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KNEE REPLACEMENT
How Long Does a Knee Replacement Last?
The honest answer: it depends. On the implant, on you, and on what you do after surgery. Here’s what the data says.
The Short Answer
Modern knee replacements typically last 15–20+ years. That’s the number most surgeons quote, and it’s backed by decades of joint registry data. Many last longer. Some don’t make it to 15. The difference usually isn’t the brand of implant. It’s the patient it’s put into, and what happens in rehab and in the years after.
If you’re having surgery in your mid-60s or later, there’s a good chance your implant outlives you. If you’re having it at 50, you’re likely looking at a second surgery at some point. That’s a conversation worth having with your surgeon up front. Not a reason to avoid the first one.
What the Registry Numbers Actually Say
National joint registries track hundreds of thousands of knee replacements over decades, so this isn’t guesswork. The broad picture: roughly 90% of knee replacements are still functioning at 15 years. At 20 years, survival rates are still high, commonly cited in the 80–90% range depending on the registry and implant type.
A few things worth knowing behind those numbers:
- “Still functioning” doesn’t mean “as good as new.” Survivorship means the implant hasn’t been revised. Some functioning implants are pain-free and excellent; some patients live with minor limitations without needing another operation.
- The numbers keep improving. Modern polyethylene (the plastic liner in the joint) is more wear-resistant than the materials used 20 years ago. Today’s implants are expected to outlast the registry curves built on older designs.
- Partial replacements revise sooner. Worth knowing if you’re comparing options. Our breakdown of partial vs total knee replacement covers the rehab differences too.
What Wears a Knee Replacement Out Faster
Implants fail for a few predictable reasons. The mechanical ones are the ones you can influence:
- Age at surgery. A 55-year-old puts 25–30 years of use on an implant; a 70-year-old puts 10–15. Younger patients revise more often. Not because the implant is worse, but because it gets used longer and harder.
- Body weight. Every step loads the implant. More weight means more wear per step, over millions of steps. Weight management is one of the few longevity levers fully in your control.
- High-impact activity. Running and jumping hammer the plastic liner, which is the wear item in the joint. This doesn’t mean you should be sedentary. It means choosing the right activities.
- Poor alignment or abnormal loading. An implant that moves the way it was designed to moves less wears less. This is where rehab quietly matters more than people think (more below).
Some failures are out of your hands: infection, rare early loosening. Those are uncommon and they’re your surgeon’s territory, not yours.
The revision question. A revision (re-do) surgery is more complex than the first operation. There’s less bone to work with and recovery is typically harder. That’s the real argument for protecting your first implant: you want the first one to be your only one.
What Makes One Last 25 Years
The patients who get decades out of a knee replacement tend to share a profile:
- Healthy weight. Or they got there after surgery.
- Low-impact cardio: cycling, swimming, walking, doubles tennis and golf over running and singles tennis. The joint loves movement; it just dislikes pounding.
- Strong quads and full range of motion. This is the rehab piece. A knee that bends and straightens fully and is driven by strong quadriceps moves the way the implant was engineered to move. A stiff, weak knee compensates. And compensations load the implant unevenly.
- They stay active. The 25-year knees belong to people who kept moving, not people who babied the joint into weakness. Muscle protects implants.
How Rehab Protects Your Implant
This is the part most patients underestimate. Rehab doesn’t just get you walking again. It sets the mechanical conditions your implant will live in for the next two decades.
- Full range of motion first. A knee that can’t fully straighten changes your gait: shorter steps, more force through the joint, uneven loading. Getting ROM back early is the single highest-leverage rehab goal. Especially extension. If your knee won’t straighten, that’s a problem worth reading about: why your knee won’t straighten after knee replacement.
- Quad strength second. The quadriceps are the knee’s shock absorber. Weak quads mean every step lands harder on the implant. Progressive strengthening is what protects the joint long term. Not just the hospital’s six weeks of basics, but a real program.
- The hospital pathway gets you started, not finished. BC’s standard post-op pathway covers about six weeks. That’s enough to get you walking and functional. It isn’t a strength program built for a 20-year implant. Continuing with your own physiotherapist after the pathway ends is where the long game is won.
Our week-by-week knee replacement recovery guide walks through what each phase should look like, including where the funded hospital visits end and your own rehab takes over.
Frequently Asked Questions
Do knee replacements “expire” at 15 years?
No. Fifteen years is a population average, not an expiry date. Plenty of implants function well past 20 years, especially in older patients with healthy weight and low-impact lifestyles. Your surgeon monitors the implant with periodic X-rays; a worn implant usually gives warning signs (pain, swelling, instability) well before it becomes urgent.
Can I run on a knee replacement?
Most surgeons say no. Running and high-impact sports wear the plastic liner faster and shorten the implant’s life. Cycling, swimming, walking, hiking, golf and doubles tennis are the encouraged alternatives. If running is non-negotiable for you, that’s a specific conversation to have with your surgeon. Not something to decide on your own.
What are the signs a knee replacement is wearing out?
The usual sequence: new or returning pain in the knee, swelling after activity that didn’t used to cause it, a feeling of looseness or instability, and reduced range of motion. These symptoms can have other causes. But they always warrant an assessment and an X-ray, not a wait-and-see approach.
Is a younger patient better off waiting for surgery?
Sometimes, but waiting has its own cost: years of pain, deconditioning, and compensatory damage to the other knee and hips. A 55-year-old who waits until 65 has lost a decade of activity. And enters surgery weaker, which hurts both recovery and implant longevity. This is a decision for you and your surgeon, with honest math about your age, weight, and activity level.
Protecting Your New Knee Starts in Rehab.
1-on-1 post-op physiotherapy in Richmond, BC. After your hospital pathway ends.
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