Sandra Donaldson's clinical background is in kinesiology where she worked in orthopaedics for 5 years. She then crossed over to work in clinical research where she has been working for over 10 years. Sandra has worked at University Hospital (London), Princess Margaret and Women's College Hospitals. She is now working as a clinical research associate in paediatric orthopaedic clinical trials in Toronto while pursuing her Masters of Journalism through the University of Queensland.

In Canada, 46 per cent of people who had a joint replacement in 2003-2004 were defined as obese, with a body mass index of 30 or higher, according to the Canadian Institute for Health Information's annual report. That's much higher than in the general Canadian population, with a 23-per-cent rate of obesity. After adjusting for the effects of age and gender, the obese are three times as likely to need a hip or knee joint replacement.

"Our data tell us that being obese or overweight not only increases the likelihood of needing a joint replacement, but it also has a negative impact on how well a patient recovers and how long a patient remains in the hospital following surgery," explains Margaret Keresteci, manager of clinical registries at the institute.

The annual report says that "being obese or overweight can also increase the necessity for repeat surgeries – modifications to or replacements of the artificial joints-because the extra weight adds more wear and tear on the prostheses," although this subject has been highly controversial in medical research journals. One U.S. study indicates obesity doesn’t increase the need for hip or knee revision surgeries while another study demonstrates reduced survival of the joint replacement in as little as five years in obese patients.

Researchers suggested that once obese patients had a joint replacement and their mobility increased, the weight would come off. But a study on 100 knee and hip joint replacement patients revealed that those with a normal BMI and those who were obese did not lose weight. The research team from the Joint Replacement Institute at Orthopaedic Hospital in California concluded: "Obesity should be treated as an independent disease that is not the result of inactivity from arthritis."

A more frightening trend from the Canadian Institute for Health Information's annual report shows knee replacements in patients aged 45 to 54 have increased by 99 per cent in men and 133 per cent in women over the past 10 years. In addition, 82 per cent of joint replacement patients aged 45 to 84 were obese or overweight.

Obesity costs. Obese people are more likely to need joint replacements, experience post-operative complications, not lose their excess weight following their joint replacement and need surgical revisions as their weight increases the wear and tear on the artificial joint.

So should patients be forced to lose weight before receiving a joint replacement?

Dr Gillian Hawker, a rheumatologist and osteoarthritis researcher at Sunnybrook and Women’s College Health Sciences Centre in Toronto, says patients should be encouraged to lose weight. However, she acknowledges that is very difficult for people who suffer severe pain when walking or doing any weight-bearing activity. "There is good evidence now that obesity does increase the risk for both development and progression of knee osteoarthritis; the link is less strong for hip osteoarthritis."

The NHS decision was based on financial restraint. But would it actually reduce costs?

"Absolutely not – joint replacement surgery is cost effective, possibly cost saving, as a result of decreased need to visit the doctor for joint pain," Hawker argues. She estimates that costs would be higher in those waiting to lose weight before surgery but acknowledges there is no data in this particular area.

It seems that refusing to replace joints in obese patients, who are at the end stage of their disease, is not the answer.

"I would put my money on increasing physical activity and maintaining healthy weights in kids and young people to prevent knee osteoarthritis as the strategy most likely to succeed," Hawker says. In the British Medical Journal on Dec. 3, 2005, the British Medical Association’s Jonathan Fielden echoes Hawker’s negative response to the decision.

"The decisions on whether patients should receive treatment should always be based on clinical need and not solely financial reasons," Fielden said, adding that clinical guidelines are there to promote safety and appropriate treatment but each case should be considered individually.

With our aging population and increasing health-care costs, could this type of rationing be in Canada’s future health care system?