Three-dimensional quantitative analysis of the proximal femur and the pelvis in children and adolescents using an upright biplanar slot-scanning X-ray system

The anatomy and biomechanics of the pelvis and lower limbs play a key role in the development of orthopaedic disorders. This study aimed to establish normal reference standards for the measurement of gender-specific pelvic and femoral parameters in children and adolescents with the EOS 2-D/3-D system. EOS 2-D images of 508 individuals (ages 4-16 years) were obtained as part of routine diagnostics. Patients with lower limb abnormalities were excluded. Pelvic and femoral surface 3-D models were generated and clinical parameters calculated by sterEOS 3-D reconstruction software. Data were evaluated using Spearman correlation, paired-samples and independent-samples t-test and linear regression analysis. Changes in anatomical parameters were found to correlate with age and gender in 1) femoral mechanical axis length: 27.3-43.7 cm (males), 25.5-41.2 cm (females), 2) femoral head diameter: 29.4-46.1 mm (males), 27.7-41.3 mm (females), 3) femoral offset: 26.8-42.4 mm (males), 25.5-37.9 mm (females) and 4) femoral neck length: 35.1-52.9 mm (males), 32.8-48.1 mm (females). There was no gender-specific correlation for the neck shaft angle with values from 130.4A degrees to 129.3A degrees, for femoral torsion (22.5A degrees-19.4A degrees), for sacral slope (39.0A degrees-44.4A degrees) and for lateral pelvic tilt (5.1 mm-6.2 mm). Sagittal pelvic tilt exhibited no significant correlation with age showing average values of 6.5A degrees. The EOS 2-D/3-D system proved to be a valuable method in the evaluation of female and male developmental changes in pelvic and lower limb anatomical parameters, in normal individuals younger than 16 years of age.