Radical resection of a tumor from the fibula, including removal of wide margins of surrounding normal bone and soft tissue.

Verified May 8, 2026 · 8 sources ↓

Medicare: $1,389.81
Total RVUs: 41.61
Global, days: 90
Region: Foot & ankle

Drawn from CMSAAPCFindacodeEohhsAcgme

Documentation requirements

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

Source · Editorial brief grounded in 8 cited references ↓

Pathologic or clinical diagnosis prompting radical resection (malignant tumor type, grade, or severe chronic osteomyelitis with failed prior treatment)
Operative note specifying extent of resection including measured margins of normal bone and soft tissue removed
Pre-operative imaging (MRI preferred) documenting tumor size, location within fibula, and relationship to neurovascular structures
Intraoperative or post-resection specimen description confirming en bloc removal and margin adequacy
If modifier 22 appended: explicit documentation of factors increasing complexity beyond typical radical resection (e.g., neurovascular encasement, prior radiation field, salvage after failed resection)
Staged reconstruction intent documented in initial operative note if modifier 58 will be used for a planned subsequent procedure

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 50 Bilateral procedure 51 Multiple procedures 57 Decision for surgery 58 Staged or related 62 Co-surgeons 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon AS PA/NP/CNS assistant LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 8 cited references ↓

CPT 27646 covers radical resection of a fibula tumor — an aggressive, wide-margin excision performed for malignant bone tumors (primary sarcomas, metastatic lesions) or severe chronic osteomyelitis unresponsive to conservative treatment. The procedure removes the tumor en bloc with a cuff of normal tissue to achieve oncologically clear margins. It is a core limb-salvage procedure tracked by ACGME musculoskeletal oncology fellowship programs.

The 90-day global period means all routine post-op care through day 90 is bundled into the payment. Staged reconstruction — such as fibular allograft, vascularized flap coverage, or prosthetic replacement performed as a planned second operation — should be billed with modifier 58 to reset the global clock. An unplanned return to the OR for a related complication uses modifier 78; an unrelated procedure in the global window uses modifier 79.

The MUE for 27646 is 1 unit per date of service (PRA-adjudicated), so bilateral fibula resections — rare but possible — require modifier 50 with documentation supporting bilateral disease. Modifier 22 applies when operative complexity substantially exceeds the typical case, such as a massive tumor with extensive neurovascular involvement; the operative note must quantify the added work, not just state it.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	22.63
Practice expense RVU	14.16
Malpractice RVU	4.82
Total RVU	41.61
Medicare national rate	$1,389.81
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	$1,389.81
HOPD (APC 5113) Hospital outpatient department	$3,342.87
ASC (PI G2) Ambulatory surgical center (freestanding)	$1,644.87

Common denial reasons

The recurring reasons claims for CPT 27646 get rejected.

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

Insufficient diagnosis specificity — ICD-10 code does not confirm malignancy or severity of osteomyelitis warranting radical (versus partial) resection
Operative note lacks margin documentation, triggering down-coding to 27641 (partial excision, fibula) on audit
Modifier 22 appended without operative note language quantifying substantially increased work, leading to denial of the increased payment request
Staged reconstruction billed without modifier 58, causing denial as duplicate or unbundled service within the 90-day global period
MUE exceeded — billing more than 1 unit on same date without modifier 50 and bilateral disease documentation

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 8 cited references ↓

01What distinguishes 27646 from 27641?

27641 is a partial excision (saucerization, craterization, or diaphysectomy) typically used for osteomyelitis debridement or benign lesion curettage. 27646 is a radical resection — wide-margin en bloc removal of the fibula segment including surrounding normal tissue, the standard oncologic approach for malignant or aggressive tumors.

02Can I bill 27646 with fibular allograft reconstruction on the same date?

If reconstruction is performed in the same operative session, bill both codes with modifier 51 on the secondary code. If reconstruction is a planned staged return, bill it separately with modifier 58, which resets the 90-day global clock.

03Does 27646 require a malignant diagnosis to be payable?

No — severe chronic osteomyelitis refractory to conservative management is also an accepted indication. Document prior treatment failures and the clinical necessity for radical (not partial) debridement to support medical necessity under a non-malignant diagnosis.

04When should modifier 57 be used with 27646?

Append modifier 57 to the E/M code when the decision for surgery is made on the day of or the day before the procedure. Because 27646 carries a 90-day global, modifier 57 is the correct modifier — not 25 — to allow separate payment for that decision visit.

05Is 27646 performed in an ASC or hospital outpatient setting?

Both settings are valid. The site-of-service differential is significant — see the HOPD and ASC payment figures rendered on this page. For complex resections requiring ICU-level post-op monitoring or intraoperative pathology consultation, a hospital outpatient or inpatient setting is standard. ASC use is more common for smaller, well-defined lesions in otherwise healthy patients.

06What ICD-10 codes are commonly paired with 27646?

Primary malignant bone tumors (C40.20, C40.21, C40.22), metastatic disease to the fibula (C79.51), and osteosarcoma or Ewing sarcoma codes are the most frequent pairings. Chronic osteomyelitis of the fibula (M86.361–M86.369) is used for non-oncologic cases. The ICD-10 specificity must match the laterality documented in the operative note.

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 tumor anatomic location on the fibula (proximal, diaphyseal, distal), resection margins in centimeters, whether adjacent neurovascular structures were dissected or sacrificed, and the estimated additional operative time versus a standard resection. That detail directly supports modifier 22 when invoked and prevents down-coding to 27641 when auditors scrutinize whether the resection was truly radical in extent.

See how Mira captures CPT 27646 documentation