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HIGH RISK AND POTENTIAL THERAPY FOUND FOR KNEE OSTEOARTHRITIS
One new study finds that the risk of developing knee osteoarthritis is high, while another examines the effects of special footwear engineered to reduce knee load
Arthritis is among the leading causes of disability in the U.S. and osteoarthritis (OA) is the most common type of this debilitating disease. One new study on knee OA examined the lifetime risk of developing the disease, while another examined the potentially therapeutic effect of footwear specifically engineered to reduce joint loads. The studies were published in the September issue of Arthritis Care & Research (www.interscience.wiley.com/journal/arthritis).
In the first study of the lifetime risk of symptomatic knee OA, Louise Murphy of the Centers for Disease Control and Prevention in Atlanta, led an analysis of data from the Johnston County Osteoarthritis Project, a study based at the Thurston Arthritis Research Center at the University of North Carolina, on the risk of symptomatic knee OA. Researchers conducted baseline (1990-1997) and follow-up (1999-2003) home interviews and clinical exams (including X-rays) of more than 3,000 black and white residents of Johnston County, N.C. who were at least 45 years old. They found that the lifetime risk of knee OA – the probability of a person developing symptomatic OA in at least one knee by the age of 85 – was nearly 1 in 2 overall and nearly 2 in 3 for those who were obese.
“Although Johnston County is rural area in the Southern U.S., the high lifetime risks observed in this population-based sample suggest that the lifetime risk of symptomatic knee OA is likely high in the U.S. and other populations, especially given the aging of the population and the increasing prevalence of obesity,” the authors state. They note that the high lifetime risk shown in this study illustrates the significant public health burden of this condition, that weight loss can lead to a decreased risk of developing OA and that the study “further underscores the need for public health weight loss and management interventions that would contribute to a decreased lifetime risk of OA.”
Noting that the potential impact of footwear on knee OA has not been widely recognized or critically evaluated, researchers on another study published in the same issue conducted gait analyses on patients with knee OA. Led by Najia Shakoor of Rush Medical College in Chicago, they designed a flexible, lightweight shoe (referred to as the mobility shoe) engineered to incorporate the potential biomechanic advantages of barefoot walking, which they had previously shown enhances mobility compared to conventional footwear. For example, the mobility shoe does not contain lifts at the heel, which have been shown to increase knee loads, and its flexible sole is designed to mimic the flexible movement of a bare foot. The results showed that the mobility shoes effectively reduced knee loads while walking.
“Because dynamic loading across the knee is pathophysiologically important to the onset and progression of knee OA, these findings suggest that altering the characteristics of footwear might have a substantial impact on the overall disease process of knee OA,” the authors state. They note that most studies of wedge orthotics that are inserted into shoes have shown a five to eight percent reduction in load, while the present study showed eight to 13 percent reduction in load with the mobility shoes.
The authors conclude that footwear may represent a novel therapeutic target for the treatment of knee OA, adding that “the types of shoes worn by subjects with knee OA should be evaluated more closely in terms of their contribution to the disease, and long-term intervention trials to evaluate the clinical effects of shoe design on pain and disease progression in OA should be considered.”
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Articles:
“Effects of Specialized Footwear on Joint Loads in Osteoarthritis of the Knee,” Najia Shakoor, Roy H. Lidtke, Mondira Sengupta, Louis F. Fogg, Joel A. Block, Arthritis & Rheumatism (Arthritis Care & Research), September 2008; 59:9; pp. 1214-1220.
“Lifetime Risk of Symptomatic Knee Osteoarthritis,” Louise Murphy, Todd A. Schwartz, Charles G. Helmick, Jordan B. Renner, Gail Tudor, Gary Koch, Anca Dragomir, William D. Kalsbeek, Gheorghe Luta, Joanne M. Jordan, Arthritis & Rheumatism (Arthritis Care & Research), September 2008; 59:9; pp. 1207-1213.
