A medical-necessity denial for total knee replacement (27447) or total hip replacement (27130) arrives either as a denied prior authorization request or as a claim adjusted with CO-50. If no authorization was on file, the claim may instead show CO-197, which calls for a different response. Either way, the appeal turns on whether your records show the payer’s criteria were met.

This guide covers the criteria payers publish, what to check in the denial, the appeal packet, peer-to-peer review, deadlines by payer type and a letter outline. For the wider denial picture, see our guide to common orthopedic claim denials.

What criteria do payers use for total knee and hip replacement?

The three policies below differ in detail but share four elements: imaging that shows advanced arthritis, pain that limits function, a failed course of nonoperative care, and attention to modifiable risks such as BMI. Each lets the surgeon skip nonoperative care when the record explains why it isn’t appropriate.

Check versions. Aetna’s bulletins show a last review date of November 20, 2023. Cigna’s EviCore guidelines (version 1.0.2026) took effect August 4, 2026, and Carelon’s guideline took effect November 15, 2025. Appeal against the version in effect on the date of service, and cite it by number.

Medicare Advantage plans must follow national coverage determinations, local coverage determinations and Traditional Medicare coverage rules. Where those don’t fully set criteria, a plan may use internal criteria only if it publishes them with the evidence and rationale behind them (42 CFR 422.101(b)(6)). Ask the plan which criteria it applied.

What should you check in the denial notice first?

• The code and channel. A pre-service denial is appealed before surgery. A claim denial shows CO-50 or CO-197 on the remittance, and group code CO keeps the balance with the practice.

• The specific reason. Since January 1, 2026, the CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) has required impacted payers to give a specific reason when they deny a prior authorization request, however it was sent. Impacted payers include Medicare Advantage organizations, Medicaid and CHIP programs and plans, and QHP issuers on the federally facilitated exchanges.

• The deadline. Note the notice date and calendar the filing deadline before anything else.

• Documentation claims. If the denial says records were missing, confirm what you sent. In its 2022 review, HHS OIG found Medicare Advantage plans sometimes denied requests for insufficient documentation when the existing records were sufficient.

What should the appeal packet include?

• The denial notice, claim or authorization number, and the payer policy number and version you’re answering.

• A letter of medical necessity from the surgeon that maps each criterion to dated evidence.

• Imaging reports with the grade (Kellgren-Lawrence, Tönnis or Outerbridge) and findings such as joint-space narrowing, osteophytes, sclerosis, cysts or bone-on-bone contact.

• Notes showing pain severity, duration and specific functional limits, such as walking distance, stairs or work tasks, plus exam findings like range of motion and gait.

• A dated nonoperative-care timeline: physical therapy notes, medications, injections, activity changes, assistive devices and weight-loss efforts. Aetna accepts therapy notes or claims history as proof of physical therapy.

• Optimization records: BMI, HbA1c for patients with diabetes, tobacco status and the shared decision-making note.

• If nonoperative care was skipped, the clinical reason in the surgeon’s words.

• If you appeal as the patient’s representative in Original Medicare, an Appointment of Representative form (CMS-1696). Non-contracted providers appealing a Medicare Advantage payment denial need a signed waiver of liability.

Should you ask for a peer-to-peer review?

A peer-to-peer is a call between the treating surgeon and the payer’s physician reviewer. It works best when the denial reflects a misread chart or a single missing element. Check the denial notice for any time limit on requesting one.

Prepare as you would for an appeal. The surgeon, not staff, should take the call with the criteria map open. Cite the policy by number, walk through the imaging grade, functional limits and dates of failed treatment, and ask exactly which criterion is unmet and what evidence would satisfy it. Record the reviewer’s name, the date and the outcome.

A peer-to-peer doesn’t replace a formal appeal. For Medicare Advantage, CMS guidance calls these discussions voluntary and says plans shouldn’t use them to push a physician toward a lower level of service to win approval. The filing window runs from the denial notice, so keep the appeal on schedule while you wait for the call.

What are the appeal levels and deadlines?

Medicare presumes you received a notice five days after its date. For Medicare Advantage, CMS states the reconsideration window as 65 calendar days from the notice date; the regulation phrases it as 60 days after receipt, with receipt presumed five days after the notice. A treating physician can request a pre-service reconsideration on the patient’s behalf after notifying the patient.

Payment disputes differ by network status. A non-contracted provider can appeal a Medicare Advantage payment denial after signing a waiver of liability. When an in-network provider’s payment is denied and the patient owes nothing more, the dispute goes through your contract with the plan instead. Medicare Advantage reconsiderations of medical-necessity denials must be decided by a physician with expertise suited to the service, though not necessarily the same specialty.

For commercial plans, the ACA timelines above apply to member appeals. Your participation agreement may set a separate provider dispute process with its own deadline, so check it before you file.

How should you structure the appeal letter?

1. Header: payer, appeal level, claim or authorization number, date of service, CPT and ICD-10-CM codes, and the patient identifiers the payer requires.

2. Request: one sentence stating what you want, such as approval of, or payment for, a right total knee replacement (27447).

3. Denial summary: notice date, the reason cited, and the policy number and version.

4. Criteria map: each criterion, the evidence that meets it, and the date and page where that evidence appears.

5. Clinical narrative: the surgeon’s short account of symptoms, function, failed treatments and why surgery is needed now.

6. Rebuttal: a direct answer to each stated reason, including any policy exception for skipping nonoperative care.

7. Risk optimization: BMI, HbA1c, tobacco status and the shared decision-making discussion.

8. Regulatory points that apply, such as Medicare coverage rules or a Medicare Advantage plan’s published internal criteria.

9. Enclosures: a numbered list of every attached record.

10. Signature: the treating surgeon’s name, credentials and direct contact, with an offer to discuss the case.

How Rette helps

Rette reads the operative and clinical notes in the EHR your practice already uses and supports prior authorization, denials and appeals from one prioritized work queue. Its agents also suggest codes and check claims against NCCI, NCD and LCD rules before submission.