Billing code 21183: Cranial reconstructionMedicare rate & RVUs in Massachusetts
Cranial vault reconstruction with grafting for multiple-suture craniosynostosis, reported when surgery remodels the skull to address the fused-suture pattern.
CMS doesn’t publish an office rate for 21183 in Massachusetts.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What 21183 covers
21183 represents operative cranial-vault remodeling for craniosynostosis affecting multiple sutures, with bone grafting as part of the reconstruction. The surgeon reshapes and repositions cranial bone to correct the vault deformity and create room for brain growth. Craniofacial surgeons and pediatric neurosurgeons commonly perform this major operation in a hospital operating room, often as part of a multidisciplinary craniofacial plan.
Select this code when the operative record supports multiple-suture synostosis and the reconstruction matches this extent; a single-suture repair or a secondary extensive reconstruction falls under a different family level. Documentation should identify the fused sutures, deformity, bone remodeling and osteotomies, graft use, and reconstructive work. CMS assigns a 90-day major-surgery global, including the day-before preoperative visit and related postoperative care through day 90. For multiple procedures in one session, the highest-valued procedure is paid in full and others at 50%. Modifier 50 is not appropriate for this cranial anatomy. An assistant at surgery may be paid; co-surgeon payment requires supporting documentation, and team-surgery billing is not permitted.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 21183 pays more and less in Massachusetts
| Payment locality | Office | Facility |
|---|---|---|
| Metropolitan Boston | Unavailable | $2,152.55 |
| Rest Of Massachusetts | Unavailable | $2,014.83 |
How the 21183 rate is calculated
Each of 21183’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 21183
RVUs × geographic indexes × conversion factor
Work34.81
34.81 RVUs× 1.000 GPCI
Practice expense18.81
18.81 RVUs× 1.000 GPCI
Malpractice6.46
6.46 RVUs× 1.000 GPCI
Adjusted RVUs
60.0800
Conversion factor
$33.4009
Medicare rate
$2,006.73
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 21183
21183 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 21183
Cranial reconstruction
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 090 | Major surgery: the day before, the day of, and 90 days after are included. |
| Multiple procedures | 2 | Standard reduction: highest-valued procedure at 100%, others at 50%. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 2 | Paid. |
| Co-surgeons (62) | 1 | Permitted with supporting documentation. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
| Split (54/55/56) | 0.10/0.69/0.21 | Share of the payment for pre-op, the procedure itself, and post-op care. |
Global surgery period · 21183
Cranial reconstruction
90-day global period ends
Dec 30, 2026
Covers Sep 30, 2026 through Dec 30, 2026 (92 days, including the day before surgery).
Visit on Oct 31, 2026
Day 30 of the 90-day post-op period: related follow-up care is included in the surgical payment.
Pre-op dayGlobal period
What modifiers do to the payment
Modifier 51 · payment effect
With and without the modifier
21183 without 51 · national facility
$2,006.73
Cranial reconstruction
21183-51 · Second procedure: 50%
$1,003.37
When this isn’t the highest-valued procedure in the session, Medicare pays 50% of its fee schedule amount (the highest is paid at 100%).
21183 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 21182Cranial cranioplasty
- 21182 is the related level for craniosynostosis involving a single suture; 21183 is for multiple-suture disease.
- 21184Cranial reconstruction
- 21184 describes secondary, extensive cranial reconstruction. Distinguish it from 21183 by the documented secondary status and extent of the reconstruction.
- 21188Midface reconstruction
- 21188 addresses midface reconstruction with Le Fort III advancement. 21183 is cranial-vault reconstruction for multiple-suture craniosynostosis.
21183 billing questions
How does 21183 differ from 21182?
21183 is for craniosynostosis involving multiple sutures; 21182 is the related single-suture level. The operative documentation should establish the suture pattern.
When would 21184 be considered instead?
21184 describes a secondary, extensive cranial reconstruction. Use the documented procedure and extent to distinguish that work from a multiple-suture reconstruction reported with 21183.
Should modifier 50 be appended?
No. Modifier 50 is inappropriate for this cranial reconstruction.
What documentation supports 21183?
Document the fused sutures, cranial-vault deformity, bone remodeling and osteotomies, graft use, and the reconstructive work performed.
How are assistant and co-surgeon services handled?
An assistant at surgery may be paid. Co-surgeon payment requires supporting documentation; team-surgery billing is not permitted.
What happens when other procedures are performed in the same session?
CMS applies the standard multiple procedure reduction: the highest-valued procedure is paid in full and other procedures are paid at 50%.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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