Surgical excision or curettage of a bone cyst or benign tumor located in the tibia or fibula, without bone grafting.

Verified May 8, 2026 · 7 sources ↓

Medicare: $545.77
Total RVUs: 16.34
Global, days: 90
Region: Foot & ankle

Drawn from KzanowAAPCFindacodeMdclarityPayerprice

Documentation requirements

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

Source · Editorial brief grounded in 7 cited references ↓

Operative note must name the specific bone involved — tibia or fibula — and the anatomic location of the lesion
Document lesion type (cyst vs. benign tumor) with pathology or imaging correlation to support medical necessity
Confirm no bone graft was used — if graft was placed, 27637 is the correct code, not 27635
Record surgical technique: excision versus curettage, extent of cortical involvement, and cavity management
Pre-operative imaging (X-ray, CT, or MRI) identifying the lesion should be in the chart to support ICD-10 diagnosis coding
If modifier 22 is appended, the note must quantify the additional work — unusual size, depth, proximity to neurovascular structures, or prolonged operative time

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 51 Multiple procedures 59 Distinct service 76 Repeat, same physician 78 Unplanned return — related 79 Unrelated during global LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 27635 covers open excision or curettage of a bone cyst or benign tumor of the tibia or fibula — no bone grafting included. The surgeon incises down to the affected cortex, removes or scrapes out the lesion, and closes. If the defect is then packed with autograft or allograft, that work is captured under 27637 instead. Choose between these two codes based on what the operative note actually documents, not on preoperative intent.

The code descriptor says 'tibia or fibula' — one code covers either bone, and CMS policy limits billing to one unit per date of service regardless of how many foci are addressed. A MUE (Date of Service Clinical Edit, effective January 1, 2021) enforces this ceiling. Attempting to report 27635 twice on the same DOS — even for ipsilateral tibia and fibula involvement — will be denied.

The 90-day global period means all routine postoperative care through day 90 is bundled. Fracture management, hardware removal, or new unrelated problems arising in that window need modifier 78 (unplanned return, related) or 79 (unrelated procedure) to break out of the global and get paid.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	7.83
Practice expense RVU	7.12
Malpractice RVU	1.39
Total RVU	16.34
Medicare national rate	$545.77
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	$545.77
HOPD (APC 5113) Hospital outpatient department	$3,342.87
ASC (PI A2) Ambulatory surgical center (freestanding)	$1,644.87

Common denial reasons

The recurring reasons claims for CPT 27635 get rejected.

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

Billing two units of 27635 same-day — CMS MUE limits this code to one unit per DOS regardless of how many lesion sites were addressed
Upcoding to 27637 when the operative note documents curettage only with no bone grafting performed
Missing or insufficient pathology/imaging documentation to establish medical necessity for surgical excision of a benign lesion
Routine post-op services billed separately within the 90-day global period without modifier 24 or 25
Laterality modifier absent when payer requires LT or RT for site-specific adjudication

Frequently asked questions

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

01Can I bill 27635 twice if the surgeon treated both the tibia and fibula during the same surgery?

No. CMS has a MUE limiting 27635 to one unit per date of service, effective January 1, 2021. The code descriptor uses 'or' but CMS policy overrides that — one unit maximum regardless of how many bones are addressed.

02What is the difference between 27635 and 27637?

27637 is used when bone graft material — autograft or allograft — is placed into the defect after excision or curettage. If the cavity is left alone or filled only with bone cement, 27635 is correct. The operative note must explicitly document graft placement to support 27637.

03Does 27635 require a laterality modifier?

Not universally required by CMS, but many commercial payers and Medicaid MACs require LT or RT for musculoskeletal surgery to adjudicate correctly. Append LT or RT as a standard practice to prevent site-specific denials.

04What modifiers apply if the patient needs an unplanned return to the OR within the 90-day global?

Use modifier 78 if the return procedure is related to the original surgery — for example, managing a fracture through the curettage site. Use modifier 79 if the new procedure is completely unrelated to the original bone lesion case.

05Can 27635 be billed for a malignant bone tumor?

The code description references benign tumors and cysts. Malignant lesions generally map to oncologic excision codes. Use the ICD-10 diagnosis code to reflect actual pathology; if the lesion is confirmed malignant on final pathology, payer scrutiny increases and the diagnosis code must match the operative intent documented preoperatively.

06What ICD-10 diagnoses typically support 27635?

Common supporting diagnoses include unicameral bone cyst (M85.56x), aneurysmal bone cyst (M85.46x), fibrous dysplasia (M85.06x), and osteochondroma of the tibia or fibula (D16.2x). The specific laterality extension must match the operative 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 specific bone (tibia vs. fibula), lesion type (cyst or tumor), surgical technique (excision vs. curettage), whether bone graft material was placed, and anatomic location along the shaft or metaphysis — directly from dictation. This prevents the most common audit flag: operative notes that don't distinguish 27635 (no graft) from 27637 (with graft), which triggers downcoding or a request for records.

See how Mira captures CPT 27635 documentation