Abstract:
An intramedullary bone fixation device suitable for treatment of fractures of the tubular bones of the hand or feet. The implantable device can be used singly or introduced through both the radial and ulnar aspects. The device includes a stem having a tip portion at one end and a base member at the opposite end of the stem. The stem and tip portions are configured with a unique configuration and cross section to facilitate insertion into and through the canal and provide the necessary forces on the stem portion within the canal. The base is sized and configured to minimize tissue damage while as the same time providing a strong point of fixation.

Description:
This application claims the benefit of Provisional Patent Application No. 61/101,890, entitled, “Intramedullary Bone Fixation”, filed on Oct. 1, 2008, the entire contents of which is hereby expressly incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of bone implants, and, more particularly, to bone fracture implants for long bones and related methods. 
     BACKGROUND OF THE INVENTION 
     Presently there are a number of approaches in use to treat complex fractures of the hand or foot. One common approach is the use of plating to provide the necessary internal fixation. One significant drawback to plating is the necessity to form a large incision in the vicinity of the fracture. In addition, the muscle, ligament and other sensitive tissue is often moved so as to provide access to the surface of the bone. The disturbance of these tissues can extend the time required for recuperation and rehabilitation. The plate is attached to one or more fragments in such as way so as to position the fracture in a proper alignment for healing. Due to the aforementioned drawbacks, plating is used primarily for those case where there is a need to stabilize complex fractures. 
     Where the bone fractures are less complex it is possible to treat the fracture with a cast. While casting is a more conservative approach this fixation technique may not produce sufficient immobilization of the fragments so as to result in a favorable outcome. Casting is generally not as effective when the fracture is oblique rather than transverse as the bone segments can move relative to one another resulting in a less than desirable outcome. 
     Other forms of bone fixation approaches include wiring the bone fragments together, pinning the bone fragments to a rigid metal frame positioned outside of the patient&#39;s body, and use of percutaneous pins that are inserted introfocally and subsequently connected to a rigid metal frame external to the body. These approaches tend to cause irritation of sensitive tissues, such as tendons, ligaments, muscle, and nerves and can results in irritation, pain, as well as infection due to incisions and open wounds adjacent the pins. 
     Although a large number of approaches are available to treat fractures, none to date provide a percutaneous intrafocal plate that is simple and safe to use and is an effective bone fixation device. Many fixation devices for use in stabilizing bone fractures lack the ability to easily, efficiently and safely and require an invasive approach which can result in increased pain, and infection for the patient and extended recuperation and rehabilitation time frames. 
     DESCRIPTION OF THE PRIOR ART 
     U.S. Pat. No. 6,379,359, to Dahners, discloses a plate apparatus for addressing metaphyseal and similar bone fractures. The apparatus comprises an elongated plate element having a flat plate surface at one end thereof defining a top surface and a bottom surface and a leading end and a trailing end. A longitudinally extending resilient body element depends from the trailing end of the flat surface and defines a shoulder at one end which joins the flat plate surface and an arcuate pin at the other end. The intrafocal plate is formed so that a force applied at the arcuate pin end causes a force to be applied in the opposite direction at the flat plate surface. 
     U.S. Pat. No. 6,730,090, to Orbay et al, discloses a fixation device that includes a proximal nail portion and a distal plate portion. The nail portion includes a flexible tapered section and a rigid distal section larger in diameter and is adapted to be inserted into a medullary canal of the fractured bone. The plate portion has a low, narrow profile and includes three longitudinally displaced peg holes, each of which is adapted to orient a peg in a different orientation from the others. The plate portion is adapted to be positioned on the outside of a fractured bone when the nail portion is within the medullary canal. The device provides the benefits of both an intramedullary nail and a bone plate in a single device. 
     U.S. Pat. No. 6,706,046, to Orbay et al, discloses a fixation device having a nail portion and a plate portion, preferably horizontally and vertically offset relative to the nail by a neck portion. The nail portion includes threaded screw holes, and the plate portion includes longitudinally displaced peg holes, each of which is adapted to orient a peg in a different orientation for the others. The system also includes unicortical screws having a reasonably large head adapted to seat against the outer surface of the bone and a threaded shaft adapted to engage in the peg holes. Bone is clamped between the nail portion and the head of the head of the unicortical screws. The pegs provide stabilization and support for subchondral fragments. Moreover, as the pegs preferably enter the subchondral fragments from a plurality of directions, additional fixation of the device into the bone is provided. 
     U.S. Published Patent Application No. 2006/0149257, to Orbay et al, is directed to a fracture fixation device that includes a plate portion and an intramedullary nail portion which is offset relative to the plate portion by a neck portion. The plate portion includes longitudinally displaced peg holes which orient pegs along an imaginary surface parallel to subchondral bone of an articular surface. The upper surface of the plate portion includes a dimple to reference a jig. The nail portion includes threaded screw holes oriented normal to an endosteal surface, and a smaller K-wire alignment hole parallel to the screw holes. The jig has a first portion which references with the dimple and second portion in alignment over the screw holes of the nail portion. The back portion of the first portion of the jig is curved upward to facilitate maneuvering of the jig. The first and second portions of the jig include K-wire guide holes which direct K-wires relative to holes in the device. 
     U.S. Published Application No. 2006/0161156, to Orbay, is directed to a fracture fixation device that includes a plate portion and an intramedullary nail portion which is offset relative to the plate portion by a neck portion. The plate portion overhangs the neck portion and includes longitudinally displaced holes which orient pegs along an imaginary surface parallel to subchonodral bone of an articular surface. The nail portion includes threaded screw holes oriented normal to an endosteal surface, and a smaller K wire alignment hole parallel to the screw holes. The back portion of the first portion of the jig is curved upward to facilitate maneuvering of the jig. The first and second portions of the jig include K-wire guide holes which direct K-wires relative to holes in the device. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention the bone fixation implant device is suitable for treatment of fractures of the tubular bones of the hand or feet. The implant can be used singly or introduced through both the radial and ulnar aspects. The bone fixation implant implant device has been designed to be introduced though the collateral ligament regions of the phalanges, metacarpal and metatarsals. The implant can also be utilized by antegrade insertion. The device includes a stem having a tip portion at one end and a base member at the opposite end of the stem. The stem and tip portions are configured with a unique configuration and cross section to facilitate insertion into the canal and provide the necessary forces on the stem portion within the canal. The base is sized and configured to minimize tissue damage while as the same time providing a strong point of fixation. 
     Accordingly, it is an objective of the instant invention to provide an intramedullary bone fixation implant that can be percutaneously implanted for fixation of tubular bone of the hands and feet. 
     It is a further objective of the instant invention to provide a bone fixation device that can be implanted using minimally invasive techniques. 
     It is yet another objective of the instant invention to provide an implantable bone fixation device that can be inserted using a simplified process of open reduction internal fixation (ORIF) and enabling the treatment of moderately complex fractures by a single surgeon in venues where equipment and assistance may be modest. 
     It is a still further objective of the invention to provide an implantable bone fixation device configured with a geometry that affords instant stability thereby accelerating motion recovery. 
     Other objects and advantages of this invention will become apparent from the following description taken in conjunction with any accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. Any drawings contained herein constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a front side view of the bone fixation implant according to the present invention. 
         FIG. 2  is a backside view of the bone fixation implant of  FIG. 1 . 
         FIG. 3  is a side elevational view of the bone fixation implant of  FIG. 1 . 
         FIG. 4  is a top side plan view of the bone fixation implant of  FIG. 1 . 
         FIG. 5 . is a bottom side plan view of the bone fixation implant of  FIG. 1 . 
         FIG. 6  is a perspective view of the bone fixation implant of  FIG. 1 . 
         FIG. 7  is a cross-sectional view taken along line  7 - 7  of  FIG. 6 . 
         FIG. 8  is a perspective view of another embodiment of the bone fixation implant according to the present invention. 
         FIG. 9  is a side elevational view of the bone fixation implant of  FIG. 8 . 
         FIG. 10  is a cross-sectional view taken along line  10 - 10  of  FIG. 8 . 
         FIG. 11  is a perspective view of yet another embodiment of the bone fixation implant according to the present invention. 
         FIG. 12  is a cross-sectional view taken along line  12 - 12  of  FIG. 11 . 
         FIG. 13  is a perspective view of another embodiment of the bone fixation implant according to the present invention. 
         FIG. 14  is a side elevational view of the bone fixation implant of  FIG. 13 . 
         FIG. 15  is a cross-sectional view taken along line  15 - 15  of  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described more fully hereinafter with references to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and multiple prime notation is used to indicate similar elements in alternative embodiments. 
     Referring initially to  FIGS. 1-7 , a bone fixation implant  20  according to the present invention is now described. The bone fixation implant  20  illustratively includes a stem  22 , a tip  21  extending from a distal end of the stem, and a base  23  extending from a proximal end of the stem. The base  23  is coupled to the stem  22  via a joint  27  on the bottom side of the base  23 . The base illustratively includes a fastener-receiving passageway  24  surrounded by a beveled edge  25  on the upper surface of base  23 . While most fractures will require a single it should be understood that multiple head configurations can be used where appropriate. In addition, variable or fixed angle screw or screws can be utilized as the situation requires. As perhaps best seen in  FIG. 7 , the stem  22  has a cross-sectional pentagonal shape, having five discrete surfaces;  26   a ,  26   b ,  26   c ,  26   d  and  26   e . Surface  26   a  is a first surface and extends longitudinally from the base  23  to the tip  21  as clearly shown in  FIG. 4 . The width of first surface  26  tapers as it approaches the tip end  21  of stem  22 . Along each side of the first surface are edge surfaces  26   b  and  26   e  that extend longitudinally along the length of the first surface and are formed at an angle greater than 90 degrees with respect to the first surface. A second surface  26   d  and third surface  26   c  are located on the side of the stem opposite the first surface  26   a  as is clearly shown in  FIG. 5 . Second surface  26   d  extends longitudinally from base  23  to the tip  21  having a first side portion contiguous with edge surface  26   e  and a second side portion contiguous with third surface  26   c . The opposite side portion of third surface  26   c  is contiguous with edge surface  26   b . The stem  22  as viewed from the side in  FIG. 3  has a concavo-convex profile. It is includes a first arcuate portion  28  that extends from joint  27  that terminates when it transitions into a second arcuate portion  29 . Second arcuate portion  29  is curved is a direction diametrically opposed to the first arcuate portion  28 . Second arcuate portion  29  terminates when in transitions into a third arcuate portion  30 . Third arcuate portion  30  is curved in a direction diametrically opposite to the second arcuate portion  29  and similar to the first arcuate portion  28 . The third arcuate portion terminates at the tip  21 . The bone plate implant  20  may comprise metal suitable for surgical implantation, for example. The bone fixation implant  20  and fastener receiving aperture  24  can be formed in a variety of sizes to suit the particular application. 
     As will be appreciated by those skilled in the art, the bone fixation implant  20  may be used to treat fractures, for example, a spiral fracture, of the long bones, for example, the phalanges, metacarpals, or metatarsal. During implantation, the tip  21  is inserted through a damaged or cracked portion of the fractured bone and into the intramedullary canal/cavity. The tip configuration permits facile introduction and passage through the canal while the concavo-convex design results in a three point bending relationship with the canal. The pentagonal cross section of the stem  22  is designed to increase the surface area and strength of the stem. The base  23  is positioned on the extramedullary surface of the bone and affixed thereon by inserting a fastener through the fastener-receiving passageway  24 , for example, a surgical screw. The ability to secure the implant with a screw or screws will maintain the location and the force on the stem portions located within the canal. Once implanted, the tip  21  applied outward pressure on the surfaces of the intramedullary canal, thereby aiding in fixation treatment of the fractured bone. Multiple implants can be employed to stabilize a given fracture. 
     Referring now to  FIGS. 8-10 , another embodiment of the bone fixation implant  20 ′ is now described. In this embodiment of the bone fixation implant  20 ′, those elements already discussed above with respect to  FIGS. 1-7  are given prime notation and most require no further discussion herein. This embodiment differs from the previous embodiment in that the base  23 ′ is integrally formed the stem  22 ′ via a curved bend  27 ′ rather than a joint on the bottom side of the base  23 ′. Moreover, the stem  22 ′ has a greater thickness for providing mechanical robustness. As perhaps best seen in  FIG. 10 , the stem  22 ′ has a cross-sectional pentagonal shape, having five discrete surfaces;  26   a ′,  26   b ′,  26   c ′,  26   d ′ and  26   e ′. Surface  26   a ′ is a first surface and edge surface  26   b ′ extend longitudinally from the base  23  to the tip  21  as clearly shown in  FIG. 8 . The stem  22 ′ as viewed from the side in  FIG. 9  has a concavo-convex profile. It is includes a first arcuate portion  28 ′ that extends from joint  27 ′ that terminates when it transitions into a second arcuate portion  29 ′. Second arcuate portion  29 ′ is curved is a direction diametrically opposed to the first arcuate portion  28 ′. Second arcuate portion  29 ′ terminates when in transitions into a third arcuate portion  30 ′. Third arcuate portion  30 ′ is curved in a direction diametrically opposite to the second arcuate portion  29 ′ and similar to the first arcuate portion  28 ′. 
     Referring now to  FIGS. 11-12 , another embodiment of the bone plate implant  20 ″ is now described. In this embodiment of the bone fixation implant  20 ″, those elements already discussed above with respect to  FIGS. 1-7  are given double prime notation and most require no further discussion herein. As perhaps best seen in  FIG. 12 , this embodiment differs from the previous embodiment in that the stem  22 ″ differently has a rectangular shape, i.e. the stem  22 ″ has four sides  26   a ″- 26   c ″. The corners contiguous with adjacent sides are rounded to permit facile introduction and ease of passage into and through the canal. 
     Referring now to  FIGS. 13-15 , another embodiment of the bone plate implant  20 ′″ is now described. In this embodiment of the bone fixation implant  20 ′″, those elements already discussed above with respect to  FIGS. 1-7  are given triple prime notation and most require no further discussion herein. As perhaps best seen in  FIG. 15 , this embodiment differs from the previous embodiment in that the stem  22 ′″ differently has a cross-sectional rectangular shape, i.e. the stem  22 ′″ has four sides  26   a ′″- 26   c ′″. Moreover, the base  23 ′″ is formed to include the stem  22 ′″ via a curved bend  27 ′″ rather than a joint on the bottom side of the base  23 ′″. Moreover, the stem  22 ′″ has a greater thickness for providing mechanical robustness. The corners contiguous with adjacent sides are rounded to permit facile introduction and ease of passage into and through the canal. The stem  22 ′″ as viewed from the side in  FIG. 14  has a concavo-convex profile. It is includes a first arcuate portion  28 ′″ that extends from joint  27 ′″ that terminates when it transitions into a second arcuate portion  29 ′″. Second arcuate portion  29 ′″ is curved is a direction diametrically opposed to the first arcuate portion  28 ′″. Second arcuate portion  29 ′″ terminates when in transitions into a third arcuate portion  30 ′″. Third arcuate portion  30 ′″ is curved in a direction diametrically opposite to the second arcuate portion  29 ′″ and similar to the first arcuate portion  28 ′″. 
     All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. 
     It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein. 
     One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.