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Cellulitis (severe) — UKMLA MCQ

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HardInfectious DiseasesCellulitis (severe)UKMLAMRCEM SBAMRCP Part 1

A patient with a prosthetic knee develops acute severe pain, effusion and fever. Blood pressure and lactate are normal. Radiographs show no loosening. What diagnostic step should precede antimicrobial therapy?

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Correct answer: C — Urgent joint aspiration before antibiotics in the stable patient

The best answer is “Urgent joint aspiration before antibiotics in the stable patient”. Acute prosthetic-joint infection requires urgent orthopaedic assessment and joint aspiration for cell count, crystals and microbiological culture before antibiotics when the patient is stable. This preserves diagnostic yield and informs debridement and antimicrobial planning. If sepsis or instability develops, antibiotics must not be delayed. CRP and plain films cannot identify the organism or exclude crystal disease. Bone scanning is too slow and nonspecific, while intra-articular steroid in an infected prosthesis can worsen infection.

Reference: BOAST prosthetic knee joint infection guideline: https://www.boa.ac.uk/resource/boast-investigation-and-management-of-prosthetic-joint-infection-in-knee-replacement.html