i am trying to find a good code for a RFTC neurotomy of the SI joint " leap frog" intra articular.

Op report reads: pat was places in prone position.........sive polar 10 millimeter active needle were placed in the inferior pole until about two inches worth of the lower portion of the SI joint was walked in a bipolar lesioning protocol. No more than 5 millimeters seperating the needle tips at any one time. 80 degrees celsius 60 second burns were made. a few hard copys were made to show that we were defintaly within the joint.

there is not a specific code for this so i came to either 64999 or 64640... any input? am i correct?? any info helps thanks!