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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

Purpose

Who is knee replacement for?

Knee replacement is usually considered when arthritis pain and stiffness limit everyday life, such as walking, climbing stairs, sleeping or working, and non-surgical treatments are no longer enough.1,45 There is no strict age or X-ray cutoff. The decision rests on how much the knee affects your life, your overall health, and what you hope to get back.

Treatments usually tried first

  • Physical therapy and strengthening exercise
  • Weight loss, which reduces the load on the knee
  • Pain relievers and anti-inflammatory medicines, as your doctor advises
  • Injections into the knee
  • A cane, brace or activity changes

What to expect from surgery

Most people get substantial pain relief and better function. But it helps to go in with realistic expectations: about 1 in 5 people are not fully satisfied with their new knee, and some have lasting pain.3,5 In one large study, the strongest predictor of dissatisfaction was having expectations that weren't met.4 Talking openly with your surgeon about what the knee will and won't do is part of good preparation.

Things that can raise the risk

Obesity, smoking and diabetes are each linked to more complications, especially infection.38,39,40 These don't automatically rule out surgery, but your team may ask you to work on them first. Stopping tobacco before surgery appears to lower the risk.39

Clinical detail
  • Dissatisfaction was associated with unmet expectations (10.7 times the risk), a low 1-year WOMAC (2.5x), preoperative pain at rest (2.4x) and a complication requiring readmission (1.9x).4
  • In 3.1 million TKAs, BMI 30 or above was associated with all-cause revision (OR 1.15) and deep infection (OR 1.47); in BMI 40 or above, deep infection OR 1.98.38
  • TKA-specific PJI risk factors: type 2 diabetes OR 2.09, smoking OR 1.65, rheumatoid arthritis OR 2.64 and preoperative anemia OR 1.82 (observational associations).40

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. Gunaratne R, et al. Patient dissatisfaction following total knee arthroplasty: a systematic review of the literature. J Arthroplasty. 2017;32(12):3854-3860. doi:10.1016/j.arth.2017.07.021
  3. Bourne RB, et al. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res. 2010;468(1):57-63. doi:10.1007/s11999-009-1119-9
  4. Beswick AD, et al. What proportion of patients report long-term pain after total hip or knee replacement for osteoarthritis? A systematic review of prospective studies in unselected patients. BMJ Open. 2012;2(1):e000435. doi:10.1136/bmjopen-2011-000435
  5. Onggo JR, et al. Greater risk of all-cause revisions and complications for obese patients in 3 106 381 total knee arthroplasties: a meta-analysis and systematic review. ANZ J Surg. 2021;91(11):2308-2321. doi:10.1111/ans.17138
  6. Bedard NA, et al. Tobacco use and risk of wound complications and periprosthetic joint infection: a systematic review and meta-analysis of primary total joint arthroplasty procedures. J Arthroplasty. 2019;34(2):385-396.e4. doi:10.1016/j.arth.2018.09.089
  7. Gao H, et al. Factors associated with periprosthetic joint infection following total knee arthroplasty: an updated systematic review and meta-analysis. Arch Orthop Trauma Surg. 2026;146(1). doi:10.1007/s00402-026-06492-0
  8. American Academy of Orthopaedic Surgeons, OrthoInfo. Total knee replacement. orthoinfo.org/treatment/total-knee-replacement

All references