Drivers for inserts to bone anchors

1. A driver for delivering an insert to a bone anchor, the bone anchor having an internal cavity with a set of internal threads, the driver adapted to rotate with respect to a bone anchor that is anchored in a vertebral body in order to engage external threads on the insert with the set of internal threads in the bone anchor and axially advance the threadedly engaged insert within the bone anchor while simultaneously preventing the bone anchor from rotating with respect to the vertebral body the driver having:

a threaded retention rod for engaging a bore in the insert;

a driver head distinct from the threaded retention rod, the driver head to engage with the insert to apply torque to the insert and rotate the insert; and

an anchor stabilizer distinct from the threaded retention rod and distinct from the driver head, the anchor stabilizer to engage with a proximal face of the bone anchor to prevent the bone anchor from rotating with respect to the vertebral body

wherein the threaded retention rod may be rotated relative to the driver head and the anchor stabilizer to allow the threaded retention rod to engage the insert; and

wherein the driver head may be rotated relative to the anchor stabilizer to rotate the insert relative to the bone anchor engaged with the anchor stabilizer.

2. The driver of claim 1 wherein the anchor stabilizer engages with an engagable surface accessible from an end of the bone anchor that receives the insert.

3. The driver of claim 1 wherein the driver is adapted to axially advance fingers on the anchor stabilizer to engage with slots in the bone anchor along a perimeter of an end of the bone anchor that receives the insert.

4. The driver of claim 1 wherein the threaded retention rod is adapted to engage the insert with a threaded element connected to the driver so that the insert is threadedly engaged with the driver until threadedly engaged with the bone anchor and released from threaded engagement with the driver.