Overview
Periprosthetic joint infection (PJI) is one of the most serious complications following joint replacement surgery. It occurs when microorganisms colonize the tissues surrounding a prosthetic joint implant, leading to inflammation, implant loosening, and joint dysfunction. PJI is most commonly associated with total hip arthroplasty and total knee arthroplasty.
The incidence of PJI after primary joint replacement is approximately one to two percent, but the consequences can be devastating for patients. Infection may lead to prolonged hospitalization, multiple surgeries, functional impairment, and significant healthcare costs.
Management of periprosthetic joint infection requires a multidisciplinary approach involving orthopaedic surgeons, infectious disease specialists, microbiologists, and rehabilitation teams. Early diagnosis and appropriate treatment strategies are essential for successful outcomes.
Etiology and Pathogenesis
Periprosthetic joint infections occur when microorganisms adhere to the surface of an implant and form a biofilm. Biofilm formation allows bacteria to survive within a protective matrix that shields them from host immune responses and antibiotics.
The most common organisms responsible for PJI are Gram positive bacteria, particularly Staphylococcus species.
| Organism | Clinical Association |
|---|---|
| Staphylococcus aureus | Acute postoperative infections |
| Staphylococcus epidermidis | Chronic low grade infections |
| Streptococcus species | Hematogenous infections |
| Gram negative bacteria | Immunocompromised patients |
Biofilm formation on implant surfaces significantly complicates treatment because bacteria embedded in biofilms exhibit resistance to antibiotics and immune defense mechanisms.
Routes of Infection
Periprosthetic joint infection can occur through several routes depending on the timing and mechanism of bacterial entry.
- Direct contamination during surgery
- Hematogenous spread from distant infection sites
- Contiguous spread from adjacent soft tissue infection
Intraoperative contamination is believed to be responsible for most early infections following arthroplasty procedures.
Classification Based on Timing
Periprosthetic joint infections are commonly classified according to the time of onset following surgery.
| Type | Time of Onset | Typical Features |
|---|---|---|
| Early infection | Within 3 months | Acute pain, wound drainage, erythema |
| Delayed infection | 3 to 24 months | Persistent joint pain and loosening |
| Late infection | More than 24 months | Hematogenous infection |
Risk Factors
Several patient related and procedure related factors increase the risk of periprosthetic joint infection.
- Diabetes mellitus
- Obesity
- Immunosuppression
- Malnutrition
- Revision arthroplasty
- Prolonged surgical duration
- Poor soft tissue condition
Optimization of these factors prior to surgery can significantly reduce infection risk.
Clinical Features
Clinical presentation depends on the timing and severity of infection.
- Persistent joint pain
- Swelling around the joint
- Warmth and erythema
- Sinus tract communicating with the prosthesis
- Wound drainage
- Fever in acute infections
A sinus tract communicating with the prosthetic joint is considered diagnostic of periprosthetic joint infection.
Investigations
Diagnosis of periprosthetic joint infection requires integration of clinical findings, laboratory tests and imaging studies.
- Elevated ESR and CRP levels
- Joint aspiration with synovial fluid analysis
- Microbiological cultures
- Plain radiographs to detect implant loosening
- Nuclear medicine imaging in selected cases
Synovial fluid leukocyte count and neutrophil percentage are particularly useful diagnostic markers.
Treatment Strategies
Management of periprosthetic joint infection depends on the chronicity of infection, organism involved, and stability of the prosthesis.
| Treatment Method | Indication |
|---|---|
| Debridement with implant retention | Early infections with stable implant |
| One stage revision | Selected chronic infections |
| Two stage revision | Gold standard for chronic infection |
| Resection arthroplasty | Severe infection or poor host factors |
Two stage revision arthroplasty remains the most commonly used method for treating chronic periprosthetic joint infections.
Prevention Strategies
Prevention of periprosthetic joint infection is a critical aspect of joint replacement surgery.
- Perioperative antibiotic prophylaxis
- Strict sterile surgical technique
- Optimization of patient comorbidities
- Laminar airflow operating theatres
- Minimization of operative time
These measures significantly reduce infection rates following arthroplasty procedures.
Exam Pearls
- Staphylococcus species are the most common cause of periprosthetic joint infection
- Biofilm formation protects bacteria from antibiotics
- A sinus tract communicating with the prosthesis is diagnostic
- Two stage revision arthroplasty is the gold standard treatment for chronic infection
- ESR and CRP are useful screening investigations