Medicare Part B covers knee replacement if your doctor says you need it

Yes, Medicare Part B will cover knee replacement surgery if your doctor determines it is medically necessary. You pay 20 percent of the approved cost after you meet your Part B deductible for the year. The surgery itself, the hospital stay, anesthesia, and related care all fall under Part B coverage — but what you actually pay depends on which hospital you use and whether your surgeon is in the Medicare network.

The key word is medically necessary. Medicare does not cover knee replacement for cosmetic reasons or to improve athletic performance. Your doctor has to document that you have tried other treatments first — usually physical therapy, injections, or medication — and that those did not work well enough. If your doctor believes surgery is the right next step, Medicare will cover it.

Key Takeaways

  • Medicare Part B covers the surgery, hospital facility, anesthesia, and surgeon fees if your doctor documents medical necessity and you have tried other treatments first.
  • You pay 20 percent of the Medicare-approved amount after you meet your yearly Part B deductible, which is $240 in 2024 but changes each year.
  • If you use an out-of-network surgeon or hospital, you may pay more because Medicare only covers the approved amount, not the full bill.
  • Medigap or Medicare Advantage plans can cover some or all of your 20 percent cost-sharing, depending on the plan you have.
  • Pre-authorization is not required by Medicare, but your surgeon's office should verify coverage before the procedure.

How much you pay out of pocket

Your out-of-pocket cost depends on three things: whether you have met your Part B deductible, whether your providers are in the Medicare network, and whether you have a Medigap or Medicare Advantage plan.

First, you pay the Part B deductible once per calendar year. In 2024, that is $240. After you meet it, Medicare pays 80 percent of the approved cost and you pay 20 percent. The approved cost is what Medicare decides the procedure is worth in your area — not necessarily what the hospital charges. If a surgeon charges $50,000 and Medicare's approved amount is $40,000, you pay 20 percent of $40,000 ($8,000), not 20 percent of $50,000. The surgeon cannot bill you for the difference if they are in-network.

If you have a Medigap plan (also called Medigap insurance), it typically covers your 20 percent cost-sharing, which means you pay little or nothing out of pocket. If you have a Medicare Advantage plan instead, your cost-sharing works differently — you may have a copay, coinsurance, or out-of-pocket maximum instead. Check your plan documents or call the plan to find out your exact responsibility before surgery.

What is covered and what is not

Medicare Part B covers the surgeon's fee, the operating room, anesthesia, implants (the artificial knee joint), and the hospital stay. It also covers pre-surgery tests like X-rays and blood work, and post-surgery follow-up visits with your surgeon for up to 90 days after the procedure.

Medicare does not cover physical therapy that happens after those first 90 days unless it is medically necessary and ordered by your doctor. Outpatient physical therapy after discharge is covered under Part B, but only if your doctor orders it and you go to a Medicare-approved facility. Home health services after surgery are covered if a doctor orders them and you meet Medicare's homebound criteria.

Prescription pain medication after surgery is covered under Part D (prescription drug coverage) if you have it. Devices like a walker or crutches may be covered as durable medical equipment under Part B, but you will pay 20 percent after your deductible, and you must rent or buy from a Medicare-approved supplier.

In-network versus out-of-network providers

Medicare does not have a formal network the way private insurance does. All doctors and hospitals that accept Medicare are considered "in-network" for Medicare purposes. However, some surgeons and hospitals may not accept Medicare assignment, which means they do not agree to accept Medicare's approved amount as full payment.

If your surgeon accepts assignment, they bill Medicare directly and you pay your 20 percent of the approved amount. If they do not accept assignment, they can bill you for up to 15 percent more than Medicare's approved amount — this is called balance billing. Before scheduling surgery, ask your surgeon's office whether they accept Medicare assignment. Most do, but it is worth confirming.

Hospital outpatient departments and ambulatory surgery centers that accept Medicare must accept assignment, so balance billing is not an issue there. If your surgery is done at a hospital as an inpatient (you stay overnight), the hospital also must accept assignment.

Pre-authorization and what to do before surgery

Medicare does not require pre-authorization for knee replacement, which means your surgeon does not have to get permission from Medicare before scheduling you. However, your surgeon's office should verify your coverage before the procedure to make sure you are enrolled in Part B and that your deductible status is correct.

Call your surgeon's office and ask them to verify your Medicare benefits. Bring your Medicare card to your appointment. If you have a Medigap or Medicare Advantage plan, also bring that card so the office can note your secondary coverage. Ask the office to give you an estimate of what you will owe based on your deductible status and your plan.

If you are having surgery at a hospital, the hospital's financial counselor can also walk you through your costs. Do not wait until the day of surgery to ask — call ahead so you have time to understand your bill and plan for payment.

Medicare Advantage and other plan options

If you are enrolled in a Medicare Advantage plan (Part C) instead of Original Medicare, your coverage for knee replacement works differently. Medicare Advantage plans must cover everything Original Medicare covers, including knee replacement, but they can charge you different amounts. Some plans have a copay for surgery, others have coinsurance, and many have an out-of-pocket maximum you hit after paying a certain amount.

Call your Medicare Advantage plan before scheduling surgery and ask what you will owe. Plans vary widely — one plan might charge you $500 and another might charge you $5,000 for the same surgery at the same hospital. Your plan will also tell you which surgeons and hospitals are in-network and whether you need a referral from your primary care doctor.

If you have Original Medicare and a Medigap plan, your Medigap plan covers most or all of your 20 percent cost-sharing, depending on which Medigap plan you have. Plans G, N, and F (if you were may be able to access before 2020) cover the most. Call your Medigap insurer to confirm what they will cover for your surgery.

What happens if your doctor says it is not medically necessary

If your doctor has not documented that you tried other treatments first, Medicare may deny the claim. If that happens, you will receive a notice called an Explanation of Benefits that explains why. You have the right to appeal the decision.

To appeal, you can ask your surgeon's office to submit additional documentation showing that you did try other treatments or that surgery is necessary for another reason. You can also file a formal appeal with Medicare. The process takes time, so do not delay if you want to move forward with surgery — work with your surgeon's office to gather the documentation Medicare needs.

If you disagree with Medicare's decision after appeal, you can request an independent review. Your Explanation of Benefits will explain how to do this.

Frequently Asked Questions

Do I need to wait a certain amount of time after trying physical therapy before Medicare will cover surgery?

Medicare does not set a specific waiting period. Your doctor decides when you have tried conservative treatment long enough and when surgery is the right next step. Different doctors may reach that conclusion at different times depending on your situation. What matters is that your doctor documents the treatments you tried and why surgery is now necessary.

Will Medicare cover a second knee replacement if I already had one?

Yes. Medicare covers knee replacement on either knee or both knees if your doctor says each one is medically necessary. You will pay your 20 percent cost-sharing for each surgery. If both surgeries happen in the same calendar year, you only pay the Part B deductible once.

What if I am still working and have employer health insurance — does Medicare still cover knee replacement?

If you are over 65 and enrolled in Medicare, Medicare is your primary payer even if you have employer coverage. Your employer plan becomes secondary. However, the rules are complex and depend on your employer's plan. Contact your employer's benefits office and Medicare to understand the order of payment before surgery.

Does Medicare cover the cost of a knee brace or compression sleeve after surgery?

Compression sleeves and braces are not typically covered by Medicare. Crutches, walkers, and other durable medical equipment ordered by your doctor are covered under Part B at 20 percent cost-sharing. Ask your surgeon which items they recommend and whether any may have access to as durable medical equipment.

Can I choose which type of artificial knee joint Medicare will cover?

Medicare covers the surgery and a standard artificial knee joint. If you want a more advanced implant with special features, Medicare covers the standard version and you pay the difference out of pocket. Discuss implant options with your surgeon and ask which ones Medicare covers fully and which ones have an extra cost.