OSTEOARTHRITIS AND OBESITY
Tuesday, May 10th, 2011There is a well-documented link between osteoarthritis and obesity, although the cause is not completely clear. It is often assumed that the connection between lower-limb arthritis and excess body weight is merely due to the increased load these susceptible joints have to support, usually over many years. But it has also been suggested that damage to the joint surface is due to a metabolic effect, caused by the release of cytokines from adipose tissue having a direct inflammatory action leading to arthritis. A cohort of the Framingham study looked at the relative risk of radiographic osteoarthritis of the knee for various weight groups, adjusted for age, physical activity and uric acid levels. It was discovered that women in the heaviest quintile for weight had more than double the risk of osteoarthritis in the knee, whereas men had 1.5 times the risk, but the precise cause of the condition was not postulated. A study at St Thomas’ Hospital found a link between obesity and osteoarthritis of the carpometacarpal joints of the hand, which suggests a metabolic cause because these joints are non-weight-bearing. Van Saase et al found that obesity was clearly associated with osteoarthritis in all those joints most frequently affected, whether or not they were weight bearing. This implies a metabolic cause and, although not offering an explanation, does suggest the scope for prevention of osteoarthritis by weight loss.A recent paper demonstrated a link between symptomatic spinal osteoarthritis and low birth weight, but also concluded that the problem is worse in those who were low birth weight babies but went on to become overweight as adults. This suggests that weight gain is an important aetiological factor in the condition. A second study on the effects of changing weight revealed that increased weight in women, but not men, was linked to worsening of symptoms of knee osteoarthritis, whereas a reduction of 10% weight by men, but not women, resulted in a significant reduction in symptoms.The most common explanation is backed by the NHANES study, which concluded that there is a link between osteoarthritis and obesity, and that additional mechanical stress is the cause.*1/312/5*