Impact of sleeve gastrectomy on hip structural analysis in adolescents and young adults with obesity

Abstract

Background: Sleeve gastrectomy (SG), the most commonly performed metabolic and bariatric surgery, is associated with reductions in areal bone mineral density at multiple sites, and changes in bone structure at the distal radius and tibia without reductions in strength estimates at these peripheral sites. Data are lacking regarding effects on hip strength estimates.

Objective: To evaluate effects of SG on measures of hip structural analysis in adolescents and young adults over 12 months using dual-energy x-ray absorptiometry.

Settings: Translational and Clinical Research Center.

Methods: We enrolled 48 youth 14- to 22-years old with moderate-to-severe obesity; 24 underwent SG and 24 controls were followed without surgery (18 females, 6 males in each group). Hip structure was assessed using dual-energy x-ray absorptiometry at baseline and 12 months. Analyses are adjusted for age, sex, race, and the baseline bone measure.

Results: The SG group lost 25.9% weight versus .3% in controls. Compared with controls, SG had reductions in narrow neck, intertrochanteric and femoral shaft bone mineral density Z-scores (P ≤ .012). Furthermore, SG had greater reductions in narrow neck and intertrochanteric region (but not femoral shaft) cross-sectional area, cortical thickness, cross-sectional moment of inertia and section modulus, and increases in buckling ratio (P ≤ .039). Differences were attenuated after adjusting for 12-month body mass index change. At 12 months, differences were minimal after adjusting for age, sex, race, and weight.

Conclusions: Over 12 months, SG had negative effects at the narrow neck and intertrochanteric regions of the hip, but not the femoral shaft. Reduced body mass index may compensate for these deleterious effects on bone.

Keywords: Adolescents; Bone strength; Bone structure; Hip structural analysis; Metabolic and bariatric surgery; Sleeve gastrectomy.

Figure 1:

Hip image from Hologic DXA scanner showing locations of HSA narrow neck, intertrochanteric and femoral shaft regions of interest (ROI). From Laskey MA, Price RI, Khoo BCC, Prentice A. Proximal femur structural geometry changes during and following lactation. Bone. 2011 Apr 1; 48(4): 755–759. Copyright Elsevier 2011.

Figure 2:

Percent change in hip structural analysis (HSA) measures at the narrow neck and intertrochanteric region in the surgical vs. non-surgical groups over 12 months. The groups differed for percent change in several measures at the narrow neck and intertrochanteric region. No differences were noted in percent changes in HSA measures at the femoral shaft (not shown). CSMI: cross sectional moment of inertia; Ct.: cortical; *P<0.05; **P<0.10 (both after controlling for age, sex and race).