BMI no better than other risk factors
Although high BMI is independently associated with a higher risk of complications, the increased risk of complications conferred by a BMI at or above 40 is similar to or lower than those of other comorbidities that surgeons generally accept, said Nicholas Giori, MD, PhD, professor of orthopedic surgery at Stanford (Calif.) University, and chief of orthopedic surgery at the VA Palo Alto Health Care System. These other comorbidities include age older than 75, hypertension that requires medication, and insulin-controlled diabetes. “The independent risk of just having the diagnosis of insulin-dependent diabetes is actually comparable to the independent risk of having obesity by itself,” he told this news organization, “and all of us operate on [patients with] diabetes.”
Dr. Nicholas Giori
Also, there is no BMI at which the risk of complications suddenly increases, according to the American Academy of Orthopaedic Surgeons. “It’s a rising complication rate as you go into higher BMIs,” Dr. Giori said. “If you operate on someone with a BMI of 39 vs. 41, you’re not going to find that much of a difference [in risk].” But if a medical system enforced a hard BMI cutoff of 40, one patient would qualify for surgery while the other would be barred.
Weight not as “modifiable” as previously thought
Weight is often considered a “modifiable factor” for a person considering undergoing total joint arthroplasty, but research suggests that the issue is more complicated. “Obesity is tricky, because some people are successful [in weight loss],” said Dr. Giori. Those tend to be the more memorable stories. “But a large majority have a really hard time losing substantial weight – enough to make a difference in risk,” he continued.
A study conducted in North Carolina found that restricting patients with a BMI over 40 from having elective total joint arthroplasty procedures until their weight was optimized did not result in successful weight loss. Only 20% of patients who originally presented with a BMI above this limit eventually underwent surgery after 2 years, and fewer than half of these patients had achieved a BMI of less than 40 at the time of their surgery. A third of all patients in the study did not return to the orthopedic office after their first visit.
“To hold a hard cutoff when it’s very, very hard to modify ... is essentially telling people that they are not going to ever have surgery,” Dr. Giori said; “I think that can be unfair to some patients.”
Bariatric surgery is often suggested for patients with obesity who have not experienced successful weight loss with diet and lifestyle changes alone, but bariatric surgery comes with its own complications. Research on outcomes from total joint arthroplasty among patients with who have lost weight with bariatric surgery has yielded mixed results. “I rarely push anyone hard to go that route but present it as an option for certain patients,” said Benjamin M. Stronach, MD, an orthopedic surgeon at the University of Arkansas for Medical Sciences, in Little Rock. He usually brings up bariatric surgery with patients with a BMI in the high 40s or higher to gauge their interest. If patients are already considering weight loss surgery, his office provides referrals.
Dr. Benjamin M. Stronach
But even bariatric surgery does not result in successful long-term weight loss for every patient, Dr. Stronach said. He’s seeing more and more patients who come for consultations after having undergone bariatric surgery 10 to 15 years ago. These patients lost a significant amount of weight, but then gained the weight back. He noted that bariatric surgery can be very successful for some patients who adhere to their postbariatric regimen. “We typically see fairly impressive results in the short term,” he said.