MON-211 Two-year Change in Individual Trabecula Segmentation Parameters at Weight-bearing and Non-Weight-bearing Sites Following Gastric Bypass and Sleeve Gastrectomy in Youth

Abstract Disclosure: M. Misra: Regeneron Pharmaceuticals, Consultant, Amgen Inc, Drug Donation, Up To Date, Contributor. S. Nimmala: None. V. Singhal: None. A.P. Lopez Lopez: None. D.M. Mitchell: None. M. Bouxsein: None. H. Lee: None. E.W. Yu: None. M. Bredella: None. Data are lacking regarding effects of Roux-en-Y gastric bypass (RYGB) on skeletal outcomes in youth. We examined the impact of RYGB vs. sleeve gastrectomy (SG) and no surgery (NS) on trabecular (Trab) structure in youth with moderate to severe obesity aged 14-26 years. We hypothesized that RYGB would result in the greatest deleterious effects on Trab parameters. 79 subjects were enrolled (30 undergoing SG, 13 RYGB and 36 NS controls) (mean: 18.5±0.3 years). 12-month (12M) data were available for 24, 10 and 20 subjects, and 24M data for 29, 10 and 18 subjects respectively. We assessed Trab parameters at the distal tibia (weight-bearing site) and radius (non-weight-bearing site) using high resolution peripheral quantitative CT (HR-pQCT) and individual trabecula segmentation (ITS), and report data for percent change over time. JMP software (v18) was used for analysis. RYGB and SG had higher BMI at baseline than NS, with greater BMI reductions over 24M than NS (-33.7±2.8 and -25.7±2.4 vs. 2.9±1.5%, p<0.0001). At the tibia, over 12M, decreases were greater for RYGB vs. NS for Trab BMD (p=0.001), and for RYGB and SG vs. NS for Trab number (p≤0.01). Over 24M, both RYGB and SG had greater reductions in Trab BMD and number vs. NS (p<0.0001), with greater reductions following RYGB than SG for Trab BMD (p=0.02), even after adjusting for weight change (p=0.004). Reductions in rod BV/TV were greater following both RYGB and SG vs. NS at 12 and 24M (p≤ 0.013). Groups did not differ for changes in plate and axial BV/TV and Trab thickness. At the radius, decreases were greater for SG vs. NS at 12M for Trab BMD (p=0.025), and for both RYGB and SG vs. NS at 24M (p≤0.0002); decreases were greater after RYGB than SG (p=0.025), even after adjusting for weight change (p=0.01). The RYGB group had reductions in Trab number vs. NS at 12M (p=0.031), and vs. SG and NS at 24M (p≤0.012). Reductions in rod BV/TV were greater following RYGB vs. SG and NS at 24M (p≤ 0.017). SG (but not RYGB) had reductions in plate BV/TV at 24M (p=0.002). Groups did not differ for changes in axial BV/TV or trab thickness. Percent change in BMI correlated with percent change in radius Trab number, BMD and rod BV/TV in the surgical groups (r≥0.45, p≤0.02). RYGB and SG in youth result in deleterious Trab outcomes at weight-bearing and non-weight-bearing sites related to reductions in BMI; RYGB has a greater impact than SG. Further studies are necessary to devise preventative and therapeutic strategies. Presentation: Monday, July 14, 2025