I totally disagree with the answer. An add-on code by definition is not a stand alone code and cannot be used except with the code group it is an add-on to. 64787 is definitely designated as an add-on code only per CPT. Our practice billed it out in error a few times with 28080 and each time the payer denied it because of its not being billed with the correct primary code. I would use unlisted 64999 or 28899 and compare to 64787. Or have the surgeon include a statement supporting the use of a 22 modifier and add it to 28080.
Debbi Credit COSC