For knee arthroplasty, typical prophylaxis duration is?

• A. 10–14 days.
• B. 3–4 weeks.
• C. 14 days to 4 weeks per protocol.
• D. 6 months.

Answer: (C)

Prevention of venous thromboembolism after knee arthroplasty relies on pharmacologic prophylaxis that is guided by the specific protocol in use. The need for protection extends through the early postoperative period, and the exact duration is not fixed universally but is determined by institutional guidelines and patient risk factors. In practice, many protocols provide prophylaxis for about two weeks up to four weeks after surgery, which is why a duration stated as 14 days to 4 weeks per protocol best captures the typical range and the requirement to follow local guidelines. Shorter durations like 10–14 days may be used for lower-risk patients, but extending to six months is generally unnecessary and increases bleeding risk without additional benefit.