Which antibiotic is commonly used for perioperative prophylaxis in arthroplasty, and when is it typically given?

• A. Cefazolin within 60 minutes before incision
• B. Vancomycin after wound closure
• C. Doxycycline during skin preparation
• D. No antibiotic is used

Answer: (A)

Preventing prosthetic joint infection relies on having effective antibiotic levels in the tissues right at the moment the incision is made. Cefazolin is the antibiotic most commonly used for this purpose in arthroplasty because it covers the common skin flora that cause these infections (such as MSSA and streptococci) and is easy to dose and tolerate. The key timing is IV administration within about 60 minutes before incision so peak tissue concentrations are present when the skin is cut. In longer surgeries or with substantial blood loss, the dose may be redosed to maintain protection. If a patient cannot receive a beta-lactam, alternatives like vancomycin or clindamycin can be used, but they are still given before incision to ensure coverage at the start of surgery. Giving vancomycin after wound closure would not protect the incision site at the critical moment, and doxycycline is not standard for perioperative prophylaxis in arthroplasty.