wire form 26 which is extremely flexible in multiple directions provides tip 16 with a range of flexibility relative to shaft 14 such that bumper 22 and the active electrically conductive portion 46 of electrode 34 remains substantially in contact with articular tissue surface 50 while traveling over complex geometries the resistance to deformation of the nitinol in its superelastic state is constant providing a spring action that helps bumper 22 and the electrically conductive surface of portion 46 follow the curvature of tissue surface 50 while maintaining a controlled approximately uniform contact pressure of the bumper 22 and electrode 34 against articular cartilage surface 50 over complex geometries as nitinol wire 26 is deflected the spring action of nitinol wire 26 also biases bumper 22 towards tissue surface 50 when probe 10 is pressed towards tissue surface 50 nitinol wire 26 can be referred to as a spring and other springs or spring materials such as for example stainless steel spring wire can be used referring to fig8 sheath 18 can be slid forward relative to stainless steel tube 17 to cover tip 16 to provide temporary rigidity to flexible tip 16 for insertion into and removal from the joint capsule sheath 18 includes ribs 52 fig1 that facilitate grasping of sheath 18 to extend and retract sheath 18 when covering tip 16 sheath 18 also protects tip 16 and limits catching of tip 16 on tissue power is preferably delivered to probe 10 under the control of an impedance feedback loop to maintain the probe in an ablative mode in addition since the impedance rises when the.