CPT code 27447: Total knee arthroplasty billing guide

Key Takeaways

CPT code 27447 describes total knee arthroplasty replacing both the medial and lateral compartments, with or without patella resurfacing.

Since January 2018, CMS removed 27447 from the Medicare Inpatient-Only list, making outpatient and ASC billing valid for eligible patients.

Synovectomy, meniscectomy, and minimal bone grafting performed in the same session are bundled into 27447 and must not be billed separately.

Pabau’s claims management software helps orthopedic practices track modifiers, flag bundling errors, and reduce denials on high-value surgical codes.

CPT code 27447 is the CPT code for total knee arthroplasty — the surgical replacement of both the medial and lateral compartments of the knee joint, with or without patella resurfacing. Maintained by the American Medical Association (AMA), it carries the official descriptor: Arthroplasty, knee, condyle and plateau; medial AND lateral compartments with or without patella resurfacing (total knee arthroplasty).

This guide covers the code’s clinical scope, applicable modifiers, inpatient and outpatient billing distinctions, Medicare reimbursement context, documentation requirements, and the related codes most likely to cause confusion.

What is included in CPT code 27447

The total knee arthroplasty procedure covered by CPT code 27447 replaces the articular surfaces of both the medial and lateral compartments of the knee joint. It is classified under “Repair, Revision, and/or Reconstruction Procedures on the Femur (Thigh Region) and Knee Joint” in the CPT code set. Understanding what the code bundles is essential before submitting any claim.

The following procedures are included in 27447 when performed during the same operative session and must not be billed separately:

• Synovectomy: Removal of synovial tissue performed as part of the arthroplasty preparation is bundled. Do not report a separate synovectomy code.
• Meniscectomy: Meniscal removal carried out to facilitate component placement is included. Billing a standalone meniscectomy (CPT 29881) alongside 27447 is a common NCCI edit trigger.
• Minimal bone grafting: Small amounts of bone graft used during the same session to support component fixation are included, consistent with standard CMS bundling principles. Verify against current NCCI edits before billing separate bone grafting codes.
• Patella resurfacing: The descriptor explicitly covers “with or without patella resurfacing,” so resurfacing the patella does not warrant an additional code.
• Osteophyte removal: Debridement of bone spurs performed incidentally during the approach is part of the global procedure.

Computer-assisted surgical navigation (CPT 20985) is an add-on code that may be reported separately when used, but coverage varies significantly by payer. Confirm prior authorization and medical necessity criteria with each insurer before including 20985 on the claim.

CPT code 27447 modifiers

Modifier selection is where orthopedic billing teams lose the most revenue on 27447 claims. Applying the wrong modifier, or omitting one entirely, triggers either an automatic denial or a reduced payment that requires a time-consuming appeal.

For practices managing sports medicine and orthopedic cases, having a reliable modifier checklist built into the billing workflow prevents the most common errors.

One edge case to know: if a first implant fails and must be replaced during the same operative session without the patient leaving the operating room, you report 27447 only once. Do not add 27487-58 in this scenario, as CMS and AAPC guidance is clear that you cannot code for intraoperative corrections.

Inpatient vs outpatient billing for CPT code 27447

Before January 2018, total knee arthroplasty was on the Medicare Inpatient-Only (IPO) list, meaning CMS would not reimburse the procedure performed in an ambulatory surgical center (ASC) or hospital outpatient department (HOPD).

The American Academy of Orthopaedic Surgeons (AAOS) successfully advocated for its removal, and since then orthopedic practices have had flexibility to bill 27447 in both inpatient and outpatient settings for Medicare patients.

Setting selection affects both the code pathway and the reimbursement structure. Understanding those differences reduces billing errors for practices that handle orthopedic and physical therapy cases across multiple care settings.

• Inpatient (hospital): The physician bills the professional fee (Part B) using 27447. The facility submits a separate UB-04 claim under DRG payment. No ASC facility fee applies.
• Hospital Outpatient Department (HOPD): Physician bills 27447 for the professional component. The hospital bills an Ambulatory Payment Classification (APC) rate for the facility component using the CMS OPPS fee schedule.
• Ambulatory Surgical Center (ASC): Physician bills 27447 on a CMS-1500. The ASC bills a separate facility fee based on the ASC payment indicator for 27447 under the Medicare ASC fee schedule. Confirm the current ASC payment indicator annually, as CMS updates it each fiscal year.

Payer-specific prior authorization requirements for outpatient TKA vary widely. Commercial insurers and state Medicaid programs often require documented conservative treatment failure before approving 27447 in any setting. Verify authorization requirements before scheduling the procedure.

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Medicare reimbursement for CPT code 27447

Medicare reimburses 27447 under the Medicare Physician Fee Schedule (MPFS), calculated using relative value units (RVUs) multiplied by the annual conversion factor and adjusted for geographic practice cost indices (GPCIs). Rates change each January, so always verify current figures using the CMS Physician Fee Schedule Search tool before quoting expected reimbursement to patients or administrators.

CPT code 27447 carries a 90-day global surgical package. This means the surgeon’s fee covers all pre-operative visits one day before surgery, the procedure itself, and all related post-operative care for 90 days after the procedure. Billing separately for post-operative visits within that window (without a relevant modifier) results in automatic claim denial.

Several RVU components determine the final payment:

• Work RVU (wRVU): Reflects the physician’s time, skill, and mental effort. This is the largest component for a major surgical code like 27447.
• Practice Expense RVU (PE RVU): Covers overhead costs. The non-facility PE RVU (used for office or ASC) differs from the facility PE RVU (used for inpatient or HOPD), which affects total payment by setting.
• Malpractice RVU (MP RVU): Reflects the liability insurance cost associated with the procedure.

For the most accurate 2026 payment figures by locality, use the AAPC Codify tool or the CMS fee schedule search, filtering by your Medicare Administrative Contractor (MAC) jurisdiction.

Documentation requirements for CPT code 27447

Medical necessity is the most common denial trigger for total knee arthroplasty claims. Payers require documented evidence that conservative treatment failed before approving CPT code 27447, and the documentation must appear in the medical record at the time of submission, not after a denial.

Practices that use digital intake forms and structured clinical notes can capture the required elements consistently across every patient encounter. For orthopedic and physical therapy practices, having documentation templates that prompt for each medical necessity element reduces the risk of incomplete records reaching the billing team.

Required documentation elements typically include:

• Diagnosis with ICD-10-CM code: The most common pairing codes are M17.11 (primary osteoarthritis, right knee) and M17.12 (primary osteoarthritis, left knee). Post-traumatic osteoarthritis uses M17.31 (right) or M17.32 (left). The diagnosis code must align precisely with the operative findings.
• Conservative treatment failure: Documentation of physical therapy, weight loss attempts, NSAIDs, corticosteroid injections, or other non-surgical interventions tried over an appropriate timeframe before surgery was recommended.
• Functional limitation: Specific description of how the condition limits the patient’s daily activities, using measurable outcome scores where possible (range of motion measurements, knee pain scales, ambulation distance).
• Radiographic evidence: X-ray or MRI findings consistent with the degree of joint degeneration requiring total replacement. Note the date and interpreting radiologist.
• Operative report: The note must confirm that both the medial and lateral compartments were addressed. An operative note describing only one compartment cannot support CPT code 27447 and should instead use 27446.

Practices managing orthopedic documentation at scale benefit from structured patient records that link clinical notes, imaging results, and prior authorization records in one place. When a payer requests records for an audit or appeal, the complete file is immediately available.

CPT code 27447 vs 27446, 27486, and 27487

The most common coding errors on knee arthroplasty claims involve selecting 27447 when a different code is required, or missing a revision scenario that demands 27486 or 27487. Each code has a distinct clinical trigger.

A conversion from a unicompartmental (27446) or patellofemoral arthroplasty to a total knee replacement is not covered by a specific revision code in CPT. Per AAPC guidance, this scenario is typically reported as 27447, since the procedure constitutes a total knee arthroplasty regardless of what was done previously, not as a revision under 27486 or 27487. Document the conversion clearly in the operative report.

Practices billing multiple knee arthroplasty codes benefit from having automated billing workflow tools that flag when a revision code is submitted alongside a primary arthroplasty code in the same date of service, helping catch claim errors before submission. For practices billing a range of knee procedures, from unlisted knee and femur procedures to revision codes, a structured approach to code selection prevents the most common mix-ups.

Common billing errors and how to avoid them

Billing teams focused on high-volume orthopedic practices see the same errors on CPT code 27447 claims repeatedly. Recognizing them in advance reduces denials without requiring a retroactive appeals process.

• Unbundling synovectomy or meniscectomy: Adding a separate synovectomy or meniscectomy code alongside 27447 when the procedure was performed as part of the arthroplasty approach triggers an NCCI bundling edit and an automatic denial. If a distinct and separately identifiable procedure was performed for a different condition, such as a distinct meniscus tear, modifier 59 may apply, but this requires explicit documentation.
• Wrong code for the operative findings: Submitting 27447 when the operative report describes only one compartment being replaced is an upcoding error. Read the operative note carefully before code selection.
• Missing or incorrect laterality: Many commercial payers and some Medicare Advantage plans require modifier LT or RT on every unilateral knee procedure. Missing laterality modifiers cause rejections at the clearinghouse level.
• Billing post-op visits within the global period: The 90-day global surgical package for 27447 includes all related post-operative care. Billing E/M visits for routine follow-up within that window without an appropriate modifier results in denial. Use modifier 24 (unrelated E/M during global period) or 79 (unrelated procedure) only when the visit is genuinely unrelated to the surgery.
• Incorrect setting designation: Submitting a facility claim using non-facility RVUs (or vice versa) creates a payment discrepancy. Confirm the place of service code matches the setting where the procedure was performed.

Practices that rely on claims management software with built-in editing tools catch most of these errors before submission. For practices managing clinical documentation and billing workflows together, connecting the operative note directly to the billing code selection removes the manual handoff where errors occur.

Conclusion

CPT code 27447 is one of the highest-RVU surgical codes in orthopedic practice, and the documentation, modifier, and bundling rules around it are precise. Getting them right consistently requires both clinical accuracy in the operative note and clean billing workflow execution downstream.

Pabau’s claims management tools help surgical and orthopedic practices connect clinical documentation to the billing workflow, reducing the manual steps where 27447 errors most commonly appear. To see how Pabau supports physical therapy and orthopedic EMR workflows, book a demo.

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