Bone Strength Is Preserved Following Bariatric Surgery

Background: There is an increasing concern that bariatric surgery results in excessive bone loss as demonstrated by studies that use areal bone mineral density (aBMD) outcomes by dual energy X-ray absorptiometry (DXA). Thus, we explored the effect of bariatric surgery on bone mechanical strength.Methods: Bone strength and body composition outcomes were measured in 21 adults (age 45.3 years; BMI 45.7 kg/m²) at baseline (pre-surgery) and 3, 6, and 12 months post-surgery. Bone geometry, density and strength were assessed by peripheral quantitative computed tomography (pQCT) at the distal (4 %) sites of the radius and tibia and at the midshaft sites of the tibia (66 %) and radius (50 %). Participants were divided into tertiles (high, medium, and low) of percentage weight loss at 6 months post-surgery.Results: Participants in all three tertiles lost significant body weight by 6 months post-surgery (mean loss −5 to −30 %, all p < 0.05). At 6 months, all tertiles lost significant fat mass (−9 to −51 %, all p < 0.05), but only the high tertile lost significant fat-free mass (−8 %, p < 0.05). Despite a slight increase in tibia bone strength (SSIp) at 3 months (+1.1 %, p < 0.05), estimates of bone strength at the radius and tibia sites did not change at later post-surgical time points regardless of weight loss.Conclusions: Contrary to DXA-based aBMD outcomes in the current literature, these results suggest that bone strength was preserved up to 12 months following bariatric surgery. Future longer-term studies exploring bone strength and geometry are needed to confirm these findings.