Before a knee replacement, the facts that matter most are these: you walk on the day of surgery, go home in 1 to 4 days, stop using walking aids at about 6 weeks, and take 4 months to a year to recover fully. Pain is worst in the first few weeks, infection affects about 1 in 100 knees, and a 2019 Lancet analysis found 82% of total knee replacements still in place after 25 years. The work you do before surgery, on weight, fitness, smoking and your home, shapes how the first weeks go.
When is a knee replacement the right decision?
A knee replacement is the right decision when pain disrupts sleep or daily life, other treatments have failed, and you understand what the surgery and recovery involve. Those are the MedlinePlus criteria, which add that it is also considered when you cannot walk and care for yourself. The Cleveland Clinic says knee arthritis is the most common reason, with arthritis after a fracture a rarer one.
The NHS lists the alternatives an orthopaedic surgeon expects you to have tried first:
- Losing weight to reduce strain on the knee if you are overweight.
- Low-impact exercise such as swimming, walking or cycling, and strengthening the knee muscles with a physiotherapist.
- Pain relief medicines, gels or creams.
- Steroid (hydrocortisone) injections into the joint.
- Other operations such as arthroscopy or osteotomy, which the NHS says are not suitable for everyone.
Age matters for the implant, not for the operation. MedlinePlus says knee replacement is most often done in people aged 60 and over, and that younger patients may put extra stress on the artificial knee and wear it out early. The Cleveland Clinic says a partial replacement, which replaces only the damaged part of the knee, is more common in younger adults with an injury, and the NHS says recovery from a partial replacement is shorter.
What should you do in the weeks before surgery?
Use the waiting time to get stronger, lighter, smoke-free and organised at home. The NHS says doctors may advise exercises before and after surgery, a healthy diet, weight management and stopping smoking, and that these matter because waiting lists can be long. MedlinePlus says continuing to smoke slows wound and bone healing, and the AAOS advises stopping at least 4 weeks before surgery.
Pre-surgery exercise, often called prehab, has modest evidence. A 2019 systematic review in the Indian Journal of Orthopaedics pooled five randomised trials and found preoperative exercise shortened hospital stay by 0.93 days on average, with moderate-quality evidence, but found no significant difference in pain or function scores, where the evidence was very low quality. A physiotherapist can also teach the crutch and stair technique you will need on day one, which MedlinePlus recommends practising beforehand.
Weight is the other lever. The AAOS says a BMI above 40 raises the chance of serious complications during and after surgery, that risk rises with BMI without a sudden cut-off, and that obesity raises the risk of wound-healing problems and infection. A 2018 Mumbai study of 213 patients with BMI 30 to 39.9 reported good knee scores and 0% deep infection, so moderate obesity alone need not stop surgery; the study excluded BMI 40 and above.
MedlinePlus lists the practical steps: tell the team every medicine, including supplements; you may be asked to stop aspirin, ibuprofen or blood thinners 1 to 2 weeks before; and report any cold or fever. The Cleveland Clinic adds a dental check, because mouth bacteria can reach the new joint.
What does the recovery timeline really look like?
Recovery runs from walking on the day of surgery to full recovery at 4 months to a year; the table puts dates to it from NHS, MedlinePlus and Cleveland Clinic guidance. The NHS says age and general health change the pace.
| Stage | What to expect | Source |
|---|---|---|
| Day 0 to 1 | Walking with a frame or crutches, helped by physiotherapists; painkillers started | MedlinePlus, NHS |
| Day 1 to 4 | Home when you can get around safely on crutches; compression stockings fitted | NHS (MedlinePlus: same day to 2 days) |
| Day 5 to 6 | Shower allowed if the surgeon agrees; do not soak the wound | MedlinePlus |
| About day 10 | Stitches or clips removed | NHS |
| Weeks 1 to 3 | Pain at its worst; daily home exercises; ice 20 minutes several times a day | Cleveland Clinic |
| 3 weeks | Driving after a partial replacement, with doctor's agreement | NHS |
| 6 weeks | Walking without an aid; stockings off; follow-up visit; driving after a total replacement; most usual activities | NHS, Cleveland Clinic |
| 6 to 12 weeks | Return to work, depending on the job | NHS |
| 3 months | Heavy housework such as carrying shopping can restart | NHS |
| 4 months to 1 year | Full recovery; physiotherapy may continue for a few months | MedlinePlus, Cleveland Clinic |
Indian stays run a little longer: the 2018 Mumbai series discharged patients on day 3 to 5. The NHS says no cross-legged sitting for the first 6 weeks and no kneeling until the doctor says it is safe, which rules out floor sitting and Indian-style toilets early on; arrange a chair, a commode seat and a raised bed before admission.
How much pain should you expect, and how is it managed?
Expect real pain for the first few weeks, controlled rather than absent, and improving month by month. The Cleveland Clinic says pain is usually worst in the first few weeks and is treated with a combination of prescription painkillers, anti-inflammatory tablets if they are safe for you, and paracetamol. The NHS says you take painkillers for several days after surgery because the knee will be sore, and that you should keep the leg raised to reduce swelling and avoid standing for long periods because the ankle swells.
MedlinePlus gives two useful rules:
- Take your pain medicine when pain starts, and about 30 minutes before exercise or physiotherapy, so you can do the exercises.
- Do not sit for more than 45 minutes at a time; short, frequent walks are better than one long one.
The NHS says starting the exercise programme early improves long-term strength and movement and prevents complications, so pain control exists to make the exercises possible, not to let you rest. Ongoing pain and stiffness is on the NHS list of complications, and bending the knee can stay difficult for some people.
Opioid painkillers cause constipation and drowsiness; the diet guide on this site covers how to manage that. Two things make pain worse than it needs to be: skipping the exercises because they hurt, and doing too much on a good day. The physiotherapist sets the pace. Severe pain that medicine does not touch is a reason to call the surgeon, not to wait.
What are the real risks, with numbers?
The serious risks are blood clots, infection of the new joint, stiffness and, over decades, loosening of the implant; each is uncommon. The NHS says clots in the leg are possible and can travel to the lungs, which is why you wear compression stockings for at least 6 weeks and walk on day one. The 2018 Mumbai series recorded deep vein thrombosis in 1.24% of 402 knees.
Infection is the complication that leads to further surgery. A 2024 meta-analysis in the Journal of Orthopaedic Surgery and Research pooled 27 studies covering 3,664,589 knee replacements and estimated infection of the new joint at 0.83% to 1.08% depending on the statistical model, with the Asian subgroup at 0.90% to 1.49%; about one knee in 100. The paper lists obesity, diabetes, smoking and low albumin (poor nutrition) as risk factors, which is why preparation matters.
The NHS also lists damage to a blood vessel, nerve or ligament as not common and usually repairable, and ongoing pain and stiffness. MedlinePlus notes that a loosened replacement can be redone, but results are usually not as good as the first time.
See a doctor the same day if you have throbbing or cramping leg pain, a fever or feel hot and shivery, pus or oozing from the wound, or redness, swelling or pain in the knee that is getting worse. Call 112 or go to emergency if you have chest pain or difficulty breathing, which can mean a clot in the lung.
The Cleveland Clinic adds a fever above 101°F (38.3°C), new calf or foot pain, and severe pain that medicine does not relieve.
How long will the new knee last?
Most knee replacements last about 25 years, and the best evidence puts the figure at 82% still in place at 25 years. The NHS states that most knee replacements last for about 25 years and that needing a further replacement is not common. A 2019 systematic review and meta-analysis in The Lancet (Evans and colleagues) pooled national registry data on 299,291 total knee replacements and found 93% surviving at 15 years, 90% at 20 years and 82% at 25 years. Partial (unicompartmental) replacements did less well, at about 70% surviving 25 years in registry data.
MedlinePlus gives a similar picture: over 90% of artificial knees last more than 15 years, some last 25 years before they loosen, and periodic check-ups with the surgeon are recommended. The Cleveland Clinic says almost everyone has improved knee function for at least 10 to 15 years and that implants may last the rest of a person's life.
The Lancet authors added caveats worth knowing: the 20- and 25-year registry data came from Finland alone, the estimates were not adjusted for age or sex, and the study could not count problems that did not lead to a second operation. It also cannot tell you how long your particular implant will last. What you control is the load you put on it: MedlinePlus says younger, more active patients wear implants out sooner, and the AAOS says forces across the knee can exceed 7 times body weight, so every kilogram counts.
What does knee replacement involve in India, and who pays?
In India, knee replacement is done in both private and government hospitals, and the main scheme question is whether your hospital is empanelled and whether the package covers the implant. A 2023 analysis in BMJ Global Health describes Ayushman Bharat PM-JAY as cashless hospitalisation cover of up to ₹5 lakh per family per year for the poorest 40% of households, across 1,970 procedures in 27 specialties, with package rates revised in 2022 and now varying by city tier. A surgical package there is a fixed sum covering pre-procedure tests, the operation, the stay and 15 days of post-discharge medicines. The paper does not name the knee replacement package, and this guide could not open a government page listing it, so ask the Ayushman-empanelled hospital whether total knee replacement is on its approved orthopaedics list and which implant is included.
CGHS beneficiaries should ask a CGHS-empanelled hospital for the current package rate and implant ceiling in writing before admission; this guide found no official page it could cite for the figures.
Questions to put to the surgeon before you agree:
- Total or partial replacement, and why.
- Which implant, and its published survival data.
- How many of these operations the surgeon and the hospital do each year.
- The blood clot prevention plan and how long it runs.
- Who runs physiotherapy after discharge.
- The total cost including implant, physiotherapy and follow-up X-rays.
Compare hospitals on these answers, not on the brochure. This guide is general information from the sources listed below, not medical advice; a registered doctor makes decisions with you.
