Flexible bone implant

Abstract

Examples of devices and methods for stabilizing a fracture in a bone include a body having an elongate distal portion having an outer surface defining a screw thread and an elongate proximal portion having a non-threaded outer surface.

What is claimed is: 
     
         1 . A bone implant for stabilizing bone fractures, the implant comprising:
 a body defining a longitudinal axis extending between a proximal end and a distal end;   an elongate distal portion of the body having an outer surface defining a distal screw thread, the distal screw thread having a minor diameter, a major diameter, and a pitch; and   an elongate, headless, proximal portion of the body having a non-threaded outer surface having a diameter, the diameter of the proximal portion being greater than or equal to the major diameter of the distal screw thread.   
     
     
         2 . The bone implant of  claim 1  wherein major diameter is less than 4.0 mm and the ratio of the major diameter to the minor diameter is greater than 1.7. 
     
     
         3 . The bone implant of  claim 1  wherein major diameter is less than 4.0 mm and the ratio of the major diameter to the minor diameter is greater than 2.0. 
     
     
         4 . The bone implant of  claim 1  wherein the ratio of the major diameter to the pitch is less than 2.0. 
     
     
         5 . The bone implant of  claim 1  wherein the ratio of the major diameter to the pitch is less than 1.5. 
     
     
         6 . The bone implant of  claim 1  wherein the ratio of the minor diameter to the pitch is less than 1.0. 
     
     
         7 . The bone implant of  claim 1  wherein the ratio of the minor diameter to the pitch is less than or equal to 0.75. 
     
     
         8 . The bone implant of  claim 1  further comprising a passage formed through the proximal portion transverse to the longitudinal axis from a first opening on the surface of the proximal portion to a second opening on the surface of the proximal portion. 
     
     
         9 . The bone implant of  claim 8  wherein the proximal portion has a length measured from a free end to a proximal start of the distal screw thread, the proximal portion having a maximum diameter, the maximum diameter being uniform over at least one-fourth of the proximal portion length. 
     
     
         10 . The bone implant of  claim 9  further comprising a driver engaging feature formed at the proximal end for engaging a driver in torque transmitting relationship, the driver engaging feature having a maximum dimension normal to the longitudinal axis that is less than or equal to the maximum diameter. 
     
     
         11 . The bone implant of  claim 10  wherein the driver engaging feature comprises a socket formed into the proximal end. 
     
     
         12 . The bone implant of  claim 1  wherein the body comprises a sleeve surrounding a separate core, the sleeve and core being joined together to form the body. 
     
     
         13 . The bone implant of  claim 12  wherein the distal threaded portion is operable to bend as it is threaded into a bone to follow a curved path. 
     
     
         14 . The bone screw of  claim 1  further comprising a helical thread formed on the proximal portion. 
     
     
         15 . The bone screw of  claim 14  further comprising a mid-portion between the distal thread and the proximal thread, wherein the proximal thread has a major diameter and a minor diameter, the proximal thread minor diameter being equal to the mid-portion outer diameter and the mid-portion diameter is greater than or equal to the distal thread major diameter. 
     
     
         16 . A method of stabilizing a fractured long bone having an intramedullary canal, the method comprising:
 providing a bone implant comprising a body defining a longitudinal axis extending between a proximal end and a distal end; an elongate distal portion of the body having an outer surface defining a screw thread, the screw thread having a minor diameter and a major diameter; and an elongate, headless, proximal portion of the body having a non-threaded outer surface having a diameter, the diameter of the proximal portion being greater than or equal to the major diameter of the distal screw thread; and   inserting the bone implant into an intramedullary canal of a bone so that the proximal portion spans a fracture in the bone.   
     
     
         17 . The method of  claim 16  wherein inserting the bone implant comprises rotating the bone implant to cause the threaded distal portion to engage the bone and pull the proximal portion of the bone implant into a positioning spanning the fracture. 
     
     
         18 . The method of  claim 16  wherein the proximal portion has a length measured from a free end to a proximal start of the threads of the distal portion, the proximal portion having a maximum diameter, the maximum diameter being uniform over a region of at least one-fourth of the proximal portion length, the method further comprising inserting the bone implant to a position in which the region spans the fracture. 
     
     
         19 . The method of  claim 16  wherein the proximal portion includes a passage formed through the proximal portion transverse to the longitudinal axis from a first opening on the surface of the proximal portion to a second opening on the surface of the proximal portion, the method further comprising inserting a pin or screw so that it extends through the passage and through a portion of the bone. 
     
     
         20 . The method of  claim 16  further comprising:
 turning the threaded distal portion of the bone implant into the tunnel so that the threaded distal portion bends to follow a curve in the intramedullary canal.