Study Links Weight Loss Surgery in Adolescents, Young Adults to Weakened Bones

Miriam Bredella, MD
Credit: Harvard Medical School

New research from a Harvard Medical School-led team is calling attention to potential effect of weight loss surgery on bone health among adolescents and young adults with obesity.

An analysis of data more than 54 participants, including 25 who underwent sleeve gastrectomy between the age of 13-24 years, results of the study suggest patients undergoing surgery experienced a greater degree of weight loss, but appeared to have had a significant increase in bone marrow fat and a decrease in bone density estimates in the lumbar spine.¹

“Childhood obesity is on the rise and weight-loss surgery is the most effective way to reduce weight and improve cardiometabolic comorbidities,” said lead investigator Miriam A. Bredella, MD, professor of radiology at Harvard Medical School and vice chair for Faculty Affairs and Clinical Operations in the Department of Radiology at Massachusetts General Hospital.² “This is the first study in adolescents and young adults that examined the long-term effects of sleeve gastrectomy, the most common type of weight-loss surgery, on bone strength and bone marrow fat.”

As the obesity epidemic has grown so has the abundance of data related to the safety and efficacy profile of bariatric surgery as a treatment for severe obesity. . Although studies have boasted improved weight loss and long-term cardiovascular outcomes, other studies have purported a potential increase in risk for reductions in bone mineral density and increased risk of fracture among patients who had undergone bariatric surgery.¹

With this in mind, Bredella and a team of investigators launched the current study with the intent of exploring the effects of sleeve gastrectomy on vertebral bone strength, density, and bone marrow adipose tissue among adolescents and young adults with obesity. A nonrandomized, prospective, longitudinal study, investigators enrolled a cohort of 54 patients from an academic medical center between 2015 and 2020.¹

For inclusion in the study, patients needed to be between the age of 13-24 years and have moderate to severe obesity, which was defined as a BMI of 35 kg/m2 or greater for adults and a BMI 120% or more of the age- and sex-specific 95th percentile for adolescents. Those in the surgical group intended to undergo sleeve gastrectomy and had at least 1 obesity-related comorbidity or a BMI of 40 kg/m2 or greater. Investigators noted those in the control group received dietary and exercise counseling without surgery.¹

Per study protocol, all participants underwent quantitative computed tomography (CT) scans of the L1 and L2 levels of the Lunar spine, proton magnetic resonance (MR) spectroscopy of L1 and L2 levels of the lumbar spine, and MRI of the abdomen and thigh. The primary outcomes of interest for the study were 24-month changes between and within groups for bone density and strength, bone marrow adipose tissue, and body composition.¹

Upon analysis, results indicated the sleeve gastrectomy group experienced a mean BMI decrease of 11.9 (Standard deviation [SD], 5.21; P < .001) kg/m2 and the control group experienced a mean BMI increase of 1.49 (SD, 3.10; P = .02) kg/m2. Analysis of primary outcomes of interest indicated mean bone strength of the lumbar spine decreased among the surgery group compared to the control group (mean decrease, —728 N [SD, 691] vs —7.24 [SD, 775]; P < .001) and bone marrow adipose tissue of the lumber spine increased after sleeve gastrectomy (mean lipid-to-water ratio increase, 0.10 [SD, 0.13]; P = .001).¹

Investigators also highlighted observed changes in vertebral density and strength correlated positively with changes in BMI and body composition (R = 0.34 to R = 0.65; P = .02 to P < .001), but were inversely associated with vertebral bone marrow adipose tissue (R = −0.33 to R = −0.47; P = .03 to P = .001).¹

“As bariatric surgery is increasingly performed in adolescents, its effect on bone health needs to be emphasized, especially to the physicians who will continue to provide routine medical care for these patients,” Bredella said.² “We hope that our study will raise awareness on the effects of weight-loss surgery on bones in adolescents with obesity.”

References:

1. Huber FA, Singhal V, Tuli S, et al. Two-year Skeletal Effects of Sleeve Gastrectomy in Adolescents with Obesity Assesses with Quantitative CT and MR Spectroscopy. Radiology. Published online June 13, 2023. doi:10.1148/radiol.223256
2. Radiological Society of North Americas. Weight-loss surgery weakens bones of teens and young adults. Press Releases. June 13, 2023. Accessed June 13, 2023. https://press.rsna.org/timssnet/media/pressreleases/14_pr_target.cfm?ID=2439.