Bone loss after bariatric surgery is observed mainly in the hip trabecular compartment and after hypoabsorptive techniques

We evaluated the impact of bariatric surgery on bone mineral density (BMD) and microarchitecture over one year using dual-energy X-ray absorptiometry (DXA), the trabecular bone score (TBS), and 3D-DXA to assess changes after different surgical techniques. This prospective, single-center study of 153 patients with severe obesity contrasts the effects on bone health of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and duodenal switch/single anastomosis duodeno-ileostomy with sleeve gastrectomy (DS/SADIS). To our knowledge, this is the first study to evaluate patients undergoing DS/SADIS and to incorporate 3D-DXA analysis in the assessment of bone loss. Patients were 81 % female with a mean age of 50 ± 9 years. Fifty-four per cent underwent SG; 16 %, RYGB; and 30 %, DS/SADIS. Our findings revealed a significant decrease in areal BMD at the LS (−3.49 ± 5.44 %), FN (−5.24 ± 5.86 %), and TH (−8.06 ± 5.14 %) one year after bariatric surgery. Bone microarchitecture at the LS assessed by TBS was degraded in 30 % of patients. Proximal femur 3D-DXA analysis showed that surgery-induced bone loss predominantly affects the trabecular compartment (Trabecular volumetric (v) BMD: −8.00 ± 6.57 %) rather than the cortical compartment (Cortical vBMD: −1.37 ± 2.79 %). These results suggest hypoabsorptive and mixed techniques (DS/SADIS and RYGB) were associated with greater BMD loss and deterioration of microarchitecture than restrictive techniques (SG). The primary determinants of bone density and impairment of microarchitecture were the extent of weight loss and the type of surgical procedure. Despite overall bone loss, Z-score assessments indicated that post-surgical bone status remained within or above the average ranges compared to a healthy population, except for TH following DS/SADIS. In conclusion, our research shows differences in the impact of bariatric surgery techniques on bone density and microarchitecture, emphasizing the need for careful postoperative monitoring of bone health, particularly in patients undergoing hypoabsorptive and mixed procedures. •Significant bone loss occurs within one year following bariatric surgery.•Bone loss is greater in the trabecular rather than the cortical bone of the hip.•Bone loss is more pronounced following hypoabsorptive than restrictive techniques.•Spinal trabecular microarchitecture is low in 30 % of patients one year after surgery.•Individuals at high risk of fracture may benefit more from restrictive techniques.