Which combination best describes the early signs of prosthetic joint infection and the recommended initial workup?

• A. Wound healing without systemic signs; plain X-ray only.
• B. Fever, wound drainage, increasing joint pain, erythema; CBC, CRP/ESR, joint aspiration with culture and cell count, and imaging as needed.
• C. Headache and dizziness; urinalysis and electrolyte panel.
• D. Joint aspiration is unnecessary; treat empirically.

Answer: (B)

The main idea is recognizing that prosthetic joint infection often presents with a combination of local and systemic signals and requires a targeted diagnostic workup. Early signs include fever, wound drainage, increasing joint pain, and surrounding redness. These clues point toward infection rather than simple healing, so relying on imaging alone isn’t sufficient to confirm infection right away.

The best initial workup combines laboratory markers and direct joint analysis. CBC helps detect leukocytosis, while inflammatory markers like CRP and ESR are sensitive indicators of inflammation that can rise with infection. The pivotal step is obtaining synovial fluid from the joint through aspiration and sending it for culture and cell count; the culture can identify the responsible organism and the cell count in the fluid supports an inflammatory/infectious process. Imaging plays a supportive role, helping assess prosthesis integrity and exclude other problems, but plain X-ray or other imaging alone cannot diagnose early infection.

Other options miss key elements: symptoms like headache or dizziness aren’t typical signs of PJI, urinalysis/electrolytes don’t address the joint infection, and treating empirically without aspiration deprives you of definitive culture data essential for guiding treatment.