Sleeve Gastrectomy Has Similarly Detrimental Effects on Bone in Adolescents and Adults
Key findings
- This study compared changes in volumetric bone mineral density (vBMD, measured with quantitative CT) and marrow adipose tissue (MAT, measured with 1H-MRS) in adolescents vs. adults after sleeve gastrectomy
- Sleeve gastrectomy was associated with significant reduction of lumbar spine vBMD after 12 months in adults and a similar trend in adolescents, with no significant difference between the age groups
- Likewise, MAT increased by a similar magnitude in the two groups
- Change in MAT was positively associated with change in abdominal subcutaneous adipose tissue in adolescents and with change in visceral adipose tissue in adults
- These observations confirm that sleeve gastrectomy, the most popular bariatric surgical procedure, has detrimental skeletal effects in both adolescents and adults
Bariatric surgery is very effective in treating cardiometabolic complications of obesity, but some research shows it has detrimental effects on bone. Skeletal integrity is determined not just by bone mineral density (BMD) but also by marrow adipose tissue (MAT).
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The impact of bariatric surgery on the skeleton may differ by age. Bone accrual is greatest during adolescence, which might permit adaptation to any damaging skeletal effects of bariatric surgery.
However, Miriam Bredella, MD, a musculoskeletal radiologist and vice-chair for Faculty Affairs in the Department of Radiology at Massachusetts General Hospital, and colleagues have found that sleeve gastrectomy, the most commonly performed bariatric procedure, had similar effects on BMD and MAT in adolescents and adults. Their report appears in Bone.
Study Methods
The study participants were 10 adolescents (average age, 18; range, 14–21) and 10 adults (average age, 50; range, 25–65) with body mass index (BMI) ≥35 kg/m2 who were scheduled to undergo sleeve gastrectomy. The age groups were matched by sex, race and BMI within 2 kg/m2.
The researchers measured volumetric BMD of the lumbar spine (L1–L2) using quantitative CT, which has a smaller error following extreme weight loss compared with dual-energy X-ray absorptiometry. The imaging was done preoperatively and 12 months after surgery.
At the same timepoints, magnetic resonance spectroscopy of L1–L2 was used to measure MAT, and MRI was used to determine abdominal adipose tissue depots at L4 and measure visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (SAT).
Effects of Bariatric Surgery on Bone Outcomes
The researchers expected that changes in BMD and MAT after surgery would be less pronounced in adolescents than in adults due to bone anabolism. Contrary to this hypothesis:
Lumbar spine volumetric BMD
- Adolescents—3.7% reduction, not statistically significant
- Adults—3.9% reduction (P=0.005)
- The difference between groups was not statistically significant
Lumbar spine MAT
- Adolescents—38.8% increase (P=0.03)
- Adults—20.5% increase (P=0.03)
- The difference between groups was not statistically significant
Body Composition and Changes in MAT
The researchers examined whether the 12-month changes in MAT could be explained by changes in body composition:
- In both adolescents and adults—increases in MAT were greater among those who lost less body weight, which seems counterintuitive
- Adolescents—positive correlation between change in MAT and SAT
- Adults—positive correlation between change in MAT and VAT
Longer follow-up is needed to assess the progression of these changes and whether they increase fracture risk.
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