A recent study, published in Arthritis & Rheumatism, a journal issued by Wiley-Blackwell on behalf of the American College of Rheumatology (ACR), has revealed an unexpected correlation between smoking and arthroplasty (total joint replacement). Researchers have reported that people who never smoke seem to be at a higher risk of undergoing total joint replacement surgery compared to those who smoke. The study has also established a link between the physical state of a person and the risk of arthroplasty. Scientists have stated that people who are overweight or involved in intense physical activity are at a higher risk of undergoing total joint replacement surgery.

Previous studies have shown that in developed nations, total hip and knee replacement surgeries are among the most common elective surgeries performed.

Data from the 2007 National Hospital Discharge Survey shows that in America alone, an estimated 230,000 people had hip replacement surgery and 543,000 more, underwent knee replacements. The most commonly reported cause of arthroplasty was severe osteoarthritis (OA).

In the current study, the correlation of smoking, body mass index (BMI), and physical activity to the risk of joint replacement surgery in men was studied by George Mnatzaganian, a PhD student from the University of Adelaide in Australia, and his colleagues. Researchers combined the hospital morbidity data and mortality records with the clinical data of 11,388 study participants, who were participating in the Health in Men Study (HIMS). Smoking history and physical activity were the focus of the initial health screening between 1996 and 1999 among HIMS subjects.

Scientists analyzed clinical data from baseline through March 2007 and identified 857 men who underwent arthroplasty. Out of these, 59% of men had total knee replacement and the remaining 41% had total hip replacement. Participants were categorized into three age groups: 65-69 years, 70-74 years, and 75 or more years.

Upon analyzing the data, researchers have demonstrated that being overweight can increase the risk of total joint replacement even in the absence of other predisposing factors. It was also shown that smoking can decrease the risk of arthroplasty, with men who smoked 48 years or more being up to 51% less likely to undergo total joint replacement. The risk-lowering effect of smoking was most evident after 23 years of exposure to smoking. Researchers also stated that in the 70-74 year age group, intense physical activity can lead to an increased risk of joint replacement in men.

Mnatzaganian confirmed:

"Our study is the first to demonstrate a strong inverse correlation between smoking duration and risk of total joint replacement. The independent inverse associations of smoking with risk of total joint replacement were evident also after adjusting for major confounders and after accounting for the competing mortality risk in this elderly cohort of men. Further investigation is needed to determine how smoking impacts the development of OA."

"Smoking, Body Weight, Physical Exercise and Risk of Lower Limb Total Joint Replacement in a Population-Based Cohort of Men."
George Mnatzaganian, Philip Ryan, Paul E. Norman, David C. Davidson, Janet E. Hiller.
Arthritis & Rheumatism; Published Online: July 8, 2011 (DOI: 10.1002/art.30400).

Written by Anne Hudsmith