Infected Total Knee Replacement: Procedure, Recovery and Results

An infected total knee replacement is a serious but treatable complication in which bacteria or, less often, other microorganisms affect tissues around a knee implant. Treatment is individualized and may involve antibiotics, surgical cleaning or revision surgery, followed by rehabilitation and close follow-up.

Overview: What happens if you get an infection in a total knee replacement?

An infected total knee replacement, also called a periprosthetic joint infection, occurs when microorganisms infect the tissue around a knee implant. It can develop soon after surgery, months later, or years after an otherwise successful total knee arthroplasty. Although this complication is uncommon, it requires timely review because bacteria can form a protective layer, called a biofilm, on implant surfaces.

Infection after total knee replacement surgery may cause increasing pain, swelling, warmth, wound drainage, stiffness or difficulty using the leg. Some people have fever or feel unwell, but others—especially with a slower infection—may only notice persistent pain or declining function. The goal of treatment is to control the infection, preserve or restore safe knee function, and reduce the chance of infection spreading.

Care is usually planned jointly by an orthopedic surgeon, infectious diseases specialist, microbiology laboratory team, anesthesiologist and rehabilitation professionals. The best approach depends on the timing of infection, test results, implant stability, soft-tissue condition and the person’s general health.

Symptoms and warning signs

Symptoms of an infected total knee arthroplasty can overlap with normal postoperative healing during the first weeks. Mild soreness, swelling and warmth can be expected after surgery, but symptoms that are worsening rather than gradually improving should be assessed. New symptoms after a period of good recovery also deserve medical review.

Possible signs include persistent or increasing knee pain, redness, warmth, swelling, drainage from the incision, delayed wound healing, stiffness, instability or pain when bearing weight. An infected total knee incision may leak cloudy, bloody or foul-smelling fluid, or the wound edges may separate. These signs do not always mean there is a deep implant infection, but they should not be managed at home without clinical advice.

A late infection can occur when bacteria enter the bloodstream from another infection and settle around an implant. Symptoms may begin abruptly after a skin, dental, urinary, respiratory or other infection, although a source is not always identified. People should tell clinicians that they have a knee implant whenever they are being evaluated for a significant infection elsewhere.

What percent of total knee replacements get infected?

Deep infection after primary total knee replacement is generally reported in about 1% to 2% of cases, although estimates vary between health systems, patient populations and the definition used. The risk is higher after revision knee surgery than after a first-time knee replacement because revision procedures can be more complex and may involve more scar tissue, bone loss or prior infection.

Several factors can increase risk, including diabetes that is not well controlled, smoking, obesity, poor nutrition, immune-suppressing medicines, inflammatory arthritis, kidney disease, skin ulcers and previous surgery or infection in the same knee. These factors do not mean infection will occur; they help the care team plan risk reduction before and after surgery.

Hospitals reduce risk through measures such as careful skin preparation, sterile operating techniques, preventive antibiotics around surgery, blood glucose management where appropriate and wound-care guidance. Following instructions about medicines, bathing, activity, dressing care and follow-up appointments also supports safer healing.

Diagnosis and deciding who may need revision

Diagnosis begins with a detailed history and examination. The team considers when symptoms began, how the knee has functioned, recent illnesses or procedures, wound changes, prior antibiotic use and medical conditions that may affect healing. Blood tests that measure inflammation can support assessment, but no single test confirms every case.

X-rays may help assess implant position, loosening or bone changes. In many cases, the clinician obtains fluid from the knee using a needle. This sample is examined for cells and sent for culture to identify microorganisms and guide antibiotic selection. During surgery, several tissue samples may also be collected for laboratory testing.

Candidacy for an infected knee replacement revision is individualized. Surgical planning considers whether the implant is stable, whether the infection is early or longstanding, the microorganism and its antibiotic sensitivity, the quality of surrounding bone and skin, and whether the person can safely undergo anesthesia and rehabilitation. Antibiotics should ideally be guided by cultures when the person is clinically stable; however, urgent treatment is started promptly when severe infection or sepsis is suspected.

Procedure options: how treatment works

Antibiotics alone rarely eliminate a deep infection attached to a knee implant because biofilm can protect bacteria. For some early postoperative infections or sudden bloodstream-related infections with a stable implant, surgeons may perform debridement, antibiotics and implant retention. During this procedure, infected and unhealthy tissue is removed, the joint is thoroughly washed, and removable plastic components may be exchanged while the main metal components remain in place.

For many established infections, the preferred approach is an infected knee replacement revision. In a two-stage revision, the surgeon first removes the implant, removes infected tissue and cleans the area. A temporary antibiotic-containing spacer may be placed to help maintain joint space and deliver local antimicrobial treatment. After a period of targeted antibiotics and reassessment, a new knee implant is placed in a second operation when infection control is considered adequate.

In selected circumstances, a one-stage revision may be appropriate: the old implant is removed, the joint is cleaned and a new implant is placed during the same operation. Less commonly, when reconstruction is not safe or infection cannot be controlled, options may include fusion of the knee or, rarely, amputation. The team discusses the likely benefits, limitations and alternatives for the individual situation.

Revision procedures are complex and should be planned by an experienced orthopedic infection team. Knee replacement surgery may include primary and revision approaches, with the final plan based on diagnostic findings and shared decision-making.

Step-by-step treatment and recovery timeline

Before surgery, the team reviews imaging, blood results, culture findings, medications and anesthesia risks. Existing medical conditions are optimized where possible. During the operation, the surgeon takes multiple samples, removes infected tissue, washes the joint and either retains, removes or replaces implant components according to the treatment strategy. The procedure may require bone grafting or specialized revision components when bone has been lost.

Immediately after surgery, pain relief, blood-clot prevention, wound monitoring and early guided movement are important. Antibiotic treatment is selected with infectious diseases and microbiology input, often beginning intravenously and sometimes continuing with oral medication. The exact length and route of treatment vary according to the procedure, culture results and clinical response.

How long does it take to recover from an infected knee replacement? Recovery is usually longer than recovery from an uncomplicated primary replacement. Early wound healing and mobility gains take weeks, while strength, endurance and confidence with walking often improve over several months. A two-stage revision can extend the overall process because there is recovery and rehabilitation after each operation, as well as a period of infection treatment between stages.

Physiotherapy is tailored to the procedure, the spacer or implant used, weight-bearing instructions and the person’s health. Follow-up appointments monitor the incision, symptoms, knee movement, inflammatory markers when appropriate and medication side effects. It is important to attend all visits and contact the team before stopping antibiotics or changing wound-care plans.

Benefits, risks and everyday self-care

The main benefit of treatment is infection control, with the aim of reducing pain, protecting general health and improving the chance of a functional knee. Even with expert treatment, outcomes vary. Infection may persist or recur, and knee movement or comfort may not return to the level achieved before infection. Clear communication about personal goals—such as walking, transfers, stairs or independent daily activities—helps guide rehabilitation.

Potential risks include bleeding, blood clots, wound problems, stiffness, fracture, nerve or blood-vessel injury, reactions to anesthesia, antibiotic side effects, implant loosening and the need for further surgery. The team works to lower these risks, but no treatment can remove them completely. Seeking help early for new symptoms is an important part of reducing complications.

At home, people should follow instructions for wound and dressing care, use mobility aids as advised, take medicines exactly as prescribed and maintain adequate nutrition and hydration. Avoid smoking, as it can impair wound healing. New drainage, increasing redness, fever, calf pain, chest pain or shortness of breath should be reported promptly rather than waiting for a routine appointment.

Acibadem International’s multidisciplinary specialists at JCI-accredited hospitals assess and treat complex knee replacement infections for international patients, coordinating orthopedic surgery, infectious diseases care and rehabilitation when needed.

When to seek medical care

Contact the orthopedic team promptly for increasing pain after it had been improving, new or persistent drainage, spreading redness, a wound that opens, increasing swelling, a new fever, chills or an unexplained decline in the ability to walk. These symptoms may have other causes, but assessment is important after knee replacement surgery.

What does sepsis look like after knee surgery? Sepsis is the body’s extreme response to infection and can become life-threatening. Warning signs can include fever or abnormally low temperature, fast heartbeat, rapid breathing, severe weakness, confusion, mottled or clammy skin, markedly reduced urine output, dizziness or a feeling of being very unwell. Symptoms can vary, especially in older adults.

Emergency medical care is needed for confusion, difficulty breathing, fainting, severe weakness, blue or gray lips or skin, chest pain, or rapidly worsening illness with possible infection. People should not drive themselves if they feel seriously unwell. Bringing information about the knee replacement, recent operations and current medicines can help emergency clinicians act quickly.

Frequently asked questions

Can an infected total knee replacement be cured?

Many infections can be controlled with appropriately selected surgery and antimicrobial treatment. However, treatment can be lengthy, and some people need more than one procedure. The chance of success depends on factors such as infection timing, the organism involved, implant stability and overall health.

Is pain always present with a knee replacement infection?

Pain is common, but its severity can vary. Some slower infections mainly cause stiffness, swelling, recurrent fluid buildup or a gradual loss of function. Any unexplained change in a replaced knee should be discussed with an orthopedic clinician.

Can antibiotics cure an infection after total knee replacement surgery without surgery?

Antibiotics may be used alone in limited situations, such as when surgery is not safe or appropriate, but they often cannot fully clear bacteria attached to an implant. Deep infections commonly need a procedure to remove infected tissue, alongside culture-guided antibiotics. A specialist team can explain the safest option for the individual.

What is the difference between a one-stage and two-stage knee revision for infection?

A one-stage revision removes the infected implant and places a new one in the same operation. A two-stage revision removes the implant first, often uses a temporary spacer and antibiotic treatment, then places a new implant later. The decision depends on the organism, soft tissues, bone, medical condition and local surgical expertise.

Can an infected knee replacement occur years after surgery?

Yes. Late infections can occur years after implantation, sometimes after bacteria enter the bloodstream from another infection. Sudden pain, swelling or fever in a previously well-functioning replaced knee should be assessed promptly.

How can patients lower the risk of infection before knee replacement surgery?

Risk reduction can include stopping smoking, managing diabetes and other long-term conditions, addressing active skin or other infections and following preoperative hygiene guidance. The surgical team should review all medicines, including immune-suppressing drugs, and provide personalized instructions. These steps reduce risk but cannot eliminate it completely.

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.