Surgical · Knee

Combined epiphyseal arrest of the distal femur, proximal tibia, and fibula to permanently halt growth plate activity across all three bones in a single operative session.

Verified May 8, 2026 · 7 sources ↓

Medicare: $849.38
Total RVUs: 25.43
Global, days: 90
Region: Knee

Drawn from CMSAAPCMdclarityPayerprice

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 all growth plates addressed (distal femur, proximal tibia, proximal fibula) and explicitly state that each was arrested — vague language like 'standard epiphysiodesis' invites audits.
Document the specific technique used (e.g., percutaneous drilling, screw epiphysiodesis, tension-band plating) — the code is method-neutral but technique absence is a red flag on review.
Laterality must be stated in both the operative note and the diagnosis: left leg, right leg, or bilateral — required to append LT, RT, or modifier 50 correctly.
Pre-op imaging (standing long-leg X-rays or MRI) confirming open physes and the limb length discrepancy calculation should be in the record to support medical necessity.
Patient age and skeletal maturity assessment (bone age study) must be documented to justify growth plate arrest as indicated rather than premature.
Inpatient admission order and attending physician's inpatient status note are required — CMS treats 27479 as inpatient-only; outpatient site-of-service will trigger automatic denial under Medicare.

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 24 Unrelated E/M during global 25 Significant separate E/M 50 Bilateral procedure 51 Multiple procedures 52 Reduced services 57 Decision for surgery 58 Staged or related 59 Distinct service 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 27479 describes a combined epiphyseal arrest — stopping growth plate activity at the distal femur and proximal tibia and fibula simultaneously. The technique (drilling, stapling, tension-band plating, or percutaneous physeal ablation) is surgeon's choice; the code is method-neutral. It sits above its component codes 27475 (distal femur only) and 27477 (proximal tibia and fibula only) because it addresses both sites in one encounter.

The word 'combined' in the full descriptor is the coding crux. AAPC forum consensus holds that any combination of distal femur plus proximal tibial/fibular arrest satisfies 27479, even when the operative note omits the fibula — because no standalone code exists for distal femur plus proximal tibia without fibula. Reporting 27475 and 27477 separately on the same date would be incorrect; 27479 is the single correct code. Modifier 52 is an option if the fibula was genuinely untouched and the surgeon documents reduced scope, but most coders and the forum discussion advise against it given the code's combination intent.

CMS classifies 27479 as an inpatient-only procedure under the OPPS (status indicator C in the original Addendum E listing), which means Medicare will not reimburse it when performed in a hospital outpatient setting — it must be billed as an inpatient admission. The 90-day global period covers all routine post-op management; E/M services during that window unrelated to the arrest require modifier 24, and unplanned returns to the OR for a related complication require modifier 78.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	12.83
Practice expense RVU	9.87
Malpractice RVU	2.73
Total RVU	25.43
Medicare national rate	$849.38
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	$849.38
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI G2) Ambulatory surgical center (freestanding)	$3,695.53

Common denial reasons

The recurring reasons claims for CPT 27479 get rejected.

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

Site-of-service mismatch: Medicare denies 27479 billed in a hospital outpatient or ASC setting — it is CMS inpatient-only and requires an inpatient claim.
Unbundling: billing 27475 and 27477 separately on the same date instead of the single combination code 27479 triggers NCCI bundling edits.
Missing laterality modifier when payer requires LT or RT — claims without laterality designation are rejected by many commercial payers for unilateral procedures.
Insufficient medical necessity documentation: absent limb length discrepancy measurements or skeletal maturity studies leads to payer denial for lack of clinical justification.
Global period conflict: E/M or post-op visit billed without modifier 24 or 25 within the 90-day global window is automatically bundled and denied.

Frequently asked questions

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

01Can I bill 27479 in an outpatient hospital or ASC setting under Medicare?

No. CMS designates 27479 as inpatient-only under OPPS. Billing it with a place-of-service 22 (outpatient hospital) or 24 (ASC) will result in automatic denial for Medicare claims. The procedure requires an inpatient admission.

02What if the surgeon only arrested the distal femur and proximal tibia — not the fibula?

27479 is still the correct code. No CPT code exists for distal femur plus proximal tibia without the fibula. AAPC forum guidance interprets 'combined' to mean any combination of those anatomic sites. Modifier 52 is an option if the surgeon explicitly documents reduced scope, but it is not required by the code language.

03Should I bill 27475 and 27477 together instead of 27479 when both sites are done?

No. Billing 27475 and 27477 on the same date is incorrect and triggers NCCI bundling edits. When both the distal femur and proximal tibial/fibular physes are arrested in one session, 27479 is the single correct code.

04What modifiers apply when 27479 is performed bilaterally?

Use modifier 50 for a bilateral procedure billed on a single line, or LT and RT on separate lines depending on payer preference. Verify with each commercial payer — some require separate line items with LT/RT; Medicare generally accepts modifier 50.

05How does the 90-day global period affect follow-up billing?

All routine post-op visits, wound checks, and related care within 90 days are bundled into the 27479 payment. To bill an E/M during that window for an unrelated condition, append modifier 24. For a new surgical procedure unrelated to the arrest during the global period, use modifier 79. An unplanned return to the OR for a complication related to the arrest requires modifier 78.

06Is 27479 appropriate for hemiepiphyseal arrest (guided growth)?

No. Hemiepiphyseal arrest — where only one side of the physis is targeted, typically with a tension-band plate or staple for angular correction — is reported with 27485. Use 27479 only when the full physis at both the distal femur and proximal tibia/fibula is being arrested to halt overall leg growth.

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 surgeon's dictation of which growth plates were arrested (distal femur, proximal tibia, proximal fibula), the technique used, and explicit laterality — then flags if the fibula is not mentioned so the coder can decide on modifier 52 before the claim is submitted. This prevents the most common audit flag: an operative note that doesn't reconcile with the 'combined' descriptor of 27479.

See how Mira captures CPT 27479 documentation