Ultrasound femoral anteversion (FAV) and tibial torsion (TT) after school screening for adolescent idiopathic scoliosis (AIS)

Abstract

Torsion and counter-torsion in the spine are features of the three-dimensional deformity of adolescent idiopathic scoliosis, Vertebral axial rotation has recently been found in the normal adult thoracic spine. Torsion in the lower limbs, femora and tibiae is a feature of normal human skeletal postnatal development. In recent years, femoral anteversion (FAV) and tibial torsion (TT) have been studied in normal children by imaging techniques, especially ultrasound. This paper reports summaries of the application of real-time ultrasound to FAV and TT of normal children and scoliosis school screening referrals. In the scoliosis girls and boys, the FAV decrease and FAV asymmetry compared with normals may result from abnormally increased femoral detorsion maturationally earlier with left-right asynchrony which, if repeated as a growth plate anomaly in the trunk (spine and/or periapical ribs), might initiate the AIS deformity, given other requirements. In scoliosis boys relative to girls, the TT decrease without asymmetry may result from sexually dimorphic maturation at knee tibial growth plates ? maturationally delayed TT with left-right synchrony.