Posterior spinal fixation screws

Abstract

The present disclosure includes bone screws and assemblies thereof for surgical procedures of the spine including but not limited to posterior spinal fixation procedures.

We claim: 
     
         1 . A bone screw comprising:
 a bone screw shank comprising a shank head; and   a dual-head receiver comprising:
 a first receiver comprising a first base having a cavity therewithin, the cavity configured to securely receive the shank head, a first pair of arms extending upwardly from the first base, and a first rod channel defined between the first pair of arms; 
 a second receiver comprising a second base having a second rod channel defined between a second pair of arms; and 
 a connection between the first receiver and the second receiver, wherein the connection is integral to one arm of the first pair of arms and movable relative to the second pair of arms, and 
 wherein the second receiver is movable in multiple dimensions including roll, pitch and yaw. 
   
     
     
         2 . The bone screw of  claim 1 , wherein the first rod channel extends in a first direction, and the second rod channel extends in a second direction substantially parallel to the first direction. 
     
     
         3 . The bone screw of  claim 1 , wherein the first rod channel extends in a first direction, and the second rod channel extends in a second direction that is tilted by an angle relative to the first direction. 
     
     
         4 . The bone screw of  claim 1 , wherein the first rod channel and the second rod channel are at an identical level along a proximal to distal direction. 
     
     
         5 . The bone screw of  claim 1 , wherein the first rod channel and the second rod channel are at two different levels along a proximal to distal direction. 
     
     
         6 . The bone screw of  claim 1 , wherein the first receiver comprises a longitudinal axis extending in a proximal to distal direction, and wherein the connection between the first receiver and the second receiver extends substantially perpendicular to the longitudinal axis of the first receiver. 
     
     
         7 . The bone screw of  claim 1 , wherein the connection between the first receiver and the second receiver extends in a direction that is perpendicular to a direction of extension of the first rod channel or tilted by an angle from the direction of extension of the first rod channel. 
     
     
         8 . The bone screw of  claim 1 , wherein the connection between the first receiver and the second receiver extends laterally from an outer surface of one arm of the first pair of arms, wherein the second receiver is movably coupled with the connection, wherein the second receiver comprises a slot in one arm of the second pair of arms, wherein the connection extends through the slot and permits rotation, translation, and tilting of the second receiver relative to the connection. 
     
     
         9 . The bone screw of  claim 1 , wherein the first receiver comprises a first tool engagement groove at an outer surface of the first pair of arms at or near a top surface thereof, and wherein a top edge of the connection between the first receiver and the second receiver is distal to the first tool engagement groove. 
     
     
         10 . The bone screw of  claim 1 , wherein the second receiver comprises a second tool engagement groove at an outer surface of the second pair of arms at or near a top surface thereof, and wherein a top edge of the connection between the first receiver and the second receiver is distal to the second tool engagement groove. 
     
     
         11 . The bone screw of  claim 1 , wherein the first receiver comprises a proximal opening that is configured to receive a first closure top that presses against a first rod within the first rod channel thereby securing the first rod therewithin. 
     
     
         12 . The bone screw of  claim 1 , wherein the second receiver is shorter than the first receiver along a proximal to distal direction. 
     
     
         13 . The bone screw of  claim 1 , wherein a second arm of the second pair of arms is closed at an outer surface thereof such that the connection does not extend through the second arm. 
     
     
         14 . The bone screw of  claim 1 , further comprising a load ring configured to be bottom-loaded into the first receiver, wherein the shank head is configured to be bottom loaded with space for a clip ring or a lock ring to be assembled below the shank head. 
     
     
         15 . The bone screw of  claim 1 , wherein a gap exists between the second receiver and the first receiver during movement of the second receiver in each of the multiple dimensions. 
     
     
         16 . The bone screw of  claim 15 , wherein the gap is sufficient to prevent contact between the first receiver and the second receiver during movement of the second receiver in all of the multiple dimensions. 
     
     
         17 . The bone screw of  claim 1 , wherein the first and second rod channels are aligned substantially parallel with one another, and are offset in each of two dimensions. 
     
     
         18 . The bone screw of  claim 1 , wherein the second receiver is rotatable relative to an axis of the connection to position the second receiver at an acute angle relative to the axis of connection, and wherein the connection is monolithic with the one arm of the first pair of arms. 
     
     
         19 . The bone screw of  claim 1 , wherein a gap exists between the second receiver and the first receiver during movement of the second receiver in each of the multiple dimensions, wherein a primary axis of the gap is aligned with the axis of the connection between the first receiver and the second receiver.