Knee replacement infection: rates, signs and treatment

How common is it?

In a large Medicare sample of almost 70,000 knee replacements, 1.55% developed infection within 2 years, and another 0.46% between 2 and 10 years.¹ A 2024 meta-analysis put the overall rate at about 1.1%, with wide variation between regions and studies.²

Warning signs

Call your surgeon promptly if you notice:¹³

• Increasing redness, warmth or swelling around the knee
• Drainage from the incision, especially after the first week or so
• Pain that is getting worse, or pain at rest as well as with activity
• New pain or stiffness in a knee that had been doing well
• Fever or chills (though fever isn't always present)

Who is at higher risk?

In a 2026 meta-analysis of knee replacement studies, factors linked to higher infection risk included:³

• Obesity (BMI 30 or above)
• Type 2 diabetes
• Rheumatoid arthritis
• Smoking
• Anemia before surgery, or needing a blood transfusion
• A urinary tract infection after surgery
• Being male

A larger review covering hip and knee replacements found a similar list, including obesity, smoking, diabetes and steroid use.⁴ These are associations, not proof that each factor causes infection.³

How infected knees are treated

Bacteria on an implant form a protective layer called a biofilm, so antibiotics alone rarely cure the infection.¹³ The main options are:

• Washout with implant retention (DAIR). The surgeon cleans out the joint and usually swaps the plastic spacer, keeping the metal implant, followed by antibiotics. It works best for infections caught early. In a review of 81 studies, it failed in about 34% of early infections and 74% of chronic ones.⁵ In US registry data, 48% of knees treated this way had another infection-related event within 8 years.⁶
• One-stage revision. The implant is removed and a new one put in during the same operation.
• Two-stage revision. The implant is removed, an antibiotic spacer is placed for several weeks to months, and a new implant is put in once the infection is cleared.

Re-infection rates after one-stage and two-stage revision were similar in a large review, about 8 to 9%.⁷ Your surgeon will recommend an approach based on how long the infection has been present, the bacteria involved and your health.

Why it's taken so seriously

Knee infection requiring revision is a major health event. In a review of patients treated with two-stage revision, 1-year mortality was about 4%, roughly three times that of similar-age people in the general population.⁸ That's one reason surgeons focus so much on prevention.

How to lower your risk

• Stop smoking. Tobacco use roughly doubled infection risk, and former smokers had lower risk than current smokers.⁹
• Get blood sugar under control. Poor control is linked to more surgical infections, though no single cutoff has been proven.¹⁰
• Ask about skin decolonization. Screening and treating for staph bacteria before surgery roughly halved surgical infections in a meta-analysis.¹¹
• Treat other infections first, such as skin, urinary or dental infections, before surgery.

Do I need antibiotics before dental work?

The American Dental Association says that, in general, antibiotics are not recommended before dental procedures for people with joint replacements.¹² Some surgeons still recommend them for patients with special risk factors, so ask your surgeon what applies to you.

Sources

1. 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
2. Ma T, et al. Incidence of periprosthetic joint infection after primary total knee arthroplasty shows significant variation: a synthesis of meta-analysis and bibliometric analysis. J Orthop Surg Res. 2024;19(1):649. doi:10.1186/s13018-024-05099-8
3. 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
4. Kunutsor SK, et al. Patient-related risk factors for periprosthetic joint infection after total joint arthroplasty: a systematic review and meta-analysis. PLoS One. 2016;11(3):e0150866. doi:10.1371/journal.pone.0150866
5. Abbaszadeh A, et al. Efficacy of debridement, antibiotics, and implant retention in total hip and knee arthroplasty: a systematic review and meta-analysis. J Arthroplasty. 2026;41(1):19-38. doi:10.1016/j.arth.2025.05.121
6. De A, et al. What is the incidence of and outcomes after debridement, antibiotics, and implant retention (DAIR) for the treatment of periprosthetic joint infections in the AJRR population? Clin Orthop Relat Res. 2024;482(11):2042-2051. doi:10.1097/CORR.0000000000003138
7. Kunutsor SK, et al. Re-infection outcomes following one- and two-stage surgical revision of infected knee prosthesis: a systematic review and meta-analysis. PLoS One. 2016;11(3):e0151537. doi:10.1371/journal.pone.0151537
8. Lum ZC, et al. Mortality during total knee periprosthetic joint infection. J Arthroplasty. 2018;33(12):3783-3788. doi:10.1016/j.arth.2018.08.021
9. 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
10. Shohat N, et al. Inadequate glycemic control is associated with increased surgical site infection in total joint arthroplasty: a systematic review and meta-analysis. J Arthroplasty. 2018;33(7):2312-2321.e3. doi:10.1016/j.arth.2018.02.020
11. Lin L, et al. Efficacy of preoperative screening and decolonization for Staphylococcus aureus in total joint arthroplasty: a meta-analysis. Asian J Surg. 2021;44(6):807-818. doi:10.1016/j.asjsur.2020.12.037
12. Sollecito TP, et al. The use of prophylactic antibiotics prior to dental procedures in patients with prosthetic joints: evidence-based clinical practice guideline for dental practitioners. J Am Dent Assoc. 2015;146(1):11-16.e8. doi:10.1016/j.adaj.2014.11.012
13. American Academy of Orthopaedic Surgeons, OrthoInfo. Infection after joint replacement. orthoinfo.org/diseases--conditions/joint-replacement-infection