What is the standard perioperative antibiotic prophylaxis for arthroplasty?

• A. No antibiotics are used for arthroplasty
• B. Prophylactic IV antibiotics given within 24 hours of incision
• C. Prophylactic IV antibiotics given within 60 minutes of incision, typically cefazolin, and continued for about 24 hours post-op
• D. Prophylactic antibiotics for 72 hours

Answer: (C)

The key idea is to ensure protection during the time the joint is most vulnerable—around the time of incision—while minimizing unnecessary antibiotic exposure afterward. The standard approach is an IV antibiotic given within 60 minutes before the incision, typically cefazolin, and continued for about 24 hours after surgery. This timing guarantees adequate tissue levels at the moment of incision and provides a protective window through the immediate postoperative period, when the risk of infection is highest. Cefazolin is chosen because it covers the common skin bacteria, especially Staphylococcus species, that are most often implicated in prosthetic joint infections.

Giving antibiotics within 24 hours of the incision (rather than within the 60-minute preincisional window) can miss the optimal concentration at the time of surgery. Not using antibiotics at all is obviously inappropriate for arthroplasty, and extending prophylaxis to 72 hours does not improve outcomes and increases risks such as antibiotic resistance and C. difficile infection.