A percutaneous and minimally invasive instrument system for implanting an interspinous process spacer into a patient is disclosed. The insertion instrument system includes an inserter and a driver. The inserter is configured to releasably clamp to an interspinous process spacer for its delivery, implantation and deployment. The driver is configured for removable insertion into a proximal end of a passageway of the inserter. The driver has a distal spacer engaging portion configured to engage that part of the spacer requiring activation for the deployment of the spacer from at least one undeployed configuration to at least one deployed configuration and vice versa. As the spacer goes from the undeployed to the deployed configuration and vice versa, the system advantageously provides a degree of deployment information to the user via at least one deployment indicator.
