Surgical · Knee

27485

Surgical arrest of hemiepiphyseal growth at the distal femur or proximal tibia/fibula to correct angular deformity such as genu varus or genu valgus.

Verified May 8, 2026 · 5 sources ↓

Medicare
$633.28
Total RVUs
18.96
Global, days
90
Region
Knee
Drawn from CMSAAPCMdclarityGenhealth

Documentation requirements

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

Source · Editorial brief grounded in 5 cited references ↓

  • Identify the specific physis treated: distal femur, proximal tibia, or proximal fibula — side (medial vs. lateral) must be documented
  • Standing long-leg radiographic measurements documenting the degree of angular deformity (mechanical axis deviation) used to justify the procedure
  • Implant type and size: staples, screws, or tension-band plate — generic references to 'growth plate device' are audit flags
  • Patient age and skeletal maturity assessment confirming sufficient remaining growth for guided correction
  • Laterality of the operative limb (left or right) to support modifier LT or RT billing
  • Intraoperative fluoroscopy use documented if performed, with notation that it guided implant placement across the physis

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

What this code covers

Source · Editorial summary grounded in 5 cited references ↓

CPT 27485 covers a growth-arrest procedure targeting one side of the physis — the distal femur or proximal tibia/fibula — to redirect bone growth and correct progressive angular deformity. The surgeon places a device such as staples, screws, or a tension-band plate across the affected side of the growth plate. Over time, the untreated side continues growing while the arrested side slows, gradually correcting the angulation. Indications include significant genu varus (bow-leggedness) or genu valgus (knock-knees) that has not responded to conservative management, as well as leg-length discrepancy driven by asymmetric physeal growth.

This is a pediatric procedure — the patient must have sufficient remaining growth for the correction to occur. Pre-operative planning includes standing long-leg radiographs to quantify the mechanical axis deviation, and the operative note must identify the specific physis treated and the implant used. Fluoroscopic guidance is routinely used intraoperatively; given NCCI guidance that fluoroscopy is integral when used during a procedure at the same site, do not bill a separate fluoroscopy code unless it supports a distinct, separately documented service. The 90-day global period means all routine post-op visits through day 90 are bundled — bill modifier 24 for unrelated E/M services in that window.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU8.9
Practice expense RVU8.16
Malpractice RVU1.9
Total RVU18.96
Medicare national rate$633.28
Global period90 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

SettingMedicare rate (national)
Office (PFS non-facility)
Procedure performed in physician's office
$633.28
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 27485 get rejected.

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

  • Missing laterality — claim submitted without LT or RT modifier causes payer system rejection or auto-denial
  • Skeletal maturity not documented — payers deny when records don't confirm the patient has open physes and adequate growth remaining
  • Unbundling of fluoroscopy — separately billing fluoroscopy guidance when it is integral to the physeal procedure triggers NCCI edits
  • Wrong code selection for temporary hemiepiphysiodesis — using 27485 without modifier 52 or opting for an unlisted code when a temporary plate/staple technique is performed creates payer pushback on code-procedure mismatch
  • Site mismatch — documentation describes ankle or distal tibia physis but 27485 is billed; that site requires a different or unlisted code

Frequently asked questions

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

01Should I bill modifier 52 for a temporary hemiepiphysiodesis with a tension-band plate?
This is a genuine gray area. 27485 describes hemiepiphyseal arrest at the distal femur or proximal tibia/fibula without distinguishing permanent from temporary technique. Some coders append modifier 52 for temporary implants (plates/staples intended for later removal) because no tissue is excised and the procedure is less extensive than a permanent epiphysiodesis. Others use 27485 as-is and document the planned staged removal. Check with your payer before defaulting to 52; some payers reduce payment unpredictably. If the procedure doesn't fit any descriptor well, an unlisted code (27599) with documentation and a crosswalk to 27485 is defensible.
02Can 27485 be billed bilaterally?
Yes. If both legs are treated in the same session, bill 27485-50 on a single claim line for physician billing. For ASC billing, report two claim lines with modifiers LT and RT per NCCI guidance on bilateral surgical procedure reporting in the ASC setting.
03What is the global period for 27485 and what does it cover?
27485 carries a 90-day global period. The day-before visit, the surgery itself, and all routine post-op care through day 90 are bundled. Unrelated E/M services in the global window need modifier 24. A staged implant removal within the global period (e.g., plate removal after correction) requires modifier 58 if planned, or modifier 78 if the return to the OR was unplanned and related.
04Is 27485 the right code for hemiepiphysiodesis at the ankle or distal tibia?
No. 27485 is limited to the distal femur and proximal tibia or fibula — near the knee. A hemiepiphyseal arrest at the distal tibia or fibula (ankle region) does not have a specific CPT code and should be reported with an unlisted musculoskeletal procedure code (27899 or 28899 depending on region), with documentation supporting the crosswalk to 27485.
05Can fluoroscopy be billed separately with 27485?
Generally no. Fluoroscopy used to guide implant placement during the physeal arrest procedure is integral to 27485 under NCCI principles. Bill fluoroscopy separately only if it supports a distinct, separately documented procedure performed at a different site during the same encounter, and only with an appropriate NCCI-associated modifier.
06What ICD-10 diagnosis codes support 27485?
Primary supporting diagnoses include M21.161/M21.162 (genu valgus, right/left), M21.171/M21.172 (genu varus, right/left), and Q74.1 (congenital malformation of knee) for structural deformity cases. Leg-length discrepancy driving the procedure maps to M21.761/M21.762. Use the code that matches the documented clinical indication — payers cross-check diagnosis against the corrective intent of the surgery.

Mira AI Scribe

Mira's AI scribe captures the specific physis treated (distal femur medial/lateral, proximal tibia, or proximal fibula), the implant type and size, intraoperative fluoroscopy use, and the operative limb side from the surgeon's dictation. This prevents the most common audit flags: vague implant documentation, missing laterality, and undifferentiated references to 'standard growth arrest technique' that leave the treated physis ambiguous.

See how Mira captures CPT 27485 documentation

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