Excision or curettage of a bone cyst or benign tumor from the tibia or fibula, with defect repair using an autograft harvested during the same operative session.

Verified May 8, 2026 · 6 sources ↓

Medicare: $707.77
Work RVU: 10.05
Global, days: 90
Region: Foot & ankle

Drawn from CMSAAPCFindacodeAaoms

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Specify bone involved (tibia vs. fibula) and anatomic location within the bone (proximal, mid-shaft, distal)
Confirm lesion type — bone cyst vs. benign tumor — with pre-op imaging (X-ray, MRI, or CT) referenced in the note
Document the autograft harvest site and quantity harvested; do not leave 'graft obtained from donor site' without specifying location
Operative note must distinguish this as an excision or curettage, not merely a biopsy or incisional procedure
Pathology report or intraoperative frozen-section findings should correlate with benign pre-op diagnosis to support medical necessity
If performed same-day as another procedure, document independent medical necessity for the lesion excision in a separate operative note section

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 58 Staged or related 59 Distinct service 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon AS PA/NP/CNS assistant LT Left side RT Right side XS Separate structure

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

27637 covers open removal or curettage of a benign bone lesion — cyst or tumor — located in the tibia or fibula, followed by packing the resulting defect with autogenous bone graft. The autograft harvest is included in the code; do not separately bill a graft-harvesting code. This distinguishes 27637 from its sibling code 27635, which covers the same excision without any graft or with allograft only.

The procedure carries a 90-day global period. All routine postoperative visits, wound checks, and suture removals through day 90 are bundled. A separate E/M during that window requires modifier 24 (unrelated) or 25 (separate, significant service on the day of procedure). An unplanned return to the OR for a related complication — fixation of a pathologic fracture through the lesion site, for example — bills with modifier 78.

If the surgeon performs 27637 at the same session as a major procedure such as TKA (scenario seen in the AAPC forum for proximal tibial cysts), the lesion excision must be separately documented and medically necessary on its own merits. Modifier 59 or XS may be required to bypass bundling edits, but payer policy varies — confirm NCCI PTP status before submitting.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU vs. total RVU

The work RVU (10.05) is the surgeon's own effort — the figure physician pay and productivity targets are built on. The total RVU (21.19) adds practice overhead and malpractice, and is what drives the Medicare payment below.

Work RVU	10.05
Practice expense RVU	9.14
Malpractice RVU	2
Total RVU	21.19
Medicare national rate	$707.77
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	$707.77
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI J8) Ambulatory surgical center (freestanding)	$4,665.10

Common denial reasons

The recurring reasons claims for CPT 27637 get rejected.

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

Separate billing of a bone graft harvest code (e.g., 20900) when autograft is already included in 27637
Missing or vague imaging documentation — payers deny when pre-op studies confirming a benign lesion are not referenced
Bundling denial when billed same-day as a major leg or knee procedure without modifier 59 or XS to establish distinct service
ICD-10 diagnosis mismatch — submitting a malignant neoplasm code against a code designated for benign lesions or cysts
Lack of documentation distinguishing curettage from simple biopsy, resulting in down-coding or denial for insufficient complexity

Frequently asked questions

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

01Is the bone graft harvest separately billable with 27637?

No. The autograft harvest is bundled into 27637. Billing 20900 or a similar harvest code alongside 27637 will trigger an NCCI edit and likely a denial or overpayment flag on audit.

02What code covers the same procedure when no autograft is used?

27635 covers excision or curettage of a bone cyst or benign tumor of the tibia or fibula without graft or with allograft. Use 27637 only when the surgeon harvests and places autogenous bone at the same session.

03Can 27637 be billed same-day as a total knee arthroplasty for a proximal tibial cyst?

It can, but it requires robust separate documentation of independent medical necessity and modifier 59 or XS to bypass bundling. Many payers scrutinize this combination heavily; verify NCCI PTP status and individual payer policy before submitting.

04What modifier applies if the surgeon does not personally harvest the graft?

Append modifier 52 (reduced services) when the autograft is not harvested by the operating surgeon. This reflects the reduced scope relative to the full code descriptor.

05Does 27637 apply to malignant bone tumors of the tibia or fibula?

No. 27637 is designated for benign cysts and benign tumors. Resection of malignant lesions of the tibia or fibula maps to different CPT codes in the tumor resection series. Using 27637 with a malignant ICD-10 diagnosis will trigger a diagnosis-procedure mismatch denial.

06What global period applies and what does it cover?

27637 carries a 90-day global period. Routine postoperative visits, wound care, and suture removal through day 90 are all bundled. Unrelated E/M services in that window need modifier 24; a separate significant E/M on the surgery date needs modifier 25.

Sources & references

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

Mira Scribe

Mira's AI scribe captures the lesion type (cyst vs. benign tumor), specific bone (tibia or fibula), anatomic segment, autograft harvest site, and the defect repair technique directly from dictation. It flags if the harvest site goes undocumented — the single most common audit trigger for 27637 — before the note is finalized, preventing denials tied to unbundling or medical necessity gaps.

See how Mira captures CPT 27637 documentation