Percutaneous access devices and bone anchor assemblies

Abstract

A percutaneous access device includes an inner tube and an outer tube disposed about at least a portion of the inner tube. The outer tube may be sized to span from a skin incision in a patient to a site proximate the spine of the patient. The distal end of the outer tube may be adapted to releasably engage a bone anchor. The inner tube may be adjustable relative to the outer tube between a first position and a second position in which the distal end of the inner tube contacts the bone anchor. A bone anchor assembly includes a bone anchor having a distal bone engaging portion and a receiving member having a recess for receiving a spinal fixation element. The proximal end of the receiving member may have an arcuate groove formed on an exterior surface thereof to facilitate connection of an instrument to the receiving member.

1 - 46 . (canceled) 
     
     
         47 . A bone anchor assembly comprising:
 a receiver, the receiver having a top side surface, a front side surface and a back side surface and includes a first pair of upwardly extending arms forming a channel therebetween and mateable with a closure to securely lock a bone anchor with respect to a rod positionable within the channel of the receiver, wherein:   each upwardly extending arm having an outward facing horizontal elongated radiused groove about a circumference of the receiver extending to at least one of the front side surface and the back side surface and located a distance from the top side surface, wherein the distance remains constant along a horizontal length of the groove, the grooves of each upwardly extending arm opposed in parallel relation to each other, and wherein the closure is positioned inwardly in the receiver with respect to the grooves and only engages the rod and the receiver.   
     
     
         48 . The bone anchor assembly of  claim 47 , wherein the grooves are symmetrically positioned on the receiver. 
     
     
         49 . A pivotal bone anchor assembly comprising:
 a) a shank having an elongate body for fixation to a bone, and a central bore along an entire length thereof;   b) a receiver pivotally attached to the shank and having a top side surface, a front side surface, a back side surface, and first and second arms defining a channel, each of the first and second arms having an outer, elongated, horizontally extending groove radiused about a circumference of the receiver and located a distance from the top side surface, wherein the distance remains constant along a horizontal length of the groove, and extending to at least one of the front side surface and the back side surface; and   c) a closure for closing the channel, the closure engaging only the receiver and a rod within the channel on a top surface thereof, and wherein the closure is positioned inwardly in the receiver with respect to each groove, so as to remain spaced from the grooves.   
     
     
         50 . The assembly of  claim 49 , further comprising a separate retainer that is sized and shaped to be positioned into the receiver and that engages the shank having an Upper capture portion, wherein the shank can polyaxially pivot relative to the receiver during positioning of the shank with respect to the receiver. 
     
     
         51 . A bone anchor assembly adapted to be attached to a vertebra of a patient, comprising:
 a receiver, the receiver mateable with a closure to securely lock a bone anchor, wherein
 a) the receiver includes a top side surface, a front side surface, a back side surface and a first pair of upwardly extending arms forming a rod receiving channel therebetween, at least one arm having an outward facing, horizontal elongated groove radiused about a circumference of the receiver extending to at least one of the front side surface and the back side surface and located a distance from the top side surface, wherein the distance remains constant along a horizontal length of the groove, and wherein the closure when mated to the receiver remains spaced from the elongate, horizontal groove and engages only the receiver and a rod. 
   
     
     
         52 . A bone anchor comprising a receiver, the receiver mateable with a closure to securely lock the bone anchor, wherein:
 (a) the receiver includes a top side surface, a front side surface, a back side surface and a first pair of upwardly extending arms forming a channel therebetween, at least one arm having an outward facing, horizontal elongated groove radiused about a circumference of the receiver extending to at least one of the front side surface and the back side surface and located a distance from the top side surface, wherein the distance remains constant along a horizontal length of the groove, and wherein the closure is mateable with the receiver and the outward facing, elongate, horizontal groove remains spaced from the closure and wherein the closure only engages the receiver and a rod.