20955

Harvest and transfer of a vascularized fibula bone graft using microvascular technique, including anastomosis of the accompanying blood supply to the recipient site.

Verified May 8, 2026 · 7 sources ↓

Medicare: $2,267.92
Total RVUs: 67.9
Global, days: 90
Region: General

Drawn from CMSAAPCMdclarityAaomsAAHKS

Documentation requirements

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

Source · Editorial brief grounded in 7 cited references ↓

Identify the specific indication requiring vascularized bone graft (e.g., tumor resection defect, avascular necrosis, failed prior graft, congenital pseudarthrosis)
Document the donor-site anatomy: fibula segment length harvested and the named vascular pedicle (peroneal artery and venae comitantes) taken with the graft
Record the recipient-site vessel names used for microvascular anastomosis and confirm vascular patency at the conclusion of the case
Specify whether the operating microscope was used for the anastomosis, to support separate billing of 69990
If two surgeons participated, document each surgeon's distinct role — harvest team versus recipient-site team — to support modifier 62 billing
Note estimated blood loss, graft dimensions, ischemia time, and any intraoperative complications that would support modifier 22 for increased complexity

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 51 Multiple procedures 52 Reduced services 59 Distinct service 62 Co-surgeons 76 Repeat, same physician 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 20955 describes a free fibula flap procedure: the surgeon harvests a segment of the fibula along with its periosteal blood supply — typically the peroneal artery and venae comitantes — and transfers it to a distant recipient site where microvascular anastomoses restore perfusion. The live vascular pedicle is what separates this from a conventional non-vascularized graft; it allows the transferred bone to survive, remodel, and integrate rather than simply serve as a scaffold. Indications include massive long-bone defects after tumor resection, avascular necrosis of the femoral head, failed prior grafting, mandibular reconstruction, and congenital pseudarthrosis.

This is a high-complexity procedure carrying a 90-day global period. All routine post-operative care through day 90 is bundled — including wound checks, dressing changes, and cast or splint management — unless an unrelated service is billed with modifier 79. Two-surgeon co-billing under modifier 62 is common because the graft harvest and the recipient-site preparation often run simultaneously. Code 69990 (operating microscope) is separately reportable when the microvascular anastomosis is performed under the microscope, and it should be appended without modifier 51 per CPT guidelines. Site-of-service matters: HOPD and ASC payments differ substantially, and payers will scrutinize whether the chosen facility setting was appropriately documented.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	39.25
Practice expense RVU	21.35
Malpractice RVU	7.3
Total RVU	67.9
Medicare national rate	$2,267.92
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	$2,267.92
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI J8) Ambulatory surgical center (freestanding)	$4,682.29

Common denial reasons

The recurring reasons claims for CPT 20955 get rejected.

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

Missing or vague documentation of microvascular anastomosis — payers downcode to a non-vascularized graft code when the operative note omits vessel names or patency confirmation
Modifier 62 denied because both surgeons' notes describe identical work rather than distinct procedural roles
69990 (operating microscope) bundled into 20955 when the operative note fails to specify that the microscope was used for the anastomosis rather than visualization only
Modifier 52 applied incorrectly when synthetic material was used instead of harvested fibula — payers expect modifier 52 to reduce the fee but still require documentation that harvest was not performed
Global period violations: post-op visits billed without modifier 24 or 79 when the condition is unrelated, triggering automatic denial within the 90-day window

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 7 cited references ↓

01Can I bill 69990 (operating microscope) separately with 20955?

Yes. When the microvascular anastomosis is performed under the operating microscope, 69990 is separately reportable. Append it without modifier 51. The operative note must specify that the microscope was used for the anastomosis itself, not just for incidental visualization.

02When does modifier 62 apply to 20955?

Modifier 62 applies when two surgeons operate simultaneously as co-primary surgeons — typically one team harvesting the fibula while the other prepares the recipient site. Each surgeon bills 20955-62 and submits a separate operative note describing their distinct work. If one surgeon performs both portions sequentially, modifier 62 does not apply.

03What is the global period for 20955, and what does it bundle?

20955 carries a 90-day global period. All routine post-op care from the day of surgery through day 90 is bundled — wound checks, dressing changes, suture removal, and cast or splint management related to the procedure. Bill unrelated conditions with modifier 79; use modifier 24 for unrelated E&M visits in the global window.

04Should modifier 52 be used when synthetic graft material substitutes for harvested fibula?

Yes. If the surgeon does not harvest fibula bone — for example, because synthetic material was used instead — reduce 20955 with modifier 52. Document clearly that no harvest was performed and specify the material used. Payers expect the fee reduction and will audit cases where modifier 52 is absent but no harvest is described.

05How does 20955 differ from non-vascularized fibula graft codes?

20955 requires that the graft is transferred with an intact vascular pedicle and that microvascular anastomosis restores blood flow at the recipient site. Non-vascularized grafts use the fibula as a structural scaffold only, without vessel transfer. Using 20955 for a case where no anastomosis was performed is upcoding and will be reversed on audit.

06Is 20955 performed in an ASC, and does site of service affect payment?

20955 can be performed in a hospital outpatient department or an ASC, though the complexity and length of this procedure means it is most commonly done in an HOPD or inpatient setting. HOPD and ASC payment rates differ materially — see the Site of Service comparison on this page. Confirm facility contracting before scheduling, as payer authorization requirements may also vary by site.

Sources & references

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

Mira AI Scribe

Mira's AI scribe captures the fibula segment length, named donor vessels (peroneal artery and venae comitantes), recipient-site vessel identities, anastomosis technique, intraoperative patency confirmation, and whether the operating microscope was used — pulling these details directly from dictation. That prevents the most common downcoding scenario: a payer treating the case as a non-vascularized graft because the operative note never named the vascular pedicle or confirmed flow.

See how Mira captures CPT 20955 documentation