If a surgeon has told you it is time for a knee replacement, there is a second question to ask before you book anything, and it is about which operation you get.
Most people know total knee replacement exists. Far fewer know that a partial is a separate operation with a different risk profile, and that plenty of candidates never get told about it. This post walks through the difference the way a surgeon explained it to us on the radio, what decides who gets which, and what the rehab looks like on our side of the handoff.
By The First Rehabilitation Team · Reviewed by Dr. Dave Kashuba, Ph.D.
The numbers a surgeon gave us on air
Orthopedic surgeon Dr. Richard Weiner, M.D., who has been in practice since before our clinic opened in 1991, laid this out on Episode 6 of the Pain 2 Power podcast. He trained in both engineering and medicine at the University of Pennsylvania and has thousands of hip and knee replacements behind him, so when he talks about how a knee is put together, we listen. Statistics show that over 40% of everyone receiving a total knee could have had a partial instead, he said, while in the United States only about 10% actually get one.
His explanation for the gap is not clinical. "Most of the surgeons who do total knees are not trained to do partials," he said, "so they don't even offer it as an option." Fewer than half of orthopedic surgeons do knee replacements at all. Of those, fewer than half do partials. Of those, fewer than half will do the lateral compartment.
All of which means the operation you are offered can depend on who you happen to be sitting across from. That's an uncomfortable thing to hear when you have already spent a year limping around the grocery store. It's also useful, because it tells you exactly what to ask.
What makes partial and total knee replacement different operations
The knee has separate compartments, including one on the inside and one on the outside. Arthritis does not always take all of them. A partial replaces only the worn one and leaves the rest of your knee alone. A total replaces the whole joint surface.
What happens to the ligaments
The structural difference Dr. Weiner emphasises is the ligaments. A total knee "requires dislocation of the joint," a much larger procedure, and the anterior cruciate ligament comes out. About half the time the posterior cruciate goes too. A partial preserves all of them, and that is the reason for the thing patients notice most: "a partial knee can feel like a normal knee, because all the ligaments are preserved." A total knee, in his words, never quite does. It is a tremendously successful operation and it still feels a little different.
He tied the feel of the knee directly to the ligaments, and the ligaments are what you will live with every time you step off a curb or turn for a ball on the pickleball court.
Pain, risk, and getting back to the court
His shorthand for the rest was a repeated phrase. Pain, less than half. Risk of infection, less than half. Time to get back to sport, less than half. Blood loss and clot risk, lower again, though the risks with a modern total knee are low to begin with.
Which compartment wears matters too. The inside of the knee goes about eight to ten times more often than the outside, which is the reason worn knees tend to look bow legged. The smaller group who wear the outside look knock kneed, and that lateral partial takes training that fewer surgeons have.
| Question | Partial knee | Total knee |
|---|---|---|
| What gets replaced | Only the worn compartment | The whole joint surface |
| The joint during surgery | Not dislocated | "Requires dislocation of the joint" |
| Cruciate ligaments | All preserved | ACL removed; the PCL about half the time |
| How it feels afterward | "Can feel like a normal knee" | Very successful, but feels a little different |
| Pain, infection risk, return to sport | Less than half of a total, on each | The baseline he compared against |
| Who performs it | A smaller group of surgeons; fewer still do the outside compartment | Most surgeons who replace knees |
| Long term | Well under one in ten end up converted to a total | Not discussed as a conversion question |
Who is a candidate for a partial knee replacement?
Not everyone, and the decision is not made from a scan alone. "You don't treat an X-ray, you treat the patient," Dr. Weiner said, and his sequence starts with your symptoms and your history, then a clinical exam, then imaging, including stress X-rays that show whether the other compartments are holding up.
A partial only makes sense if the parts of the knee you keep are healthy enough to carry you for years. If the stress views show the other compartments starting to go, a partial just postpones the conversation.
The question he weighs is durability. A small share of partials, well under one in ten, eventually need converting to a total. Over 90% do not. When the odds of it lasting look good, that is what he recommends.
Age is less of a barrier than people assume. He described doing a partial knee for a 95 year old patient of twenty years, who had done therapy and injections for as long as they worked and then decided she wanted the knee. Ninety-five. If you're in your eighties and assume nobody is going to bring up options with you, keep that story in your back pocket.
Questions to take to your surgeon
A good appointment takes a short list and the nerve to ask it. Here's the one we would bring:
- Which compartment of my knee is worn, and are the others holding up?
- Have I had stress X-rays, or would they change the picture?
- Am I a candidate for a partial, and do you perform both operations?
- If not, who would you send me to for a second look?
- What is your therapy protocol afterward, and when do you want it to start?
Dave's advice about choosing anyone who treats you applies here more than usual: do your homework, and do not take the recommendation from the person next to you in the Publix line.
Surgery is still the last resort
None of this is an argument for having a replacement. "Surgery is the last resort," Dr. Weiner said. "The first thing is conservative treatment."
That means avoiding what aggravates the joint, then therapy, then medication or a targeted injection, and only then bracing or an operation. On therapy he was direct about why it comes first: "physical therapy is key because you need to have strong muscles to stabilize the knee to have fewer symptoms." He also prefers injections to pills for a single joint, on the logic that you put the oil where it squeaks rather than exposing the whole body.
If you're still on the early rungs of that ladder, our post on knee arthritis treatment before surgery covers the conservative side in detail, including the four exercises Dave gave listeners and the weight math Dr. Weiner shared. And if your scan shows one small damaged spot rather than worn compartments, read how cartilage transplant knee recovery works, because that is a different conversation again.
Dave added one aside during the Weiner interview. He told Dr. Weiner he loses money on partials, because those patients need far less rehab than a total knee does.
What rehab looks like after a partial or total knee
Both operations need therapy, and the partial needs less of it. The work is the same in kind: restoring range, then rebuilding the muscles that support the joint, quadriceps first and glutes and calves alongside them, because the knee is carried from above and below.
Your surgeon's protocol sets the pace
We don't invent a timeline. Every surgeon has a protocol, some start therapy within days and some protect the repair longer, and we follow it exactly. Bring your post-op paperwork to the first visit. The evaluation takes about an hour, one-on-one, and it measures where you are today: how far the knee bends and straightens, how you walk, how you handle a step. Treatment usually starts that same day.
From there, the program on our knee pain page describes the shape of it: manual therapy for joint mobility, progressive strengthening of the quadriceps, hips and glutes, and functional retraining for stairs, walking distance and getting back to whatever you came in wanting to do. For some people that's eighteen holes at a course up in Jupiter. For others it's the stairs to a second-floor condo, or getting down on the floor with a grandchild and back up again.
We'd be guessing if we gave you a number of visits here, and a guess is worse than no answer. A partial and a total follow different timelines, and two people with the same operation recover differently. Your therapist sets milestones at the evaluation and re-checks them as you go, so you are never coming in for visits you do not need.
Should you do prehab first?
Prehab means building strength before the operation. Two surgeons on our show came at it from slightly different angles.
Dr. Rami Elkhechen, M.D., the sports medicine surgeon from Episode 7, does it routinely and put the case simply: "The stronger your base is as you're coming in, in terms of strength and your activity level, you're probably going to come out the other side much better in terms of recovery."
Dr. Michael Leighton, MD, an orthopedic surgeon with Palm Beach Orthopedic Institute in Palm Beach Gardens who performs robotic-arm assisted knee replacement, was more selective when he joined us for Episode 12. Prehab, he said, "is basically tuning this patient up for surgery prior to surgery and it's not a one-size-fits-all situation." He saves it mostly for people who have been away from activity and are deconditioned.
Those two views fit together better than they first sound. If you have been sitting more because the knee hurts, a few weeks of targeted work before surgery is cheap insurance. If you are still walking the beach every morning, you may already be in the shape your surgeon wants. You can start with the knee exercises Dave walks through on the show and bring the rest to an evaluation.
Paying for rehab after a knee replacement
Two thirds of the people we treat are 65 or older, so the Medicare questions usually come up on the first phone call. Our Medicare guide has the full detail. The short version for outpatient therapy under Original Medicare in 2026, from CMS figures, is a yearly Part B deductible of $283, then 20% of the Medicare-approved amount per visit. There is no yearly cap on therapy when the care is medically necessary. Past $2,480 in physical therapy charges for the year, the clinic adds the KX modifier to confirm the need is documented, and therapy carries on.
Medicare Advantage and the paperwork
Medicare Advantage plans cover the same benefit under their own rules, and they often want prior authorization before therapy starts. We request it for you. Either way, Medicare requires your doctor to certify the plan of care your therapist writes after the evaluation, and we chase that signature so it does not become one more errand. Our front desk verifies Medicare and commercial benefits before your first visit, so you know where you stand before you walk in.
One more practical note: we're a Medicare-certified Comprehensive Outpatient Rehabilitation Facility, a CORF, which means coordinated rehab at one location with physician review of the plan. There's a free lot right at the building on US-1, so the hardest part of the trip is usually getting in and out of the car, which, as it happens, is something we practice.
Bring us in early
If you are weighing a knee replacement, or recovering from one, we can help with the part that decides how well it goes. Ask your surgeon whether you are a candidate for a partial and whether they perform both. Then call us, before or after, whichever comes first.
We see patients from North Palm Beach and across the county, including Palm Beach Gardens. Call 561-624-4263 or request an evaluation. Read more about post-surgical rehabilitation, browse the physical therapy questions in our FAQ, or hear the full conversation on the Pain 2 Power podcast.
This article is general information, not medical advice. Every situation is different, so please consult a qualified professional about yours.