Surgical · Knee

Surgical arrest of the proximal tibial and fibular growth plates (epiphysiodesis), performed by any method, to halt longitudinal bone growth at that level.

Verified May 8, 2026 · 5 sources ↓

Medicare: $687.39
Total RVUs: 20.58
Global, days: 90
Region: Knee

Drawn from CMSNIHGenhealthCgsmedicare

Documentation requirements

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

Source · Editorial brief grounded in 5 cited references ↓

Operative note must name the specific technique used (e.g., percutaneous transphyseal screws, open physeal ablation, stapling) — 'standard epiphysiodesis' is insufficient for audit purposes
Document which physes were treated: proximal tibia and fibula specifically, to distinguish from 27475 (distal femur) or 27479 (combined sites)
Pre-op skeletal age determination — bone age radiograph with growth remaining calculation (e.g., Moseley straight-line graph, Anderson-Green tables) supporting the medical necessity decision
Laterality must be explicit in the operative note; bilateral cases require documentation that both sides were treated in the same session
Pre-operative limb length discrepancy measurements (scanogram or EOS imaging) documenting the clinical basis for growth arrest timing
Informed consent documenting discussion of irreversibility of the procedure and predicted correction at skeletal maturity

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 52 Reduced services 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 5 cited references ↓

CPT 27477 covers epiphyseal arrest at the proximal tibia and fibula — a procedure performed in skeletally immature patients to slow or stop growth on one side of a limb length discrepancy or angular deformity. Any technique qualifies: open physeal ablation, percutaneous drilling, stapling, or transphyseal screw fixation (the PETS technique). The code is grouped with femur and knee reconstruction procedures (27400–27499) and carries a 90-day global period.

Patient selection depends on precise skeletal age assessment and growth remaining calculations. The operative approach, hardware type (if any), and which physes were treated must be explicit in the record — proximal tibia and fibula together are what 27477 covers, distinguishing it from distal femoral arrest (27475) or combined tibia/fibula and distal femur arrest (27479). Bilateral procedures are reported with modifier 50.

The 90-day global covers all routine post-op visits, hardware checks, and dressing changes. Unrelated E/M visits in the global window need modifier 24. If hardware removal becomes necessary under a separate anesthesia after the primary procedure, report that with the appropriate removal code and modifier 79 (unrelated) or 78 (if the return is directly related to a complication).

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	9.89
Practice expense RVU	8.59
Malpractice RVU	2.1
Total RVU	20.58
Medicare national rate	$687.39
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	$687.39
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI J8) Ambulatory surgical center (freestanding)	$5,078.26

Common denial reasons

The recurring reasons claims for CPT 27477 get rejected.

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

Wrong code level selected — 27475 (distal femur) or 27479 (combined femur and tibia/fibula) billed when only the proximal tibia and fibula were addressed
Missing or insufficient skeletal age documentation; payers require objective growth remaining data to establish medical necessity for an elective, irreversible procedure
Bilateral procedure billed as a single unit without modifier 50, causing one side to be denied as a duplicate
Global period violations — routine post-op visits billed without modifier 24 within the 90-day window, triggering automatic denial
Lack of diagnosis specificity — ICD-10 code does not reflect limb length discrepancy or the underlying etiology driving the need for growth arrest

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01What separates 27477 from 27475 and 27479?

27475 is distal femoral arrest only. 27477 is proximal tibia and fibula only. 27479 covers a combined arrest of both the distal femur and the proximal tibia and fibula in the same session. Bill 27479 — not 27477 plus 27475 — when both sites are treated on the same leg.

02Can 27477 be billed bilaterally?

Yes. When epiphysiodesis is performed on the proximal tibia and fibula of both legs in the same operative session, report 27477 with modifier 50 on a single line for Medicare. For ASC claims, bill two lines using LT and RT modifiers per CMS NCCI guidance.

03Does the technique affect the code selection?

No. The code covers arrest by any method — open physeal ablation, percutaneous drilling, stapling, or transphyseal screw fixation all map to 27477 when the proximal tibia and fibula physes are the target. Document the technique anyway; auditors flag records that don't name it.

04What global period applies and what does it cover?

27477 carries a 90-day global period. That includes the day-before visit, the surgery, and all routine follow-up through post-op day 90 — office visits, wound checks, and hardware monitoring. Any unrelated E/M in that window needs modifier 24; a staged procedure needs modifier 58.

05If screws are removed after the 90-day global, how is that billed?

Hardware removal after the global period closes is billed with the appropriate removal code (e.g., 20680 for deep implant removal) without a linking modifier to 27477. If removal occurs within the global and is unrelated to a complication, use modifier 79. If it's a return for a direct complication of the original procedure, use modifier 78.

06What ICD-10 diagnoses typically support 27477?

Limb length discrepancy codes (M21.70–M21.779) are the most common. Angular deformity codes and post-traumatic physeal arrest diagnoses may also apply depending on the underlying etiology. The diagnosis should reflect the condition driving the need for growth modulation, not just the procedure performed.

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 technique (transphyseal screws, open ablation, stapling), which physes were treated (proximal tibia and fibula), laterality, and the pre-operative growth remaining calculation from dictation. That prevents the most common audit flag for 27477 — operative notes that omit technique and site detail, which reviewers treat as insufficient documentation to distinguish this code from 27475 or 27479.

See how Mira captures CPT 27477 documentation