I am having trouble finding some info on cpt codes to use for a posterior cervical spine fusion. The fusion was performed on C1-C2-C3. Physician requested the coding to be 22595,22614,22840,61783,20936. Unfortunately, 22614 is not the add on code for 22595 Arthrodesis, posterior technique, atlas-axis (C1-C2) , and while researching, I found there is no add on code for 22595. The only article I have found regarding this subject stated that you could use 22600 Arthrodesis, posterior or posterolateral technique, single level; cervical below C2 segment when you bill 22590 Arthrodesis, posterior technique, craniocervical (occiput-C2). Is it appropriate to use the 22600 code with 22595? Encoder is allowing it with a 51 modifier, but I am not sure if it is appropriate to bill.