Periprosthetic Joint Infection: The 2025 Consensus Updates

Visual Element: A "Consensus Timeline" graphic showing the evolution of PJI definitions from MSIS 2011 -> ICM 2013 -> MSIS 2018 -> ICM 2025.

Periprosthetic Joint Infection (PJI) remains the most devastating complication of total joint arthroplasty, casting a long shadow over otherwise highly successful procedures. It is the leading cause of revision knee replacement and the third leading cause of revision hip replacement globally. The economic burden on healthcare systems is astronomical, but the human cost—multiple complex surgeries, prolonged immobility, devastating functional decline, and systemic antibiotic toxicity—is largely incalculable.

For those currently navigating the rigors of orthopaedic surgery training, mastering the diagnosis and management of PJI is not just a clinical necessity; it is a critical component of fellowship exam preparation. Examiners consistently test this topic because it separates the safe, knowledgeable surgeon from the unsafe one. The management of PJI has historically been based on "expert opinion" and eminence-based medicine. However, the successive iterations of the International Consensus Meeting (ICM) have definitively shifted this paradigm towards rigorous, evidence-based medicine.

This comprehensive guide synthesizes the pivotal updates from the 2025 ICM meeting that every arthroplasty surgeon, registrar, and fellow must know to optimize patient outcomes and ace their board and fellowship examinations.

The Pathophysiology Refresher: The Biofilm Paradigm

Before diving into the updated diagnostic criteria, we must understand why PJI is so difficult to eradicate. The answer lies in the biofilm.

When planktonic (free-floating) bacteria encounter a foreign body like a titanium or cobalt-chrome implant, they adhere to the surface and begin producing an extracellular polymeric substance (EPS)—a slimy, impenetrable matrix of polysaccharides, proteins, and extracellular DNA. Once encased in this biofilm, bacteria shift into a sessile, metabolically inactive state.

In this state, the Minimum Biofilm Eradication Concentration (MBEC) of an antibiotic can be up to 1,000 times higher than its standard Minimum Inhibitory Concentration (MIC). This is why systemic antibiotics alone cannot cure a mature periprosthetic joint infection. Mechanical disruption (surgery) is an absolute prerequisite.

Examiners love to ask why we can't just treat a 6-month-old PJI with IV antibiotics. The buzzwords you need to deliver are glycocalyx, extracellular polymeric matrix, and the shift from planktonic to sessile bacterial metabolism, rendering standard IV antibiotics ineffective.

Part 1: Diagnosis - The 2025 New Definition

We have moved far beyond the simple "Cell Count and Culture" days. The 2025 criteria further refine the scoring system introduced in 2018, adjusting the weighting of novel biomarkers to maximize both sensitivity and specificity.

Major Criteria (Definitive Diagnosis)

The presence of just ONE of the following represents an absolute, definitive diagnosis of PJI:

Two separate tissue or fluid cultures growing the same organism (phenotypically identical).
A sinus tract communicating directly with the joint space. (Note: A superficial wound dehiscence does not count; it must demonstrably track to the prosthesis).

Minor Criteria (The 2025 Weighted Scoring System)

If Major criteria are absent, we utilize the weighted scoring system. The thresholds have been subtly tweaked in the 2025 consensus to account for higher sensitivity in modern laboratory assays.

Marker	Threshold	Score
Serum CRP	> 10 mg/L	2
D-Dimer	> 860 ng/mL	2
Synovial WBC	> 3,000 cells/µL	3
Synovial PMN %	> 80%	2
Synovial Alpha-Defensin	Positive	3
Synovial LE	++	1
Intra-op Purulence	Positive	3

Interpretation:

Score ≥ 6: Definitive PJI.
Score 2-5: Inconclusive/Possible PJI. (This is where advanced diagnostics like Next-Gen Sequencing come into play).
Score 0-1: Not Infected.

Clinical Pearl: The D-Dimer

Serum D-Dimer has emerged as a highly valuable screening test for PJI. It is elevated in the presence of infection due to the degradation of fibrin. However, it is remarkably non-specific in the early post-op period (<6 weeks) or in patients with recent DVT/PE. Its true diagnostic value shines in the chronic PJI workup where ESR and CRP might occasionally yield false negatives (especially with low-virulence organisms like Cutibacterium acnes).

Diagnostic Adjuncts in the "Inconclusive" Range

When your patient lands in the dreaded 2-5 score range, you must dig deeper:

Alpha-Defensin: An antimicrobial peptide released by neutrophils in response to pathogens. The 2025 consensus solidifies its role as an excellent "rule-in" test due to its high specificity, though it is expensive.
Leukocyte Esterase (LE) Strip: A standard, inexpensive urine dipstick used off-label on synovial fluid. It detects neutrophil activity. Warning: Blood heavily obscures the reading. The fluid must be centrifuged first if it is grossly bloody.
Next-Generation Sequencing (NGS): Amplifying 16S ribosomal RNA to detect bacterial DNA. It is highly sensitive but can pick up "dead" bacterial DNA, leading to false positives.

The 'Dry Tap' Protocol

What do you do when you stick a needle in a painful knee and get nothing back? Do not just inject local anesthetic and leave. Inject 10-20cc of sterile normal saline, range the joint to wash the gutters, and aspirate it back. Send this "lavage fluid" for cell count, LE strip, and culture (preferably in blood culture bottles). Inform the lab that it is a diluted sample.

Part 2: Prevention Updates and Host Optimization

The absolute best treatment for a PJI is preventing it from happening in the first place. The 2025 consensus heavily emphasized Host Optimization as a non-negotiable step prior to elective arthroplasty. Surgical education is shifting away from purely technical skills towards holistic perioperative medical management.

Essential Host Optimization Targets (The "Non-Negotiables")

Before listing a patient for a primary joint, ensure the following parameters are met. If they are not, delay surgery.

Glycemic Control: HbA1c strictly < 7.5% (ideally < 7.0%). Perioperative hyperglycemia drastically impairs neutrophil phagocytosis.
Nutritional Status: Check serum Albumin (> 3.5 g/dL) and Total Lymphocyte Count (> 1500 cells/mm³). Malnourished patients cannot heal massive surgical dead spaces.
Smoking Cessation: Complete cessation of nicotine products for a minimum of 4-6 weeks prior to surgery. Nicotine causes microvascular vasoconstriction, devastating wound healing.
BMI: Generally restricted to < 40 kg/m² in most centers, though patient-specific factors must be weighed.

1. Nasal Decolonization

Consensus: Screening and treating Staphylococcus aureus carriers (both MSSA and MRSA) significantly reduces Surgical Site Infections (SSI).
Standard Protocol: Mupirocin (Bactroban) nasal ointment twice daily for 5 days pre-op, combined with Chlorhexidine (CHG) body washes.
2025 Update: Povidone-Iodine nasal solution (applied immediately in the pre-op holding area) has emerged as an equally effective alternative. It bypasses the issue of patient compliance with a 5-day at-home regimen and mitigates the growing concern of Mupirocin resistance.

2. Intra-operative Irrigation Protocols

Consensus: A dilute Betadine (0.35%) soak for 3 minutes before final fascial closure significantly reduces infection rates.
Technique: Mix 17.5 mL of standard 10% povidone-iodine in 500 mL of normal saline.
Warning: Do not use full-strength betadine (it is profoundly cytotoxic to osteoblasts and fibroblasts). Do not use Hydrogen Peroxide in closed spaces due to the well-documented risk of fatal air embolus.

3. Antibiotic Prophylaxis Nuances

Weight-based dosing: Cefazolin 2g for patients <120kg, or 3g for patients >120kg.
Redosing Rules: Must be redosed every 4 hours during the case, or immediately if intraoperative blood loss exceeds 1500mL.
Dual Therapy: The addition of prophylactic Vancomycin to Cefazolin is now recommended only for known high-risk carriers (MRSA colonization) or in institutions with a documented, exceptionally high MRSA prevalence. Routine dual therapy for all comers is discouraged due to the synergistic risk of Acute Kidney Injury (AKI).

Part 3: Management Shifts - The Surgical Arsenal

The surgical management of PJI is dictated by the timing of the infection, the health of the host, and the virulence of the organism.

1. DAIR (Debridement, Antibiotics, and Implant Retention)

DAIR remains the gold standard for specific, narrow windows of presentation. It is the most common PJI scenario you will face as a registrar on call.

Indications:
- Acute Post-Operative PJI: Within 4 weeks of the index arthroplasty.
- Acute Hematogenous PJI: A sudden onset of an acutely infected joint (e.g., secondary to bacteremia from a dental abscess or UTI) in a previously well-functioning joint, with symptoms present for less than 3 weeks.
The Technique: This is not a simple washout. It is a radical, extensile surgical debridement. You must excise all fibrinous exudate, perform a complete synovectomy, use copious pulsatile lavage (minimum 9L), and you absolutely must exchange all modular components (polyethylene liners, head balls) to access and debride the posterior recesses and trunnions.

2. The "One-Stage" Revolution

Historically, the single-stage or direct exchange was popular in Europe but viewed with deep skepticism in North America, reserved only for the "easiest" of cases. The 2025 consensus marks a significant global shift in its acceptance.

2025 View: One-Stage exchange is highly effective and equivalent to Two-Stage revisions when strict criteria are met.
The Strict Criteria:
- Healthy host (no severe systemic immunocompromise).
- Pristine soft tissue envelope capable of primary closure.
- Known, highly sensitive organism identified via pre-operative aspiration (e.g., susceptible Streptococcus or MSSA). Never perform a one-stage for a culture-negative PJI or for multi-drug resistant bugs like MRSA/VRE.
- No sinus tract present.
Pros: Single trip to the operating room, drastically lower overall healthcare cost, better preservation of bone stock, and superior functional outcomes.
Cons: If the one-stage fails, your subsequent revision options are significantly compromised, and morbidity skyrockets.

3. The Gold Standard: Two-Stage Exchange

For the majority of chronic infections, the two-stage exchange arthroplasty remains the ultimate fallback.

Stage 1: Complete explantation of all components and cement mantles. Radical debridement. Implantation of an Antibiotic-Loaded Cement Spacer (ALCS).
- Exam Tip: Differentiate between prophylactic cement (1g of antibiotic per 40g bag) and treatment cement (typically 3-4g of heat-stable antibiotics—like Vancomycin and Tobramycin—per 40g bag).
The Interval: Systemic IV or targeted oral antibiotics for generally 6 weeks, guided strictly by an infectious disease specialist.
Stage 2: Re-implantation. How do you know they are ready? The ESR and CRP must be trending down or normalized. The soft tissues must look quiescent. If in doubt, re-aspirate the spacer prior to Stage 2.

The Culture-Negative Nightmare

Culture-Negative PJI accounts for 20-30% of all cases and represents a massive clinical challenge.

Primary Cause: Prior administration of antibiotics (the most common error made by referring primary care physicians).
The Strategy: You must hold all antibiotics for a strict minimum of 14 days before aspirating the joint. At the time of surgery, take a minimum of 3 to 5 separate periprosthetic tissue samples with clean instruments for each. Ask the lab to hold cultures for 14-21 days to catch slow-growing fastidious organisms like C. acnes.

Part 4: Chronic Antibiotic Suppression & Salvage

What happens when a two-stage fails, or when a patient is simply too frail to survive an explantation? We enter the realm of salvage and suppression.

Chronic Antibiotic Suppression (SATT - Suppressive Antibiotic Therapy)

Indications: The patient is medically unfit for major revision surgery, or the patient outright refuses further surgical intervention, AND the implant is mechanically stable.
Success Rates: Highly variable. Literature suggests roughly 50-60% of patients can retain their implant for 2 years on suppression.
Consensus: It is a valid, palliative option to maintain a functional limb, but it is not a cure. The patient must be monitored for antibiotic toxicity (e.g., LFT elevations, renal impairment, gastrointestinal distress).

Salvage Procedures

When infection cannot be controlled, systemic sepsis is looming, or bone loss is catastrophic:

Resection Arthroplasty (Girdlestone): Removal of the hip joint without reimplantation. Leaves the patient with a significant limb length discrepancy and reliance on walking aids, but eradicates the infection.
Arthrodesis: Fusion of the joint (more common in the knee than the hip). Provides a stable, painless, straight limb at the cost of all motion. Highly technically demanding in the setting of massive bone loss.
Amputation: The ultimate salvage. Above-knee amputation (AKA) or hip disarticulation is a life-saving measure when necrotizing infection or intractable sepsis threatens the patient's life.

Conclusion

The 2025 International Consensus Meeting updates push the orthopaedic community towards far more precise diagnostic accuracy utilizing advanced biomarkers, and more aggressive, nuanced surgical management. The era of blindly defaulting to a two-stage revision for every infected joint is definitively ending.

To excel in orthopaedic surgery training, and ultimately in independent practice, you must be a surgical scientist—optimizing the host aggressively, interpreting complex lab data critically, and tailoring the surgical intervention precisely to the pathogen and the patient.

ICM 2025 Summary PDF

Download the executive summary of the consensus meeting for your offline exam prep library.