A system comprising: a cannula assembly configured to be coupled with an automated driver, the cannula assembly comprising: a cannula hub; and a cannula attached to the cannula hub and defining a lumen, the cannula being configured to be introduced into a bone as the cannula assembly is driven by the automated driver; an elongated instrument comprising a distal tip, the elongated instrument being positioned within the lumen of the cannula; and a shield coupled with each of the cannula hub and the elongated instrument while in an unlocked state, the shield being configured to: remain coupled with the cannula hub and the elongated instrument in the unlocked state as the cannula assembly is driven by the automated driver and the cannula is introduced into the bone; while in the unlocked state, remain coupled with the cannula hub while permitting the elongated instrument to translate proximally relative to the shield as the elongated instrument is retracted from the lumen of the cannula; and automatically transition from the unlocked state to a locked state as the elongated instrument is further retracted from the lumen of the cannula, the shield attaching to a distal end of the elongated instrument to restrict access to the distal tip of the elongated instrument when transitioned to the locked state, wherein the shield comprises a resilient arm (162, 163) configured to transition the shield from the unlocked state to the locked state, and to engage the cannula hub when the shield is in the unlocked state and to disengage from the cannula hub when the shield transitions to the locked state. a cannula hub; and a cannula attached to the cannula hub and defining a lumen, the cannula being configured to be introduced into a bone as the cannula assembly is driven by the automated driver; an elongated instrument comprising a distal tip, the elongated instrument being positioned within the lumen of the cannula; and a shield coupled with each of the cannula hub and the elongated instrument while in an unlocked state, the shield being configured to: remain coupled with the cannula hub and the elongated instrument in the unlocked state as the cannula assembly is driven by the automated driver and the cannula is introduced into the bone; while in the unlocked state, remain coupled with the cannula hub while permitting the elongated instrument to translate proximally relative to the shield as the elongated instrument is retracted from the lumen of the cannula; and automatically transition from the unlocked state to a locked state as the elongated instrument is further retracted from the lumen of the cannula, the shield attaching to a distal end of the elongated instrument to restrict access to the distal tip of the elongated instrument when transitioned to the locked state, remain coupled with the cannula hub and the elongated instrument in the unlocked state as the cannula assembly is driven by the automated driver and the cannula is introduced into the bone; while in the unlocked state, remain coupled with the cannula hub while permitting the elongated instrument to translate proximally relative to the shield as the elongated instrument is retracted from the lumen of the cannula; and automatically transition from the unlocked state to a locked state as the elongated instrument is further retracted from the lumen of the cannula, the shield attaching to a distal end of the elongated instrument to restrict access to the distal tip of the elongated instrument when transitioned to the locked state, wherein the shield comprises a resilient arm (162, 163) configured to transition the shield from the unlocked state to the locked state, and to engage the cannula hub when the shield is in the unlocked state and to disengage from the cannula hub when the shield transitions to the locked state.