A screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation

Abstract

The invention discloses a screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation, comprising two pulling-screws ( 2 ), two supporting-screws ( 1 ), two variable cross section fixing rods ( 3 ), two lock nuts ( 4 ) and a bracing beam ( 5 ). Each of the variable cross section fixing rods ( 3 ) is configured to connect a supporting-screw ( 1 ) and a pulling-screw ( 2 ), the bracing beam ( 5 ) is configured to connect both of the variable cross section fixing rods ( 3 ); wherein each of the supporting-screws ( 1 ) comprises a first tail ( 11 ) and a first head ( 12 ), and each of the pulling-screws ( 2 ) comprises a second tail ( 21 ) and a second head ( 22 ); both the first tail ( 11 ) and the second tail ( 21 ) are provided with nail grooves, with U-shaped grooves on the sides; wherein each of the nail grooves is provided with internal thread inside, and the lock nut ( 4 ) is connected with the nail groove; each of the variable cross section fixing rods ( 3 ) passes through the U-shaped grooves and is fastened by the lock nut ( 4 ); the bottoms of the nail grooves of the supporting-screws ( 1 ) are 2-6 mm higher than the bottoms of the nail grooves of the pulling-screws ( 2 ). The aforementioned screw-rod instrument not only increases the safety and convenience of a surgery, but also improves the function of spondylolisthesis reduction of the screw-rod system through raising the bottoms of the nail grooves 2-6 mm higher.

1 . A screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation, wherein the screw-rod instrument comprises two pulling-screws, two supporting-screws, two variable cross section fixing rods, two lock nuts and a bracing beam;
 wherein each of the variable cross section fixing rods is configured to connect a supporting-screw and a pulling-screw, the bracing beam is configured to connect both of the variable cross section fixing rods;   wherein each of the supporting-screws comprises a first tail and a first head, and each of the pulling-screws comprises a second tail and a second head; both the first tail and the second tail are provided with nail grooves, with U-shaped grooves on the sides;   wherein each of the nail grooves is provided with internal thread inside, and the lock nut is connected with the nail groove by the internal thread; each of the variable cross section fixing rods passes through the U-shaped grooves and is fastened by the lock nut;   the bottoms of the nail grooves of the supporting-screws are 2-6 mm higher than the bottoms of the nail grooves of the pulling-screws.   
     
     
         2 . The screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation according to  claim 1 , wherein each of the variable cross section fixing rods is provided with an anti-rotation joint portion matched with the U-shaped grooves; the anti-rotation joint portion has a plane and/or a curved surface fitting the U-shaped grooves closely. 
     
     
         3 . The screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation according to  claim 1 , wherein the second tail is a long arm nail groove, with an annular recess configured on the middle part of the outer wall. 
     
     
         4 . The screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation according to  claim 1 , wherein the pulling-screw is a polyaxial screw, with the second head connected to the second tail which has a tapered thread tip. 
     
     
         5 . The screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation according to  claim 1 , wherein the first head of the supporting-screw is a single-axial screw which is fastened to the first tail, having a tapered thread tip; or the first head of the supporting-screw is a polyaxial screw which is fastened to the first tail, having a tapered thread tip. 
     
     
         6 . The screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation according to  claim 1 , wherein the bracing beam comprises lock-rod nuts, lateral combination nuts and a lateral connection plate; wherein both sides of the lateral connection plate are provided with oval openings; wherein one end of the lock-rod nut is connected to the first tail or the second tail through thread, the other end of the lock-rod nut is fastened by one of the lateral combination nuts after the other end passes through one of the oval openings. 
     
     
         7 . The screw-rod instrument specially used for posterior atlantoaxial vertebrae fixation according to  claim 6 , wherein the lateral connection plate is a straight plate or a curved plate.