prosthetic joint infection
Prosthetic Joint Infection
| Prosthetic joint infection |
|
|
|
|
Early onset |
Delayed onset |
Late onset |
| Time to onset after surgery |
<3 months |
3-12 months |
>12 months |
| Presentation |
Acute pain. Wound infection or breakdown. Fever |
Chronic joint pain. Implant loosening. Sinus tract formation |
Acute symptoms in previously asymptomatic joint. Recent infection at distant site |
| Most common organisms |
Staphylococcus aureus. Gram-negative rods. Anaerobes |
Coagulase-negative staphylococci. Propionibacterium species. Enterococci |
Staphylococcus aureus. Gram-negative rods. Beta-hemolytic streptococci |
- early onset: < 3 months, staph aureus
- delayed onset: 3-12 months, CoNS, S. epidermidis
- late onset: > 12 months: staph aureus
PJI can be acquired by perioperative contamination of the joint or by extension from an overlying wound infection:
- Infections due to virulent organisms (eg, Staphylococcus aureus, Pseudomonas aeruginosa) typically present within the first 3 months after surgery (early onset infection) with acute pain, fever, leukocytosis, and overt local signs of infection (eg, erythema, purulent drainage), not seen in this patient.
- Infections due to less virulent organisms (eg, coagulase-negative staphylococci, Propionibacterium species), as in this patient, are likely to have a delayed onset (3-12 months) and present with chronic pain, implant loosening, gait impairment, or sinus tract formation. Fever and leukocytosis are usually absent. Staphylococcus epidermidis is a coagulase-negative staphylococcus commonly implicated in delayed-onset PJI.
- Late-onset infections presenting >12 months after surgery are unlikely to have been acquired perioperatively and are usually due to hematogenous spread of a distant infection (eg, urinary tract infection).
- prolonged, low grade onset
- minimal swelling
- can present acutely
- xray: prosthesis loosening, periosteal reaction
- removal of prosthesis
- IV a bx 6-8 weeks
This patient has subacute pain in his prosthetic knee 6 months after arthroplasty. The synovial fluid analysis shows a mildly elevated leukocyte count with a predominance of neutrophils. This is consistent with an inflammatory process, most likely a prosthetic joint infection (PJI). The leukocyte count in the synovial fluid in PJI is usually elevated to >1000/mm3 but is often lower than in septic native joints (usually >50,000/mm3).