Knee replacement
An operation that replaces a worn or damaged knee joint with an artificial one to ease pain and help you move more easily.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- A knee replacement is mainly for pain relief and better movement when severe knee arthritis is affecting your daily life.
- Around 1 in 5 people are not fully satisfied or still have some pain afterwards, so it does not guarantee a perfect, pain-free knee.
- Recovery is gradual and depends heavily on your own physiotherapy; it can take up to a year to feel the full benefit.
- Most knee replacements last around 20 years, but no implant is guaranteed forever and some people need a further (revision) operation.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your surgeon will give you advice for your situation.
Often gives good relief from knee pain that has not settled with other treatments
Your knee pain is mild or controlled well enough with exercise, weight management and pain relief.
A physiotherapist helps you stand, walk a few steps with aids and start gentle knee bending. You are given pain relief and clot-prevention treatment.
A clear, supervised physiotherapy plan with goals for movement.
A physiotherapist helps you stand, walk a few steps with aids and start gentle knee bending. You are given pain...
You keep doing your exercises several times a day to regain bend and straightening. The wound heals; swelling is...
Walking usually becomes easier and you rely less on aids. Bending continues to improve with effort. Driving may be...
Strength, bend and stamina continue to improve. Many return to office work and gentle activity. Swelling and night...
What is a knee replacement?
A knee replacement is an operation to replace worn or damaged surfaces of the knee joint with artificial parts (an implant) made of metal and plastic. It is most often done for osteoarthritis, when the smooth cartilage in the knee wears away and the bones rub together, causing pain and stiffness.
In a total knee replacement, the worn surfaces of the joint are resurfaced. In a partial (unicompartmental) knee replacement, only the damaged part of the knee is replaced, which suits some people whose arthritis affects just one side.
The main aim is to reduce pain and improve movement so you can do more in daily life. It does not make the knee 'like new', and a meaningful minority of people still have some pain or stiffness afterwards.
Surgery is usually considered only once pain, stiffness or loss of movement is affecting your daily life and non-surgical treatments — such as exercise, weight management, painkillers and physiotherapy — have not given enough relief.
Types & techniques
There isn't one single operation. The right approach depends on you — which is something to discuss with your surgeon.
Total versus partial knee replacement
| Total | Partial | |
|---|---|---|
| Replaces | Whole joint surface | One worn part only |
| Suits | Wider arthritis | Arthritis on one side |
| Recovery | Often slower | Often quicker |
| Further surgery | Less likely | More likely later |
Not everyone is suitable for a partial replacement. Your surgeon decides based on where and how badly the knee is worn.
Preparing for your surgery
- Talk through why surgery is being suggested, what it can and cannot fix, and whether it is the right time for you.
- Ask whether you have tried enough non-surgical treatment first, such as physiotherapy, weight management and pain relief.
- Tell the team about all your health conditions and medicines, including blood thinners.
- If you smoke, stopping beforehand lowers your risk of wound and chest problems; managing weight and other conditions also helps.
- Go to any pre-operative assessment, where blood tests, heart checks and an anaesthetic review may be arranged.
- Start any 'pre-hab' exercises advised, as stronger muscles before surgery can help recovery.
- Plan your home and arrange help, time off work and a lift home, as you will not be able to drive at first.
What happens
The operation is usually done under a spinal anaesthetic (numbing you from the waist down), a general anaesthetic (asleep), or a combination, often with extra pain relief around the knee. Your anaesthetist will discuss the safest choice for you.
The surgeon makes a cut over the front of the knee, removes the worn surfaces and fits the new parts, which may be cemented or fitted so bone grows onto them. The operation usually takes around one to two hours.
Afterwards you are watched closely as the anaesthetic wears off. A physiotherapist usually helps you start moving the knee and standing on the same day or the next day. You are given pain relief and medicine to lower the risk of blood clots, and bending exercises begin early.
Is this operation right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- Your knee pain is mild or controlled well enough with exercise, weight management and pain relief.
- You have an active infection, or a medical condition that makes major surgery and anaesthetic too risky right now.
- Your pain comes mainly from another source, such as the hip or back, rather than the knee itself.
- You are not able or willing to take part in the physiotherapy that recovery depends on.
Delay surgery if…
- You have an active infection anywhere, including skin, urine, chest or dental infection.
- Other health conditions (such as poorly controlled diabetes, heart or chest problems) need optimising first.
- You are still working through non-surgical options and your symptoms are bearable.
- Your weight, smoking or another modifiable factor could be improved first to lower your risk.
- You cannot yet arrange the help and time off you will need to recover safely.
Alternatives to discuss
- Structured exercise and physiotherapy to strengthen the muscles around the knee.
- Weight management to reduce load on the joint.
- Pain relief and, in some cases, a steroid injection for temporary relief.
- Walking aids, supportive footwear and changes to daily activities.
- Waiting and reviewing, as it is reasonable to delay surgery while symptoms are manageable.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Anaesthetic choices
The safest option depends on the operation, your health, the facility and your surgeon/anaesthetist. Ask what is planned and why.
Benefits
- Often gives good relief from knee pain that has not settled with other treatments
- Can improve how far and how comfortably you can walk
- Can make stairs, standing and everyday tasks easier
- May reduce the need for regular strong painkillers over time
- For many people, improves overall quality of life and independence
Risks & complications
- Pain, bruising and swelling around the knee for several weeks
- Stiffness and a limited bend at first, which improves with exercises
- Tiredness and reduced stamina while you recover
- Some lasting numbness around the scar
- Ongoing aching or 'awareness' of the knee in some people
- Wound infection, usually treated with antibiotics
- Blood clot in the leg (DVT), which the team takes steps to prevent
- A knee that stays stiff and does not bend as far as hoped
- Ongoing pain or a feeling of instability
- Nerve or blood vessel injury near the knee
- Deep infection in the joint that may need further surgery
- Blood clot travelling to the lungs (pulmonary embolism), which can be serious
- Fracture of the bone around the implant
- Loosening or wearing of the implant over time, needing a revision operation
- Serious medical complications such as heart attack, stroke, or, very rarely, death
The most important things to discuss are that around 1 in 5 people are not fully satisfied or still have some pain, and that infection, blood clots, stiffness and eventual loosening can occur. Your personal risk depends on your age, weight, other health conditions and the state of the knee. Ask your surgeon how these apply to you.
Published figures to discuss
Outcomes are generally good, but figures vary by patient, surgeon, implant and how 'success' is measured. Importantly, satisfaction depends not just on the surgery but on expectations and pre-existing pain. The figures below are cautious and should be discussed in the context of your own health.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Not fully satisfied / ongoing pain | Around 1 in 5 (about 20%) in systematic reviews | More likely if pain is mild before surgery, or with anxiety, low mood or other pain conditions. | UK SAFE — mid–late term revision risk after knee replacement — PMCpmc.ncbi.nlm.nih.govPublished figure |
| Needing revision surgery | Less than about 1 in 20 within roughly 13 years in NJR patient-facing data; lifetime risk is higher for younger patients | Higher over a longer lifetime, in younger or more active people, and after partial replacement. | UK SAFE — mid–late term revision risk after knee replacement — PMCpmc.ncbi.nlm.nih.govPublished figure |
| Deep infection of the joint | Uncommon, generally around 1–2% or lower after primary surgery, higher after revision or in higher-risk patients | Can need further surgery; risk is higher in some health conditions and in revision operations. | UK SAFE — mid–late term revision risk after knee replacement — PMCpmc.ncbi.nlm.nih.govPublished figure |
| Blood clot on the lungs (pulmonary embolism) | Rare, usually well under 1% with modern clot prevention, but serious | Clot-prevention medicine and early movement are used to reduce the risk. | UK SAFE — mid–late term revision risk after knee replacement — PMCpmc.ncbi.nlm.nih.govPublished figure |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
Recovery — what to expect, and when
Recovery is gradual and needs your active effort, especially exercises to regain movement. Many people feel their old pain ease within weeks, but rebuilding strength and a good bend takes months, and reaching the final result can take up to a year.
- Swelling and warmth around the knee for weeks to months
- Discomfort and stiffness, especially first thing or at night
- A limited bend at first that improves with regular exercises
- An area of numbness to the outer side of the scar
- Slow, steady gains rather than a sudden return to normal
Aftercare
- Do your physiotherapy exercises regularly — regaining movement depends on this.
- Use ice, elevation and pain relief as advised to manage swelling.
- Keep the wound clean and dry, and watch for signs of infection.
- Take any clot-prevention medicine exactly as directed.
- Build up walking gradually and use your aids until you feel steady.
- Avoid high-impact activity such as running and jumping unless cleared.
- Keep follow-up appointments so healing and movement can be checked.
- Tell future dentists and doctors that you have a knee implant if asked.
- Crutches or a frame arranged
- Ice packs and a way to elevate the leg ready at home
- Trip hazards (loose rugs, cables) cleared
- Help arranged for the first 1–2 weeks
- Pain relief and clot-prevention medicine collected
- Time off work and a lift home booked
- Clinic and out-of-hours contact numbers saved
Scars and how they heal
You will have a scar down the front of the knee. It is usually firm and pink at first and fades over months. Numbness to the outer side of the scar is common and may be lasting, because small skin nerves are crossed during surgery. Protecting the wound from strong sun while it heals helps it settle.
⚠ Get urgent help if…
- Increasing redness, heat, swelling or discharge from the wound (possible infection)
- A high temperature or feeling generally unwell after surgery
- Calf pain, swelling, redness or warmth (possible blood clot)
- Sudden breathlessness or chest pain — call 999, as this may be a clot on the lungs
- Severe pain, a sudden inability to move the knee, or the leg giving way
- Bleeding that will not stop, or a wound that opens up
Who to contact: your surgeon or clinic first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your surgeon gives you.
Results & realistic expectations
A good result usually means much less knee pain and easier movement, letting you return to many everyday activities. However, a knee replacement is not a perfect new joint: around 1 in 5 people are not fully satisfied, often because of ongoing pain, stiffness or an unfamiliar feeling in the knee.
It does not treat arthritis in other joints, and high-impact sport is generally not advised. Your surgeon should be honest about what level of comfort and activity is realistic for you, and about the chance of some residual symptoms.
Most knee replacements last around 20 years or more. National joint registry data show that most people have less than a 1 in 20 chance of needing revision surgery within about 13 years. No implant is guaranteed forever, and younger or more active people, and those who have a partial replacement, are more likely to need a further operation during their lifetime.
Combining with other procedures
Knee replacement is usually done one knee at a time. If both knees are badly affected, surgery is often staged, though some centres consider doing both together in carefully selected patients. This should be a clear, individual discussion about the added risks and the demands on your recovery.
Follow-up & long-term care
You will usually be reviewed after surgery to check the wound, your movement and progress with physiotherapy. Many people are then followed up at intervals, sometimes with X-rays, to check the implant over the years. You should be told who to contact if you have concerns such as new pain, swelling, stiffness or signs of infection.
- Keep up strengthening and mobility exercises long term
- Manage your weight to reduce load on the new joint
- Stay active with lower-impact activities your team recommends
- Attend any long-term implant check-ups offered
- Report new or worsening knee pain or instability rather than ignoring it
Revision and secondary surgery reality
- No implant lasts forever; some people need a revision as parts wear or loosen.
- Partial knee replacements are more likely than total ones to need further surgery later.
- Persistent stiffness sometimes leads to a procedure to free up the knee under anaesthetic.
- Infection, fracture around the implant or instability can also lead to further surgery.
Ask your surgeon for their own revision rate, what counts as a revision, and what is included in the written aftercare policy.
What good aftercare looks like
- A clear, supervised physiotherapy plan with goals for movement.
- Written advice on swelling control, wound care and clot prevention.
- A named contact and out-of-hours route for problems such as infection.
- Planned follow-up, sometimes with X-rays, to check the implant over time.
- Honest advice about activity limits and the chance of some residual symptoms.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The surgeon's fee and the anaesthetist's fee
- Hospital or facility fee, theatre time and length of stay
- The type of implant used and whether the kneecap is resurfaced
- How complex your case is, including any previous knee surgery
- Physiotherapy and rehabilitation included in the package
- Follow-up appointments and any X-rays
- What is covered if a complication or further surgery is needed
- The surgeon's and anaesthetist's fees
- The hospital, theatre and inpatient stay
- The implant and any equipment such as crutches
- Physiotherapy and follow-up appointments
- What happens, and who pays, if a complication occurs
- The cancellation and rescheduling policy
- How any revision surgery would be funded
On the NHS? Knee replacement is widely available on the NHS when knee damage is severe and other treatments have not helped; private care may be chosen for shorter waits or choice of surgeon.
You're entitled to your total cost in writing — including aftercare and any revision — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Implying the knee will feel completely normal or fully pain-free.
- Not mentioning that around 1 in 5 people are not fully satisfied.
- Not discussing non-surgical options or whether it is the right time to operate.
- No clear plan for physiotherapy, follow-up or who to contact with problems.
- Not setting realistic limits on high-impact activity and sport.
Marketing red flags
- Claims of a 'quick' or 'simple' knee replacement that play down major surgery.
- Promises of a perfect, pain-free knee or a return to all previous sports.
- Heavy promotion of one 'special' implant, robot or approach without balanced evidence.
- Before-and-after stories that ignore months of rehabilitation.
- No mention of revision, infection, stiffness or blood-clot risk.
Choosing a surgeon safely
- Check your surgeon is on the GMC Specialist Register for this area.
- Make sure they practise at a CQC-registered location, and look for membership of bodies like BAAPS or BAPRAS.
- You're entitled to a two-stage consent process with time to reflect (a cooling-off period). The surgeon who will operate must consent you — not a salesperson.
- Be wary of pressure: time-limited offers, discounts or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including aftercare and any revision — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good surgeon will welcome every one of these.
- Why do you think I need a knee replacement now, rather than continuing other treatments?
- Am I suitable for a partial knee replacement, or do I need a total one?
- What are my personal chances of ongoing pain or stiffness afterwards?
- What are my risks of infection, blood clots and further surgery?
- What does the rehabilitation involve and how much bend should I expect?
- What activities will I realistically be able to do afterwards?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the surgeon who carries out my operation, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this operation not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Will a knee replacement make my knee pain-free?
How long does a knee replacement last?
How long is the recovery?
What is the difference between a total and a partial knee replacement?
Can I have it on the NHS?
Do I need surgery now, or can I wait?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — Knee replacement NHS — Knee replacement: Risks National Joint Registry — Knee replacement (patients) NICE NG226 — Osteoarthritis in over 16s: diagnosis and management Patient satisfaction after total knee replacement: systematic review — PMC UK SAFE — mid–late term revision risk after knee replacement — PMC
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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