Apparatus for Dynamic External Fixation of Distal Radius and Wrist Fractures

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.

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 of  claim 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 of  claim 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 of  claim 3 , said pivot member further comprising a plurality of recesses into which said set screws may extend. 
   
   
       5 . The device of  claim 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 of  claim 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 of  claim 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 of  claim 1 , wherein said distal member, said pivot member, said distraction member, and said radial member are radiolucent. 
   
   
       9 . The device of  claim 8 , wherein said distal member, said pivot member, said distraction member, and said radial member are transparent. 
   
   
       10 . The device of  claim 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 of  claim 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 of  claim 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 of  claim 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 of  claim 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 of  claim 15 , said pivot member further comprising a plurality of recesses into which said set screws may extend. 
   
   
       17 . The device of  claim 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 of  claim 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 of  claim 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 of  claim 11 , wherein said distal member, said pivot member, said distraction member, and said radial member are radiolucent. 
   
   
       21 . The device of  claim 11 , wherein said distal member, said pivot member, said distraction member, and said radial member are transparent. 
   
   
       22 . The device of  claim 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 of  claim 11 , wherein said distal member and said radial member further define a well coaxial with said mounting aperture. 
   
   
       24 . The device of  claim 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 of  claim 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 of  claim 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 of  claim 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 of  claim 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.