US20090125068A1 - Apparatus for Dynamic External Fixation of Distal Radius and Wrist Fractures - Google Patents

Abstract

The fixator is an apparatus for repairing fractures of the distal radius and wrist. Distal, pivot, distraction, and radial members provide an anatomically contoured, radiolucent apparatus that permits the wrist to move through a substantially normal range of motion. A means for distraction of the bones by the fixator is also provided. The fixator may be affixed to the lower arm and hand by spaced-apart elongate distal mounting pins with lower ends adapted or mounting in tile metacarpal bone and by spaced-apart elongate radial mounting pins with lower ends adapted for mounting in the radius.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS
• The present application is a continuation and claims the benefit of the filing date of an application entitled, “Apparatus for Dynamic External Fixation of Distal Radius and Wrist Fractures” U.S. Pat. No. 7,367,977, issued May 6, 2008 and filed Feb. 28, 2003, assigned to the assignee of the present application, and herein incorporated by reference.
BACKGROUND
• 1. Technical Field
• The present invention relates generally to a dynamic bone fixator for repairing fractures of the distal radius and wrist. More particularly, the present invention is adapted to reduce and stabilize the relative positions of the fractured bone at the fracture site to promote proper healing and recovery.
• 2. Description of the Related Art
• The first external fixator was developed for reducing and maintaining patellar fractures. Since that time, various fixators have been invented for splinting various bone fractures. Most of these fixators have common features. In particular, they rely on transcutaneous pins or screws secured in the bone on either side of the fracture site. An external apparatus is attached to the pins to allow their relative positions to be adjusted, thus enabling a surgeon to reestablish alignment of the bone pieces at a fracture site. Once the bone is properly set, the articulations in the fixator may be locked into place to maintain the chosen alignment.
• Principal variations among the many fixator designs include the number of degrees of freedom permitted the wrist and the relative independence of each articulation, both mechanical and geometric. The first external fixator, for instance, was adjustable only in length and squeezed the fracture together by gripping opposed ends of the patella. Fixators designed to repair central fractures of the long bones typically have relatively few articulations or degrees of freedom. In contrast, fixators adapted to treat Fractures of bones in joint regions must permit articulation through many more degrees of freedom. Where there is insufficient room to place pins in the bone fragment between the fracture and the joint, bone alignment must be established using pins placed in a bone on the side of the joint opposite the fracture. Such treatment of fractures near joints such as the wrist, which can rotate, flex and abduct, requires that a fixator permit some movement through the range of motion of the joint in a manner allowing a surgeon to establish proper fracture alignment by using forces transmitted through the joint.
• Modem fixators permit articulation by various methods. Probably the most common articulation is provided by a ball joint. A ball joint provides one rotational and two pivotal degrees of freedom. A single setscrew or other locking mechanism can fix all three degrees of freedom simultaneously. The disadvantage of this method of articulation is that it is not possible to loosen the joint to permit motion in only one of the possible degrees of freedom. Thus, a surgeon cannot loosen the ball joint slightly to pivot it a small amount in one direction without the possibility of introducing changes affecting the other pivot and rotation settings.
• In order to overcome this limitation, some fixators eliminate ball joints and rely instead on a combination of independent articulations to provide the necessary freedom of movement. The benefit of such a system is that each degree of freedom is mechanically independent of every other degree of freedom. A surgeon may thus adjust the position of a single articulation in the fixator without affecting the settings of other articulations.
• Most fixators also include some type of extensible/contractible articulation to permit the longitudinal spacings between the pins on opposite sides of the fracture to be controlled. This type of translational freedom can be used to accommodate individuals of varying size, as well as to distract the fracture, if necessary.
• The Wrist joint permits the hand to move in three degrees of freedom relative to the forearm. First, the hand can move in supination and pronation. i.e., the rotation about the longitudinal axis of the forearm. Second, the hand can move in adduction and abduction, i.e., lateral flexion, or pivoting about an axis perpendicular to the plane of the palm. The last type of mobility of the hand is dorsal-palmar flexion, which is the pivotal motion about an axis in the plane of the palm and perpendicular to the longitudinal axis of the forearm.
• Dynamic fixators allow for some movement while affixed to a joint region, such as a lower arm, wrist and hand, yet maintain sufficient alignment of the fracture while it heals. Such prescribed movement can reduce and assist in recovery from stiffness associated with immobilization of the fracture.
• Fixators have typically been designed from a purely functional viewpoint. Fixator design and construction has generally been bulky and unsightly, and generally increase the effective dimensions of the wearer's hand, wrist and arm to an awkward degree. Further, these fixators have typically been far more robustly designed than is necessary. Tile size and weight of these fixators thus add an undesirably bulky and clumsy addition to the wearer's arm and hand.
• One of the more common fractures requiring a fixator for proper treatment is a fracture of the distal radius, or Colles fracture. This type of fracture usually results from a fall upon an outstretched hand. The fracture line is usually quite close to the distal head of the radius and sometimes the head is communicated. Because of the lack of space and the number of tendons and nerves in the area, it is difficult to mount pins in the radius on the distal side of the fracture. Therefore, such fractures are typically reduced using a pair of pins set in the index, or second metacarpal and a pair of pins set in the radius on the proximal side of the fracture. In order to avoid damage to tendons and nerves, the radial pins are usually set in the third quarter of the radius, i.e., the proximal half of the distal half of the radius. With the pins are set on opposite sides of the wrist joint, the fixator must be sufficiently articulate to reduce the fracture using forces transmitted through the wrist joint.
SUMMARY OF THE CLAIMED SUBJECT MATTER
• The present invention is an apparatus for dynamic external fixation of the distal radius and wrist for fracture repair. A pivot member provides two planes through which the wrist may move, namely, dorsal-palmar flexion and lateral flexion. A distal member pivotably connected to a pivot member provides a plurality of pin-mounting holes for fixation of the apparatus to pins set in the index metacarpal. A distraction member, pivotably connected at one end to the pivot member and translationally connected to a radial member at the other end, provides a means for distraction of the affected bones by means of a threadably advanceable screw to promote healing by proper alignment and spatial reduction of the fracture. Tile radial member further provides a plurality of pin-mounting holes for fixation of the apparatus to pins set in the radius. The invention is affixed to the human lower arm and hand by spaced-apart elongate distal mounting pins having one end adapted for mounting in the metacarpal bone and spaced-apart elongate radial mounting pins having one end adapted for mounting in the radius.
• Visual indication of the degree of angular displacement of the pivoting members may be provided by graduations marked into the pivoting members. Visual indication of the translational separation between the distraction and radial members may be provided by a graduated tab situated along the line of translation.
• Set screws are provided to limit or prevent, if necessary, the angular displacement of the pivoting members.
• The present invention is further designed to address the psychological impact of the fixator on the patient to whom it is affixed. The awkward profile and bulk of a fixator may be distressing to the wearer, as well as to other people who may come into contact with the wearer, particularly during meals and in public. It is therefore desirable to mitigate the deleterious psychological impact of wearing a fixator, to whatever extent possible, yet allow for medical examination, e.g., visually or by x-ray, without disturbing the fixator.
• It is therefore an object of the present invention to provide a dynamic external fixator for use on fractures of the distal radius or wrist.
• It is another object of the present invention to provide a dynamic external fixator for use on fractures of the distal radius that is articulated to permit the wrist to move through a substantially normal range of motion.
• It is an additional object of the present invention to provide a dynamic external fixator, for use on fractures of the distal radius, that provides a sufficient range of mobility to accommodate wrist flexibility and imprecise pin placement yet still have sufficient range of motion to reduce the fracture.
• It is yet another object of the present invention to provide a dynamic external fixator for use on fractures of the distal radius with sufficient free articulations to facilitate easy mounting of the fixator pins set in the radius and metacarpal bones.
• An additional object of the present invention is to provide a dynamic external fixator for use on fractures of the distal radius that allows a surgeon to achieve accurate and rapid reduction of the fracture.
• A further object of the present invention is to provide a dynamic external fixator for use on fractures of the distal radius that allows a surgeon to achieve accurate and rapid distraction of the fracture.
• Another object of the present invention is to provide a dynamic external Fixator of relatively light weight having an anatomy-conforming, low profile for functional and cosmetic appeal.
• It is an object of the present invention to provide an anatomy-conforming, low profile by utilizing members having a generally plate-like configuration.
• Another object of the present invention is to provide a dynamic external fixator comprised, in whole or in part, of a radiolucent material, such as polycarbonate.
• Another object of the present invention is to provide a dynamic external fixator comprised, in whole or in part, of a transparent material.
• These and other objects and advantages will become apparent from a consideration of the accompanying drawings and ensuing description.
• This summary is not intended as a comprehensive description of the claimed subject matter but, rather, is intended to provide a brief overview of some of the functionality associated therewith. Other systems, methods, functionality, features and advantages of the claimed subject matter will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description.
BRIEF DESCRIPTION OF THE FIGURES
• A better understanding of the claimed subject matter can be obtained when the following detailed description of the disclosed embodiments is considered in conjunction with the following figures, in which:
• FIGS. 1A-1E are various views of an assembled fixator of the present invention.
• FIG. 1F depicts, for an assembled fixator of the present invention, the preferred orientation of graduations and preferred locations of set screws.
• FIGS. 2A-2F are various views of the distal member, in a keyhole engagement embodiment.
• FIGS. 3A-3B are various views of the distal member, in a snap-in engagement embodiment.
• FIGS. 4A-4C are various views of the pivot member, in a keyhole engagement embodiment.
• FIGS. 5A-5C are various views of the pivot member, in a snap-in engagement embodiment.
• FIGS. 6A-6D are various views of the distraction member, in a keyhole engagement embodiment.
• FIGS. 7A-7B are various views of the distraction member, in a snap-in engagement embodiment.
• FIGS. 8A-8D are various views of the radial member.
• FIGS. 9A-9B are various views of a ball cap.
• FIGS. 10A-10B are various views of a pin ball.
• FIG. 11 depicts a rail.
• FIG. 12 depicts placement of a fixator of the present invention with respect to a human hand in dorsal (plan) view.
• FIG. 13 depicts placement of a fixator of the present invention with respect to the human hand in an elevational view.
• Even though the present invention is described with reference to the drawings and certain embodiments, it will be understood that such description is not intended to limit the invention to those embodiments. Rather, those skilled in the art will appreciate that the claims appended hereto are intended to broadly cover all alternatives, modifications, and equivalents reasonably understood to fall within their scope.
DETAILED DESCRIPTION OF THE FIGURES
• As may best be seen inFIGS. 1A-1F, the present invention is comprised of four primary members, adistal member1, apivot member30, adistraction member50, and aradial member70, which generally embody an anatomy-conforming, plate-like configuration. These members, as more fully described below, are assembled such that themajor plane2 of thedistal member1 is generally perpendicular to themajor plane51 of thedistraction member50 and themajor plane74 of theradial member70. Such assembly, when fixed bypins92 to the human wrist about afracture106, as seen inFIGS. 12 and 13, preferably permits the wrist to move through a substantially normal range of motion, namely, in palmar-dorsal flexion (up-down), lateral (side-to-side) flexion, and supination-pronation (rotational) flexion. Each of the primary members are preferably comprised, in whole or in part, of radiolucent material. For ease of reference, each primary member is defined, in part, by its respective desired orientation to the human hand, wrist, and/or arm.
• The present invention is best described with respect to the human hand, wrist and arm when the arm is placed on a flat surface, such as a typical hospital operating table, in a manner that permits the palm of the hand to face and contact the fat surface, such that the index (second)metacarpal100 is coaxially aligned with theradius104, as inFIG. 12. Again, for ease of reference, each primary member is described individually with respect to its orientation to the hand, wrist or arm, and then described with respect to the other primary members, i.e., assembled.
• Thedistal member1 is provided with multiple points for fixation of the dynamic external fixator to theindex metacarpal100, as may be seen inFIGS. 2A-2F,12 and13. Thedistal member1 is generally planar, whichmajor plane2 is oriented generally parallel to the dorsal aspect of the hand, and which long axis is further generally aligned with theindex metacarpal100. The first, or arm-lacing,end3 of thedistal member1 is defined by a semicircle of given radius. Afirst end4 of the semicircle defines the first end of aline tangent5 to the semicircle at that point, suchtangent line5 being parallel to the long axis of thedistal member1. A tapering curve6 of varying radii extends from thesecond end7 of the semicircle to intersect thetangent line5 at a near perpendicular angle so as to define thedistal member1 edge facing the fifth metacarpal102 (little finger). The intersection of the tapering curve6 and thetangent line5 generally defines thesecond end7 of thedistal member1. Those skilled in the art will appreciate that the edge defined by the tapering curve6 may be, for example, a straight line, or a series of straight lines, and may intersect thetangent line5 at angles other than perpendicular or near perpendicular.
• Thetangent line5 defines a break in themajor plane2 of thedistal member1 wherefrom aflange9 extending beyond thetangent line5 toward the thumb-facing edge of thedistal member1 curves away from themajor plane2 and toward the first metacarpal101 (thumb). The radial focal line of the curve of theflange9 is preferably the long axis of theindex metacarpal100. A first mountinghole10 defined through the thickness of thedistal member1 is preferably located in theflange9 near thesecond end8 of thedistal member1, the axis of which first mountinghole10 is preferably a radius of the curvature of theflange9. A second mountinghole11 defined through the thickness of thedistal member1 is preferably located in themajor plane2 of thedistal member1 proximally to the first mountinghole10 but closer to thefirst end3 of thedistal member1, the axis of which second mountinghole11 is preferably perpendicular to themajor plane2 of thedistal member1. A third mountinghole12 defined through the thickness of thedistal member1 may be preferably located in theflange9 proximally to the second mountinghole11, but closer to thefirst end3 of thedistal member1, the axis of which third mountinghole12 is preferably a radius of the curvature of theflange9. Preferably, none of the axes of the mountingholes1011 &12 share, with respect totangent line5, a longitude or latitude, and the axis of each of the mountingholes1011 &12 preferably focuses radially on the long axis of theindex metacarpal100. As seen inFIG. 12, thedistal member1 is preferably of sufficient length that the center point of the semicircle of thefirst end3 is located generally over the virtual rotational center of the proximalcarpal bones103 of the wrist and the axes of the mountingholes1011 &12 focus generally on the proximal two-thirds of theindex metacarpal100. Those skilled in the art will appreciate that the number, location, and orientation of the mounting holes may vary as required for optimal pin placement.
• Thefirst end3 of thedistal member1 is preferably provided with akeyed post13 that allows pivotable keyhole-type engagement with thefirst end32 of thepivot member30, described below. Thekeyed post13 extends out of themajor plane2 along the central axis of the semicircle.
• Alternatively, as inFIGS. 3A-3B, thefirst end3 of thedistal member1 is provided with a plurality of arc-shapedflanges15 to permit snap-in pivotable engagement with thefirst end32 of thepivot member30 to form the dorsal hinge. Theflanges15 extend out of themajor plane2 along the central axis of the semicircle. A protrudinglip14 extends across the width of eachflange15 and tapers to an edge defining the free end of eachflange15.
• As may be seen inFIGS. 4A-4C,12 and13 thepivot member30 functions primarily to orient themajor plane51 of thedistraction member50 andmajor plane74 of theradial member70 preferably generally perpendicularly to themajor plane2 of thedistal member1. Theplane31 of thefirst end32 of thepivot member30 is preferably coplanar with themajor plane2 of thedistal member1 that is, theplane31 of thefirst end32 is generally parallel to the dorsal aspect of the hand. Theplane33 of thesecond end34 oftile pivot member30 is generally perpendicular to theplane31 of thefirst end32.
• For the keyhole engagement system, a first keyedpivot hole35 defined through the thickness of thepivot member30 and further defined to accept thekeyed post13 of the distal member1 (not shown), is located near thefirst end32, the axis of which first keyedpivot hole35 is generally perpendicular to theplane31 of thefirst end32. A second keyedpivot hole36 defined through the thickness of thepivot member30 and further defined to accept thekeyed post60 of the distraction member50 (not shown), is located near thesecond end34, the axis of which second keyedpivot hole36 is generally perpendicular to theplane33 of thesecond end34. The axes of the first keyedpivot hole35 and second keyedpivot hole36 may lie in a common geometric plane.
• As seen inFIGS. 5A-5B, for the snap-in engagement system, thefirst pivot hole37 is formed to accept theflanges15 of the distal member1 (not shown), and thesecond pivot hole38 is formed to accept theflanges58 of the distraction member50 (not shown).
• Thedistraction member50 provides a means for selective distraction of the arm, wrist and/or hand bones, as seen inFIGS. 6A-6D and13. Themajor plane51 of thedistraction member50 is oriented generally perpendicularly to themajor plane2 of thedistal member1. Thedistraction member50 is generally planar, and is defined along its long axis by generallyparallel edges52 defining the width of thedistraction member50. Thedistraction member50 is further defined at afirst end53 by a semicircle, the center point of which lies upon the long axis, and at the second end54 by astraight edge55 that preferably angularly intersects the parallel edges52. Those of skill in the art will appreciate that the width of thedistraction member50 need not be defined byparallel edges52, but may be defined, for example, by curved edges or non-parallel edges. Those skilled in the art will also appreciate that thestraight edge55 may be, for example, curved, or comprised of multiple straight edges or curves, and may intersect theparallel edges52 at any angle.
• Thefirst end53 of thedistraction member50 is preferably provided with akeyed post60 that allows pivotable keyhole-type engagement with thesecond end34 of the pivot member30 (not shown). Thekeyed post60 extends out of themajor plane51 along the central axis of the semicircle.
• Again, as seen inFIGS. 7A-7B, for the snap-in engagement system, thefirst end53 of thedistraction member50 is provided with a plurality of arc-shapedflanges58 to permit snap-in pivotable engagement with thesecond end34 of the pivot member30 (not shown). Theflanges58 extend out of themajor plane51 along the centerline axis of the semicircle. A protrudinglip59 extends across the width of eachflange58 and tapers to an edge defining the free end of eachflange58.
• The drawings and the present description address a keyhole engagement system and a snap-in engagement systems allowing for pivotable engagement. Those skilled in the art will recognize other means of pivotable engagement, such as by bolt or rivet, or other customary engagement means, may be utilized to pivotably engage thefirst end3 of thedistal member1 to thefirst end32 of thepivot member30, and thefirst end53 of thedistraction member50 to thesecond end34 of thepivot member30.
• Within thedistraction member50, two spaced-apart rail holes56 are defined to lie parallel to and along the long axis and extend into, but not through, the thickness of thedistraction member50 from thestraight edge55. Eachrail hole56 is preferably of a constant diameter, and preferably has a smooth bore.
• Further within thedistraction member50 is defined adistraction hole57 extending along the long axis completely through thedistraction member50.Distraction hole57 may be threaded to accept a screw, such as screw91 (not shown), or defined to receive a nut (not shown) through which a screw may be threaded.
• Theradial member70, as seen inFIGS. 8A-8D,12 and13, is provided with multiple points for fixation of the fixator to theradius bone104. The long axis of theradial member70 is aligned with the long axis of the distraction member50 (not shown) such thatradial member70 andmajor plane51 of thedistraction member50 are generally coplanar. At afirst end71 of theradial member70 is astraight edge72 fashioned and oriented to complement the angledstraight edge55 of thedistraction member50. Thesecond end73 of theradial member70 generally tapers toward a narrow radius. The surface of theradial member70 curves gradually out of themajor plane74 to generally follow tile curvature of thepivot member70 and to generally conform to the lower arm. A first mountinghole75 defined through the thickness of theradial member70 is preferably located near thesecond end73 of theradial member70, the axis of which first mountinghole75 is preferably a radius of the curvature of theradial member70. A second mountinghole76 defined through the thickness of theradial member70 is preferably located in themajor plane74 proximally to the first mountinghole75 but closer to thefirst end71 of theradial member70, the axis of which second mountinghole76 is preferably perpendicular to themajor plane74 of theradial member70. A third mountinghole77 defined through the thickness of theradial member70 is preferably located proximally to the second mountinghole76, but closer to thefirst end71 of theradial member70, the axis of which third mountinghole77 is preferably a radius of the curvature of theradial member70. As seen inFIGS. 12 and 13, the axes of each of the mountingholes7576 &77 generally focus radially on the long axis of theradius bone104. Theradial member70 is preferably of such a length that, when assembled with the distraction member50 (not shown), thepins92 may be set within the distal half of theradius bone104. Those skilled in the art will appreciate that the number, location, and orientation of the mounting holes may vary as required for optimal pin placement.
• Theradial member70 further defines rail holes78 to lie parallel to the long axis and extend into, but not through, theradial member70, and correspond coaxially to the rail holes56 of the distraction member50 (not shown). Eachrail hole78 is preferably of a constant diameter, and preferably has a smooth bore.
• As seen inFIGS. 1A-1F, thedistal member1pivot member30 anddistraction member50 are assembled to permit the wrist to move through a substantially normal range of motion. For keyhole pivotable engagement, thekeyed post13 of thedistal member1 is inserted through thefirst pivot hole35 of thepivot member30, and thedistal member1 is rotated sufficiently to capture thekeyed post13 within thefirst pivot hole35. Likewise, for thedistraction member50, thekeyed post60 is inserted through thesecond pivot hole36 of thepivot member30, and thedistraction member50 is rotated sufficiently to capture thekeyed post60 within thesecond pivot hole36.
• For snap-in pivotable engagement, theflanges15 of thefirst end3 of thedistal member1 are urged into one side of thefirst pivot hole37 of thepivot member30 so that the lip of eachflange15 clears the far side of thefirst pivot hole37 such that thedistal member1 may not be removed from thepivot member30 unless the free ends of theflanges15 are simultaneously urged toward the centerline axis of thefirst pivot hole37. Theflanges58 of thefirst end53 of thedistraction member50 are urged into one side of thesecond pivot hole38 at thesecond end34 of thepivot member30 so that the lip of eachflange58 clears the far side of thesecond pivot hole38 such that thedistraction member50 may not be removed from thepivot member30 unless the free ends of theflanges58 are simultaneously urged toward the centerline axis of thesecond pivot hole38.
• It will be appreciated by those skilled in the art that the pivot member may be provided with thekey posts13 &60 and the distal anddistraction members1 &50 may be provided with corresponding “keyholes,” in other words reversing the relative position of the constituent keyhole engagement parts. Those skilled in the art will appreciate that the same may be accomplished for the flanges and holes of the snap-in engagement system.
• The angular relationship of thedistal member1 to thepivot member30, and the angular relationship of thedistraction member50 to tilepivot member30, may be indicated bygraduations17,39 &62 formed into, or otherwise affixed to those members, as seen inFIG. 1F. Angular displacement of thedistal member1 relative to thepivot member30, and the angular displacement of thedistraction member50 relative to thepivot member30 may be limited or prevented by adjustment ofset screws16 &61 provided indistal member1 anddistraction member50, respectively. The set screws16 &61 are preferably threaded through the thickness of the distal anddistraction members1 &50, respectively, to engage thepivot member30. Thepivot member30 is preferably provided with multiple depressions or recesses (not shown) into which theset screws16 &61 may extend so as to fix the relationship of the members.
• Tworails90, as seen inFIG. 11, are provided for translational connection of thedistraction member50 toradial member70. Eachrail90 is preferably press fit at one end into arail hole56 of thedistraction member50, and preferably slidably inserted at the other end into a correspondingrail hole78 of theradial member70 so as to permit translational movement. At a first extreme of translational movement, travel will cease when the respectivestraight edges52 &72 of thedistraction member50 andradial member70 complementally abut. At the second extreme of translational movement, thedistraction member50 andradial member70 are separated until theradial member70 is completely disengaged from arail90. Therails90 may be comprised of, for example, stainless steel or radiolucent material. Therails90 are preferably of constant diameter. It is preferred that therails90 lit snugly into the rail holes78 of theradial member70 to minimize any looseness, or “play” of therails90 within theholes78 to prevent undesired misalignment of the fracture. Those skilled in the art will appreciate that a single rail, having a circular or polygonal cross-section, may be utilized in place of multiple rails.
• Between the first and second extremes of translational movement, the minimum distance separating thedistraction member50 andradial member70 may be adjusted by advancing ascrew91 through thedistraction hole57 of thedistraction member50 toward theradial member70 such that thescrew91 protrudes from thedistraction member50 to abut theradial member70 at adivot79 preferably provided in theradial member70. Thescrew91 may be comprised of, for example, stainless steel or radiolucent material. It will be appreciated that thescrew91 may perform the distraction member-to-radial member alignment function of arail90.
• For visual indication of the relative position of, or distance of distraction between thedistraction member50 and theradial member70, a graduatedtab63 may be formed into, or otherwise affixed to thedistraction member50 to extend to theradial member70 such that thegraduations62 on the graduatedtab63 correspond tograduations80 associated with theradial member70, as seen inFIG. 1F. The graduatedtab63, of course, may be formed into, or otherwise affixed to theradial member70 to correspond tograduations62 associated with thedistraction member50.
• In the present invention, the respective mountingholes10,11,12,75,76 &77 of thedistal member1 andradial member70 are each preferably defined withinwells95 defined in those distal1 and radial70 members, into each of which well aball cap94, as seen inFIGS. 9A-9B, may be threadably inserted to immovably trap and fix apin ball93, seen inFIGS. 10A-10B, around the shank of apin92 such that thepin92 is prevented from sliding through thepin ball93, as seen inFIGS. 12 and 13. This manner of mounting the fixator to the hand and arm toleratesimprecise pin92 placement in the bone, and allows the distance between the fixator and the arm, wrist and/or hand to be appropriately set by sliding thepin ball93 up or down thepin92 before theball cap94 is advanced into the well95 to immovably trap thepin ball93. Bothball cap94 andpin ball93 are preferably comprised of radiolucent polycarbonate material, but may be of any suitable non-radiolucent material.
• The dynamic external fixator of the present invention is preferably comprised, either in whole or in part, of radiolucent material. Such radiolucent material is preferably polycarbonate material.
• The present invention may be scaled up or down in size to accommodate variations in human anatomy. Accordingly, it is preferred that the fixator be manufactured in sizes to accommodate, for example, a large adult, a small adult and a child. Additionally, those skilled in the art will recognize that a dynamic external fixator for one hand may be constricted, mirrored geometrically, for affixation to the other hand.
Use of the Dynamic External Fixator
• The dynamic external fixator of the present invention is attached to the lower arm and hand by an accepted and well-known method of using elongate pins adapted at one end for affixation in bone, such as described below.
• A folded standard operating room sterile towel or lap sponge is used to establish a preferably one-fourth inch distance between the fixator and the skin of the patient. Care is taken to avoid contact between the skin of the patient and the fixator.
• The fixator is positioned over the arm and hand such that thepivot hole35 is coaxial with the virtual center of rotation for lateral flexion of the hand, and thepivot hole36 is coaxial with the virtual center of rotation for palmar-dorsal flexion of the hand. This arrangement permits the wrist and fixator to move together. Wrist/fixator motion, i.e., the relative motion between the distraction member and pivot member, and distal member and pivot member, may be limited or prevented by adjustment of the hinge set screws.
• The fixator is further positioned over the arm and hand such that the third hole of the distal member is preferably placed over the tendon of insertion of the extensor carpi radialis longus overlying the metaphyseal base of the index metacarpal. An insertion immediately proximal to the fibers of the first dorsal interosseous muscle avoids inadvertent insertion into the carpometacarpal joint.
• A pin is inserted through the third mounting hole of the distal member and driven under radiographic assistance into the index metacarpal to a secure and proper depth. The distance between the fixator and the patient's skin can be adjusted and fixed by sliding the pin ball along the shalt of the pin and trapping it in the well of the third hole by threading the ball cap into the well. Pins may be placed through remaining available mounting holes in bone at appropriate places as needed, and the fixator affixed to them as described.
• Distraction of the wrist bones is accomplished by threadably advancing the screw through the distraction hole of the distraction member to abut the radial member and force the distraction and radial members apart along the direction of the rails.

Claims (30)

1. An external fixation device for facilitating the healing and repair of bone fractures, the device comprising:

a distal member;

a pivot member comprising a first pivotal engagement hub and a second pivotal engagement hub;

a distraction member; and

a radial member, wherein said distal member is pivotally connected to said pivot member at said first pivotal engagement hub, said distraction member is pivotally connected to said pivot member at said second pivotal engagement hub, and said radial member is translationally connected to said distraction member.

2. The device ofclaim 1, further comprising:

a guide rail; and

a distraction screw, wherein said guide rail is disposed partially within said distraction member and partially within said radial member, and said distraction screw is disposed through said distraction member such that advancement of said distraction screw will urge said distraction member and said radial member apart.

3. The device ofclaim 2, said distal member and said distraction member each further comprising a set screw disposed so as to engage said pivot member.

4. The device ofclaim 3, said pivot member further comprising a plurality of recesses into which said set screws may extend.

5. The device ofclaim 1, said distal member further comprising graduations and said pivot member further comprising graduations, said graduations of said distal member oriented to correspond to said graduations of said pivot member to provide a visual indication of the relative angular relationship of said distal member and said pivot member.

6. The device ofclaim 1, said distraction member further comprising graduations and said pivot member further comprising graduations, said graduations of said distraction member oriented to correspond to said graduations of said pivot member to provide a visual indication of the relative angular relationship of said distraction member and said pivot member.

7. The device ofclaim 1, said distraction member further comprising a graduated tab extending therefrom adjacent said radial member, said radial member further comprising graduations oriented to correspond to said graduated tab to provide a visual indication of the relative position of said radial member to said distraction member.

8. The device ofclaim 1, wherein said distal member, said pivot member, said distraction member, and said radial member are radiolucent.

9. The device ofclaim 8, wherein said distal member, said pivot member, said distraction member, and said radial member are transparent.

10. The device ofclaim 1, wherein said distal member, said pivot member, said distraction member, and said radial member substantially conform to the human lower arm and hand in a low-profile and aesthetic manner.

11. An external fixation device for facilitating the healing and repair of bone fractures of the hand, wrist and lower arm, the device comprising:

a distal member comprising a dorsal pivotal engagement hub and defining a mounting aperture;

a pivot member comprising a first pivotal engagement hub and a second pivotal engagement hub, wherein the rotational axes of said first and second hubs are generally orthogonal;

a distraction member comprising a lateral pivotal engagement hub; and

a radial member defining a mounting aperture wherein said dorsal pivotal engagement hub of said distal member is connected to said first pivotal engagement hub, forming a revolute joint, to define lateral flexion of the hand with respect to the lower arm, said lateral pivotal engagement hub of said distraction member is connected to said pivot member at said second pivotal engagement hub, forming a revolute joint, to define palmar-dorsal flexion of the hand with respect to the lower arm, and said radial member translationally connected to said distraction member.

12. The device ofclaim 11, further comprising:

a guide rail; and

a distraction screw wherein said guide rail is disposed partially within said radial member and partially within said distraction member to allow translation of said radial member along said guide rail, and said distraction screw is disposed through said distraction member such that advancement of said distraction screw will urge said distraction member and said radial member apart.

13. The device ofclaim 11, wherein said dorsal engagement hub and said first pivotal engagement hub, and said lateral engagement hub and said second pivotal engagement hub, are adapted to form said revolute joints by snap-in engagement.

14. The device ofclaim 11, wherein said dorsal engagement hub and said first pivotal engagement hub, and said lateral engagement hub and said second pivotal engagement hub, are adapted to form said revolute joints by keyhole engagement.

15. The device ofclaim 11, said distal member and said distraction member each further comprising a set screw disposed so as to engage said pivot member.

16. The device ofclaim 15, said pivot member further comprising a plurality of recesses into which said set screws may extend.

17. The device ofclaim 11, said distal member further comprising graduations and said pivot member further comprising graduations, said graduations of said distal member oriented to correspond to said graduations of said pivot member to provide a visual indication of the relative angular relationship of said distal member and said pivot member.

18. The device ofclaim 11, said distraction member further comprising graduations and said pivot member further comprising graduations, said graduations of said distraction member oriented to correspond to said graduations of said pivot member to provide a visual indication of the relative angular relationship of said distraction member and said pivot member.

19. The device ofclaim 11, said distraction member further comprising a graduated tab extending therefrom adjacent said radial member, said radial member further comprising graduations oriented to correspond to said graduated tab to provide a visual indication of the relative distance between said radial member and said distraction member.

20. The device ofclaim 11, wherein said distal member, said pivot member, said distraction member, and said radial member are radiolucent.

21. The device ofclaim 11, wherein said distal member, said pivot member, said distraction member, and said radial member are transparent.

22. The device ofclaim 11, wherein said distal member, said pivot member, said distraction member, and said radial member substantially conform to the human lower arm and hand in a low-profile and aesthetic manner.

23. The device ofclaim 11, wherein said distal member and said radial member further define a well coaxial with said mounting aperture.

24. The device ofclaim 23, further comprising a pin ball and ball cap, wherein an elongate pin may be slidably disposed through said pin ball and one of said mounting apertures, and said pin ball may be trapped within said well by said ball cap such that both pin ball and said elongate pin are rendered immovable by unaided human force and wherein said elongate pin may be positioned so as to be affixed at one end to a human bone.

25. A method for facilitating the healing and repair of a distal radius bone fracture, the method comprising:

affixing a plurality of spaced-apart elongate pins in the radius on the proximal side of the fracture,

affixing a plurality of spaced-apart elongate pins in a metacarpal on the distal side of the fracture; and

mounting an external wrist fixator to said pins, wherein said mounting comprises for each of said plurality of pins the following, in order:

guiding said pin through a mounting aperture defined in said Fixator;

guiding a pin ball onto said pin through a central bore of said pin ball;

sliding said pin ball along said pin to seat said pin ball within a well associated with said mounting aperture; and

fixing said pin ball within said well by use of a ball cap such that said pin and said pin ball are rendered immovable.

26. A method for facilitating the healing and repair of a distal radius bone fracture, the method comprising:

affixing a plurality of spaced-apart elongate pins in the radius on the proximal side of the fracture;

affixing a plurality of spaced-apart elongate pins in a metacarpal on the distal side of the fracture; and

mounting an external wrist fixator to said pins, said fixator comprising:

a distal member;

a pivot member comprising a first pivotal engagement hub and a second pivotal engagement hub;

a distraction member; and

a radial member, wherein said distal member is pivotally connected to said pivot member at said first pivotal engagement hub, said distraction member is pivotally connected to said pivot member at said second pivotal engagement hub, and said radial member is translationally connected to said distraction member.

27. The method ofclaim 26, wherein said external fixator further comprises:

a guide rail; and

a distraction screw, wherein said guide rail is disposed partially within said distraction member and partially within said radial member, and said distraction screw is disposed through said distraction member, and said method further comprises the step of advancing said distraction screw to urge said distraction member and said radial member apart.

28. The method ofclaim 26, wherein said external fixator comprises:

a distal member comprising a dorsal engagement hub and defining a mounting aperture;

a pivot member comprising a first pivotal engagement hub and a second pivotal engagement hub, wherein the rotational axes of said first and second hubs are generally perpendicular;

a distraction member comprising a lateral engagement hub;

a radial member defining a mounting aperture, wherein said dorsal engagement hub of said distal member is connected to said pivot member at said first pivotal engagement hub, forming a revolute joint, to define lateral flexion of the hand with respect to the lower arm, said lateral engagement hub of said distraction member is connected to said pivot member at said second pivotal engagement hub, forming a revolute joint, to define palmar-dorsal flexion of the hand with respect to the lower arm, and said radial member is translationally connected to said distraction member.

29. The method ofclaim 28, wherein said fixator further comprises:

a guide rail; and

a distraction screw wherein said guide rail is disposed partially within said radial member and partially within said distraction member to allow translation of said radial member and said distraction member along said guide rail, and said distraction screw is disposed through said distraction member, and said method further comprises the step of advancing said distraction screw to urge said distraction member and said radial member apart.

30. The method ofclaim 26, further comprising, in order:

guiding a said pin through a mounting aperture defined in said fixator;

guiding a pin ball onto said pin through a central bore of said pin ball;

sliding said pin ball along said pin to seat said pin ball within a well associated with said mounting aperture; and

trapping said pin ball within said well by use of a ball cap such that said pin and said pin ball are rendered immovable by unaided human force.

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