Modular Pedicle Screw System

Abstract

A modular anchoring device including a threaded shank for anchoring within a vertebra, an intermediate element and a head portion configured to receive and secure a rigid or non-rigid stabilization rod. The threaded shank, the intermediate element and the head portion of the anchoring device are cannulated to permit percutaneous implantation of the device. The intermediate portion is designed to be removable from the threaded shank portion subsequent to implantation of the anchoring device to enable substitution of another intermediate element having different dynamic characteristics.

1 . A modular dynamic pedicle screw system comprising:
 a plurality of modular dynamic pedicle screws and a rod,   each modular pedicle screw including a head portion, an intermediate portion, and a threaded shank portion,   said head portion including a cylindrical wall with diametrically opposed grooves that extend downward from the top of said cylindrical wall, said grooves are sized and configured to receive said rod within said diametrically opposed grooves, and a lock screw configured to engage threads formed on an inner surface of said cylindrical wall thereby securing said rod to said head portion, said head portion including a first channel formed coincident with its longitudinal axis and open at the top and the bottom of the head portion, and, a first coupling element connected to said head portion,   said intermediate portion including an elastic portion and an upper coupling member and a lower coupling member, said elastic portion being directly molded onto said upper and lower coupling, said intermediate portion including a second channel extending coincident with its longitudinal axis and open at the top and bottom of said intermediate member,   said threaded shank portion including a threaded and tapered outer surface and a second coupling member formed at one end thereof, said threaded shank portion and said second coupling member each having a third channel formed coincident with the longitudinal axis of said threaded shank portion and open at the top and bottom of said threaded shank portion,   said first, second and third channels are configured to be in alignment with one another,   whereby a wire can pass freely from the open bottom end of the threaded shank portion, through the intermediate portion, and out the open top end of the head portion and be completely removed from the pedicle screw.   
   
   
       2 . The modular dynamic pedicle screw system of  claim 1 , wherein the first coupling of the head portion is threadably engaged by the upper coupling of the intermediate portion. 
   
   
       3 . The modular dynamic pedicle screw system of  claim 1 , wherein the second coupling of the threaded shank portion is threadably engaged by the lower coupling of the intermediate portion. 
   
   
       4 . The modular dynamic pedicle screw system of  claim 1 , wherein said upper coupling member includes an upper cylindrical portion, a cylindrical post portion depending therefrom and a cylindrical interengaging portion depending from the cylindrical post portion. 
   
   
       5 . The modular dynamic pedicle screw system of  claim 4 , wherein in the lower coupling member includes a lower cylindrical portion and extending upwardly from the lower cylindrical portion is a hollow cylindrical wall, the upper portion of the hollow cylindrical wall terminating in an annular flange that extends radially inward to form a cylindrical cavity having a reduced diameter aperture. 
   
   
       6 . The modular dynamic pediele screw system of  claim 4 , wherein the diameter of the aperture is sufficiently large to allow the interengaging cylindrical portion to pass there through when introduced at an appropriate angle, a synthetic material located between the upper coupling member and the lower coupling member. 
   
   
       7 . The modular dynamic pedicle screw system of  claim 1  wherein said head portion includes a ball and socket connection between the cylindrical wall portion and the first coupling element. 
   
   
       8 . The modular dynamic pedicle screw system of  claim 1 , wherein said rod is flexible. 
   
   
       9 . The modular dynamic pedicle screw system of  claim 1 , wherein said rod is rigid. 
   
   
       10 . The modular dynamic pedicle screw system of  claim 1 , wherein said lower coupling includes at least one surface that can be engaged by a tool passing through the second channel whereby the intermediate portion can be rotated in either direction causing the lower coupling to be either threaded or unthreaded from the second coupling on the threaded shank. 
   
   
       11 . The modular dynamic pedicle screw system of  claim 1 , wherein the dimensions and or composition of the elastic member can be varied to affect the amount of elasticity of the intermediate element. 
   
   
       12 . A modular dynamic pedicle screw comprising:
 said modular dynamic pedicle screw including a head portion, an intermediate portion, and a threaded shank portion,   said head portion including a cylindrical wall with diametrically opposed grooves that extend downward from the top of said cylindrical wall, said grooves are sized and adapted to receive a rod within said diametrically opposed grooves, and a lock screw configured to engage threads formed on an inner surface of said cylindrical wall thereby securing said rod to said head portion,   said head portion including a first channel formed coincident with its longitudinal axis and open at the top and the bottom of the head portion, and, a first coupling element connected to said head portion,   said intermediate portion including an elastic portion and an upper coupling member and a lower coupling member, said elastic portion and said upper and lower coupling being directly molded onto said upper coupling member and said lower coupling member, said intermediate portion including a second channel extending coincident with its longitudinal axis and open at the top and bottom of said intermediate member,   said threaded shank portion including a threaded and tapered outer surface and a second coupling member formed at one end thereof, said threaded shank portion and said second coupling member each having a third channel formed coincident with the longitudinal axis of said threaded shank portion and open at the top and bottom of said threaded shank portion,   said first, second and third channels are configured to be in alignment with one another,   whereby a wire can pass freely from the open bottom end of the threaded shank portion, through the intermediate portion, and out the open top end of the head portion and be completely removed from the modular dynamic pedicle screw.   
   
   
       13 . The modular dynamic pedicle screw of  claim 12 , wherein the first coupling of the head portion is threadably engaged by the upper coupling of the intermediate portion. 
   
   
       14 . The modular dynamic pedicle screw of  claim 12 , wherein the second coupling of the threaded shank portion is threadably engaged to the lower coupling of the intermediate portion. 
   
   
       15 . The modular dynamic pedicle screw of  claim 12 , wherein said elastic portion is generally cylindrical in shape. 
   
   
       16 . The modular dynamic pedicle screw of  claim 15 , wherein said upper coupling member includes an upper cylindrical portion, a cylindrical post portion depending there from and a cylindrical interengaging portion depending from the cylindrical post portion and
 said lower coupling member includes an lower cylindrical portion and extending upwardly from the lower cylindrical portion is a hollow cylindrical wall, the upper portion of the hollow cylindrical wall terminating in an annular flange that extends radially inward to form a cylindrical cavity having a reduced diameter aperture.   
   
   
       17 . The modular dynamic pedicle screw of  claim 16 , wherein the diameter of the aperture is sufficiently large to allow the interengaging cylindrical portion to pass there through when introduced at an appropriate angle, and further including a synthetic material located between the upper coupling member and the lower coupling member. 
   
   
       18 . The modular dynamic screw of  claim 12 , wherein said head portion includes a ball and socket connection between the cylindrical wall portion and the first coupling element. 
   
   
       19 . The modular dynamic screw of  claim 12 , wherein said lower coupling includes a socket that can be engaged by a tool passing through the second channel whereby the intermediate portion can be rotated in either direction causing the lower coupling to be either threaded or unthreaded from the second coupling on the threaded shank. 
   
   
       20 . The modular dynamic screw of  claim 12 , wherein the dimensions and or composition of the elastic member can be varied to affect the amount of elasticity of the intermediate element. 
   
   
       21 . A kit for a modular screw stabilization system comprising;
 components to assemble a plurality of modular pedicle screws and one or more rods,   each modular pedicle screw including a head portion, an intermediate portion, and a threaded shank portion,   said kit including a plurality of said head portions each including a cylindrical wall with diametrically opposed grooves that extend downwards from the top of said cylindrical wall, said grooves are sized and configured to receive said rod within said diametrically opposed grooves, and a lock screw configured to engage threads formed on an inner surface of said cylindrical wall thereby securing said rod to said head portion, said head portions including a first channel formed coincident with its longitudinal axis and open at the top and the bottom of the head portion, and, a first coupling element connected to each of said head portion,   said kit further including a plurality of intermediate portions each including an elastic portion or a rigid portion directly molded onto an upper coupling member and a lower coupling member, said elastic or rigid portion and said upper and lower coupling being fixedly connected, each of said plurality of intermediate portions including a second channel extending coincident with its longitudinal axis and open at the top and bottom of said intermediate member,   said kit also including a plurality of said threaded shank portions, each including a threaded and tapered outer surface and a second coupling member formed at one end thereof, each said threaded shank portions and each of said second coupling members each having a third channel formed coincident with the longitudinal axis of each of said threaded shank portions and open at the top and bottom of each of said threaded shank portions, said first, second and third channels are configured to be in alignment with one another,   whereby a wire can pass freely from the open bottom end of the threaded shank portion, through the intermediate portion, and out the open top end of the head portion and be completely removed from the pedicle screw.   
   
   
       22 . The kit for a dynamic screw stabilization system as set forth in  claim 21 , wherein said plurality of threaded shank portions are of the same or different lengths and external diameters. 
   
   
       23 . The kit for a dynamic screw stabilization system as set forth in  claim 21 , wherein at least some of the threaded shank portions have fenestrated and partially fenestrated threads. 
   
   
       24 . The kit for a dynamic screw stabilization system as set forth in  claim 21 , wherein the plurality of intermediate portions have elastic portions of same or varying rigidity. 
   
   
       25 . The kit for a dynamic screw stabilization system as set for in  claim 24 , wherein the elastic portion varies in rigidity from rigid to flexible. 
   
   
       26 . A modular dynamic pedicle screw system comprising:
 a plurality of pedicle screws and a rod,   each modular pedicle screw including a head portion, an intermediate portion, and a threaded shank portion,   said head portion including a cylindrical wall with diametrically opposed grooves that extend downward from the top of said cylindrical wall, said grooves are sized and configured to receive said rod within said diametrically opposed grooves, and a lock screw configured to engage threads formed on an inner surface of said cylindrical wall thereby securing said rod to said head portion, said head portion including a first channel formed coincident with its longitudinal axis and open at the top and the bottom of the head portion, and, a first coupling element connected to said head portion,   said intermediate portion including a rigid portion and an upper coupling member and a lower coupling member, said rigid portion and said upper and lower coupling being fixedly connected, said intermediate portion including a second channel extending coincident with its longitudinal axis and open at the top and bottom of said intermediate member,   said threaded shank portion including a threaded and tapered outer surface and a second coupling member formed at one end thereof, said threaded shank portion and said second coupling member each having a third channel formed coincident with the longitudinal axis of said threaded shank portion and open at the top and bottom of said threaded shank portion,   said first, second and third channels are configured to be in alignment with one another,   whereby a wire can pass freely from the open bottom end of the threaded shank portion, through the intermediate portion, and out the open top end of the head portion and be completely removed from the modular pedicle screw.