Devices and methods for bone fixation using axial implants

Abstract

The invention comprises a method for fixating bones in the foot by aligning the bones in their desired position, inserting a screw in the aligned bones, inserting at least one transverse element near the head or tip of the screw, and tightening the screw to compress the bones. The screw comprises a shaft having first and second ends with spirally wound screw threads beginning near the first end and extending along the shaft. Advantageously, the screw is cannulated and screw threads are formed on an interior surface of the cannulation. Illustratively, the transverse elements may be staples, open-ended washers, or open-ended nuts. Reduction instruments and drill guides used in the invention are also disclosed.

What is claimed is: 
     
         1 . A method for compressing bones comprising:
 aligning the bones in a desired configuration,   inserting a screw into a borehole in the aligned bones,   inserting a first transverse element adjacent the screw at a first position, and   tightening the screw to compress the bones.   
     
     
         2 . The method of  claim 1  wherein the step of inserting a first transverse element adjacent the screw at a first position comprises the steps of:
 drilling first and second holes on opposite sides of the screw at the first position, and 
 inserting the first transverse element into the first and second holes. 
 
     
     
         3 . The method of  claim 1  further comprising the step of inserting a second transverse element adjacent the screw at a second position. 
     
     
         4 . The method of  claim 3  wherein the steps of inserting a first transverse element adjacent the screw at a first position and inserting a second transverse element adjacent the screw at a second position comprise the steps of:
 drilling first and second holes on opposite sides of the screw at the first position, 
 drilling third and fourth holes on opposite sides of the screw at the second position; 
 inserting the first transverse element into the first and second holes, and inserting the second transverse element into the third and fourth holes. 
 
     
     
         5 . The method of  claim 1  wherein the screw is cannulated and the step of inserting the screw into the borehole comprises:
 mounting the screw on a guide wire in the borehole, and 
 inserting the screw into the borehole on the guide wire. 
 
     
     
         6 . The method of  claim 1  wherein the bones that are compressed are in a human foot. 
     
     
         7 . The method of  claim 1  wherein the first transverse element is a staple, open washer or open nut. 
     
     
         8 . The method of  claim 1  wherein the screw has threads at one end and the first transverse element engages the threads when it is inserted adjacent the screw. 
     
     
         9 . A method for compressing bones comprising:
 aligning the bones in a desired configuration,   forming a borehole on the aligned bones,   inserting a screw into the borehole,   attaching a guide element to the screw in the borehole,   using the guide element to drill first and second holes on opposite sides of the screw at a first position,   inserting a first transverse element into the first and second holes, and   tightening the screw to compress the bones.   
     
     
         10 . The method of  claim 9  further comprising the steps of:
 using the guide element to drill third and fourth holes on opposite sides of the screw at a second position, and 
 inserting a second transverse element into the third and fourth holes. 
 
     
     
         11 . The method of  claim 9  further comprising the step of using the guide element at the first and/or second position to guide an osteotome in cutting bone around the screw. 
     
     
         12 . The method of  claim 9  wherein the screw is cannulated and the step of inserting the screw into the borehole comprises:
 mounting the screw on a guide wire in the borehole, and 
 inserting the screw into the borehole on the guide wire. 
 
     
     
         13 . The method of  claim 9  wherein the bones that are compressed are in a human foot. 
     
     
         14 . The method of  claim 9  wherein the first and second transverse elements are staples, open washers or open nuts. 
     
     
         15 . The method of  claim 9  wherein the screw has threads at one end and the first transverse element engages the threads when it is inserted adjacent the screw. 
     
     
         16 . A screw assembly comprising:
 a shaft having first and second ends,   threads on the shaft near the first end,   a head on the shaft at the second end,   a first transverse element that engages the threads on the shaft.   
     
     
         17 . The screw assembly of  claim 16  further comprising a second transverse element that engages the shaft at a second position. 
     
     
         18 . The screw assembly of  claim 16  wherein the first and second transverse elements are staples, open washers or open nuts. 
     
     
         19 . The screw assembly of  claim 16  wherein the shaft is cannulated. 
     
     
         20 . The screw assembly of  claim 16  wherein the cannulated shaft has an interior surface that is threaded. 
     
     
         21 . A guide element for drilling holes adjacent a screw comprising:
 a first element for mounting on the longitudinal axis of the screw,   a second element enclosing first and second holes, the second element being located in the guide element such that when the first element is mounted on the axis of the screw, the first and second holes are located at a position such as to guide a drill to make holes on opposite sides of the screw at a first desired position along the axis of the screw, and   a third element enclosing at least third and fourth holes, the third element being located in the guide element such that when the first element is mounted on the axis of the screw, the third and fourth holes are located at a position such as to guide a drill to makes holes on opposite sides of the screw at a second desired position along the axis of the screw.   
     
     
         22 . The guide element of  claim 21  further comprising a slot between at least one of the first and second holes and the third and fourth holes that is large enough to guide an osteotome. 
     
     
         23 . The guide element of  claim 21  further comprising a first slot between the first and second holes and a second slot between the third and fourth holes, each slot being large enough to guide an osteotome. 
     
     
         24 . The guide element of  claim 21  wherein the third element is mounted in the second element so that it can be moved in a direction substantially parallel to the longitudinal axis of the screw. 
     
     
         25 . A reduction instrument for use in positioning a guide wire in bone comprising:
 a handle with a central bore, and   a shaft mounted on the handle, the shaft having a cutting tip at an end remote from the handle and a central bore that extends from the handle to the cutting tip and is aligned with the bore in the handle, the central bore of the handle and tip having an inside diameter sufficient to pass a guide wire.