Collar bore configuration for dynamic spinal stabilization assembly

Abstract

A dynamic spinal stabilization assembly includes at least one mounting collar with a bore therethrough along a longitudinal axis, and a spinal rod slidably extending through the bore. The bore includes a medially disposed first section of reduced size that tapers both inwardly and outwardly relative to the axis, and respective end sections of relatively larger size. The bore may be defined by an interior wall that convexly curves toward the axis in the first section, advantageously with a constant non-zero radius of curvature. The bore profile helps minimize potential binding that may occur between the collar and the rod. The rod is coupled to bone anchoring elements, with at least one such connection being via the collar.

1 . An assembly for dynamic stabilization of a spine, comprising:
 at least one mounting collar comprising a bore therethrough along a longitudinal axis;   a spinal rod slidably extending through said bore;   wherein the bore comprises a medial first section of reduced size that tapers both inwardly and outwardly relative to the axis and respective end sections of relatively larger size.   
     
     
         2 - 7 . (canceled) 
     
     
         8 . The assembly of  claim 1  wherein said mounting collar comprises a first collar and wherein the assembly further comprises a second mounting collar comprising a bore therethrough along a longitudinal axis thereof; wherein the spinal rod slidably extends through the bore of the second collar. 
     
     
         9 - 10 . (canceled) 
     
     
         11 . The assembly of  claim 1  further comprising first and second bone anchoring elements disposed in spaced relation:
 wherein said mounting collar comprises a first collar having its bore is defined by an interior wall that convexly curves toward said axis in said first section; 
 wherein the assembly further comprises a second mounting collar comprising a bore therethrough along a longitudinal axis thereof; wherein the spinal rod slidably extends through the bore of the second collar; 
 wherein said rod comprises a first larger size section and an adjacent second smaller size section; wherein the second section extends through the bore of the first collar; 
 wherein the first bone anchoring element couples to the rod; and 
 wherein the second bone anchoring element slidably couples to the rod via the first collar. 
 
     
     
         12 - 26 . (canceled) 
     
     
         27 . A method of dynamically stabilizing a spinal column, comprising:
 anchoring first and second bone anchoring elements to respective vertebra;   providing an elongate rod assembly comprising:
 a mounting collar having a bore therethrough along a longitudinal axis, said bore comprising a centrally disposed first section of reduced size that tapers both inwardly and outwardly relative to the axis and respective end sections of relatively larger size; and 
 an elongate rod slidably extending though the bore; 
   slidably mounting said rod to said first bone anchoring element by affixing the collar to the first bone anchoring element;   supporting said rod with said second bone anchoring element.   
     
     
         28 . The method of  claim 27  wherein said supporting said rod with said second bone anchoring element comprises slidably mounting said rod to said second bone anchoring element. 
     
     
         29 . The method of  claim 27  wherein said rod assembly further comprises first and second elastic elements disposed about said rod on respective longitudinal sides of the mounting collar; the method further comprising compressing at least one of the elastic elements. 
     
     
         30 . The method of  claim 29  wherein said first and second elastic elements are substantially identical. 
     
     
         31 . A method of dynamically stabilizing a spinal column, comprising:
 anchoring first and second bone anchoring elements to respective vertebra;   providing ah elongate rod assembly comprising:
 at least one mounting collar having a bore therethrough along a longitudinal axis, said collar having an outer surface that is longitudinally non-curving and the collar having a first and second longitudinally-end faces facing in generally opposite directions; 
 an spinal rod slidably extending though the bore; 
 wherein the bore is defined by an interior wall with a continuously convexly curved profile with a medial first section of reduced size that tapers both inwardly and outwardly relative to the axis and respective end sections of relatively larger size; 
   providing a first elastic element disposed on a first longitudinal side of the mounting collar and disposed beyond the first longitudinally-end face with respect to the medial first section;   providing a second elastic element disposed on a second longitudinal side of the mounting collar opposite the first longitudinal side and disposed beyond the second longitudinally-end face with respect to the medial first section;
 wherein the mounting collar, first elastic element, and second elastic element are disposed such that longitudinal displacement of the mounting collar relative to the spinal rod causes the first or second elastic element to be longitudinally compressed, 
   slidably mounting said rod to said first bone anchoring element by affixing the collar to the first bone anchoring element; and   supporting said rod with said second bone anchoring element.   
     
     
         32 . The method of  claim 32  further comprising:
 spacing first and second bone anchors in spaced relation; 
 coupling first bone anchoring element to the spinal rod; and 
 slidably coupling the second bone anchoring element to the spinal rod via the collar.