Men who smoke have less risk than those who never smoked of undergoing total joint replacement surgery, researchers in Australia found.However, George Mnatzaganian, a Ph.D. student from the University of Adelaide in Australia, and colleagues, also found men who were overweight or who engaged in vigorous physical activity were more likely to need arthroplasty.The researchers examined clinical data for 11,388 male study participants and integrated it with hospital morbidity data and mortality records from baseline through March 2007, identifying 857 men who had joint replacement surgery.Of those having surgery, 59 percent had total knee replacement and 41 percent had total hip replacement.Men who smoked 48 years or more were as much as 51 percent less likely to undergo total joint replacements than those who never smoked, and vigorous exercise increased risk of joint replacement in men ages 70-74.The study, published in the Arthritis & Rheumatism, showed being overweight independently increased total joint replacement risk, while smoking lowered the risk, which was most evident after 23 years of smoking exposure.