Surgical · Other

Sliding genioplasty with interpositional bone graft augmentation, including harvest of autograft material from the patient.

Verified May 8, 2026 · 6 sources ↓

Medicare: $777.91
Total RVUs: 23.29
Global, days: 90
Region: Other

Drawn from CMSAAPCAAOS

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 6 cited references ↓

Operative note must specify that both a sliding osteotomy and interpositional bone graft were performed — not just graft augmentation alone.
Document the source of the autograft (e.g., calvarium, rib, iliac crest) and confirm harvest is not billed separately.
Record the clinical indication clearly: distinguish reconstructive (e.g., microgenia, craniofacial deformity, obstructive sleep apnea) from cosmetic intent, as coverage depends on this distinction.
Include pre- and post-operative photographs where required by payer LCD or prior authorization criteria.
Document prior authorization number when obtained, and retain in the patient record per payer requirements.
Note the specific osteotomy technique and degree of repositioning to support medical necessity and rebut cosmetic-only denial.

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 51 Multiple procedures 57 Decision for surgery 58 Staged or related 59 Distinct service 76 Repeat, same physician 77 Repeat, another physician 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 21123 covers a sliding genioplasty in which the surgeon performs an osteotomy of the chin segment, advances or repositions it, and fills the resultant gap with interpositional bone graft to augment chin projection. The autograft harvest is bundled into this code — do not separately report bone graft procurement. This distinguishes 21123 from 21121 (single sliding osteotomy, no graft) and 21122 (two or more osteotomies, no graft); if the surgeon uses graft material without an osteotomy, report 21120 instead.

Code selection within the 21120–21123 family turns entirely on two operative decisions: whether an osteotomy was performed, and whether interpositional bone graft was used. Both must be present to support 21123. Indications include microgenia, facial asymmetry, and medically necessary correction of obstructive sleep apnea, though payers treat the cosmetic versus reconstructive distinction as a coverage trigger. Medicare coverage is governed by LCD L35090; prior authorization requirements vary by payer and should be confirmed before surgery.

The global period is 90 days. Any unrelated procedure during that window requires modifier 79; a staged related return to the OR needs modifier 58. If the decision for surgery was made at the same E/M visit, append modifier 57 to the E/M code.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	11.06
Practice expense RVU	10.62
Malpractice RVU	1.61
Total RVU	23.29
Medicare national rate	$777.91
Global period	90 days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$777.91
HOPD (APC 5164) Hospital outpatient department	$3,387.27
ASC (PI A2) Ambulatory surgical center (freestanding)	$1,480.50

Common denial reasons

The recurring reasons claims for CPT 21123 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Cosmetic versus reconstructive determination: payer denies claim as non-covered cosmetic procedure when medical necessity documentation is insufficient.
Wrong code within the 21120–21123 family: billing 21123 when operative note does not document both an osteotomy and interpositional bone graft.
Separately billing bone graft harvest (e.g., 20900, 20902) alongside 21123 — graft procurement is bundled and not separately payable.
Missing or expired prior authorization, which many payers require for genioplasty regardless of indication.
Insufficient documentation linking the procedure to a covered diagnosis (e.g., no polysomnography supporting obstructive sleep apnea, or no imaging documenting skeletal deformity).

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01Can I bill the bone graft harvest separately when reporting 21123?

No. The work of obtaining the autograft is included in the valuation of 21123. Billing a separate graft harvest code (e.g., 20900 or 20902) alongside 21123 will be bundled and denied.

02What distinguishes 21123 from 21121 and 21122?

21121 is a single sliding osteotomy with no graft; 21122 is two or more osteotomies with no graft. Use 21123 only when the surgeon performs a sliding osteotomy AND fills the gap with interpositional bone graft. Both elements must be documented in the operative note.

03Is genioplasty covered by Medicare?

Coverage depends on indication. Medicare LCD L35090 governs cosmetic and reconstructive surgery. Reconstructive indications such as documented craniofacial deformity or obstructive sleep apnea may be covered; purely cosmetic genioplasty is not. Document medical necessity explicitly and confirm with the local MAC.

04Do I need prior authorization for 21123?

Many commercial payers and some Medicare Advantage plans require prior authorization for genioplasty regardless of indication. Verify with each payer before scheduling; a missing authorization is a common reason for post-service denial.

05What modifier applies if the patient returns to the OR for a related staged procedure during the 90-day global?

Use modifier 58 for a planned staged or related procedure during the global period. Reserve modifier 78 for an unplanned return to the OR for a complication related to the original surgery. Do not use 79 for related returns — that modifier is for unrelated procedures only.

06Can 21123 be billed with modifier 22 for significantly increased complexity?

Yes, if the operative work was substantially greater than typical — for example, severe anatomical distortion from prior trauma or revision after failed prior genioplasty. The operative note must explicitly describe what made the case more difficult and estimate additional time or effort. Modifier 22 without supporting narrative will be disregarded or audited.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CMS Physician Fee Schedule 2026
02CMS LCD L35090 – Cosmetic and Reconstructive Surgery: https://www.cms.gov/medicare-coverage-database/view/lcd.aspx?lcdId=35090&ver=95
03CMS Billing and Coding Article A56587 – Cosmetic and Reconstructive Surgery: https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=56587&ver=43
04AAPC Oral Surgery Coding & Reimbursement Alert – Graft and Osteotomy Genioplasty Code Selection: https://www.aapc.com/codes/scc_articles/article_pdf/94/cpt-coding-strategies-watch-graft-and-osteotomy-to-zero-in-on-right-genioplasty-code-147410
05CMS NCCI Policy Manual 2025: https://www.cms.gov/files/document/2025nccimedicarepolicymanualcompletepdf.pdf
06AAOS Resident Guide – Modifiers: https://www.aaos.org/globalassets/quality-and-practice-resources/coding-and-reimbursement/resident-guide/resident-guide_modifiers.pdf

Mira AI Scribe

Mira's AI scribe captures the operative dictation elements that determine code selection within the genioplasty family: whether a sliding osteotomy was performed, how many osteotomy cuts were made, and whether interpositional bone graft was harvested and used to fill the osteotomy gap. It also flags the graft harvest site so coders know not to add a separate harvest code. This prevents the most common coding error in this family — selecting 21121 or 21122 when graft use actually warrants 21123, or upcoding 21123 when no osteotomy was documented.

See how Mira captures CPT 21123 documentation