Overweight and obese people with knee arthritis tend to report more pain than slimmer people with the same degree of joint damage

Past studies have found that heavier people, especially women, are more likely to develop osteoarthritis and often have more severe osteoarthritis (OA). This study goes a step further. It suggests that people with a higher body mass index (BMI) may have more pain than normal-weight people with the same amount of arthritis-related damage.

Overall, 1,390 participants had already been diagnosed with knee osteoarthritis, 3,284 did not have the disease but were at risk of developing it, and 122 did not have osteoarthritis or related risk factors.

Weiss analyzed X-rays to determine the severity of patients' arthritis and used the health records to gather information on their BMI and pain levels during everyday activities.

She found that patients with a higher BMI reported more pain, even after adjusting for the severity of their joint damage. For each category of arthritis severity, pain scores were substantially higher among obese patients than among normal-weight patients. Scores for overweight patients fell somewhere in the middle.

Even though osteoarthritis is a progressive disease and its effects are irreversible, losing weight should help reduce pain related to the condition, Weiss wrote online June 17 in Rheumatology.

Losing weight could jump-start a healthy cycle, Weiss said: a decrease in body weight could lessen pain, which in turn might make people more likely to take on more physical activity, resulting in even more weight loss.

It might be difficult for a person who is already experiencing a high level of pain to become active in order to lose weight, however. Weiss suggested trying to lose the weight before starting exercise.

"It is easier to lose weight through dietary changes than through exercise. Small changes can sometimes make big differences," she said. "For example, drinking water rather than cola or finding ways to increase activity that will become a habit, like parking further from the store entrance or taking stairs instead of an elevator."

SOURCE: http://bit.ly/1mK8QcO

Rheumatology 2014.

Knee Osteoarthritis (OA): Daily Walking Maintains Function

Patients with knee OA can gain significant benefits and avoid physical function limitations by simply walking more.

"As clinicians, we should be promoting walking in our patients with knee OA. We should have them measure their physical activity with a pedometer, much like people measure their weight with a scale. Those starting on a walking program should get to a target of at least 3000 steps/day and ultimately try to reach 6000 steps/day. This is well below the popular anecdote of 10,000 steps/day, which may be good news to those starting out. It doesn't take much to get to 3000 steps/day," Dr. White told Medscape Medical News. He is research assistant professor, Department of Physical Therapy & Athletic Training, Boston University College of Health and Rehabilitation Sciences, Massachusetts.

Long-Term Study Documents Benefits of Walking in Patients With Knee OA

The researchers measured daily steps taken by 1788 people with or at risk for knee OA who were part of the Multicenter Osteoarthritis (MOST) Study, a large multicenter longitudinal cohort study of community-dwelling adults. Mean age was 67 years, mean body mass index (BMI) was 31 kg/m², and 60% of participants were female.

The researchers measured the number of steps patients walked with an ankle monitor over 7 days. They measured functional limitation at baseline and again 2 years later. The researchers defined functional limitation as walking speed less than1.0 m/s 

The authors reported, "Among study participants who did not develop slow walking at the two-year follow-up (<1.0 m/s), 80% walked at least 5300 steps/day." The minimum for preventing functional decline was between 3250 and 3700 steps/day. Walking an additional 1000 steps each day was associated with a 16% to 18% reduction in incident functional limitation 2 years later.

"Our findings add to the idea that walking is good for people with knee OA. Specifically, walking that occurs during unstructured activities, a few steps here and there, add up and do seem to make a difference in terms of prevention of functional limitation in this patient population. I hope that these findings will lead to clinicians encouraging their patients to use a pedometer to measure their physical activity and work towards the 3000 then 6000 steps/day goal," Dr. White said.

 Physical activity stimulates the expression of lubricin, a lubricant molecule of synovial fluid that is important for cartilage growth and that contributes to the delay of OA development.

More Walking Might Reduce Healthcare Costs Associated With Knee OA

According to Dr. White, data from the National Health and Nutrition Examination Survey showed that 80% of patients with OA have some limitation in movement and that 11% of adults with knee OA need assistance with personal care.

"Our findings strongly suggest that walking does work to prevent the onset of problems with physical functioning in the future in people with knee osteoarthritis," Dr. White said.

Arthritis Care Res. Published online June 12, 2014. Abstract