Abstract:
A volar fixation system includes a plate intended to be positioned against the volar side of the radial bone. The plate includes holes for receiving fasteners along a fixed axis relative to the plate. The plate is positioned against the radius bone, and a portion of the plate is preliminarily fixed to the radius bone. The fracture is reduced, and a plurality of fasteners are each inserted through a respective plate hole so as to extend immediately below the subchondral bone of the radius bone and is fixed in axial relationship relative to the plate. Together the fasteners form a stabilizing construct that conforms to the concave curvature of the articular surface of the radius bone.

Description:
This application is a continuation of U.S. Ser. No. 11/181,354, filed Jul. 14, 2005, now abandoned which is a continuation of U.S. Ser. No. 10/762,695, filed Jan. 22, 2004, now abandoned which is a continuation-in-part of U.S. Ser. No. 10/315,787, filed Dec. 10, 2002, now U.S. Pat. No. 6,706,046 which is a continuation-in-part of U.S. Ser. No. 10/159,611, filed May 30, 2002, now U.S. Pat. No. 6,730,090 which is a continuation-in-part of U.S. Ser. No. 09/735,228, filed Dec. 12, 2000 and now issued as U.S. Pat. No. 6,440,135, which is a continuation-in-part of U.S. Ser. No. 09/524,058, filed Mar. 13, 2000 and now issued as U.S. Pat. No. 6,364,882, and U.S. Ser. No. 09/495,854, filed Feb. 1, 2000 and now issued as U.S. Pat. No. 6,358,250, the complete disclosures of which are hereby incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates broadly to surgical devices. More particularly, this invention relates to a bone fixation system, and particularly to a fixation system adapted to fixate a distal radius fracture. 
     2. State of the Art 
     Referring to  FIG. 1 , a Colles&#39; fracture is a fracture resulting from compressive forces being placed on the distal radius  10 , and which causes backward displacement of the distal fragment  12  and radial deviation of the hand at the wrist  14 . Often, a Colles&#39; fracture will result in multiple bone fragments  16 ,  18 ,  20  which are movable and out of alignment relative to each other. If not properly treated, such fractures result in permanent wrist deformity. It is therefore important to align the fracture and fixate the bones relative to each other so that proper healing may occur. 
     Alignment and fixation are typically performed by one of several methods: casting, external fixation, interosseous wiring, and plating. Casting is non-invasive, but may not be able to maintain alignment of the fracture where many bone fragments exist. Therefore, as an alternative, external fixators may be used. External fixators utilize a method known as ligamentotaxis, which provides distraction forces across the joint and permits the fracture to be aligned based upon the tension placed on the surrounding ligaments. However, while external fixators can maintain the position of the wrist bones, it may nevertheless be difficult in certain fractures to first provide the bones in proper alignment. In addition, external fixators are often not suitable for fractures resulting in multiple bone fragments. Interosseous wiring is an invasive procedure whereby screws are positioned into the various fragments and the screws are then wired together as bracing. This is a difficult and time consuming procedure. Moreover, unless the bracing is quite complex, the fracture may not be properly stabilized. Plating utilizes a stabilizing metal plate typically against the dorsal side of the bones, and a set of parallel pins extending from the plate into the holes drilled in the bone fragments to provide stabilized fixation of the fragments. However, the currently available plate systems fail to provide desirable alignment and stabilization. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an improved fixation and alignment system for a Colles&#39; fracture. 
     It is another object of the invention to provide a volar fixation system which desirably aligns and stabilizes multiple bone fragments in a distal radial fracture to permit proper healing. 
     In accord with these objects, which will be discussed in detail below, a volar fixation system is provided which generally includes a T-shaped plate intended to be positioned against the volar side of the radial bone, a plurality of bone screws for securing the plate along a non-fractured portion of the radial bone, and a plurality of bone pegs which extend from the plate and into bone fragments of a Colles&#39; fracture. 
     The plate is generally a T-shaped plate defining an elongate body, a head portion angled relative to the body, a first side which is intended to contact the bone, and a second side opposite the first side. The body portion includes a plurality of countersunk screw holes for the extension of the bone screws therethrough. The head portion includes a plurality of threaded peg holes for receiving the pegs therethrough. According to a first embodiment, the peg holes are preferably non-linearly arranged. According to a second embodiment, the peg holes are preferably linearly arranged. In either embodiment, the peg holes are positioned increasingly distal in a medial to lateral direction along the second side. According to a preferred aspect of the invention, axes through the holes are oblique relative to each other, and are preferably angled relative to each other in two dimensions. The pegs having a threaded head and a relatively smooth cylindrical shaft. 
     The system preferably also includes a guide plate which temporarily sits on top of the volar plate and includes holes oriented according to the axes of the peg holes for guiding a drill into the bone fragments at the required orientation. The volar plate and guide plate are also preferably provided with mating elements to temporarily stabilize the guide plate on the volar plate during the hole drilling process. 
     In use, the volar plate is positioned with its first side against the volar side of the radius and bone screws are inserted through the bone screw holes into the radius to secure the volar plate to the radius. The bone fragments are then aligned and the guide plate is positioned on the second side of the volar plate. A drill, guided by guide holes in the guide plate, drills holes into the bone fragments, and the guide plate is then removed. 
     The pegs are then inserted through the peg holes and into the holes in the bone, and the heads of the pegs are threadably engaged in the volar plate. The volar fixation system thereby secures the bone fragments in their proper orientation. 
     Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of an extremity subject to a Colles&#39; fracture; 
         FIG. 2  is a top volar view of a right hand volar fixation system according to a first embodiment of the invention; 
         FIG. 3  is a side view of a bone peg according to the first embodiment of the volar fixation system of the invention; 
         FIG. 4  is a side view of a bone screw of the volar fixation system of the invention; 
         FIG. 5  is a side view of the right hand volar plate of the volar fixation system according to the first embodiment of the invention; 
         FIG. 6  is a front end view of the right hand volar plate of the volar fixation system according to the first embodiment of the invention; 
         FIG. 7  is an exploded side view of the right hand volar plate and guide plate according to the first embodiment of the fixation system of the invention; 
         FIG. 8  is a side view of the guide plate positioned on the right hand volar plate to provide drill guide paths in accord with the invention; 
         FIG. 9  is an illustration of the first embodiment of the volar fixation system provided in situ aligning and stabilizing a Colles&#39; fracture; 
         FIG. 10  is a top volar view of a left hand volar fixation system according to the second embodiment of the invention; 
         FIG. 11  is a lateral side view of the left hand volar fixation system according to the second embodiment of the invention; 
         FIG. 12  is a bottom view of the left hand volar fixation system according to the second embodiment of the invention; 
         FIG. 13  is an enlarged side elevation of a bone peg according to the second embodiment of the volar fixation system of the invention; 
         FIG. 14  is a proximal end view of the bone peg of  FIG. 13 ; 
         FIG. 15  is first partial top view of the head portion of the left hand volar plate according to the second embodiment of the volar fixation system of the invention; 
         FIGS. 16-19  are section views across line  16 - 16 ,  17 - 17 ,  18 - 18 , and  19 - 19 , respectively in  FIG. 15 ; 
         FIG. 20  is second partial top view of the head portion of the left hand volar plate according to the second embodiment of the volar fixation system of the invention; and 
         FIGS. 21-24  are section views across line  21 - 21 ,  22 - 22 ,  23 - 23 , and  24 - 24 , respectively in  FIG. 20 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to  FIGS. 2 through 4 , a first embodiment of a volar fixation system  100  for aligning and stabilizing multiple bone fragments in a Colles&#39; fracture generally includes a substantially rigid T-shaped plate  102  intended to be positioned against the volar side of the radial bone, a plurality of preferably self-tapping bone screws  104  for securing the plate  102  along a non-fractured portion of the radial bone, and a plurality of bone pegs  108  which extend from the plate  102  and into bone fragments of a Colles&#39; fracture. 
     Referring to  FIGS. 2 ,  5  and  6 , more particularly, the T-shaped plate  102  defines a head portion  116 , an elongate body portion  118  angled relative to the head portion, a first side  120  which is intended to contact the bone, and a second side  122  opposite the first side. The first side  120  at the head portion is preferably planar, as is the first side at the body portion. As the head portion and body portion are angled relative to each other, the first side preferably defines two planar portions. The angle Ø between the head portion  116  and the body portion  118  is preferably approximately 18° and bent at a radius of approximately 1.00 inch ( FIG. 5 ). The distal edge  121  of the head portion  116  is preferably angled proximally toward the medial side at an angle, e.g., 5°, relative to a line P, which is perpendicular to the body portion. The head portion  116  preferably has a width of 0.913 inch and a greatest proximal-distal dimension (i.e., from the corner of angle to the body portion) of approximately 0.69 inch, and the body portion preferably has a width of 0.375 inch and a length of 1.40 inches. The plate  102  preferably has a thickness of approximately 0.098 inch. The plate  102  is preferably made from a titanium alloy, such as Ti-6A-4V. 
     The body portion  118  includes three preferably countersunk screw holes  124 ,  126 ,  128  for the extension of the bone screws  104  therethrough. The first screw hole  124  has a center preferably 0.235 inch from the end of the body portion, the second screw hole  126  has a center preferably 0.630 inch from the end of the body portion, and the third screw hole  128  is preferably generally elliptical (or oval) and defines foci-like locations at 1.020 inches and 1.050 inches from the end of the body portion. The head portion  116  includes four threaded peg holes  130 ,  132 ,  134 ,  136  for individually receiving the pegs  108  therethrough. According to a first preferred aspect of the first embodiment of the invention, the peg holes  130 ,  132 ,  134 ,  136 , preferably 0.100 inch in diameter, are preferably non-linearly arranged along the head portion  116 , and are provided such that the adjacent peg holes are provided further distally in a medial to lateral direction along the second side. More particularly, according to a preferred aspect of the first embodiment of the invention, the peg holes are preferably arranged along a parabolic curve, with the center of peg hole  130  located approximately 0.321 inch proximal line P and approximately 0.719 inch medial of the lateral edge  137  of the head portion, the center of peg hole  132  located approximately 0.296 inch proximal line P and approximately 0.544 inch medial of the lateral edge  137 , the center of peg hole  134  located approximately 0.250 inch proximal line P and approximately 0.369 inch medial of the lateral edge  137 , and the center of peg hole  136  located approximately 0.191 inch proximal line P and approximately 0.194 inch medial of the lateral edge  137 . 
     In addition, according to a second preferred aspect of the first embodiment of the invention, the peg holes define fixed central axes A 1 , A 2 , A 3 , A 4  which are oblique (not parallel) relative to each other, and more preferably are angled in two dimensions (medial/lateral and proximal/distal) relative to each other; i.e., the pegs once inserted into the peg holes are also angled in two dimensions relative to each other. More particularly, the first axis A 1  of the first peg hole  130  (that is, the most proximal and medial peg hole) is preferably directed normal to the first side  120  of the head portion  116 . The axis A 2  of the adjacent peg hole  132 , i.e., the second axis, is preferably angled approximately 1-7° distal and lateral relative to the first axis A 1 , and more preferably approximately 2.5° distal and lateral relative to the first axis A 1 . The axis A 3  of the peg hole  134  laterally adjacent the second peg hole  132 , i.e., the third axis, is preferably angled approximately 7-13° distal and lateral relative to the first axis A 1 , and more preferably approximately 10° distal and lateral relative to the first axis A 1 . The axis A 4  of the peg hole  134  laterally adjacent the third peg hole  132 , i.e., the fourth axis, is preferably angled approximately 10-30° distal and lateral relative to the first axis A 1 , and more preferably approximately 20° distal and lateral relative to the first axis A 1 . The second side of the head portion  116 , distal of the peg holes  130 ,  132 ,  134 ,  136  is preferably beveled. 
     Referring back to  FIG. 3 , the pegs  108 , preferably approximately 0.872 inch in length, each have a threaded head  138  adapted to threadably engage the threads about the peg holes  130 ,  132 ,  134 ,  136 , and have a relatively smooth non-threaded cylindrical shaft  140 . The shafts  140  are preferably approximately 0.0675 inch in diameter and 0.765 inch in length. Such dimensions permit the pegs to adequately support the bone fragments such that the bone is able to heal correctly. The pegs  108  are also preferably made from titanium alloy, and may be coated in a ceramic, e.g., titanium nitride, to provide a bone interface which will not adversely affect bone healing. 
     Turning now to  FIGS. 7 and 8 , the system  100  preferably also includes a guide plate  146  which temporarily sits on the second side  122  of the volar plate  102  and includes guide holes  148 ,  150 ,  152 ,  154  (illustrated in overlapping section in  FIG. 8 ) oriented according to the axes A 1 , A 2 , A 3 , A 4  of the peg holes for guiding a drill into the bone fragments at the required orientation. That is, the guide holes together with the peg holes define a drill guide path along the axes with sufficient depth to accurately guide a drill (not shown) to drill holes at the desired pin orientations. The volar plate  102  and guide plate  146  are also preferably provided with mating elements, such as a plurality of holes  156 ,  158  on the second side of the volar plate ( FIG. 2 ), and a plurality of protuberances  160  on the mating side of the guide plate ( FIG. 7 ), to temporarily stabilize the guide plate on the volar plate during the hole drilling process. 
     Referring to  FIGS. 2 through 9 , in use, the volar plate  102  is positioned with its first side  120  against the volar side of the radius. Bone screws  104  (either self-tapping or inserted with the aid of pre-drilled pilot holes) are inserted through the bone screw holes  124 ,  126 ,  128  into the radius bone  10  to secure the volar plate  102  to the radius. The bone fragments  16 ,  18 ,  20  are then aligned with the radius  10 . Next, the guide plate  146  is positioned on the second side of the volar plate. A drill, guided by a guide path formed by the peg holes and the guide holes, drills holes into and between the bone fragments  16 ,  18 ,  20  (and possibly also a portion of the integral radius, depending upon the particular location and extent of the fracture), and the guide plate is then removed. The pegs  108  are then inserted through the peg holes  130 ,  132 ,  134 ,  136  and into the holes drilled into the fragments, and the heads of the pegs are threadably engaged in the volar plate. The pegs  108 , extending through the fixed orientation oblique-axis peg holes  130 ,  132 ,  134 ,  136 , and threadedly engaged to the plate are positioned in a fixed angular relationship relative to the head portion of the plate and extend immediately below the subchondral bone of the radius and support the bone fragments for proper healing. The volar fixation system thereby secures the bone fragments in their proper orientation. 
     Referring to  FIGS. 10-12 , a second embodiment of a volar plate  210 , substantially similar to the first embodiment (with like parts having numbers incremented by 100) and used in substantially the same manner as the first embodiment is shown. The plate  210  preferably has a length of approximately 2.35 inches, which is approximately 0.35 inch greater than in the first embodiment. This additional length accommodates an extra bone screw hole  229  in the body of the volar plate such that the volar plate preferably includes four bone screw holes  224 ,  226 ,  228 ,  229 . The additional bone screw in screw hole  229  increases plate stability over the three holes of the first embodiment. The plate  210  preferably tapers in thickness from the body portion  218  to the head portion  216 . A preferred taper provides a proximal body portion  218  thickness of approximately 0.098 inch and head portion  216  thickness of approximately 0.078 inch. The taper decreases the thickness of the head portion  216  relative to the body such that the weight of the volar plate is reduced and an improved tendon clearance is provided. The distal edge of the head portion  216  has an increased taper (preferably approximately 60° relative to a line normal to the head) to a distal edge  221 . The edge  221  is broken (i.e., made blunt) to prevent irritation or disturbance to the surrounding anatomy. 
     The head portion  216  includes four threaded peg holes  230 ,  232 ,  234 ,  236  for individually receiving pegs  208  therethrough ( FIGS. 13 and 14 ), and a guide hole  256  for alignment of a guide plate. According to a preferred aspect of the second embodiment of the invention, the peg holes  230 ,  232 ,  234 ,  236 , preferably 0.100 inch in diameter, are preferably linearly arranged along the head portion  216 , and are provided such that the adjacent peg holes are provided further distally in a medial to lateral direction along the first and second sides. Referring to  FIG. 15 , more particularly, according to a preferred dimensions of the second embodiment of the invention, the center of peg hole  230  is located approximately 0.321 inch proximal line P and approximately 0.750 inch medial of the lateral edge  237  of the head portion, the center of peg hole  232  is located approximately 0.306 inch proximal line P and 0.557 inch medial of the lateral edge  237 , the center of peg hole  234  is located approximately 0.289 inch proximal line P and approximately 0.364 inch medial of the lateral edge  237 , and the center of peg hole  236  is located approximately 0.272 inch proximal line P and approximately 0.171 inch medial of the lateral edge  237 . As such, the distance from each of the peg holes to the distal edge  221  of the volar plate is relatively greater than in the first embodiment, and provides a preferred alignment with respect to the tapered distal edge  221 . 
     Referring to  FIGS. 15-24 , in addition, as in the first embodiment, the peg holes define fixed central axes A 1 , A 2 , A 3 , A 4  which are oblique relative to each other, and more preferably are angled in two dimensions (medial/lateral and proximal/distal) relative to each other; i.e., the pegs  208  once inserted into the peg holes are also angled in two dimensions relative to each other. More particularly, as in the first embodiment, the first axis A 1  of the first peg hole  230  is preferably directed normal ( FIGS. 16 and 21 ) to the first side  220  of the head portion  216 . The axis A 2  of peg hole  232  is preferably angled approximately 1-7° distal ( FIG. 17 ) and approximately 1-7° lateral ( FIG. 22 ) relative to the axis A 1 , and more preferably approximately 2.5° both distal and lateral relative to axis A 1 . The axis A 3  of peg hole  234  is preferably angled approximately 7-13° distal ( FIG. 18 ) and approximately 7-13° lateral ( FIG. 23 ) relative to axis A 1 , and more preferably approximately 10° both distal and lateral relative to axis A 1 . Axis A 4  of the peg hole  234  is preferably angled approximately 10-30° distal ( FIG. 19 ) and approximately 10-30° lateral ( FIG. 24 ) relative to axis A 1 , and more preferably approximately 20° both distal and lateral relative to axis A 1 . 
     Referring to FIGS.  13  and  16 - 19 , each of the peg holes has a countersunk portion  270 ,  272 ,  274 ,  276 , respectively, for receiving the head  238  of peg  208 . Countersunk portions  270 ,  272  are each preferably approximately 0.030 inch deep and threaded according to the head of the pegs, as described below. Countersunk portion  274  is preferably approximately 0.042 inch deep and likewise threaded. Countersunk portion  276  is preferably approximately 0.056 inch deep and also threaded. The respective depths of the countersunk portions are adapted to better accommodate the heads  238  of the pegs  208  relative to the respective axes of the peg holes. 
     Referring to  FIGS. 13 and 14 , the pegs  208 , preferably approximately 0.872 inch in length, each have a threaded head  238  adapted to threadably engage threads about the peg holes  230 ,  232 ,  234 ,  236 , and have a relatively smooth non-threaded cylindrical shaft  240 . The heads  238  preferably include a no. 5 thread  280  at a count of 44 per inch. In addition, the heads  238  are rounded and include a hex socket  282  to facilitate stabilized threading into the peg holes. This design accommodates the reduced thickness of the volar plate at the head portion  216 . The shafts  240  are preferably approximately 0.0792 inch (2 mm) in diameter and 0.765 inch in length. Such dimensions permit the pegs to adequately support the bone fragments such that the bone is able to heal correctly. The pegs  208  are also preferably made from titanium alloy, and may be ‘tiodized’ to provide a strong finish which does not adversely affect bone healing. 
     There have been described and illustrated herein embodiments of a volar fixation system and a method of aligning and stabilizing a Colles&#39; fracture. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular materials for the elements of the system have been disclosed, it will be appreciated that other materials may be used as well. In addition, while a particular numbers of screw holes in the volar plates and bone screws have been described, it will be understood another number of screw holes and screws may be provided. Further, fewer screws than the number of screw holes may be used to secure to the volar plate to the radius. Also, fewer or more peg holes and bone pegs may be used, preferably such that at least two pegs angled in two dimensions relative to each other are provided. Moreover, while in the first embodiment it is preferred that the peg holes lie along a parabolic curve, it will be appreciated that they can lie along another curve. In addition, while a particular preferred angle between the head portion and body portion has been disclosed, other angles can also be used. Furthermore, while particular distances are disclosed between the peg holes and line P, it will be appreciated that the peg holes may be provided at other distances relative thereto. Moreover, while particular preferred medial/lateral and proximal/distal angles for the peg hole axes has been disclosed, it will be appreciated that yet other angles may be used in accord with the invention. Also, while a right-handed volar plate is described with respect to the first embodiment, and a left-handed volar plate is described with respect to the second embodiment, it will be appreciated that each embodiment may be formed in either a right- or left-handed model, with such alternate models being mirror images of the models described. In addition, aspects from each of the embodiments may be combined. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.