been drilled into the tibia. Significantly, due to the construction of fracture fixation system  100 , each of the holes drilled through upper tube cannula  111  will precisely intersect one of the holes drilled through lower tube cannula  110 . 
     Next, and looking now at  FIGS. 21 and 22 , upper tube pusher  106  is used to advance a locking member  105  into one of the bores  115  formed in the tibia. As this occurs, locking member  105  is inserted so that its window  116  ( FIG. 6 ) is aligned with one of the corresponding holes  113  in lateral malleolus  15  and distal end  10  of tibia  5 . This is accomplished (i) by virtue of the alignment mechanism provided between upper tube pusher  106  and locking member  105  (i.e., a finger  117  provided on upper tube pusher  106  as shown in  FIG. 21 , and a socket  122  formed in locking member  105  as shown in  FIG. 6 ) which aligns recess  120  ( FIGS. 4 and 21 ) in upper tube pusher  106  and a recess  118  ( FIG. 6 ) in locking member  105  when the two are temporarily co-joined, and (ii) by virtue of the alignment mechanism provided between arm  102  and upper tube pusher  106  (i.e., a rib  119  extending into the bore of arm  102  as shown in  FIG. 4  and a recess  120  formed in upper tube pusher  106  as also shown in  FIG. 4  and  FIG. 21 ). Then a second locking member  105  is advanced in the same manner into the other of the bores  115 , i.e., so that its window  116  is aligned with the corresponding hole  113  in lateral malleolus  15  and distal end  10  of tibia  5 . 
     It should be appreciated that bores  115  and locking members  105  are preferably sized relative to one another so that locking members  105  make a secure friction fit in bores  115 . 
     Looking next at  FIGS. 23-25 , an interlocking screw  101  is advanced through one of the bores in lower ratchet tubes  108  and through the aligned window  116  of a locking member  105 . In this respect it will be appreciated that as interlocking screw  101  is advanced through window  116  of locking member  105 , the threads of interlocking screw  101  engage projections  121  ( FIG. 6 ) of locking member  105  so that interlocking screw  101  is secured to locking member  105 . In this respect it will be appreciated that the distance between projections  121  ( FIG. 6 ) is matched to the pitch of the thread on interlocking screw  101 , whereby to allow the interlocking screw  101  to begin to thread into the gap between projections  121 . Since the thread on the interlocking screw  101  is helical in nature, and the projections are in parallel planes, the interlocking screw  101  feeds between the projections  121  and binds with a slight interference fit, thereby locking screw  101  to locking member  105 . Upper tube pusher  106  may then be withdrawn from arm  102  ( FIG. 25 ). Then a second interlocking screw  101  is set through the other locking member in a similar manner. 
     Next, and looking now at  FIGS. 26-29 , fracture fixation system  100  is manipulated so that lower ratchet tubes  108  are withdrawn from lateral malleolus  15  ( FIG. 26 ), and then anchoring screw  104  is withdrawn ( FIG. 27 ), and then the assembled arm  102 /pivot block  103 /lower ratchet tubes  108  are withdrawn ( FIG. 28 ), thus leaving a pair of interlocking screws  101  extending through lateral malleolus  15 , across fracture line  25 , through a corresponding locking member  105  and into distal end  10  of tibia  5  ( FIGS. 28 and 29 ), whereby to securely fix lateral malleolus  15  to the remainder of tibia  5  while healing occurs. 
     Significantly, since interlocking screws  101  are secured to locking members  105 , effective fracture fixation can be achieved even where tibia  5  may have poor bone quality. 
     In the foregoing description, fracture fixation system  100  is constructed and used so as to set a pair of interlocking screws  101  into a pair of corresponding locking members  105 . However, it will be appreciated that fracture fixation system  100  may be configured, and/or used, so as to set more or less interlocking screws  101  into corresponding locking members  105 . Thus, for example, fracture fixation system  100  may be configured and/or used so as to set just one interlocking screw  101  into a corresponding locking member  105 , or to set three interlocking screws  101  into corresponding locking members  105 , etc. 
     It should be appreciated that the present invention may be used for fracture fixations with bones other than the tibia. By way of example, but not limitation, and looking now at  FIG. 30 , fracture fixation system  100  may be used for fixation of a fracture of the olecranon B of the ulna  35 . In essence, fracture fixation system  100  may be used with substantially any other bone or bones within the body where fracture fixation, and/or other bone fixation, is desired. 
     In this respect it should also be appreciated that the various system components are intended to be appropriately sized for the particular anatomical location within which the system is intended to be used. 
     Furthermore, it should also be appreciated that the various system components can have different form factors (i.e., shapes) appropriate for the particular anatomical limitations within which the system is intended to be used. 
     Additionally, the proximal ends of interlocking screws  101  and/or locking members  105  can be shaped so as to match the surface contours of the bone segments at the locations where they will be used. And in this respect it should also be appreciated that the bores  113  for seating interlocking screws  101 , and/or the bores  115  for seating locking members  105 , can be drilled and/or otherwise formed and/or finished (i.e., shaped) so as to permit the proximal heads of interlocking screws  101  and/or locking members  105  to be low profile, flush or below the surface of the adjacent bone. 
     Looking next at  FIGS. 31-36 , it is also anticipated that arm  102  may be pivotally mounted to the host bone using an arrangement other than the aforementioned pivot block  103 , anchoring pin  104 , and clevis pin  107 . Thus, for example, and looking now at  FIGS. 31-36 , pivot block  103  may be eliminated, anchoring pin  104  may be replaced by an anchoring pin C having a ball D formed thereon, and arm  102  may comprise a ball mount E configured to slip over, and rotatably pivot on, ball D. This arrangement can be advantageous, since it can permit arm  102  to be mounted closer to the host bone, as well as providing additional degrees of pivoting freedom. 
     In addition to the foregoing, and looking now at  FIGS. 34-36 , it is also possible to selectively lock lower ratchet tubes  108  to arm  102  using other constructions. Thus, for example, a spring lever F may be used, where pressing spring lever F toward arm  102  enables movement of lower ratchet tubes  108  relative to arm  102 . Correspondingly, releasing spring lever F causes lower ratchet tubes  108  to be locked in position relative to arm  102 . 
     In yet another form of the invention, and looking now at  FIG. 37 , arm  102  may be pivotally mounted to the host bone using a finger G. In this form of the invention, a hole is made in the host bone, finger G is inserted into the hole, and then spring lever F (or other equivalent mechanism) is used to move lower ratchet tubes  108  against the fractured bone portion, whereby to hold the fractured bone portion securely against the host bone while it is secured using one or more locking members  105  and interlocking screws  101 . 
     It should be appreciated that the various components of fracture fixation system  100  are formed out of materials which are consistent with the present invention. Thus, all of the components of fracture fixation system  100  (including locking members  105  and interlocking screws  101 ) may be formed out of metal. Alternatively, one or both of locking members  105  and/or interlocking screws  101  may be formed out of an absorbable material. 
     MODIFICATIONS 
     While the present invention has been described in terms of certain exemplary preferred embodiments, it will be readily understood and appreciated by those skilled in the art that it is not so limited, and that many additions, deletions and modifications may be made to the preferred embodiments discussed herein without departing from the scope of the invention.