Giardia lamblia Reactive Arthritis Mimicking Acute Periprosthetic Knee Infection: A Case Report.

CASE: A healthy 49-year-old man with a well-functioning total knee replacement developed a painful swollen knee. The erythrocyte sedimentation rate was 12 mm/hour, and C-reactive protein was 20.3 mg/L. Aspiration revealed 24,440 white blood cells and 5% neutrophils. His 2018 International Consensus Meeting (ICM) definition score of 5 met criteria for "possibly infected." He was diagnosed with reactive arthritis (ReA) secondary to Giardia lamblia, mimicking acute periprosthetic infection. He was successfully treated with a 10-week course of multiple oral antiparasitic medications.

CONCLUSION

Systemic parasitic infectious ReA can mimic acute infection in the presence of total knee arthroplasty. Careful application of the 2018 ICM criteria can be critical for workup and the treatment of suspected periprosthetic infection.