Speaking on Sky News' Sunday Live programme Ms Hewitt said that the survey did not raise legitimate concerns, arguing that doctors have "always made these decisions about exactly what treatment is going to be right for you as an individual".
"What's happened in these particular PCTs is, as I understand it, doctors have come together and arrived at guidelines for the whole of that particular area, saying that this is what they regard as best practice," she said.
"For instance if you are very overweight, if you are obese, a hip replacement may well have a lower chance of success because of the weight that you're going to put on the joint."
The health secretary added that PCTs are "absolutely entitled" to consult with doctors on areas of clinical judgement to put forward guidance for an area.
"This isn't a matter for managers or indeed government ministers to decide who gets what operation," Ms Hewitt stressed. "It's a matter for doctors and always has been.
"The NHS will treat you with help to stop smoking if the doctor's advice is that you shouldn't have the operation until you've stopped smoking.
"That is a perfectly legitimate clinical decision. I support doctors making clinical decisions in the interests of their patients," she concluded.
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