Bone fixation device

Abstract

A bone fixation device comprising: first and second screw receiving members, each member having an aperture extending therethrough for receiving a screw; and a plastically deformable connecting arm extending between the screw receiving members along a long axis defined by the first and second screw receiving members; the arm being adapted to be more pliable than the screw receiving members such that (a) on twisting the device about its long axis the arm twists before the screw receiving members deform; and (b) on bending the device along its long axis the arm bends before the screw receiving members deform.

1 . A bone fixation device comprising:
 first and second screw receiving members, each member having an aperture extending therethrough for receiving a screw; and   a plastically deformable connecting arm extending between the screw receiving members along a long axis defined by the first and second screw receiving members;   the arm being adapted to be more pliable than the screw receiving members such that (a) on twisting the device about the long axis the arm twists before the screw receiving members deform; and (b) on bending the device along the long axis the arm bends before the screw receiving members deform.   
   
   
       2 . A bone fixation device as claimed in  claim 1 , comprising a plurality of screw receiving members connected together in a line by connecting arms. 
   
   
       3 . A bone fixation device as claimed in  claim 1 , wherein at least one connecting arm is cylindrical in cross section. 
   
   
       4 . A bone fixation device as claimed in  claim 1 , wherein at least one screw receiving member is substantially spherical. 
   
   
       5 . A bone fixation device as claimed in  claim 4 , wherein the spherical screw receiving member includes a flattened portion. 
   
   
       6 . A bone fixation device as claimed in  claim 5 , wherein the flattened portion is centered about a mouth of the aperture and is in a plane normal to the axis of the aperture. 
   
   
       7 . A bone fixation device as claimed in  claim 1 , wherein at least one aperture includes a threaded portion for receiving a screw. 
   
   
       8 . A bone fixation device as claimed in  claim 7 , wherein the aperture is cylindrical. 
   
   
       9 . A bone fixation device as claimed in  claim 8 , wherein the cross section of the cylindrical aperture is constant along a length of the aperture. 
   
   
       10 . A bone fixation device as claimed in  claim 9 , further comprising at least one screw adapted for threaded engagement with the threaded portion of the aperture, the screw having a tapered head adapted to be drawn into the aperture and to press fit with walls of the aperture on threading the screw into engagement with the threaded portion of the apertures. 
   
   
       11 . A bone fixation device as claimed in  claim 8 , wherein the cylindrical aperture has at least one step in cross section along a length of the aperture to define a lip for engagement with a tapered head of a screw. 
   
   
       12 . A method of connecting a bone fixation device to a bone utilizing screws, said method comprising the steps of:
 providing a bone having a profile;   providing a bone fixation device comprising:
 first and second screw receiving members, each member having an aperture extending therethrough, 
 a plastically deformable connecting arm extending between the screw receiving members; 
   deforming the bone fixation device to the profile of the bone;   screwing the bone fixation device to the bone by means of screws inserted through the apertures on the screw receiving members.