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Difficulty: HardOrthopedic Surgery

A 68-year-old man presents to the emergency department with a 2-day history of worsening right knee pain, swelling, and fever. He underwent a primary right total knee arthroplasty 3 weeks ago for severe osteoarthritis. His early postoperative course was uncomplicated, and he had been progressing well with physical therapy until the onset of these symptoms. His temperature is 38.9°C (102.0°F), blood pressure is 125/80 mmHg, pulse is 105/min, and respiratory rate is 18/min. Physical examination reveals a markedly swollen, erythematous, and warm right knee. The surgical incision is well-healed with no active drainage. Range of motion is severely limited by pain. Laboratory studies show a leukocyte count of 14,500/mm³ and an erythrocyte sedimentation rate of 85 mm/hr. Arthrocentesis of the right knee yields cloudy fluid with a leukocyte count of 45,000/mm³ (90% neutrophils). Gram stain shows Gram-positive cocci in clusters. Which of the following is the most appropriate next step in the management of this patient?

  1. A
    Removal of all prosthetic components and placement of an antibiotic-impregnated spacer
  2. B
    Initiation of intravenous vancomycin and cefepime without surgical intervention
  3. Surgical debridement, polyethylene exchange, and retention of the metal componentsAnswer
  4. D
    Continuous closed joint irrigation and drainage via percutaneous catheters
  5. E
    Reassurance, antipyretics, and continuation of routine postoperative physical therapy

Answer

Surgical debridement, polyethylene exchange, and retention of the metal components
The correct answer is surgical debridement, polyethylene exchange, and retention of the metal components (Debridement, Antibiotics, and Implant Retention or DAIR). This patient presents with an acute early-onset prosthetic joint infection (PJI), defined as occurring within 4 weeks of the primary arthroplasty. The standard of care for acute early PJIs or acute hematogenous infections (with < 3 weeks of symptoms) in a well-fixed prosthesis is the DAIR procedure. This involves open arthrotomy, thorough washout, exchange of modular components (like the polyethylene insert to remove any formed biofilm), and retention of the fixed metal implants, followed by a prolonged course of targeted intravenous antibiotics.

Step-by-Step Solution

1
Identify the primary diagnosis based on the clinical presentation and arthrocentesis results.
The patient has an acute early-onset prosthetic joint infection (PJI) caused by Staphylococcus species (Gram-positive cocci in clusters), indicated by fever, joint pain, and synovial fluid pleocytosis 3 weeks post-surgery.
Accurate diagnosis is required to dictate the surgical algorithm.
2
Evaluate the timeframe of the infection relative to the primary surgery.
The infection onset is at 3 weeks post-operation, placing it in the 'acute early' category (defined as less than 4 weeks post-operatively).
The chronicity of the infection determines whether the prosthetic hardware must be completely removed or can be safely retained.
3
Select the definitive management strategy based on the acute timeframe.
Debridement, antibiotics, and implant retention (DAIR) is chosen over a two-stage complete revision.
In acute early PJIs, the bacterial biofilm is immature. Thorough washout with exchange of modular parts (polyethylene insert) combined with IV antibiotics is sufficient to eradicate the infection while preserving the fixed metal hardware.

Key Concept

The management of acute early-onset prosthetic joint infections (< 4 weeks post-op) involves Debridement, Antibiotics, and Implant Retention (DAIR), rather than complete removal of the prosthesis.
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Topics

Orthopedic Surgery

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