Bone Abstracts

The aim of the present study was to evaluate bone mass and bone microarchitectural texture as assessed by trabecular bone score (TBS) modification at spine during childhood growth in girls.

The study group was composed of 415 healthy girls aged between 2 and 17 years old. Height, weight and BMI Z-scores were evaluated and compared to The WHO Child Growth Standards. Pubertal stage was evaluated using Tanner score. The areal BMD (aBMD) was assessed at spine L1–L4 using a prodigy densitometer (GE-LUNAR, USA). Pseudo 3D BMD (vBMD) was calculated based on cylindrical model proposed by Kroeger et al. (Bone Mineral 1992). TBS was evaluated using TBS iNsight v2.0 (Medimaps, France). The LMS statistical method proposed by Cole & Green (Stat Med 1992) was used to construct aBMD, vBMD and TBS age-related curves using R software (v2.15.3).

Mean age, weight, height and BMI Z-scores were respectively 10.9±4.4 years, −0.22±1.3, −0.44±1.3 and 0.02±1.2 S.D. respectively. Positive significant correlations (P<0.05) exists between TBS and age, BMI, aBMD and vBMD (r=0.39, 0.27, 0.47 and 0.43 respectively). Height, weight and BMI followed normal pattern with age (data not show).aBMD increases with the growth with an acceleration at the puberty (as presented Fig. 1a). This finding is consistent with the data of Kalkwarf et al. (JCEM 2007). When normalized by the 3D volume, effect of puberty on vBMD is more visible (see Fig. 1b). Before the puberty, vBMD trend seems to be flat. Concerning TBS, we observed first a decreasing phase until the puberty follow by an increasing phase until 17 (Fig. 1c).

Figure 1 Age-related curves for aBMD and TBS at spine L1-L4 (The black line represents the 50th centile. The dark gray represents the 25th to 75th centiles; The medium gray area represents the 5th 95th centiles; The light gray area represents the 3th to 97th centiles)

DXA can be used to assess trabecular bone microarchitectural texture, as assessed by TBS, in children with a high degree of reliability. Age-related TBS curve can be useful, in complement to the BMD curve, to help clinician to identify children with bone microarchitectural modifications induced by chronic diseases or drug therapies.

Declaration of interest: R Winzenrieth is a senior scientist at Med-Imaps.