Purpose: To determine the extent to which, a medically monitored rapid weight-loss program will improve pain, psychological status and functional abilities for morbidly obese women with knee osteoarthritis.

Method: 34 women (age 40 to 65) with morbid obesity and severe osteoarthritis of the knee that presented to an orthopedic surgeon for total knee arthroplasty were offered enrollment into a medically supervised weight loss program prior to consideration of a total knee replacement. Twenty-six subjects chose to participate in the weight loss program. They were enrolled in the Dr. Bernstein diet program, (a low-calorie, low-fat diet) at no cost to them. We collected the following questionnaires at enrollment and every six weeks while they remained in the weight loss program: WOMAC, SF36, Self-Efficacy, Health Locus of control, Dieting beliefs scale, Body image state scale, and the Beck depression inventory as well as Functional tests, namely the Timed up and go (TUG) and 6 minute walk test (6MWT). Our hypothesis was that weight loss would be associated with dramatic improvements in pain, self-report quality of life measures, psychological variables, and measured functional abilities for those patients who were successful in the weight loss program.

Results: At enrollment the mean age was 58.5 years and mean BMI was 47.8.

Subjects were significantly disabled with WOMAC (total) scores of 48+/ − 7 and impaired function in both the 6 minute walk test 229+/ − 146 metres and the timed up-go test 5.9+/ − 11.

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Subjects lost an average of 32 kilograms (range 14 to 50 kg) after six months of dieting.

Weight loss was associated with dramatic improvements in pain(p < .01), self-report quality of life measures (p < .01) and measured functional abilities (p < .01).

Successful weight loss was associated with patients’ self-report of no longer requiring TKA for their knee OA.

Initially 100% of subjects felt that they required surgery. This decreased to 9.5% after six months of weight loss.

Conclusion: A low-fat, low-calorie medically monitored weight loss program (Dr. Bernstein Diet Clinics Inc.) is effective for achieving significant weight loss in women with severe knee osteoarthritis and morbid obesity. Weight loss leads to significant improvements in pain and functional abilities and alleviates or delays the need for knee replacement surgery in the majority of middle-aged, morbidly obese women.