ESPE Abstracts

Background: A reduction in bone mass in adults and adolescents has been observed following Roux-en-Y bypass surgery with an increase in fracture risk reported in adults. However, the intragastric balloon (IGB) is a less invasive bariatric procedure.

Objective and hypotheses: Given obese adolescents are at greater risk of fracture we studied the impact of a 6 month IGB insertion on skeletal mass, geometry and strength over 2 years.

Method: We recruited 12 adolescents aged 13.8 to 16.8 years, BMI >3.5 SD, Tanner stage 4/5 to undergo IGB placement. Subtotal body and lumbar spine (LS:L1–L4) were measured by DXA and radial/tibial cortical and trabecular bone parameters were evaluated by high resolution pQCT imaging at 0, 6 and 24 months. Skeletal biomechanical parameters were defined by miocrofinite element analysis. Results are expressed as (mean difference (95%CI), significance(p)).

Results: At 6 months BMI SDS fell by −0.27 SD (−0.43, −0.10), p=0.005, due to a reduction in perecntage fat mass of −2.0 (−3.9, −0.03), p=0.05. Weight loss was not sustained at 2 years. At 6 months subtotal body BMC (g) (60.7(5.5,115.9), p=0.03), LS BMC (g) (2.5(1.4,3.6), p=0.001) and LS BA (cm²) (0.8(0.4,1.2), p=0.002) all demonstrated expected age appropriate increases. Over 2 years there were overall increases in total body BMD (g/cm²) (0.04(0.01, 0.06), p=0.01), LS BMC (g) (5.3(1.0,9.5), p=0.02) and LS BA (cm²) (2.0(0.9,3.0), p=0.003). At the tibia, consistent gains were seen from baseline to 2 years in cortical area (mm²) (10.1(1.7,18.5), p=0.02) and cortical thickness (mm) (0.09(0.002,0.173), p=0.04). Gains were only seen in cortical (14.0(8.3,19.6), p<0.001) and trabecular (4.1(0.5,7.6), p=0.03) BMD (g/cm³) BMD at the radius at 6 months. Over 2 years bone stiffness (S, kN/mm) and ultimate failure load (F.Ult, kN) at the radius (S=4.1(1.3,6.9), p=0.01), (F.Ult=0.2 (0.1,0.3), p=0.004) and tibia (S=7.5 (0.6,14.5), p=0.04), (F.Ult=0.5(0.1, 0.9), p=0.02) increased.

Conclusion: In the short term, an IGB placement offers significant reduction in BMI SDS. Unlike other bariatric procedures, bone accrual during adolescence continued at a time when bone mass accrual is critical.