a disc surgical system is provided having an elongated tubular member housing and an electrosurgical electrode for excising of or shrinking tissue . the instrument includes at least one cannula having an operative end for entering an operative field of a patient , at least one guide wire having a pointed end for piercing tissue , a tapered dilator configured to slide over a guide wire ; and a trephine configured to slide over a guide wire . the operative end has threads on an exterior surface of the cannula for engagement with the tissue of the patient .