When I was in practice, I put in my share of internal fixation devices, and removed plenty of them as well when necessary. I am not so sure that I would differentiate 20670 from 20680 on the basis of what has to be closed (layers) so much as what and how much has to be done to expose, access, and remove the fixation, i.e. how much work is required. The "larger" the procedure, the more it comes under 20680.
For 20670, I would use this for fixation pins that were buried such that the tip of the pin was subcutaneous and palpable (and usually tender) so it could be identified easily. These pins were usually meant to be removed at some time after the procedure when the fracture was sufficiently healed that their support of the fracture was no longer necessary. Their removal was usually done in the office setting under local anesthesia. A stab wound incision was usually sufficient to access the tip of the pin for removal (sometimes easier than others), but I rarely if ever put any sutures in the skin incision for closure. I usually left it open to drain and heal by itself, which it usually did without difficulty by the next office visit a week or so later (wound check). My decision as to whether to charge the 20670 was determined primarily by the timing of the procedure. If it was within the Global Period, I probably didn't charge it since it was a "planned procedure." If it was outside the Global Period, I would charge the 20670 code, once for each pin removed as each pin required its own incision, and frequently more that one pin was removed. I didn't use any Modifiers even though their removal was planned. You probably could, but I didn't and I am not aware that created any problems with payment. As in my earlier entry into this issue, if the pins are placed such that the tips of the pins penetrate the skin (i.e. are exposed), then I don't think charging 20670 is justified since these are usually intended to be removed within the Global Period, and no incision was required.
As for 20680, I used this for larger fixation devises such as plates and screws, nails, etc. that required much more of a procedure for exposure and removal, and more often than not were done in an operating room under anesthesia, not local. The number of layers between me and the device was not a consideration for me, but the amount of work required certainly was.
I realize that different payers are going to install/invoke their own "rules" about this issue, and will pretty much do whatever they can to deny payment, so unfortunately you are still at their mercy. I would encourage charging for these procedures when appropriate, and would appeal them when necessary with appropriate documentation. These are the best "guidelines" I can give you for this issue.
Respectfully submitted, Alan Pechacek, M.D>