Arthroplasty of the knee involving resurfacing of the condyle and tibial plateau in a single tibiofemoral compartment — medial OR lateral, not both.
Verified May 8, 2026 · 6 sources ↓
- Medicare
- $1,047.45
- Total RVUs
- 31.36
- Global, days
- 90
- Region
- Knee
Documentation requirements
What must appear in the operative or office note to support the claim.
Source · Editorial brief grounded in 6 cited references ↓
- Specify which compartment was treated — medial OR lateral — by name in the operative report
- Confirm both the femoral condyle and tibial plateau were resurfaced with prosthetic components
- Document that the contralateral tibiofemoral compartment and patellofemoral joint were NOT replaced (distinguishes 27446 from 27447)
- Record implant manufacturer, model, and lot numbers for each component placed
- Include pre-operative imaging (X-ray or MRI) demonstrating isolated compartmental disease supporting unicompartmental approach
- Operative note must name the surgical approach (e.g., medial parapatellar, subvastus, midvastus) — notes stating only 'standard approach' draw audit flags
- If modifier 22 is appended, include a separate narrative quantifying the additional work and time beyond typical
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 6 cited references ↓
27446 covers unicompartmental (partial) knee arthroplasty in which one tibiofemoral compartment — medial or lateral — is resurfaced with prosthetic components at the femoral condyle and tibial plateau. It is distinct from 27447, which requires resurfacing of both medial and lateral compartments. Patellofemoral arthroplasty alone does not qualify for 27446; the tibiofemoral compartment must be the surgical target.
27446 carries a 90-day global period. All routine post-operative care through day 90 is bundled — separate E/M visits during that window require modifier 24 for unrelated conditions or modifier 25 if a separately identifiable service occurs on the day of surgery. The code sits in the same APC grouping (5115) as neighboring arthroplasty codes under HOPD, and carries a J8 ASC payment indicator.
When 27437 (patellaplasty) is performed at the same session, NCCI bundles it with 27446. Modifier 59 can break the edit only when the operative note clearly documents the procedures as distinct. Modifier 51 does not override a bundling edit — document distinction, then append 59.
RVU & reimbursement
Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.
Source · CMS Physician Fee Schedule, RVU26A · January 2026
| Work RVU | 16.7 |
| Practice expense RVU | 11.13 |
| Malpractice RVU | 3.53 |
| Total RVU | 31.36 |
| Medicare national rate | $1,047.45 |
| 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 | $1,047.45 |
HOPD (APC 5115) Hospital outpatient department | $13,116.76 |
ASC (PI J8) Ambulatory surgical center (freestanding) | $9,213.82 |
Common denial reasons
The recurring reasons claims for CPT 27446 get rejected.
Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓
- Upcoding to 27447: payer determines bilateral compartment resurfacing was performed but 27446 was billed
- Patellofemoral-only procedure billed as 27446 — patellofemoral arthroplasty alone does not meet code criteria
- Post-op E/M visits billed without modifier 24 or 25 during the 90-day global period
- 27437 billed same-day without modifier 59 and supporting documentation of distinct procedural service
- Missing or mismatched laterality — LT/RT modifier absent when payer requires it, or conflicts with ICD-10 diagnosis laterality
- ICD-10 diagnosis reflects bilateral or tricompartmental disease without documentation explaining unicompartmental approach decision
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 6 cited references ↓
01What is the difference between 27446 and 27447?
02Can I bill 27446 for a patellofemoral arthroplasty?
03How do I handle the 90-day global period for 27446?
04Can 27446 and 27437 be billed on the same day?
05Which laterality modifiers are required for 27446?
06When is modifier 22 appropriate for 27446?
07Is 27446 performed in an ASC, and does site of service affect payment?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CMS Physician Fee Schedule 2026
- 02cms.govhttps://www.cms.gov/medicare-coverage-database/view/article.aspx?articleId=57685
- 03aapc.comhttps://www.aapc.com/codes/cpt-codes/27446
- 04zimmerbiomet.comhttps://www.zimmerbiomet.com/content/dam/zb-corporate/en/support/coding-guides/0774.8-US-en%20Knee%20Systems%20Coding%20Reference%20Guide.pdf
- 05orthoflorida.nethttps://www.orthoflorida.net/the-role-of-cpt-codes-in-knee-arthroplasty/
- 06aaos.orghttps://www.aaos.org/education/about-aaos-products/coding-resources/
Mira AI Scribe
Mira's AI scribe captures the treated compartment (medial vs. lateral), confirms both femoral condyle and tibial plateau resurfacing, records implant details, and flags if the patellofemoral joint was left native — the exact facts that distinguish 27446 from 27447 and prevent upcoding denials or payer downcodes at audit.
See how Mira captures CPT 27446 documentation