FRI072 Biomechanical CT To Assess Bone After Sleeve Gastrectomy In Adolescents With Obesity- Prospective Longitudinal Study

Abstract Disclosure: V. Singhal: None. F.A. Huber: None. S. Tuli: None. M. Bouxsein: None. M. Misra: None. M.A. Bredella: None. Background and Objective: Sleeve gastrectomy (SG) is effective in treating cardiometabolic complications of obesity but is associated with bone loss. Our aim was to determine the effect of SG on the lumbar spine by biomechanical computed tomography (CT) analysis in adolescents/young adults with obesity. We hypothesized that SG would lead to a decrease in strength and BMD compared to non-surgical controls. Methods: 12-month prospective non-randomized study of adolescents/young adults with obesity who either underwent SG (N=29) or were followed without surgery (controls, N=30). At baseline and 12 months, participants underwent QCT of L1 and L2 for biomechanical assessment and MRI of the abdomen and mid-thigh for body composition assessment. 12-month changes between groups were compared using Student’s t-test, and changes within groups were assessed using paired t-tests. Analyses were controlled for baseline and 12-month changes in BMI by multivariable analyses. Regression analysis was performed to evaluate the effect of body composition on bone parameters. Results: Participants in the SG group had a higher baseline BMI than controls (p=0.01) and lost an average of 34.3±13.6 kg 12 months after surgery, whereas weight was unchanged in controls (p<0.001). There were significant reductions in abdominal adipose tissue and thigh muscle area in the SG group compared to controls (p<0.001). Significant decreases in bone strength [-609 (-928, -291) vs. 103 (-173, 380) N], bending stiffness (-0.08 ± 0.16 vs. 0.07 ± 0.15 kNm/rad), average vBMD (-12 ± 12 vs. 0 ± 13 mg/cm3) and trabecular vBMD (-15 ± 13 vs. 2 ± 13 mg/cm³) were noted in the SG vs. control groups (all p<0.001). After controlling for change in BMI, a 12-month reduction in cortical BMD was significant in the SG group compared to controls (p=0.02). Reductions in strength and trabecular BMD were associated with reductions in BMI, visceral adipose tissue, and muscle (p≤0.03). Conclusion: Adolescents undergoing SG had a decrease in strength and volumetric BMD of the lumbar spine compared to non-surgical controls; reductions in cortical BMD were independent of weight reductions over the study duration. These changes were associated with a decrease in visceral fat and muscle mass. Presentation: Friday, June 16, 2023