A recent review of 17 studies, involving nearly 14,000 people, found that the incidence of fatal venous thromboembolism after surgery will occur in about 1 in 32 patients, and fatal pulmonary embolism will occur in around 1 in 100 patients. Those having knee replacement surgery had double the risk of asymptomatic deep vein thrombosis in the week following surgery than those undergoing hip replacement (Arch Intern Med, 2002; 162: 1465-71).