Excision or curettage of a bone cyst or benign tumor from the tibia or fibula, with allograft used to fill the defect.

Verified May 8, 2026 · 6 sources ↓

Medicare: $698.75
Work RVU: 10.72
Global, days: 90
Region: Foot & ankle

Drawn from CMSAAPCMdclarityGenhealthFindacode

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Specify whether lesion is from tibia or fibula — both bones fall under this code but must be documented
Confirm pathology type: bone cyst vs. benign tumor; operative note must reflect this distinction
Document that allograft was used, not autograft — graft type determines code selection (27635/27637/27638)
Record the size and location of the lesion to support medical necessity and modifier 22 if applicable
Note the graft source (allograft bank, material type) and how the defect was packed or stabilized
Include imaging (X-ray, MRI, or CT) in the record that identifies and characterizes the lesion preoperatively

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 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 6 cited references ↓

CPT 27638 covers surgical removal or curettage of a bone cyst or benign tumor arising from the tibia or fibula, followed by reconstruction of the osseous defect with allograft material. The allograft fill is integral to this code — it is not separately billable. If the surgeon instead uses autograft, report 27637. If no graft is used, report 27635.

This is a 90-day global procedure. All routine follow-up care, wound checks, and implant monitoring fall inside the global period. Bill unrelated problems with modifier 24 on E/M visits, or modifier 79 on unrelated procedures. An unplanned return to the OR for a complication tied to the original surgery uses modifier 78.

The procedure is performed in a hospital OR or ASC. Site of service matters: HOPD and ASC payment rates differ significantly — see the Site of Service comparison table. Laterality modifiers LT and RT are expected when only one leg is treated. Modifier 50 applies if the procedure is performed bilaterally in the same operative session.

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 (10.72) is the surgeon's own effort — the figure physician pay and productivity targets are built on. The total RVU (20.92) adds practice overhead and malpractice, and is what drives the Medicare payment below.

Work RVU	10.72
Practice expense RVU	8.26
Malpractice RVU	1.94
Total RVU	20.92
Medicare national rate	$698.75
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	$698.75
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI A2) Ambulatory surgical center (freestanding)	$3,695.53

Common denial reasons

The recurring reasons claims for CPT 27638 get rejected.

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

Graft type mismatch: billing 27638 when operative note documents autograft instead of allograft
Missing or vague pathology documentation — 'bone lesion' without specifying cyst or benign tumor
Unbundling: separately billing for the allograft material or graft application when it is included in 27638
Lack of preoperative imaging or biopsy results to establish medical necessity for excision
Wrong code selection when no graft was used — 27635 is the correct code in that scenario

Frequently asked questions

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

01Can I bill separately for the allograft material used in 27638?

No. The allograft is bundled into 27638. Billing separately for the graft or its application will be denied as unbundling.

02What is the difference between 27635, 27637, and 27638?

27635 is excision or curettage with no graft. 27637 is the same procedure with autograft (patient's own bone, includes harvesting). 27638 is with allograft. Graft type documented in the operative note must match the billed code.

03Do I need LT or RT modifiers on 27638?

Yes, when the procedure is unilateral. Append LT or RT to identify the operative side. Use modifier 50 only if truly bilateral — same session, both legs.

04What modifier applies if the patient returns to the OR during the 90-day global for a wound complication from this procedure?

Use modifier 78 — unplanned return to the OR for a complication related to the original procedure. Do not use modifier 79, which is reserved for unrelated procedures during the global period.

05Can 27638 be reported with a same-day E/M visit?

Only if a separately identifiable, distinct reason was documented for the E/M. Append modifier 25 to the E/M code. The surgical decision visit on the day before or day of surgery may require modifier 57 if it triggered the decision to operate.

06Is modifier 22 ever appropriate for 27638?

Yes, when the case required substantially more work than typical — for example, an unusually large lesion, complex anatomy, or extensive reconstruction. Document the added complexity explicitly in the operative note, and expect a payer request for supporting documentation.

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 bone involved (tibia vs. fibula), lesion type (cyst or benign tumor), graft type (allograft confirmed, not autograft), lesion dimensions, and the method used to fill the defect — directly from surgeon dictation. This prevents the most common denial trigger: a mismatch between the billed code (27638 requires allograft) and what the operative note actually documents.

See how Mira captures CPT 27638 documentation