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This Wikibook page is an analysis of the journal article "Effects of Intensive Diet and Exercise on Knee Joint Loads, Inflammation, and Clinical Outcomes Among Overweight and Obese Adults With Knee Osteoarthritis (2013)" by Stephen P Messier and colleagues.

Obesity and the risk for knee osteoarthritis
Obesity is a major risk factor for a number of degenerative diseases including Knee Osteoarthritis (OA). The mechanisms, by which obesity affects Knee OA, are of great concern to the field of osteoarthritis and clinicians currently trying to manage this disease. Knee OA is considered an active disease development with joint destruction that is established by bio-mechanical stress and metabolic influences like inflammation.

Obese populations with knee OA suffer chronic pain and joint damage that in severe cases may lead to muscle breakdown, decreases in mobility and poor balance which affects quality of life and productivity. An adult is approximately three times greater risk of developing knee OA if you they’re classified obese.

What is the background to this research?
Current treatment for Knee OA is poor with about half of the patients that are treated pharmacologically, experiencing a 30% pain reduction, usually with minimum improved functionality. Current drug therapies can have adverse effects, and surgical interventions are reported as having little to no efficiency on improving lives either. The limited studies that are available on long-term weight loss have shown the same modest results in improvements; however weight-loss is currently advocated as the treatment of choice for obese knee OA sufferers.

Due to the long-term public health benefits of a cheap effective treatment, Messier and colleagues (2013), hypothesised whether sustained significant weight loss of ≥10% body weight induced by diet, with or without exercise, would reduce primary mechanistic outcomes such as knee joint loads and levels of inflammation, in addition to improving clinical outcomes more than exercise interventions alone. Clinical outcomes involved self-reported pain, function, mobility, and improvements in quality of life.

Where is the research from?
This research was conducted by Dr Stephen Messier et al at Wake Forest University in conjunction with Wake Forest School of Medicine, North Carolina, USA between July 2006 and April 2011. Dr Messier is Professor and Director of the J.B Snow Biomechanics Laboratory at Wake Forest University. Messier has been at Wake Forest for over 30 years and has 26 years of experience in clinical trials research explicitly related to knee OA. Messier and his OA research team are well known for their work on the effects of exercise and weight loss on gait biomechanics, strength, function, and pain in knee OA sufferers .The article was published by JAMA internal medicine; an internationally renowned peer-reviewed medical journal that’s published twice a month by the American Medical Association.

What kind of research was this?
This research is an Intensive Diet and Exercise for Arthritis, translational, single-blind, 18 month, randomised controlled trial. Randomised control trials are the gold standard in evidence based clinical research for the effects of interventions.

What did the research involve?
After intensive exclusion criteria and pre-screening, 454 sedentary overweight and obese adults (≥ 55 years) partook in this study. Participants all showed symptoms of pain and radiographic knee OA. An effort was made to make the adults involved a good representation of the racial/ethnic demographic of the local area. Participants were randomised into one of three intervention groups

The Three Interventions


 * 1) Intensive diet-induced weight loss (diet group), aimed to achieve a weight loss in participants of 10% their baseline body weight.
 * 2) Exercise (exercise group), used both aerobic and resistance exercises that are consistent with guidelines to manage knee OA, and is supported by strong evidence  . Exercise was conducted for one hour on three days a week. During the first six months, participation was centre-based. After 6 months, options to shift to a home-based program or combine the two were available.
 * 3) Participants received both diet and exercise interventions (combined group).

What were the basic results after 18 months of intervention?
88% of the participants finished the study at the 18 month mark which is a substantial completion rate in such a large sample. Combined and diet groups lost significantly more weight on average when compared to the exercise group. Combined group averaged a loss of 11.5% body weight, diet group lost 9.5% and exercise group lost 2% their baseline weights. Nearly 80% of participants were obese at baseline, but this dropped to around 55% after completion. Fat mass was significantly less in both groups who dieted, with the exercise group showing little to no reductions. Knee loads were lowest in the diet group followed by the combined group then exercise group. Inflammation was significantly lower in the diet and combined groups relative to the exercise group. 38% of the combined group reported little to no pain when compared to the approximately 20% of the participants in both diet and exercise groups. The combined group showed greater improvements in mobility and functionality when compared to the exercise group. Dieting alone showed the least improvements in biomechanical function.

How did the researchers interpret the results?
Amid overweight and obese adults with knee OA, there is convincing evidence that a combination of diet and exercise over an 18 month period can lead to sustainable weight loss, lower levels of inflammation, less load on the knee, less joint pain, faster walking speeds, improve gait mechanics and a greater quality of life than those who just exercise or diet to lose weight.

Conclusions and implications of this research
The clinical importance of this research shows that substantial weight loss appears to benefit obese patients with knee osteoarthritis by reducing pain and inflammation whilst improving knee function. There is however risks involved in weight-loss among older adults. In addition to weight-loss and reduced fat mass, lean mass associated with muscle weakness also reduces, putting people at greater risks of falls and injury which may lead to premature death. More research into exercise treatment that improve muscle strength whilst reducing weight and fat mass among older adults, specifically obese and osteoarthritic sufferers would be beneficial.

This study had some limitations that should be considered when conducting future research. At baseline, participants were diagnosed as having mild-to-moderate knee OA and similar levels of pain. Therefor it’s unknown whether a loss of weight can reduce the pain in severe knee OA sufferers. The muscular-skeletal model that was used to calculate knee loads had several limitations itself which may have produced inadequate results on knee loads.

Further research may help alleviate the enormous physical and financial burden that health care systems are facing due to the increasing prevalence of obesity related knee OA. The exact mechanisms that link obesity and osteoarthritis are multifaceted and detailed involving both bio-mechanical and metabolic factors. Further evidence supporting the link between the two diseases will be useful in providing clinicians and researchers with targets for future exercise therapy, pharmacological treatment and diet management strategies.