It looks like as of March 2021, CPT Assistant has changed their stance on coding hypothenar flap with CTR. See below:
Question:
A patient is having an open revision carpal tunnel release in which a portion of the hypothenar fat flap was freed and transferred into the carpal tunnel. Is it appropriate to report code 64721 for carpal tunnel release and code 14040 for the additional work of the fat flap transfer?
Answer:
The work to free and transfer the hypothenar fat flap is not included in the typical work of a carpal tunnel release. When a hypothenar fat flap is performed without dissection of a named vessel included in the tissue transfer, report code 14040, Adjacent tissue transfer or rearrangement, forehead, cheeks, chin, mouth, neck, axillae, genitalia, hands and/or feet; defect 10 sq cm or less, in addition to code 64721, Neuroplasty and/or transposition; median nerve at carpal tunnel, for the open carpal tunnel release.
If the surgeon performs a dissection of feeder artery branches that come from the ulnar artery (defined as beyond third order in Appendix L of the CPT code set) and these vessels are included in the tissue transfer, then the appropriate codes to report for the procedure are codes 15740, Flap; island pedicle requiring identification and dissection of an anatomically named axial vessel, and 64721. Note the additional dissection must be documented in the operative report.
Carpal tunnel release with hypothenar fat flap freed and transferred into the carpal tunnel
CPT Assistant, March 2021 Page: 9 Category: Frequently Asked Questions