Bone mineral density in young adults 5 to 11 years after adolescent metabolic and bariatric surgery for severe obesity compared to peers

Metabolic and bariatric surgery (MBS) is associated with decreased bone mineral density (BMD) in adults. The long-term impact of MBS during adolescence on BMD is unknown. We report bone health status 5 to 11 years after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) from the Teen-LABS study cohort.

Between 2016 and 2022, BMD was measured by dual energy x-ray absorptiometry (DXA) in 106 young adults who had undergone MBS as adolescents. Volumetric BMD by peripheral quantitative computed tomography was measured on a subset. Ninety-one controls who had not undergone MBS were recruited for comparison.

In cases (RYGB: mean age 26.8 ± 1.9 years, mean BMI 42.1 ± 9.9 kg/m², VSG: mean age 25.1 ± 2.1 years, mean BMI 37.1 ± 8.4 kg/m²), compared to controls (mean age 26.5 ± 2.7 years, mean BMI 40.2 ± 8.7 kg/m²) (age p < 0.001, BMI p = 0.02), adjusted mean DXA-BMD (g/cm²) of the RYGB (n = 58) and VSG (n = 48) groups were lower at the hip (−10.0% and −6.3%), femoral neck (−9.6% and −5.7%) and ultra-distal radius (−7.9% and −7.0%; all p < 0.001), respectively. DXA-BMD did not differ between RYGB and VSG groups. Trabecular volumetric BMD at the radius and tibia were lower in the RYGB (−30% and −26%) and VSG (−15% and −14%) groups compared to the control group (p < 0.001). Greater time since MBS was associated with lower BMD Z-scores at the hip (p = 0.05) and femoral neck (p = 0.045). Percent change in body mass index (BMI) from baseline or in the first year after MBS were not associated with bone measures at a median of 9.3 years post MBS.

BMD, especially of the hip and femoral neck, was lower in young adults who underwent MBS during adolescence compared to matched peers who had not undergone MBS. BMD Z-scores of the femoral neck were inversely associated with time since MBS but were not associated with BMI change.