Does Medicare Cover Knee Replacement Surgery?

Is knee replacement covered, and under Part A or Part B?

Original Medicare covers knee replacement surgery (total or partial) when your doctor decides it is medically necessary to treat your condition. The key question for your wallet is not whether it is covered, but how it is classified.

Part A (hospital insurance) pays when you are formally admitted to the hospital as an inpatient. Part B (medical insurance) pays when the surgery is done on an outpatient basis. The surgeon's fee and anesthesia are billed under Part B in either case.

Since 2018, knee replacements no longer have to be done as an inpatient procedure. CMS removed total knee arthroplasty from the Medicare Inpatient-Only list effective January 1, 2018, and added it to the Ambulatory Surgical Center (ASC) Covered Procedures List effective January 1, 2020. As a result, many knee replacements today are performed and paid as outpatient procedures.

• Part A: covers your inpatient hospital stay if you are admitted.
• Part B: covers outpatient surgery (hospital outpatient department or ASC), plus the surgeon's fee and anesthesia.
• Both total and partial knee replacements, and knee revision surgery, are covered when medically necessary.

Inpatient vs. outpatient: why the classification matters

Your doctor decides whether you are treated as an inpatient or an outpatient. This judgment is guided by Medicare's Two-Midnight Rule — broadly, whether your care is expected to span at least two midnights in the hospital. Knee replacement stays are often short, so many cases are handled as outpatient.

This single decision determines whether Part A or Part B cost-sharing applies, and it can also affect what happens after surgery. Importantly, an outpatient-classified knee replacement does not count toward Medicare's 3-day inpatient hospital stay requirement for skilled nursing facility (SNF) coverage. If you think you may need a SNF afterward, it is worth asking your doctor and the hospital how your stay will be classified before surgery.

What you'll pay in 2026 with Original Medicare

Your out-of-pocket cost depends on whether the surgery is inpatient or outpatient. The figures below are the 2026 Medicare amounts. Most knee replacement hospital stays are short, so inpatient patients usually owe only the Part A deductible for the stay itself.

• Inpatient (Part A): $1,736 deductible per benefit period, which covers days 1-60. If a stay runs longer, coinsurance is $434/day for days 61-90 and $868/day for lifetime reserve days — though knee replacement stays are typically far shorter.
• Outpatient (Part B): $283 annual deductible, then you pay 20% of the Medicare-approved amount. For a costly outpatient 'comprehensive service' like a total knee replacement in a hospital outpatient department, that 20% applies to the entire episode of care, including drugs, lab tests, and related services.
• Hospital outpatient copay cap: the copayment for a single outpatient hospital service generally cannot be more than the Part A inpatient deductible — $1,736 in 2026.
• Surgeon's fee and anesthesia (Part B): 20% coinsurance after the $283 deductible.
• To keep Part B coverage, you must pay the Part B premium — $202.90/month standard in 2026 (higher if IRMAA applies based on income).
• Part A is premium-free if you have 40+ work quarters; otherwise it is $311/month (30-39 quarters) or $565/month (under 30 quarters) in 2026.

There is no out-of-pocket cap in Original Medicare

Original Medicare has no annual out-of-pocket maximum. Because there is no cap and you keep paying 20% on outpatient services, the total cost of a knee replacement and its recovery can add up. Two paths can limit your exposure.

A Medigap (Medicare Supplement) policy works alongside Original Medicare and can pay some or all of your Part A and Part B deductibles and coinsurance, depending on the plan you choose. A Medicare Advantage (Part C) plan replaces how you get your benefits and includes a yearly out-of-pocket maximum, which caps your in-network spending for the year.

• Medigap: helps cover the gaps (deductibles and coinsurance) in Original Medicare; what it covers depends on the lettered plan.
• Medicare Advantage: must cover knee replacement at least as well as Original Medicare, but it may require prior authorization, use network providers, and apply its own copays and out-of-pocket maximum.
• Check your specific plan documents; benefits and costs vary by plan and carrier.

Knee replacement under Medicare Advantage

Medicare Advantage (Part C) plans are required to cover everything Original Medicare covers, including a medically necessary knee replacement. How you experience that coverage can differ, though.

Many Advantage plans require prior authorization for knee replacement, meaning the plan must approve the surgery in advance. Plans also typically use provider networks, so using an in-network surgeon and facility matters for your cost. Your copays, coinsurance, and the plan's annual out-of-pocket maximum are set by the plan, not by Original Medicare. Always confirm the details in your plan's Evidence of Coverage before scheduling surgery.

Recovery: rehab, physical therapy, and equipment

Medicare also helps with the recovery side of a knee replacement, though coverage rules differ by setting.

• Skilled nursing facility (SNF): Part A can cover follow-up SNF care, including physical therapy, but only after a qualifying inpatient hospital stay of at least 3 days in a row. In 2026 you pay $0 for days 1-20 and $217/day for days 21-100; after 100 days you pay all costs. An outpatient-classified knee replacement does NOT count toward the 3-day requirement.
• Inpatient rehabilitation facility: Part A covers medically necessary care in an inpatient rehab facility when it applies to your recovery.
• Outpatient physical therapy: Part B covers PT needed for recovery, paying 80% of the approved amount after the $283 deductible (you pay 20%).
• Durable medical equipment (DME): Part B covers equipment like a walker. A continuous passive motion (CPM) device used at home is covered as DME for up to 21 days after knee replacement when your doctor prescribes it.
• How long Medicare covers recovery depends on medical necessity and the setting — SNF up to 100 days per benefit period, and outpatient PT for as long as it remains medically necessary.