Medicare Part B covers knee replacement if your doctor says it is medically necessary

Yes, Medicare Part B will pay for knee replacement surgery when a doctor determines it is medically necessary to treat your condition. Medicare does not cover the surgery straightforward because your knee hurts or you want to improve mobility — there has to be a documented medical reason, such as severe arthritis, a torn meniscus that cannot be repaired, or a fracture that requires replacement rather than repair.

The surgery itself, the surgeon's fee, anesthesia, and the hospital stay are all covered under Part B. However, you will pay your Part B deductible first (currently $240 per year, though this amount can change), and then you pay 20% of the approved amount for the surgeon and facility costs after that. If you have a Medigap or Medicare Advantage plan, your out-of-pocket costs may be lower.

The artificial knee joint itself — called a prosthesis — is covered as part of the surgical procedure, not billed separately. You do not pay extra for the implant.

Key Takeaways

  • Medicare Part B covers knee replacement when your doctor documents that it is medically necessary, not for cosmetic or preference reasons.
  • You pay your Part B deductible ($240 in 2024) and then 20% of approved costs for the surgeon and facility after that.
  • The artificial knee joint is included in the surgery cost and is not billed separately.
  • Your doctor must submit documentation to Medicare showing the medical reason for the surgery before the procedure can be scheduled.
  • Physical therapy after surgery is covered under Part B, though you will pay 20% of that cost as well.

What Medicare considers medically necessary for knee replacement

Medicare uses specific criteria to decide whether knee replacement is medically necessary. The most common reason is severe osteoarthritis that has not improved with non-surgical treatment like physical therapy, injections, or anti-inflammatory medication. Your doctor's notes must show that you have tried these other treatments first and that they did not work well enough.

Other conditions that may may have access to include a torn meniscus or cartilage damage that cannot be repaired, a fracture of the knee joint, or damage from rheumatoid arthritis. Your surgeon will need to document the severity of the damage, usually with X-rays or MRI images, and explain why surgery is the right next step for you.

Medicare will not pay for knee replacement if the surgery is being done only to improve sports performance, prevent future problems, or increase mobility for activities you want to do. The surgery must address a specific medical problem that is causing pain or loss of function.

How to learn about your situation meets Medicare's standards

Start by talking with your primary care doctor or an orthopedic surgeon about your knee problem. Tell them you have Medicare and ask whether they think knee replacement is medically necessary in your case. If they say yes, they will document their reasoning in your medical record and submit that information to Medicare before scheduling the surgery.

Your surgeon's office handles the Medicare paperwork — you do not need to contact Medicare yourself to ask permission. However, you can call Medicare at 1-800-MEDICARE (1-800-633-4227) if you want to understand what your specific out-of-pocket costs will be based on your plan. Have your Medicare card and your doctor's name ready when you call.

If your doctor thinks knee replacement might help but is not certain it meets Medicare's standard, ask them to explain what additional testing or treatment might be needed first. Sometimes Medicare requires you to try physical therapy for a set number of weeks before surgery will be covered.

Your out-of-pocket costs for knee replacement

Your costs depend on whether you have Original Medicare alone, a Medigap plan, or a Medicare Advantage plan. With Original Medicare Part B only, you pay your annual deductible ($240 in 2024) and then 20% of the approved amount for the surgeon, anesthesiologist, and facility charges. For a knee replacement, the total approved amount is typically several thousand dollars, so your 20% share can be substantial.

If you have a Medigap plan (also called Supplemental Insurance), it usually covers some or all of that 20% coinsurance, depending on which Medigap plan you chose. If you have a Medicare Advantage plan, your costs work differently — you may have a copay for the surgery instead of coinsurance, and your out-of-pocket maximum applies. Check your plan documents or call your plan's customer service to find out your exact costs before surgery.

Physical therapy after surgery is also covered under Part B, and you will pay 20% of that cost as well. Most people need several weeks of therapy, so budget for multiple copays or coinsurance payments during recovery.

What happens before surgery: pre-authorization and testing

Before your surgery date is set, your surgeon's office will send your medical records and imaging to Medicare for review. This is called pre-authorization, and it is how Medicare confirms that the surgery meets its medical necessity standard. This process usually takes one to two weeks.

You will also have pre-operative testing — blood work, an EKG, and possibly a chest X-ray — to make sure you are healthy enough for surgery. These tests are covered under Medicare Part B, and you pay 20% of the approved amount for each one.

Your surgeon will also ask about your medications, allergies, and any other health conditions. Tell them about everything, including over-the-counter medications and supplements. Some medications need to be stopped before surgery, and your surgeon needs to know about conditions like diabetes or heart disease so they can plan your care.

Hospital stay and recovery coverage

Knee replacement is usually done as an inpatient procedure, meaning you stay in the hospital overnight or for a few days. Your hospital stay is covered under Medicare Part A, not Part B. With Part A, you pay a deductible (currently $1,632 per benefit period in 2024) for the first 60 days of hospitalization, and then nothing for days 61 through 90.

After you leave the hospital, you may go to a skilled nursing facility (nursing home) for rehabilitation if you cannot care for yourself at home. Medicare Part A covers up to 100 days of skilled nursing care in a benefit period, though you pay a daily coinsurance amount starting on day 21. Your doctor must order this care, and a Medicare-approved facility must accept you.

If you go home instead of to a nursing facility, you can receive physical therapy at home or as an outpatient. Home health visits are covered under Part A if a doctor orders them and you are homebound. Outpatient physical therapy is covered under Part B, and you pay 20% of the approved amount.

Medicare Advantage plans and knee replacement

If you have a Medicare Advantage plan, the rules for knee replacement coverage are similar — your plan must cover it if it is medically necessary — but your costs and the process may be different. Some Medicare Advantage plans require you to use doctors within their network, and some require pre-authorization before surgery can be scheduled.

Call your Medicare Advantage plan's customer service number (on the back of your card) before you see a surgeon. Ask whether knee replacement is covered, what your copay or coinsurance will be, whether you need pre-authorization, and which surgeons and hospitals are in your network. Getting these answers before you schedule surgery can save you money and prevent delays.

Medicare Advantage plans often have an out-of-pocket maximum — a yearly limit on what you pay for covered services. Once you reach that limit, the plan pays 100% of covered costs for the rest of the year. Ask your plan what that maximum is so you know your worst-case cost for the surgery and recovery.

Questions to ask your doctor before surgery

Before you schedule knee replacement, ask your surgeon these questions: Why do you think I need knee replacement rather than other treatments? What does the surgery involve, and how long will recovery take? What are the risks and possible complications? Will Medicare cover this surgery, and what will my out-of-pocket cost be? Do you accept Medicare, and will you handle the pre-authorization paperwork?

Also ask: What should I do to prepare for surgery, and what medications should I stop taking? Will I need to stay in the hospital, and if so, for how long? What kind of physical therapy will I need after surgery, and for how long? When can I return to normal activities, and are there things I should not do during recovery?

Frequently Asked Questions

Does Medicare cover both knees if I need both replaced?

Yes, Medicare will cover replacement of both knees if both are medically necessary. However, surgeons typically replace one knee at a time, usually waiting several weeks or months between surgeries so you can recover and regain strength. Ask your surgeon about the timing and what Medicare will cover for each surgery.

What if my doctor says I need knee replacement but Medicare denies it?

You have the right to appeal a Medicare denial. Your surgeon's office can help you file an appeal and provide additional medical documentation. The appeal process takes time, so ask your surgeon whether it is worth pursuing or whether trying other treatments first might be a better option.

Will Medicare pay for a knee replacement if I have a Medicare Advantage plan?

Yes, Medicare Advantage plans must cover medically necessary knee replacement. However, your costs and the process may differ from Original Medicare. Contact your plan before scheduling surgery to understand your copay, whether pre-authorization is required, and which surgeons and hospitals are in your network.

Are there any knee replacement surgeries Medicare will not cover?

Medicare will not cover knee replacement if it is being done only for cosmetic reasons, to improve athletic performance, or to prevent future problems. It also will not cover experimental or investigational procedures. Your surgeon can tell you whether the specific type of surgery you need is covered.

How long after knee replacement can I travel on an airplane?

Most surgeons recommend waiting at least four to six weeks after surgery before flying, though this varies by person and by how well your recovery is going. Ask your surgeon when it is safe for you to fly. You may need a letter from your doctor to show airport security if you are wearing a brace or using a cane.