Short answer
Medicare covers medically necessary knee replacement; the part depends on the setting.
Medicare.gov says Medicare covers many medically necessary inpatient and outpatient surgical procedures. For a knee replacement, Part A applies if you are admitted as an inpatient and Part B applies if it is done as an outpatient. Medicare.gov says what you pay depends on whether you are an inpatient or outpatient, so that status is worth confirming before surgery.
Start here
What you actually came to find out
Plain answers first. Sources stay below for checking details.
Is it covered?
Medicare.gov says Medicare covers many medically necessary surgeries.
Which part pays?
Part A if inpatient, Part B if outpatient.
Why does status matter?
Medicare.gov says your cost depends on inpatient or outpatient status.
Does Medigap help?
A Medigap plan pays its share after Medicare approves the service.
Coverage
Medically necessary
Medicare.gov says Medicare covers many medically necessary surgical procedures.
Source trail: Medicare.gov
Inpatient
Part A
Medicare.gov says Part A covers inpatient hospital care.
Source trail: Medicare.gov
Outpatient
Part B
Medicare.gov says Part B covers outpatient care.
Source trail: Medicare.gov
Your cost
Depends on setting
Medicare.gov says what you pay depends on inpatient or outpatient status.
Source trail: Medicare.gov
The real planning question is your inpatient-versus-outpatient status, because it changes which part pays and what you owe.
Neutral landscape
The shape of the question
Medicare.gov is the main source because it states that Medicare covers many medically necessary inpatient and outpatient surgeries.
Source trail: Medicare.gov
The part that pays depends on setting, and Medicare.gov splits inpatient care under Part A and outpatient care under Part B.
Source trail: Medicare.gov
The cost question turns on status, which Medicare.gov says changes what you pay.
Source trail: Medicare.gov
The supplement layer matters because Medicare.gov says Medigap pays its share after Medicare approves a covered service.
Source trail: Medicare.gov
Curator core
What the authorities say
These sources are here for the reader who wants to check the work. The plain-English answer stays above them.
Source 01
Medicare.gov
Surgery Coverage
Medicare.gov explains that Medicare covers many medically necessary inpatient and outpatient surgical procedures, with costs that differ by setting.
Source framing
Medicare.gov says Medicare covers many medically necessary surgical procedures, and that what you pay depends on whether you are an inpatient or outpatient.
Strongest for: whether a surgery like knee replacement is covered
Read at Medicare.govSource 02
Medicare.gov
Parts of Medicare
Medicare.gov explains the parts of Medicare, including Original Medicare, Medigap lettered plans, and Medicare Advantage as Part C.
Source framing
Medicare.gov says Medigap plans are named by letters and supplement Original Medicare, while Medicare Advantage is Part C, an alternative way to get Medicare.
Strongest for: the difference between Medigap plan letters and Medicare Advantage
Read at Medicare.govSource 03
Medicare.gov
How Medigap Works
Medicare.gov explains that Medigap supplements Original Medicare, that policies sold after 2005 do not include drug coverage, and how Medigap pays after Medicare.
Source framing
Medicare.gov says a Medigap policy is a supplement to Original Medicare, that Medigap sold after 2005 does not include drug coverage, and that Medigap is different from a Medicare Advantage Plan.
Strongest for: how Medigap supplements Original Medicare and pairs with Part D
Read at Medicare.govPlain-English forks
The forks people face
Most retirement questions hide a few smaller decisions. These are the practical pieces that change the plan.
Inpatient or outpatient?
Why it matters: Medicare.gov ties your cost and the paying part to this status.
In real life: This fork changes Part A versus Part B and what you owe.
What to look at: What to look at: your hospital admission status before surgery.
Do you have a Medigap policy?
Why it matters: A supplement pays its share after Medicare approves the service.
In real life: This fork changes your out-of-pocket amount.
What to look at: What to look at: your Medigap plan’s cost-sharing.
Is the surgery documented as medically necessary?
Why it matters: Medicare.gov ties coverage to medical necessity.
In real life: This fork is the coverage trigger.
What to look at: What to look at: your physician’s documentation.
Common questions
Quick answers
Short, plain answers for the questions people usually have next. The source trail stays available below.
Does Medicare cover knee replacement?+
Medicare.gov says Medicare covers many medically necessary inpatient and outpatient surgeries, and a knee replacement is a surgical procedure covered when medically necessary.
Will Part A or Part B pay?+
Medicare.gov says Part A covers inpatient hospital care and Part B covers outpatient care, so the answer depends on how the surgery is performed.
Why does inpatient versus outpatient matter?+
Medicare.gov says what you pay depends on whether you are an inpatient or outpatient.
Does my Medigap Plan N help?+
Medicare.gov says a Medigap policy pays its share after Medicare pays the approved amount, so Plan N helps with the cost you owe.
How can I confirm my status?+
Ask the hospital whether you are being admitted as an inpatient or treated as an outpatient before the surgery.
How this page is curated
This page uses Medicare.gov surgery coverage, parts-of-Medicare, and how-Medigap-works. It centers inpatient-versus-outpatient status because Medicare.gov ties cost to that distinction.
Read the planner methodologyTrust anchor
Sources used on this page
Every source named above is listed here in one place.
Medicare.gov. Surgery Coverage
https://www.medicare.gov/coverage/surgeryMedicare.gov. Parts of Medicare
https://www.medicare.gov/basics/get-started-with-medicare/medicare-basics/parts-of-medicareMedicare.gov. How Medigap Works
https://www.medicare.gov/health-drug-plans/medigap/basics/how-medigap-works
Before you act on this
This plan is educational. It is not personalized financial, tax, or insurance advice. Projections illustrate the math, they do not predict the future. Talk to your own licensed financial professional before acting on any of it.