Yes, Medicare covers knee replacement surgery when it’s deemed medically necessary. The procedure is one of the most common surgeries among Medicare beneficiaries, and both Original Medicare (Parts A and B) and Medicare Advantage plans provide coverage. However, you’ll need to meet specific clinical criteria before Medicare approves the surgery, and your out-of-pocket costs will depend on whether you’re admitted as an inpatient or have the procedure done on an outpatient basis.
What Medicare Requires Before Approval
Medicare doesn’t cover knee replacement simply because you want one. The surgery must be “medically reasonable and necessary,” and CMS (the agency that runs Medicare) has laid out specific criteria your medical records need to document. The most important requirement: you must have tried non-surgical treatment for at least three months before surgery is considered. That means a documented trial of anti-inflammatory medications (or a documented reason you can’t take them) and supervised physical therapy.
Beyond the conservative treatment requirement, Medicare generally looks for three or more clinical indicators that surgery is warranted. These typically include imaging evidence of joint damage, significant pain or functional limitation, and the failed conservative therapy mentioned above. Your orthopedic surgeon and primary care provider will need to document all of this in your medical record before the procedure. If the documentation is incomplete, the claim can be denied even if the surgery was clearly needed.
How Costs Break Down Under Original Medicare
Your share of the bill depends heavily on the setting. If you’re admitted to the hospital as an inpatient, the surgery falls under Part A. You’ll owe the Part A inpatient hospital deductible, which covers the first 60 days of a hospital stay per benefit period. After that deductible, Part A covers the rest of the inpatient stay with no additional coinsurance for the first 60 days.
If the procedure is performed on an outpatient basis (increasingly common for uncomplicated total knee replacements), it falls under Part B. In 2025, the Part B annual deductible is $257. After meeting that deductible, you pay 20% of the Medicare-approved amount for the surgery and related services. For a procedure that can run $30,000 to $50,000 or more before Medicare’s negotiated rates, that 20% coinsurance on the approved amount can still be a significant sum. This is where Medigap (supplemental insurance) becomes valuable, as many Medigap plans cover some or all of that 20%.
Medicare Advantage Plans Work Differently
If you have a Medicare Advantage (Part C) plan instead of Original Medicare, you’re still covered for knee replacement, but the rules around accessing that coverage differ in important ways. Medicare Advantage plans frequently require prior authorization before surgery, meaning your plan must approve the procedure in advance. Each plan sets its own prior authorization requirements, so you’ll need to check with yours directly.
Medicare Advantage plans also use provider networks. You may need to use an in-network orthopedic surgeon and an in-network hospital, or face higher costs or a denied claim. Original Medicare, by contrast, historically has rarely required prior authorization, and you can generally see any provider who accepts Medicare without needing permission first. The tradeoff is that many Medicare Advantage plans have annual out-of-pocket maximums that cap your total spending, something Original Medicare alone does not offer.
What’s Covered After Surgery
Recovery from knee replacement typically involves weeks of physical therapy, and Medicare covers this as well. Part B pays for medically necessary outpatient physical therapy after you meet the $257 annual deductible, with you responsible for 20% of the approved amount. There is no annual cap on how much Medicare will pay for medically necessary therapy sessions, so if your recovery requires extensive rehabilitation, coverage continues as long as your doctor certifies the ongoing need.
Medicare Part B also covers durable medical equipment you’ll likely need during recovery. Walkers, canes, crutches, and other assistive devices are covered when your doctor orders them for home use. The same cost-sharing applies: 20% of the Medicare-approved amount after your Part B deductible. Your supplier must accept Medicare assignment for these rates to apply, so confirm this before picking up equipment.
If you need skilled nursing care or home health services after discharge, Medicare may cover those as well. Home health care is covered at no cost to you when ordered by your doctor, provided you’re homebound and need skilled care. Skilled nursing facility stays are covered under Part A if you were an inpatient for at least three consecutive days prior to transfer, covering up to 20 days with no coinsurance and days 21 through 100 with a daily coinsurance amount.
How to Minimize Your Out-of-Pocket Costs
The single biggest factor in reducing what you pay is whether you have supplemental coverage. A Medigap policy (particularly Plans F, G, or N) can cover most or all of your coinsurance and deductible obligations. If you’re on a Medicare Advantage plan, check your plan’s maximum out-of-pocket limit and whether your preferred surgeon and facility are in-network before scheduling surgery.
Ask your surgeon’s billing office for a cost estimate that reflects Medicare’s approved amounts, not the hospital’s list price. Request confirmation that all providers involved in your care, including the anesthesiologist, accept Medicare assignment. Out-of-network providers during an otherwise in-network hospital stay are a common source of surprise bills. Finally, make sure your medical records clearly document the three-plus months of conservative treatment. A denied claim due to insufficient documentation can leave you responsible for the full cost while you appeal.