PREVENTING weight gain from early adulthood could reduce knee replacements in Australian adults by almost 30 per cent and save the health system $373 million a year, according to new research.

The Monash University-led study found preventing weight gain from young adulthood to late midlife to reduce overweight/obesity could significantly reduce the cost burden of total-knee replacements.

The study examined the association between patterns of weight gain (body mass index – BMI – trajectories) from early adulthood to late midlife and the risk of total-knee replacement for osteoarthritis.

Senior author Prof Flavia Cicuttini, who heads the Monash School of Public Health and Preventive Medicine’s Musculoskeletal Epidemiology Unit, said the results underlined the importance of prevention in improving health and reducing health costs. While weight loss was recommended for people with osteoarthritis who were overweight or obese, this was often too little too late. 

“Preventing weight gain is feasible and effective in improving osteoarthritis health outcomes,” she said. 

“Focusing on prevention, with small average long-term changes in energy balance, can make a big difference. Reducing your caloric intake just slightly each day builds up to avoiding 8-12 kilograms of weight gain over a couple of decades, saving money and avoiding surgery. This also has cardiac health benefits.

“For example, eating the average equivalent of two fewer pieces of chocolate per week, or adding 10 minutes of exercise, can prevent the insidious 0.5-1 kilogram weight gain we see per person per year in Australia. This can result in tangible health gains, improving lives and saving money.”

Prof Cicuttini said a “call to action” was needed for knee joint health. 

“We also need to be sending out the message that it is important to make sure that people don’t continue to gain more weight,” she said. “Although recommendations to lose weight are important if a person is carrying excess weight, this can be difficult to achieve for most people.

“Too often we see people with knee pain, advise them to lose weight, only for them to return five years later having gained a further 3-5 kilograms. This is a missed opportunity because it is easier to prevent further weight gain than it is to lose it.

“We need to focus on preventing or slowing weight gain when people first present with any knee pain, even niggling knee pain. Australians tend to gain about 0.5-1 kilogram per year over adult life. This slow, steady accumulation of weight adds up, resulting in the obesity we see.”

The project used data from 24,368 participants in the Melbourne Collaborative Cohort Study.

Researchers linked weight data over a period of years with National Joint Replacement Registry records. They identified six distinct trajectories of BMI from early adulthood (age 18-21 years) to late midlife (about 62 years). These included:

• Group 1: lower normal to normal BMI (19.7 per cent)
• Group 2: normal BMI to borderline overweight (36.7 per cent)
• Group 3: normal BMI to overweight (26.8 per cent)
• Group 4: overweight to borderline obese (3.5 per cent)
• Group 5: normal BMI to class 1 obesity (10.1 per cent)
• Group 6: overweight to class 2 obesity (3.2 per cent). 

Over 12.4 years, 1328 (5.4 per cent) of subjects had a total-knee replacement. The risk of requiring one increased in all groups where someone progressed into a higher weight group.

In total, 28.4 per cent of knee replacements could be prevented if people moved to one group lower, with an average 8-12-kilogram weight loss from early adulthood to late midlife. This could save $373 million in annual health costs.

Prof Cicuttini said that assuming we can “fix” obesity after it had occurred was not very effective and prevention had multiple health and cost benefits.

“If an approach doesn’t work, why don’t we change it?” she said. “If adults can be encouraged to consider preventing the slow creep in weight from a young age, this will have multiple health benefits including reducing the need for a knee replacement in the future.”