GOOD HEALTH: Lowering BMI before surgery can provide better outcomes

By Dr. Keith Roach

DEAR DR. ROACH: I’m 72, and I have had arthritis for three years: two years in both knees, and one year in my right hip and the base of my spine. I am 5-foot-3 and weigh 221 pounds, with a body mass index (BMI) of 39. I lost 23 pounds from January to June.

What is the BMI needed for an orthopedic surgeon to do a hip replacement for someone with osteoarthritis — without a broken hip? I recently had an assessment of my hip X-rays. I was told I’m at the outer cutoff of a BMI of 39, so I’m eligible for a hip replacement operation. Then, a few weeks later, I saw the surgeon, who ended up rejecting me — claiming that 39 isn’t the outer limit, 35 is.

After a long talk, the surgeon said he’d do it for me, but I’d get a better result if I lose 20 more pounds and get my BMI down to 35. I felt jerked around, but said I’d wait and lose weight. I’m also trying to find a surgeon I like more than him.

So, what is the BMI needed for knee surgery: 35 or 39? — L.C.

ANSWER: There is no standard cutoff BMI for joint replacement surgery. It is true that people with a BMI over 40 are at higher risk for medical complications; however, it is also true that people with severe arthritis and a high BMI still get improvement in their quality of life with surgery. Denying a person a cost-effective surgery that can greatly improve their quality of life simply because of a BMI number (which, in itself, is a flawed metric) is inappropriate.

I can understand why you would want to see a different surgeon, as it sounds like you were not treated well. However, the surgeon was right that surgical outcomes are better if a person can lose at least 20 pounds, according to a 2019 study. This included shorter lengths of stay in the hospital and a lesser chance of needing surgical revision. I wonder, though, if part of the benefit seen in the study was due to increased exercise prior to surgery, which is known to be beneficial in surgical outcomes.


DEAR DR. ROACH: My 45-year-old son has hemochromatosis. The treatment is phlebotomy of a pint of blood, sometimes every two weeks, until the iron level is normalized. My understanding is that the blood is discarded. Is there anything wrong with the blood? If not, I would think blood banks would welcome the donation. What are your thoughts on this subject? — E.B.

ANSWER: Hereditary hemochromatosis is caused by the body absorbing too much iron due to a genetic defect. With no way to get rid of iron, it builds up and damages many organs, especially the heart, bone marrow, joints and adrenal gland. As you say, the best treatment is to remove iron in the form of red blood cells. This is effective at preventing most of the organ damage if started quickly enough.

There has never been anything wrong with the blood of people with hereditary hemochromatosis, and the FDA here in the U.S. has always allowed the blood to be donated. However, until recently, the American Red Cross has not accepted blood donations from people with hereditary hemochromatosis. I am pleased to say that they have just changed their policy and will now be using this precious resource to help others, so long as the person meets all the criteria for being a blood donor. The blood will undergo all the standard and rigorous testing prior to being pronounced safe for use.


Dr. Roach regrets that he is unable to answer individual questions, but will incorporate them in the column whenever possible. Readers may email questions to


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