Prosthetic Joint Infection
An infection of an artificial hip, knee, or other joint replacement
Quick Facts
- Type: Orthopedic infection
- Affected: Artificial joint replacements
- Key symptoms: Joint pain, swelling, warmth, fever
- Treatment: Antibiotics plus surgery
Overview
A prosthetic joint infection is an infection that develops in or around an artificial joint, such as a replaced hip, knee, or shoulder. Joint replacement is a very common and successful operation, and infection is an uncommon but serious complication. Bacteria can settle on the surface of the implant, where they are hard for the immune system and antibiotics to reach.
The infection can occur soon after surgery or months to years later if bacteria travel through the bloodstream from elsewhere in the body. Because the implant gives germs a surface to cling to, these infections often need both antibiotics and surgery to clear. Prompt recognition gives the best chance of saving the joint replacement.
Symptoms
Symptoms can develop quickly or come on slowly, depending on the organism and timing. They include:
- New or worsening pain in the replaced joint, sometimes even at rest
- Swelling, warmth, and redness around the joint
- Fluid draining from the surgical wound or a wound that will not heal
- Fever, chills, or night sweats
- Stiffness or a feeling that the joint is loose or unstable
Pain that returns after a previously well-functioning joint replacement, especially with fever or wound drainage, should be evaluated promptly. High fever with a hot, swollen joint needs urgent care.
Causes
Prosthetic joint infections are caused by bacteria, and less often fungi, reaching the implant. This can happen in several ways:
- At the time of surgery: Germs can enter during or soon after the operation.
- Through the bloodstream: Bacteria from an infection elsewhere, such as the skin, teeth, or urinary tract, can travel to the joint.
- Through a wound: A breakdown of the surgical wound can let germs in.
Bacteria can form a protective layer called a biofilm on the implant surface, which shields them from antibiotics and the immune system.
Risk Factors
- Diabetes or poorly controlled blood sugar
- A weakened immune system or use of immune-suppressing medicines
- Obesity
- Rheumatoid arthritis or other inflammatory conditions
- Prior joint surgery or a previous joint infection
- Smoking and poor wound healing
- Infections elsewhere in the body
Diagnosis
Diagnosing an infected joint replacement often takes several tests:
- Blood tests: Markers of inflammation such as ESR and CRP are often raised.
- Joint fluid sampling: A needle draws fluid from the joint to count cells and grow any bacteria present.
- Imaging: X-rays may show loosening of the implant; other scans can help in unclear cases.
- Tissue cultures: Samples taken during surgery help identify the exact organism and guide antibiotics.
Identifying the specific bacteria is important for choosing the right antibiotic.
Treatment
Treatment usually combines surgery and a prolonged course of antibiotics, tailored to the situation:
- Antibiotics: Often given through a vein at first and continued for several weeks; the choice is guided by the organism found.
- Debridement with implant retention: For early infections, surgeons may clean out the joint and exchange some parts while keeping the main implant.
- Implant exchange: For established infections, the implant may be removed and replaced, sometimes in two stages with antibiotic treatment in between.
- Long-term suppression: In selected cases, ongoing antibiotics keep the infection under control.
Care is usually coordinated by orthopedic surgeons and infection specialists.
Prevention
Several measures lower the risk of infecting a joint replacement:
- Careful surgical technique and preventive antibiotics around the time of surgery
- Good control of diabetes and other health conditions before surgery
- Not smoking, which improves wound healing
- Prompt treatment of infections elsewhere, including skin, dental, and urinary infections
- Keeping the surgical wound clean and reporting drainage or poor healing early
When to See a Doctor
Contact your surgeon or doctor promptly if, after a joint replacement, you notice:
- New or worsening joint pain, especially after the joint had been working well
- Swelling, warmth, or redness around the joint
- Drainage from the wound or a wound that will not heal
- Fever or chills
Seek urgent care for a high fever with a hot, very painful, swollen joint, which can signal a serious infection.
Frequently Asked Questions
What are the signs of an infected joint replacement?
Warning signs include new or worsening pain in the replaced joint, swelling, warmth, and redness, fluid draining from the wound, and fever or chills. Pain that returns after a previously well-functioning joint is especially concerning. These symptoms should be reported to your surgeon promptly.
How does a joint replacement get infected?
Bacteria can enter during or shortly after the operation, travel to the joint through the bloodstream from an infection elsewhere, or get in through a wound that does not heal. The germs can form a protective biofilm on the implant that resists antibiotics. This is why surgery is often needed in addition to antibiotics.
Can an infected joint replacement be treated without removing it?
Sometimes, especially when the infection is caught early. Surgeons may clean out the joint and replace some parts while keeping the main implant, combined with antibiotics. Established or late infections more often require removing and replacing the implant, sometimes in two stages.
How is a prosthetic joint infection diagnosed?
Doctors use blood tests for inflammation, draw fluid from the joint to look for bacteria and inflammatory cells, and may take X-rays to check for loosening. Tissue samples taken during surgery help identify the exact organism. Pinpointing the bacteria guides the choice of antibiotic.
How can I lower my risk of a joint replacement infection?
Controlling diabetes, not smoking, and keeping the surgical wound clean all help, as do preventive antibiotics given around the time of surgery. Treating infections elsewhere, including dental and urinary infections, lowers the chance of bacteria reaching the joint. Report wound drainage or poor healing to your surgeon early.
References
- American Academy of Orthopaedic Surgeons (AAOS). Joint Replacement Infection.
- Centers for Disease Control and Prevention (CDC). Surgical Site Infection.
- MedlinePlus, U.S. National Library of Medicine.
- Infectious Diseases Society of America (IDSA).