An instrument for attachment and insertion of a screw assembly into a surgical site includes a housing, an attachment shaft, and a drive shaft. The housing including a movable hub. The attachment shaft includes a proximal end for coupling to the housing and a distal end with a flexible portion for selectively attaching to a receiver of the screw assembly. The drive shaft within the attachment shaft includes a proximal end for selectively engaging the hub and a distal end with a driving feature for driving a head of the screw assembly.