Bone fixation system with curved profile threads

Abstract

A bone fastener for use in orthopedic surgery for fixing an implant to bone has a threaded or unthreaded shaft configured to engage bone and a head having a thread on an outer surface to engage the implant. The thread on the head of the fastener has a profile in cross section that includes peaks with a curved shape.

1 . A bone fastener for use in orthopedic surgery for fixing an implant to bone, comprising:
 a shaft configured to engage bone; and   a head formed on the shaft, the head having a thread on an outer surface to engage the implant, wherein the thread has a profile in cross section including peaks, wherein the peaks have a curved shape.   
     
     
         2 . The bone fastener according to  claim 1 , wherein each curved peak forms an arc segment. 
     
     
         3 . The bone fastener according to  claim 2 , wherein a radius of curvature (r) of the arc segment is between 0.05 mm and 3.0 mm. 
     
     
         4 . The bone fastener according to  claim 2 , wherein an angular range (w) of the arc segment is between 30° and 200°. 
     
     
         5 . The bone fastener according to  claim 3 , wherein an angle (k) between a plane (p) including a core diameter of the head and a tangent (t) of the arc segment is between −10° and 90°. 
     
     
         6 . The bone fastener according to  claim 1 , wherein the curved peaks are provided immediately adjacent to each other. 
     
     
         7 . The bone fastener according to  claim 1 , wherein the curved peaks are separated from each other by circumferential valleys having a planar or rounded profile. 
     
     
         8 . The bone fastener according to  claim 1 , wherein the thread of the head includes curved flanks. 
     
     
         9 . The bone fastener according to  claim 1 , wherein the thread of the head is a single or multiple thread. 
     
     
         10 . The bone fastener according to  claim 1 , wherein the head has a conical or curved shape. 
     
     
         11 . The bone fastener according to  claim 10 , wherein the head has a constant core diameter and wherein an outer diameter of the thread of the head gradually tapers. 
     
     
         12 . The bone fastener according to  claim 10 , wherein the core of the head has a conical or curved shape and wherein an outer diameter of the thread of the head gradually tapers. 
     
     
         13 . An implant system for use in orthopedic surgery for fixation of bone, comprising:
 an implant having an upper surface and a lower surface;   at least one hole extending through the implant upper surface and lower surface; and   at least one bone fastener comprising a shaft configured to engage bone and a head having a thread on an outer surface to engage the implant, wherein the thread has a profile in cross section including peaks, wherein the peaks have a curved shape.   
     
     
         14 . The implant system according to  claim 13 , wherein the at least one hole includes a threaded portion configured to mate with the thread of the head of the at least one bone fastener. 
     
     
         15 . The implant system according to  claim 13 , wherein the at least one hole includes an upper unthreaded portion and a lower threaded portion configured to mate with the thread of the head of the at least one bone fastener. 
     
     
         16 . The implant system according to  claim 15 , wherein the upper portion of the at least one hole has an inward taper having a conical or curved shape. 
     
     
         17 . The implant system according to  claim 15 , wherein the threaded portion of the at least one hole tapers inwardly toward the lower surface of the implant. 
     
     
         18 . The implant system according to  claim 14 , wherein the threaded portion of the at least one hole has a multiple thread. 
     
     
         19 . The implant system according to  claim 13 , wherein the at least one hole has a central axis which is oblique relative to a vertical axis of the implant). 
     
     
         20 . The implant system according to  claim 13 , wherein the implant is configured as a bone plate and wherein the bone fastener is configured as a bone screw.