Knee replacement surgery addressing both the medial and lateral tibiofemoral compartments, with or without resurfacing of the patella.

Verified May 8, 2026 · 7 sources ↓

Medicare: $1,159.35
Total RVUs: 34.71
Global, days: 90
Region: Knee

Drawn from CMSAAOSAAHKS

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 confirm both medial and lateral compartments were addressed — 'standard approach' language without compartment detail is an audit flag.
Document surgical approach by name (e.g., medial parapatellar, subvastus, midvastus, lateral) — vague approach language draws scrutiny.
State explicitly whether patellar resurfacing was or was not performed; the code covers both but auditors expect the note to address it.
Pre-operative records must establish advanced joint disease: imaging findings, failed conservative treatment (physical therapy, injections, NSAIDs), and functional limitations.
Implant details — manufacturer, model, and laterality — must be documented in the operative and implant records.
For bilateral same-session procedures, the note must reflect two distinct operative fields and, if co-surgeons, each surgeon's individual dictation.
Prior authorization approval documentation must be on file before billing for payers that require it.

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 62 Co-surgeons 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon AS PA/NP/CNS assistant LT Left side RT Right side

Related ICD-10 diagnoses

Diagnoses commonly reported with CPT 27447.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

M17.11 M17.12 M17.0

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 27447 covers total knee arthroplasty involving both condylar and plateau surfaces — medial and lateral compartments — with or without patellar resurfacing. It is the correct code when the full tibiofemoral joint is replaced in a single session. Unicompartmental or bicompartmental procedures limited to one side of the joint do not qualify; both compartments must be addressed.

The code carries a 90-day global period. That window includes the day-before visit, the surgery itself, and all routine post-op care through day 90 — dressing changes, stitch removal, standard follow-up visits. Billing an E/M or other service during that window for a related reason requires modifier 24 or 25. An unrelated procedure returned to the OR during the global needs modifier 79; a related return to the OR needs modifier 78.

Since CMS removed 27447 from the Medicare Inpatient-Only (IPO) list effective 2018, the procedure can be performed and billed in hospital outpatient or ASC settings — but the two-midnight rule still governs inpatient admission decisions. Payers vary on prior authorization requirements and site-of-service coverage; confirm before scheduling. Bilateral same-session TKA is subject to bilateral pricing; append modifier 50 along with LT/RT as appropriate, and if two surgeons each operate on a separate knee, add modifier 62.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	19.11
Practice expense RVU	11.58
Malpractice RVU	4.02
Total RVU	34.71
Medicare national rate	$1,159.35
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	$1,159.35
HOPD (APC 5115) Hospital outpatient department	$13,116.76
ASC (PI J8) Ambulatory surgical center (freestanding)	$9,393.16

Common denial reasons

The recurring reasons claims for CPT 27447 get rejected.

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

Medical necessity denial due to absent or insufficient documentation of failed conservative treatment prior to surgery.
Missing or incorrect laterality modifier — claims without RT or LT (or incorrectly using modifier 50 for a unilateral procedure) are routinely rejected.
Bundling errors: separately billing synovectomy, meniscectomy, or osteophyte removal already included in 27447.
Prior authorization not obtained or authorization number missing from the claim.
Site-of-service mismatch — billing HOPD rates for a procedure performed in an ASC, or vice versa.
Global period violation — billing a related E/M or procedure during the 90-day global without the appropriate modifier 24, 25, 78, or 79.

Frequently asked questions

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

01Is patellar resurfacing required to bill 27447?

No. The code covers both tibiofemoral compartments with or without patellar resurfacing. Document in the operative note whether resurfacing was performed or deliberately omitted — auditors expect the note to address it either way.

02Can 27447 be billed for an outpatient or ASC case?

Yes. CMS removed 27447 from the Medicare Inpatient-Only list effective 2018, opening hospital outpatient and ASC settings. The two-midnight rule still governs whether an inpatient admission is appropriate. Confirm individual payer policies, as some commercial plans still restrict site of service.

03How do you bill bilateral TKA performed in the same session?

Append modifier 50 to 27447 and use RT/LT to identify laterality. If two surgeons each operate on a separate knee in the same session, add modifier 62. Bilateral same-session cases are subject to bilateral pricing under CMS and most commercial contracts.

04What procedures are already bundled into 27447 and should not be billed separately?

Synovectomy, meniscectomy, removal of osteophytes, and minimal bone grafting performed during the same session are included in 27447. Billing these separately will trigger a bundling denial. Use modifier 59 only for a genuinely distinct, unrelated procedure performed in the same operative session.

05Can you bill an E/M visit during the 90-day global period?

Only with the correct modifier. A related E/M during the global requires modifier 24 (post-op, unrelated is the intent) or 25 (same day, significant separate service). A return to the OR for a related complication needs modifier 78. An unrelated procedure during the global needs modifier 79. Billing without these modifiers will be denied.

06What ICD-10-CM codes support medical necessity for 27447?

CMS LCD L39911 and associated billing article A59811 list the covered ICD-10-CM codes. Primary osteoarthritis of the knee (M17.11, M17.12) is the most common. Confirm the full list against your MAC's LCD, as covered diagnoses can vary by contractor.

07Does robotic-assisted TKA change how 27447 is billed?

The primary procedure is still reported as 27447 regardless of robotic assistance. Whether a separate code such as 20985 can be billed by the facility for robotic system use is a facility-side question governed by payer policy — confirm with your specific payer before appending.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures compartment involvement (medial, lateral, and patellar resurfacing decision), surgical approach by name, implant details, and the pre-operative course including failed conservative measures — all from dictation. That eliminates the operative note gaps that drive medical necessity denials and the vague approach language that flags audits.

See how Mira captures CPT 27447 documentation