Reading as
Plain-language core. Switch lenses to reveal technical or purchasing detail.
All topics
  1. What it is
  2. Who it helps
  3. Timing
  4. The procedure
  5. Patient journey
  6. Recovery supplies
  7. Implant designs
  8. Side-by-side
  9. Robotics and alignment
  10. US manufacturers
  11. What the evidence says
  12. Value analysis
  13. Questions to ask
  14. Resources
  15. Glossary
  16. References

When

When is the right time?

Knee replacement is almost always an elective, planned operation, so the timing is your choice, made with your surgeon. Most people decide when pain and stiffness are limiting their life more than they're willing to accept, and other treatments have stopped helping.1

Age matters for how long the implant needs to last. Modern knee replacements last a long time: pooled registry data suggest about 82% are still in place after 25 years.6 Because younger people live longer and are more active, they have a higher lifetime chance of needing a second operation (a revision).7 That's a reason to think carefully, not a reason to suffer indefinitely.

Preparing helps. Exercise before surgery ("prehab") has been linked to better function and less pain after surgery.30 It's also the time to stop smoking, get blood sugar under control and arrange help at home.

Clinical detail
  • In a UK cohort, 10-year implant survival was 96.1% and 20-year survival 89.7%. Lifetime revision risk was about 5% for patients over 70, rising to 35% for men in their early 50s (hip and knee pooled).7
  • Prehab meta-analysis of 29 RCTs: WOMAC function improved at mid-term (SMD -1.21) and long-term (SMD -0.47), with high heterogeneity.30

Sources for this page

  1. Price AJ, et al. Knee replacement. Lancet. 2018;392(10158):1672-1682. doi:10.1016/S0140-6736(18)32344-4
  2. Evans JT, et al. How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up. Lancet. 2019;393(10172):655-663. doi:10.1016/S0140-6736(18)32531-5
  3. Bayliss LE, et al. The effect of patient age at intervention on risk of implant revision after total replacement of the hip or knee: a population-based cohort study. Lancet. 2017;389(10077):1424-1430. doi:10.1016/S0140-6736(17)30059-4
  4. Wang Z, et al. Effectiveness of preoperative rehabilitation compared with usual care in total knee arthroplasty: a meta-analysis of randomized controlled trials. Arch Phys Med Rehabil. 2026;107(2):315-332. doi:10.1016/j.apmr.2025.08.022

All references