System and methods are shown having a tube-within-tube assembly with a deployable curved deflectable tube or cannula that deploys from a straight cannula or trocar. The curved cannula has pre-curved distal end to create an angular range of 0° to 180° when fully deployed from the straight trocar. The curve is configured such that the flexible element carrying a treatment device can navigate through the angular range of deployment of the curved cannula. The curved cannula allows the flexible element to navigate through a curve within bone without veering off towards an unintended direction.