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

Medicare Part B pays for knee replacement surgery when a doctor determines it is medically necessary. The surgery itself, the hospital stay, and related care in the when ready recovery period are covered. You pay a share of the cost through your Part B deductible and coinsurance, but Medicare picks up the majority of the bill.

The key requirement is that your doctor must document that the knee replacement is necessary to treat a condition — usually severe arthritis, injury, or joint damage that has not improved with other treatments. Medicare does not cover the surgery if it is elective or cosmetic. Your doctor's office can tell you whether Medicare will cover your specific situation before you schedule the procedure.

Key Takeaways

  • Medicare Part B covers the surgeon's fee, hospital facility costs, and anesthesia for knee replacement when medically necessary.
  • You will owe your Part B deductible (currently $226 per year) plus 20 percent coinsurance for the surgery and related hospital care.
  • Physical therapy after surgery is covered by Medicare Part B, but only if ordered by your doctor and performed by a Medicare-approved provider.
  • Medigap or Medicare Advantage plans can reduce your out-of-pocket costs, but coverage varies by plan.
  • Your doctor must document medical necessity before surgery; Medicare will not cover the procedure if it is deemed elective.

What costs Medicare Part B actually covers

Part B covers the surgeon's professional fee, the hospital facility charge (including the operating room, nursing care, and bed), anesthesia, and any imaging or lab work done as part of the hospital stay. If your surgery is performed at an outpatient surgical center rather than a hospital, Part B still covers it, though the facility cost structure may differ slightly.

The coverage extends to the when ready post-operative period — typically the first few days after surgery while you are still in the hospital or recovery facility. If complications arise during that initial stay and you need extra days, those are covered as long as they are medically necessary.

Implants — the artificial joint itself — are included in the facility charge. You do not pay separately for the prosthetic knee. The surgeon's choice of implant does not change your Medicare coverage, though some surgeons may discuss implant options with you.

Your out-of-pocket costs under Part B

You pay your Part B deductible once per calendar year. After you meet the deductible, you owe 20 percent coinsurance on the surgeon's fee and related services. The hospital facility charge works differently — you typically owe a copay per day for the first few days, then a different copay for additional days, rather than 20 percent coinsurance.

The exact dollar amount depends on the surgeon's fee, the length of your hospital stay, and your location. A surgeon in a high-cost urban area may charge more than one in a rural area, which changes your coinsurance bill. Your surgeon's office or the hospital billing department can give you an estimate before surgery.

If you have a Medigap policy, it may cover some or all of your deductible and coinsurance. If you are in a Medicare Advantage plan, your costs depend on that plan's rules — some Advantage plans have lower coinsurance for surgery but may require you to use in-network surgeons.

Physical therapy coverage after surgery

Medicare Part B covers physical therapy ordered by your doctor after knee replacement. The therapy must be medically necessary and performed by a Medicare-approved physical therapist or facility. Most people need several weeks of therapy to regain strength and range of motion in the knee.

You pay 20 percent coinsurance for each therapy session after you meet your Part B deductible. There is no limit on the number of sessions Medicare will cover, as long as your therapist documents that the therapy is helping you improve and is still medically necessary. Your therapist will track your progress and communicate with Medicare if the sessions need to continue beyond what might be typical.

Therapy can happen in a clinic, a hospital outpatient department, or sometimes at home if your doctor orders it. Home therapy may be covered under Part B or, in some cases, under the home health benefit, depending on your situation and the type of care you need.

How to confirm coverage before surgery

Ask your surgeon's office to submit a coverage information request to Medicare before you schedule the procedure. This is called a pre-authorization or advance beneficiary notice (ABN). The surgeon's office sends your medical records and imaging to Medicare, and Medicare tells you in writing whether the surgery is covered.

This step is not required, but it protects you. If Medicare later denies the claim and says the surgery was not medically necessary, you have the written information to dispute it. Without it, you could end up responsible for the full bill.

If your surgeon's office does not offer to do this, you can contact Medicare directly at 1-800-MEDICARE and ask them to review your case. Have your doctor's notes and any imaging results ready when you call. Medicare typically responds within 5 to 10 business days.

Medicare Advantage and Medigap coverage differences

If you are in a Medicare Advantage plan, knee replacement is still covered, but your costs and provider choices may differ from Original Medicare. Many Advantage plans require you to use in-network surgeons and hospitals, and some require prior authorization before surgery. Your plan's summary of coverage will tell you the coinsurance amount and whether there are any waiting periods.

Medigap policies are designed to cover the gaps in Original Medicare — your deductible and coinsurance. A Medigap plan that covers surgery will pay some or all of your 20 percent coinsurance and may cover your Part B deductible. The exact coverage depends on which Medigap plan (A through N) you have. Plans G and N are popular for surgical coverage, but you should review your specific policy.

If you are switching from Advantage to Original Medicare, or vice versa, do it during the annual enrollment period (October 15 to December 7) to avoid penalties. If you need surgery before the next enrollment period, you are locked into your current plan type.

What Medicare does not cover

Medicare does not cover knee replacement if your doctor determines it is elective — meaning it would improve your quality of life but is not necessary to treat a medical condition. If you have mild arthritis and your doctor says you can manage it with medication and exercise, Medicare will not cover surgery.

Certain add-ons and upgrades are also not covered. If you choose a premium implant that is more expensive than the standard option, you may owe the difference out of pocket. Ask your surgeon whether the implant they recommend is the standard Medicare-covered option or a premium choice.

Travel costs, lodging if you need to stay away from home for surgery, and any care after you leave the hospital (except ordered physical therapy) are your responsibility. Some people travel out of state or out of country for surgery; Medicare covers the surgery itself but not the travel.

Frequently Asked Questions

Will Medicare cover knee replacement if I have arthritis in both knees?

Yes, Medicare covers surgery on both knees if both are medically necessary. You would typically have one knee done, recover, and then schedule the second surgery. Each surgery counts as a separate procedure with its own deductible and coinsurance.

What happens if Medicare denies my knee replacement as not medically necessary?

You have the right to appeal. Request a reconsideration within 180 days of the denial notice. Your surgeon can submit additional medical evidence showing why the surgery is necessary. If you disagree with the reconsideration, you can request a hearing before an administrative law judge.

Does Medicare cover revision surgery if my knee replacement fails?

Yes, if the original implant fails or wears out and your doctor determines revision surgery is medically necessary, Medicare covers it the same way it covers the first surgery. You will owe deductible and coinsurance again.

Can I choose any surgeon, or does Medicare require me to use a specific one?

Under Original Medicare, you can use any surgeon who accepts Medicare. Under a Medicare Advantage plan, you must use in-network surgeons unless you get prior authorization. Check your plan's provider directory before scheduling.

How long after surgery does Medicare cover physical therapy?

There is no time limit as long as the therapy is medically necessary and you are making progress. Most people need therapy for 4 to 12 weeks, but Medicare will cover longer if your therapist documents that you still need it and are improving.