At the time of surgery (perioperative contamination):
Despite sterile precautions, a small number of bacteria can be introduced during the original procedure. These infections may become apparent within weeks to months after surgery.
PJI affects approximately 1 to 2 percent of primary joint replacements and up to 5 percent of revision cases. Despite its relative rarity, it is a devastating problem for the patients it affects. Treatment is complex, often requiring one or more surgeries, extended courses of antibiotics, and months of recovery.
Dr. Leo Zalikha trained extensively in the management of prosthetic joint infections during his fellowship at Stanford Medicine. He treats PJI as part of his practice and understands that these cases require meticulous diagnosis, individualized treatment planning, and close collaboration with infectious disease specialists.
How Prosthetic Joint Infection Develops
Bacteria can reach the joint replacement through several routes:
Through the bloodstream (hematogenous seeding):
Bacteria from other parts of the body (dental infections, urinary tract infections, skin infections, pneumonia) can travel through the blood and settle on the implant surface. This can happen months or years after a well-functioning replacement was placed.
From adjacent soft tissue:
Wound complications, delayed healing, or superficial infections can extend to the deeper tissues and the implant.
Once bacteria reach the implant surface, they form biofilm: a protective layer that shields the organisms from the immune system and from most antibiotics. This is why PJI is so difficult to treat without surgery. The biofilm must be physically disrupted or the implant removed to eradicate the infection.
Symptoms of Prosthetic Joint Infection
PJI can present acutely (obvious and dramatic) or chronically (subtle and gradual). Both require prompt evaluation.
- Sudden onset of pain, swelling, and warmth around a previously well-functioning joint
- Fever or chills
- Redness around the incision
- Drainage from the wound
- Rapid decline in function
- Persistent, low-grade pain that never fully resolved after surgery
- Intermittent swelling
- Stiffness that is not improving with therapy
- A "just not right" feeling in the joint
- Subtle decline in function over months
Chronic PJI can be difficult to distinguish from other causes of a painful joint replacement. A thorough workup is essential.
How PJI Is Diagnosed
ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein):
Markers of inflammation. Elevated levels raise suspicion for infection, though they can also be elevated for non-infectious reasons.
D-dimer:
An additional inflammatory marker that can support the diagnosis.
• Joint Aspiration
Fluid is drawn from the joint using a needle and sent for:
Synovial white blood cell count and differential:
Elevated cell counts, particularly with a high percentage of neutrophils, strongly suggest infection.
Culture:
Identifies the specific bacteria causing the infection and determines which antibiotics it is sensitive to. Cultures sometimes take days to weeks to grow, especially for low-virulence organisms.
Alpha-defensin:
A synovial fluid biomarker with high specificity for PJI.
Molecular testing:
PCR-based testing can identify bacterial DNA even when cultures are negative
• Imaging
X-rays may show signs of loosening or bone loss associated with infection. Advanced imaging (CT, bone scan, or tagged white blood cell scan) may be used in equivocal cases.
• Intraoperative Assessment
In some cases, the definitive diagnosis is made during surgery, when tissue samples are sent for culture, frozen section (cell count), and pathology.
Treatment Options for PJI
DAIR (Debridement, Antibiotics, and Implant Retention)
DAIR is appropriate for acute infections (typically within a few weeks of surgery or within a few weeks of symptom onset in a hematogenous infection) when:
- The implant is well-fixed
- The soft tissue envelope is healthy
- The causative organism is identified and susceptible to appropriate antibiotics
During DAIR, the joint is surgically opened, all infected and dead tissue is removed (debrided), the joint is thoroughly irrigated, and modular components (the polyethylene liner, the femoral head) are exchanged. The well-fixed implant components are retained. This is followed by a prolonged course of intravenous and then oral antibiotics.
Staged Revision (Two-Stage Exchange)
Two-stage revision is the traditional approach for chronic PJI and remains the standard in many cases:
All implant components and cement are removed. Infected and dead tissue is debrided. An antibiotic-loaded cement spacer is placed in the joint to deliver high local concentrations of antibiotics and maintain the joint space. The patient then receives six or more weeks of intravenous antibiotics.
After the antibiotic course is complete and infection markers have normalized, the spacer is removed and a new joint replacement is implanted.
Single-Stage Revision (One-Stage Exchange)
In select cases, all components are removed, the joint is debrided, and new implants are placed in a single operation. This approach is gaining acceptance for specific infection scenarios and offers the advantage of a single surgical event and faster return to function. Patient selection is critical, and Dr. Zalikha discusses whether a one-stage approach is appropriate on a case-by-case basis.
Chronic Suppression
For patients who are not surgical candidates due to severe medical comorbidities, long-term antibiotic suppression may be used to manage symptoms without surgery. This does not cure the infection but can control it.
What to Expect
PJI treatment is a long process. Patients should expect:
- One or more surgeries
- Weeks to months of antibiotics (intravenous and/or oral)
- Regular blood tests to monitor infection markers and medication levels
- Restricted weight-bearing during certain phases of treatment
- Close collaboration between the surgeon and infectious disease physician
- A recovery timeline measured in months, not weeks
Dr. Zalikha is transparent about what PJI treatment involves. It is demanding, but with proper management, most patients achieve a successful outcome and return to a functional, pain-free joint.
When to Seek Evaluation
If you have a joint replacement and experience new or worsening pain, swelling, warmth, drainage, fever, or a sense that something is not right, do not ignore these symptoms. Early evaluation and intervention improve the chances of successful treatment.
A virtual second opinion is available for patients who want Dr. Zalikha’s assessment before traveling to Long Beach.
If you suspect your joint replacement may be infected, prompt evaluation is important. Schedule an appointment with Dr. Zalikha or call (562) 362-5024. For patients outside the area, a virtual second opinion is available.