Risk of wrist fracture, estimated by the load-to-strength ratio, declines following sleeve gastrectomy in adolescents and young adults

Summary To understand whether the bone loss which occurs after vertical sleeve gastrectomy increases the risk of fracture, we used an engineering model to estimate risk in participants before and after surgery. We found that estimated risk decreased 1 year after surgery and remained lower, though had rebounded, at year 2. Purpose Vertical sleeve gastrectomy (VSG) improves metabolic health in young people with obesity but is accompanied by substantial loss of bone mass and estimated bone strength. We thus estimated fracture risk following VSG using the load-to-strength ratio (LSR), which integrates bone strength estimates with the predicted force of a fall. Methods Prospective 2-year study of youth ages 13–24 years with obesity undergoing VSG ( n = 24) or lifestyle therapy ( n = 34). We performed high-resolution peripheral quantitative computed tomography of the distal radius and microfinite element analysis to estimate bone strength and calculated LSR. Results VSG participants lost 26.4 ± 8.1% weight at year 1 ( p < 0.001), which was sustained at year 2, while control participants gained weight at year 2 (4.5 ± 8.3%, p = 0.009). The predicted impact force decreased at years 1 and 2 following VSG ( p < 0.001) but increased at year 2 among controls ( p = 0.011). Estimated bone strength was unchanged at year 1 but decreased ( p < 0.001) at year 2 following VSG, while bone strength did not change in controls. At year 1, the LSR decreased among VSG participants ( p < 0.001), implying a lower risk of fracture. At year 2, the LSR was lower than baseline ( p < 0.001), but higher compared to year 1 ( p = 0.001). LSR did not change in the control group. Conclusions Short-term estimated fracture risk at the radius following VSG decreases. However, ongoing bone loss despite stable weight between years 1 and 2 leads to a concerning rise in estimated fracture risk. Longer follow-up will be critical to evaluate the trajectory of fracture risk. (ClinicalTrials.gov NCT02557438, registered 9/23/2015).