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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

Research

What the evidence says

Knee replacement is one of the most studied operations in medicine, with large national registries tracking hundreds of thousands of implants. Here are the headline numbers.

82%
of knee replacements last 25 years, pooled registry data6
~1 in 5
patients not fully satisfied after surgery3
1.55%
infection within 2 years, Medicare sample9
Agreement

Implants last a long time: about 96% survive 10 years and about 90% survive 20 years.7

Agreement

Infection is the leading cause of early revision, and loosening of later revision.8

Agreement

Most design choices, such as cruciate-retaining vs posterior-stabilized or fixed vs mobile bearing, make little measurable difference.18,19

Agreement

Obesity, smoking and diabetes raise the risk of complications, especially infection.38,39,40

Disagreement

Blood clot prevention: aspirin causes less bleeding, but a large trial found more symptomatic clots with aspirin than with enoxaparin after knee surgery.11,12,51

Disagreement

Cementless fixation looks equivalent in randomized trials but showed no advantage, and higher early revision for some designs, in US registries.14,15,16

Emerging

Robotics improves cutting precision, but randomized trials haven't shown better pain or function so far.22,23

Clinical detail
  • Symptomatic in-hospital VTE with recommended prophylaxis: 1.09% after knee arthroplasty (DVT 0.63%, PE 0.27%).10
  • CRISTAL (n=9,711): 90-day symptomatic VTE 3.45% with aspirin vs 1.82% with enoxaparin after TKA; aspirin failed noninferiority. Most events were below-knee DVTs.11 An umbrella review found aspirin reduced bleeding by about 30% with comparable DVT risk (hip and knee pooled).12
  • Stiffness requiring manipulation: 6.1% prevalence in a 2017 database, with 2-year costs 1.5 to 7.5 times higher. Rates vary widely by definition.13
  • Revision causes in 781 revisions: loosening 39.9%, infection 27.4%, instability 7.5%, periprosthetic fracture 4.7%, arthrofibrosis 4.5%.8

Deeper dives: how long a knee replacement lasts, partial vs total, and robotics and alignment.

Sources for this page

  1. 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
  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. Sharkey PF, et al. Why are total knee arthroplasties failing today: has anything changed after 10 years? J Arthroplasty. 2014;29(9):1774-1778. doi:10.1016/j.arth.2013.07.024
  5. Kurtz SM, et al. Prosthetic joint infection risk after TKA in the Medicare population. Clin Orthop Relat Res. 2010;468(1):52-56. doi:10.1007/s11999-009-1013-5
  6. Januel JM, et al. Symptomatic in-hospital deep vein thrombosis and pulmonary embolism following hip and knee arthroplasty among patients receiving recommended prophylaxis: a systematic review. JAMA. 2012;307(3):294-303. doi:10.1001/jama.2011.2029
  7. Sidhu VS, et al. Effect of aspirin vs enoxaparin on symptomatic venous thromboembolism in patients undergoing hip or knee arthroplasty: the CRISTAL randomized trial. JAMA. 2022;328(8):719-727. doi:10.1001/jama.2022.13416
  8. Borazjani R, et al. Aspirin versus other anticoagulants for the initial prevention of venous thromboembolism following elective total hip and knee arthroplasty: an umbrella review and meta-analysis. J Arthroplasty. 2026;41(1):225-237. doi:10.1016/j.arth.2025.06.032
  9. Olsen AA, et al. The cost of stiffness after total knee arthroplasty. J Arthroplasty. 2023;38(4):638-643. doi:10.1016/j.arth.2022.10.040
  10. Prasad AK, et al. Cemented vs. cementless fixation in primary total knee arthroplasty: a systematic review and meta-analysis. EFORT Open Rev. 2020;5(11):793-798. doi:10.1302/2058-5241.5.200030
  11. Paull TZ, et al. Uncemented total knee arthroplasty in the State of Michigan has higher rates of revision through 5-year follow-up. J Arthroplasty. 2025;40(7S1):S263-S270. doi:10.1016/j.arth.2025.03.007
  12. Chen F, et al. What is the survivorship of TKA with a twin-peg or spikes-and-keel cementless implant compared with cemented? A registry-based cohort study. Clin Orthop Relat Res. 2025;483(7):1288-1298. doi:10.1097/CORR.0000000000003385
  13. Verra WC, et al. Retention versus sacrifice of the posterior cruciate ligament in total knee arthroplasty for treating osteoarthritis. Cochrane Database Syst Rev. 2013;(10):CD004803. doi:10.1002/14651858.CD004803.pub3
  14. Migliorini F, et al. No difference between mobile and fixed bearing in primary total knee arthroplasty: a meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2022;30(9):3138-3154. doi:10.1007/s00167-022-07065-5
  15. Abdelaziz O, et al. Comparative pain relief and functional outcomes following robotic-assisted versus conventional total knee arthroplasty: a GRADE-assessed meta-analysis with meta-regression of randomized controlled trials. J Robot Surg. 2026;20(1). doi:10.1007/s11701-026-03934-0
  16. Onggo JR, et al. Robotic-assisted total knee arthroplasty is comparable to conventional total knee arthroplasty: a meta-analysis and systematic review. Arch Orthop Trauma Surg. 2020;140(10):1533-1549. doi:10.1007/s00402-020-03512-5
  17. 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
  18. 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
  19. 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
  20. Salman LA, et al. The efficacy of aspirin versus low-molecular-weight heparin for venous thromboembolism prophylaxis after knee and hip arthroplasty: a systematic review and meta-analysis of randomized controlled trials. Knee Surg Sports Traumatol Arthrosc. 2025;33(5):1605-1616. doi:10.1002/ksa.12456

All references