Polyaxial bone anchor with helical capture connection, insert and dual locking assembly

Abstract

A medical implant assembly includes a polyaxial bone anchor having a shank, a receiver, a lower compression insert with surfaces for closely receiving an elongate connecting member and a dual closure structure that may include a single flange or helical flange. The dual closure structure independently engages the connecting member and the lower compression insert. A threaded capture connection of the bone anchor includes a shank upper surface exclusively engaging the lower compression insert and a retainer threadably attached to the shank and spaced from the upper surface, the retainer configured for polyaxial motion with respect to the receiver prior to locking.

1 . (canceled) 
     
     
         2 . In a pivotal bone screw assembly comprising a shank with a first longitudinal axis and a separate receiver with a second longitudinal axis, the shank and receiver first and second longitudinal axes co-axially alignable with respect to each other, the receiver including an upper portion with a rod-receiving channel opening onto a top thereof and a lower integral portion and having a bore centered around the receiver second longitudinal axis and extending entirely through the receiver, the improvement wherein:
 a) the shank includes a top portion having at least a partially radiused outer surface, the shank pivotally connected to the receiver at an upper end of the shank and having a central bore extending along the first longitudinal axis.   
     
     
         3 . The improvement of  claim 2 , wherein the shank top portion directly pivotally engages an interior surface of the receiver. 
     
     
         4 . The improvement of  claim 3 , wherein the interior surface of the receiver is radiused. 
     
     
         5 . A polyaxial bone screw assembly comprising:
 a) a shank having a bore along a length thereof centered around a first longitudinal axis, a body for fixation to a bone, the body aligned with the first longitudinal axis, and an integral top portion, the top portion having an outer radiused surface;   b) a receiver having a central bore centered around a second longitudinal axis, an upper portion, and an integral non-slotted lower base portion, the receiver upper portion defining an open channel for receiving a connecting member therein, the base portion having an internal surface partially defining a cavity, the channel communicating with the cavity, the shank top portion positioned within the cavity, the cavity communicating with an exterior surface of the base portion through a lower opening; and wherein   c) the shank and receiver first and second longitudinal axes are co-axially alignable with respect to each other.   
     
     
         6 . The polyaxial bone screw assembly of  claim 5 , wherein the shank top portion is bottom loaded into the receiver cavity through the receiver lower opening. 
     
     
         7 . The polyaxial bone screw assembly of  claim 5 , wherein the shank is configured to be placed over a guide wire through the shank bore. 
     
     
         8 . The polyaxial bone screw assembly of  claim 5 , wherein the receiver can pivot with respect to the shank. 
     
     
         9 . The polyaxial bone screw assembly of  claim 5 , wherein the shank further includes a drive structure on the top portion. 
     
     
         10 . The polyaxial bone screw assembly of  claim 5 , wherein the shank top portion directly pivotally engages the internal surface of the receiver. 
     
     
         11 . The polyaxial bone screw assembly of  claim 5 , wherein the internal surface of the receiver is radiused. 
     
     
         12 . The polyaxial bone screw assembly of  claim 5 , further comprising a retainer, the retainer being loaded into the receiver cavity, so as to capture the shank top portion. 
     
     
         13 . The polyaxial bone screw assembly of  claim 5 , further comprising a closure for closing the channel of the receiver, the connecting member being inserted into the receiver channel prior to the closure.