Common sense suggests that extra body weight severely stresses bones and joints. But until the findings of a new Mayo Clinic study were presented today at the annual meeting of the American Academy of Orthopedic Surgeons in Las Vegas, no one had reported how this higher, unprecedented level of obesity in the U.S. affects total hip and knee replacements.
Body Mass Index (BMI) is the measurement of choice for many physicians studying obesity. BMI uses a mathematical formula that takes into account a person’s height and weight. In this Mayo study, patients diagnosed as superobese had a BMI greater than 50. Generally, a BMI of 30 indicates obesity. A person 6-feet tall with a BMI of 30 would weigh about 225 pounds. A person that same height with a BMI of 50 would weigh 369 pounds.
In the first study, 43 patients categorized as superobese underwent total hip arthroplasty from 1996 to 2006. This surgical procedure replaces a worn, fractured or damaged hip joint with a prosthetic implant. The patients had a BMI ranging from 50 to 77, and a mean age of 56. Mayo followed them an average of three years to determine outcomes.
Results showed:
- More than half (56.5 percent) experienced either surgical or medical complications, including prolonged wound drainage.
- Five of the 43 patients required a total of 15 re-operations to correct problems such as recurring dislocation of the implant, chronic infection, and new bone fractures around the device.
In the second study, which looked at complications associated with knee replacement, results showed:
- Overall, 40.6 percent had surgical complications and 14.3 percent had medical complications — including two deaths after the surgery.
- Surgical complications included 20 knees that had prolonged wound drainage —increasing the chance of deep infection of the implant.
- Nineteen cases needed additional operations to trim slowly healing wound edges, treat deep infection, or repair failed implants.
“As with hip replacement in the superobese patient, total knee arthroplasty also is associated with a markedly higher complication rate compared to patients of normal weights,” says Mayo Clinic orthopedic surgeon David Lewallen, M.D., senior author on the study. “The real concern here is that clinicians and patients need to be aware of that fact when they are making treatment decisions. In general, this group of patients is in desperate circumstances — and we really want to help them. To do that, we are trying to get the data out there that will guide management of the superobese patient. A big part of that has to be helping them lose weight prior to knee arthroplasty whenever possible.”
In addition to Dr. Lewallen, the Mayo research team included Drs. David Polga, Aaron Altenburg and Robert Trousdale.
Below is a link to an edited youtube video with Dr. Lewallen.
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I had a complete knee replacement but it was never right. I have been unable to bend or extend my knee. I have had several second opinions. The last orthopedic doctor outside of Des Moines Iowa told me the reason was there is not enough space to allow to bend and extend. He provided me with the disk and sent one to the doctor of the Xray showing where the problem is. My question is can this surgery be done at Mayo? What would the surgery entail? How long would the surgery take? And more?
I can’t seem to get a straight answer from anyone. I would like to get knee replacements;however; my BMI shows me to be obese. I’m 6′ 255. and sixty seven years old. I’ve always been a large guy and am very comfortable at 225 of which I’ve been most of my life until a few years ago. So if I get back to 225 and am still showing too be obese what should I do about the knee replacement? I’m in considerable pain.
Thank you for your question. Dr. Lewallen’s response is that your current size would not preclude surgery if knee changes and symptoms warrant the procedure (like anyone else).
If you’d like more information, please call his office at 507 266 0466.
My father just had his 59th birthday today, my two kids and I celebrated with him. Unfortunatley he can barely walk to the bathroom, little less play with my kids. He is morbidly obese and has been for most of my life. He needs bi lateral knee arthroplasty. I can not bear to watch him struggle just to make it to the bathroom. Is there anything that can be done for him? He is 6′ 450 + or – a little. He was losing weight for awhile but his knees starting causing him to mutch pain to do any further exercise. He now spends most of his day sitting in a chair. He met with a orthopedic surgeon once that said he was to heavy to perform the surgery. That was a year ago now he can barely walk at all. I think the benefit could outweigh the risk now.