Industrialized nations are currently facing an obesity epidemic, resulting in increasing morbidity and mortality in the United States and around the world. In addition to diseases like type 2 diabetes and heart disease, obesity is known to cause a number of musculoskeletal problems that lead to joint pain and disability, in some cases severely limiting an individual’s mobility. One such disease is osteoarthritis—the most common form of arthritis—which is known to have a direct link to obesity.
The leading risk factors for osteoarthritis (OA)—aging and obesity—are affecting increasing numbers of people worldwide. Today, more than 2 out of 3 people over the age of 65 are affected by OA—a shocking 12.1% of adult Americans, or 27 million people in the United States alone. Numbers like these show that OA is the most commonly experienced joint disorder in the world, resulting in a correspondingly steep economic burden in many countries [1].
A loss of articular cartilage causes the defining symptom of OA, which is joint pain. In most sufferers, this joint pain is present mainly in the hip, knee, and hand joints. While the pain initially occurs only when the joint is being utilized, the later stages of OA are characterized by nearly constant pain that is present even during sleep.
Both surgical and non-surgical procedures are available as treatments for OA. Most people with the disease can control their symptoms with a variety of non-surgical options. These may include medication, dietary changes, lifestyle adaptations, and therapies such as acupuncture. For OA sufferers who experience severe pain that cannot be controlled with these methods, surgery may be an option.
Medications commonly used to avoid surgery and control the symptoms of OA include analgesics such as Tylenol and non-steroidal anti-inflammatory medications like Advil, Aleve, and Orudis. While these drugs can work effectively to treat the pain associated with OA, their frequent use is not without side effects and health risks. For example, one common complaint associated with pharmacological treatments of OA is gastrointestinal bleeding.
In response to the health concerns related to these medications, natural remedies for pain relief are increasing in popularity as a treatment method for OA. At least 5 millions Americans are taking dietary supplements containing glucosamine or chondroitin sulphate. Other home remedies for the treatment of OA include Bogbean and Boswellia, two side-effect-free anti-inflammatory herbs, as well as Ginger and MSM.
Is Obesity a Risk Factor For Osteoarthritis (OA)?
Obesity is a commonly accepted risk factor for OA among medical professionals. Study results have consistently found that people who are overweight have an increased risk of OA when compared to their peers who are not overweight.
A 2001 survey conducted in Australia showed that Body Mass Index (BMI, a measure of someone’s weight in relation to height) is a risk factor for OA. This remained true even when the results were adjusted for other factors like age, sex, and socioeconomic status. Among the 7500 respondents, those who were overweight were twice as likely to be diagnosed with OA.
Overweight And Knee OA
The results of large population studies have shown that there is a linear relationship between knee OA and BMI, with the relative risk of knee OA increasing as BMI increases. Among 5000 people surveyed in the United States, the risk of developing knee OA was found to double with every 5-point increase in BMI [2].
Information from 858 respondents to a Scottish survey demonstrated a positive relationship between obesity and the frequency of joint pain in the lower limb, with obese people experiencing hip, knee, ankle, and foot pain twice as frequently.
Overweight And Hip OA
Research has found that the relationship between obesity and the incidence of hip OA is not as robust as that between obesity and knee OA. This is most likely the result of the differing load placed on the hip and knee by the human body in action. Force is distributed more narrowly in the knee, and as a result this joint is subjected to a higher load than the hip joint [3].
A cross-sectional study of over 2000 people found that obesity did not appear to be a risk factor for hip OA. Other studies, however, have found an association. One study in particular found that subjects with a higher BMI at age 18 were at 5 times the risk of requiring a total hip replacement in more advanced age.
This positive correlation between BMI and hip OA was confirmed in a large cohort study in Norway, which looked at data from 1.2 million people. For men with a BMI greater than 32 (a BMI above 30 signifies obesity), the relative risk of experiencing hip arthroplasty at a later date was 3.4 times higher than that of men with a BMI of 21.
Overweight And Hand OA
Because hand joints are not weight-bearing, they don’t experience increased force as a result of excess weight. Despite this fact, research has found that overweight people are at an increased risk for hand OA when compared to people of normal weight. Because this association can’t be attributed to a difference in weight load on the hand joints, it has been suggested that reasons other than sheer weight force mediate obesity’s effect on OA [4].
Does Obesity Cause OA or is it OA That Causes Obesity?
The clear association between obesity and OA begs the question of which is the root cause. It may be that OA is a response to increased stress on the joints caused by excess weight, but it could also be that the pain of OA forces a sedentary lifestyle that results in weight gain.
Several co-relational studies extended over long periods of time have been conducted in order to address this issue of causality. One such study, the Framingham Heart Study, collected information from 1420 healthy subjects over 36 years. Data from participants showed that being overweight at age 37 was associated with an increased risk of developing OA in their 70s. Being diagnosed with OA at age 37 was very rare. This indicates that the condition that occurs first is obesity, while OA tends to appear in later stages.
In Closing
Research has shown that having excess body fat is a major risk factor for knee OA and a real but less significant risk factor for OA of the hip and hand. Those suffering from OA, particularly OA of the knees, should consider weight loss an important treatment method for the symptoms of the painful disease.
About The Author
Matthew Denos, PhD, is a biology scientist with an interest in obesity and related disorders such as OA. Matthew strives to stay up to date on the scientific research being conducted in the fields of obesity treatment and weight loss. He shares this information in his blog, where he offers an eDiets promo code and Diet To Go coupon code discounts, two dietitian-designed meal delivery programs that provide a nutritionally balanced diet for overweight arthritis patients.
References
- New horizons in osteoarthritis. Punzi L, et al. Swiss Med Wkly. 2010 May 10
- The relation between body mass index and waist-hip ratio in knee osteoarthritis. Gandhi R, et al. Can J Surg. 2010 Jun;53(3):151-4.
- The effect of obesity on the outcome of hip and knee arthroplasty. Yeung E, et al. Int Orthop. 2010 May 29.
- Obesity and osteoarthritis in knee, hip and/or hand: an epidemiological study in the general population with 10 years follow-up. Grotle M, et al. BMC Musculoskelet Disord. 2008 Oct 2;9:132.