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Body Mass Index (BMI) is the measurement of choice for many physicians studying obesity. BMI uses a mathematical formula that takes into account a persons 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.
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.
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.
In addition to Dr. Lewallen, the Mayo research team included Drs. David Polga, Aaron Altenburg and Robert Trousdale.