Bone Abstracts

Muscle and loading force application alters bone structure and increases bone mineral density (BMD), particularly during growth. However, bone microarchitectural texture, as assessed by the trabecular bone score (TBS), changes during growth is unknown. We hypothesized that TBS would be positively correlated with growth and higher in growing girls participating in regular physical exercise.

68 girls (mean age 12±0.3 years; BMI 18±2.8 kg/m²) were recruited from two middle-schools in Madison, WI. Spine DXA scans were obtained at three time points, fall 2011, spring 2012 and spring 2013, using a GE Lunar iDXA with software v13.31. Lumbar spine TBS was determined using Med-Imaps custom software to calculate raw values that were subsequently adjusted for tissue thickness based on a normative population of European girls. Tanner staging was obtained by self-report coincident with each DXA scan.

Overall, the mean L1–L4 BMD increased 1.36 S.D. (P<0.01) over 18 months, 0.845 (±0.12) to 1.022 (±0.13) g/cm². Over the same interval, adjusted TBS increased (P<0.01) 0.83 S.D. from 1.433 (±0.07) at baseline to 1.491 (±0.07) at month 18. These observations persisted (P<0.01) when limiting the sample to those categorized as Tanner stage 2 or 3 at baseline (n=52). This groug demonstrated a L1–L4 BMD increase 1.37 S.D. (P<0.01) over 18 months, 0.855 (±0.12) to 1.034 (±0.13) g/cm². Similarly, TBS increased (P<0.01) 0.94 S.D. from 1.437 (±0.07) at baseline to 1.495 (±0.07). No correlation was observed between TBS and BMD change at 18 months (P>0.1).

In conclusion, this first report of TBS in adolescent girls demonstrated BMD and TBS increases with age and Tanner stage, suggesting TBS may be of benefit in the assessment of pediatric bone health. The apparent greater increase in BMD vs TBS may suggest that bone microarchitecture has largely been established by age 12 and that the primary growth activity is bone mass/size accrual. Additionally, results may differ using groups with, longer follow-up or larger sample size. Further research documenting TBS changes during growth, and potential ways of optimizing skeletal structure in adolescents, is indicated.

Disclosure: Renaud Winzenrieth is Senior Scientist at Med-Imaps