The rib index is not practically affected by the distance between the radiation source and the examined child.

BACKGROUND: All lateral spinal radiographs in idiopathic scoliosis (IS) show a Double Rib Contour Sign (DRCS) of the thoracic cage, a radiographic expression of the rib hump. The outline of the convex overlies the contour of the concave ribs. The rib index (RI) method was extracted from the DRCS to evaluate rib hump deformity in IS patients. The RI was calculated by the ratio of spine distances d1/d2 where d1 is the distance between the most extended point of the most extending rib contour and the posterior margin of the corresponding vertebra on the lateral scoliosis films, while d2 is the distance from the least projection rib contour and the posterior margin of the same vertebra, (Grivas et al 2002). In a symmetric thorax the "rib index" is 1. This report is the validity study of DRCS, ie how the rib index is affected by the distance between the radiation source and the irradiated child. METHODS: The American College of Radiology's (2009) guidelines for obtaining radiographs for scoliosis in children recommends for the scoliotic - films distance to be 1,80 meters. Normal values used for the transverse diameter of the ribcage in children aged 6-12 years were those reported by Grivas in 1988. RESULTS: Using the Euclidean geometry, it is shown that in a normal 12-year old child d1/d2 = 1.073 provided that the distance ΔZ ≈ 12cm (11,84) and EA = 180cm, with transverse ribcage diameter of the child 22 cm. CONCLUSIONS: This validity study demonstrates that the DRCS is substantially true and the RI is not practically affected by the distance between the radiation source and the irradiated child. The RI is valid and may be used to evaluate the effect of surgical or conservative treatment on the rib cage deformity (hump) in children with IS. It is noted that RI is a simple method and a safe reproducible way to assess the rib hump deformity based on lateral radiographs, without the need for any other special radiographs and exposure to additional radiation.

Maternal age at birth: does it dictate the epigenotypic expression of the trunkal asymmetry of a child?

INTRODUCTION: Trunkal back asymmetry is considered very important for the selection of children at risk of developing scoliosis. Traditionally, this asymmetry as thoracic or lumbar hump is the main indicator for referral of subjects with idiopathic scoliosis (IS) to clinics from school-screening programs. This asymmetry is also used as the most important sign for further assessment at scoliosis clinics. There are reports suggesting that an epigenetic risk factor for IS is maternal age at birth. However, the influence of maternal age on the development of trunkal asymmetry during growth has not been reported. This report aims to assess if maternal age at birth impacts trunkal asymmetry, and how this parameter may dictate the epigenotypic expression of the trunkal asymmetry of a child. MATERIAL AND METHODS: The sample examined: 11832 (5855 males and 5977 females) children and adolescents (5-17 years old, mean age: 11.34±2.79) were screened at their school for back trunkal asymmetry and/or scoliosis. The measurements: The Prujis scoliometer was used to examine the students in standing and sitting forward bending positions. If at least one of child's measured angles was equal to or exceeded 6 or 7 degrees of scoliometer reading, it was labelled as "Asymmetry-6" and "Asymmetry-7" respectively. The age, standing height and body weight of children and maternal age were also documented, among other parameters. The maternal age at birth and children's BMI were subsequently calculated. The statistical analysis: Asymmetries were tested for correlation with maternal age at birth which was transformed to a categorical variable using 5-year intervals. Pearson's χ2 test was used for the univariate analysis, while logistic regression was used for quantitative univariate and multivariate analysis. Statistical significance level was set to p<.05. SPSS and STATA TM v. 11.0 statistical packages were used for the analysis. RESULTS: Univariate analysis: Univariate analysis showed that the prevalence of asymmetry-6 in boys tended to significantly decrease as mother's age at birth increased (mother's age at birth: <19, 20-24, 25-29, 30-34, 35-39, >40 years, % of asymmetry-6: 11.5%, 9.5%, 8.5%, 7.6%, 5.2%, 5.3%, respectively, (p=0.026). This trend, although present, was not significant in girls. The prevalence of asymmetry-7 also showed a decreasing trend, which was only significant in boys (mother's age at birth: <19, 20-24, 25-29, 30-34, 35-39, >40 years, % of asymmetry-7: 8.7%, 5.9%, 5.9%, 4.6%, 2.6%, 3.5%, respectively, p=0.010). Maternal age at birth, as a continuous variable, was inversely associated with the appearance of asymmetry-6 in both boys and girl s (OR: 0.966, 0.982, 95%CIs: 0.947-0.985, 0.965-0.999, p: 0.001, 0.040, respectively). This was also the case for asymmetry-7 only in boys: (OR: 0.961, 0.982, 95%CIs: 0.938-0.985, 0.962-1.003, p: 0.001, 0.088, respectively). Multivariate analysis: The significant and inverse effect of maternal age at birth on the appearance of asymmetry in boys remained even after adjusting for child's BMI and age. For one year increase of maternal age at birth, the odds of the boys being asymmetrical6 were reduced by 2.8% (OR:0.972, 95% CIs: 0.953-0.992, p: 0.005), adjusting for child's age and BMI. For one year increase of maternal age at birth, the odds of the boys being asymmetrical7 were reduced by 3.2% (OR:0.968, 95% CIs: 0.945-0.992, p: 0.010), adjusting for child's age and BMI. However, the aforementioned correlations were not significant for girls in both cases. DISCUSSION AND CONCLUSIONS: The influence of maternal age at birth on the development of trunkal asymmetry during growth has not been previously assessed, as evidenced from literature review. The findings of this report indicate that maternal age as an environmental factor in the general population, may possibly influence epigenetically, the occurrence of the initial presentation of trunkal asymmetry in males more than females, as well as IS during growth. Consistent findings reported from the USA, Edinburgh and Sweden reveal increased maternal age as a risk factor for AIS, suggesting maternal factors can predispose to it. It seems that males are more affected by this factor but, unexpectedly in this study, by younger and not older mothers, as reported for AIS in the literature. Low-birth weight associated with younger parental age may also be associated with increased trunkal asymmetry particularly of boys, an hypothesis that need testing. The importance our findings is based on the belief that the intra-uterine environment is crucial in programming the fetus for various health and disease outcomes throughout life.