ESPE Abstracts

Background: The effect of profound weight loss following obesity surgery on skeletal microarchitecture and strength in adolescents has not been studied. Obese children are at an increased risk of fracture and childhood obesity leads to reconfiguration of trabecular bone without augmenting bone strength.

Objective and hypotheses: To examine the impact of weight loss following 6 months treatment with an intragastric balloon supported by a lifestyle intervention programme on cortical and trabecular bone microstructure and bone strength in obese adolescents.

Method: We recruited 11 adolescents aged 13.8 to 16.8 years, BMI >3.5 S.D., Tanner stage 4/5 to undergo intragastric bariatric balloon placement. Serial distal radial and tibial high resolution pQCT (peripheral quantitative computed tomography) imaging, subtotal body and lumbar spine (LS:L1 to L4) DXA was performed at baseline and 6 months. HRpQCT measures of microstructural properties included trabecular number (Tb.N, 1/mm), trabecular thickness (Tb.Th, mm), trabecular separation (Tb.Sp, mm), and cortical thickness (Ct.Th, mm). Biomechanical parameters were defined by miocrofinite element analysis. Results are expressed as (mean difference, 95% CI, significance (p)).

Results: Weight SDS and BMI SDS decreased significantly (−0.38 (−0.62, −0.13) and −0.27 (−0.44, −0.10) respectively, P=0.005). Total body bone mineral content (BMC), LS BMC and LS bone area all demonstrated age appropriate increases following the balloon. Cortical BMD (14.0 mg/cm³ (8.2, 19.7), P<0.001) and cortical perimeter size (4.0 mm (0.5, 7.5), P=0.029) increased at the radius. Cortical area (2.4 mm² (0.1, 4.7), P=0.042), cortical BMD (11.1 mg/cm³ (4.1, 18.0), P=0.006) and cortical thickness (0.02 mm (0.001, 0.04), P=0.042) increased at the tibia. Paradoxically, total bone area at the radius diminished (−6.1 mm² (−8.9.−3.2), P=0.001). Bone stiffness and estimated ultimate failure load did not significantly change following surgery.

Conclusion: There was no evidence of skeletal deterioration following intragastric balloon insertion despite a reduction in BMI SDS. Total body and regional bone accretion continued with the greatest gains in cortical bone. In the short term, balloon bariatric surgery does not cause bone loss in adolescence.