A 68-year-old woman develops increasing pain in her total hip replacement 8 months after uncomplicated surgery. She is afebrile. Aspiration of the joint grows an organism identified as coagulase-negative staphylococcus. Based on the timing of onset, this infection is classified as:
- A Delayed infection acquired during surgery with a less virulent organism ✓
- B Early postoperative infection acquired during surgery with a virulent organism
- C Late haematogenous infection from a distant source
- D Rejection reaction unrelated to infection
Correct answer: A. Delayed infection acquired during surgery with a less virulent organism
Explanation
Prosthetic joint infections are timed as early, under 3 months, usually virulent organisms such as S aureus; delayed, 3 months to about 2 years, caused by less virulent organisms implanted at surgery such as coagulase-negative staphylococci; and late haematogenous infections beyond that. Onset at 8 months with coagulase-negative staphylococcus fits the delayed category. Late haematogenous infections typically involve more virulent organisms.
Reference: Campbell's Operative Orthopaedics, Canale and Beaty, 14th ed.
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