Patterns of extra-spinal left-right skeletal asymmetries and proximo-distal disproportion in adolescent girls with lower spine scoliosis: ilio-femoral length asymmetry & bilateral tibial/foot length disproportion.

Anomalous extra-spinal left-right skeletal length asymmetries have been detected in girls with adolescent idiopathic (AIS) in four sites (1) upper limbs, (2) periapical ribs, (3) ilium, and (4) right leg and right tibia. This paper on adolescent girls with lower spine scoliosis reports (1) a fifth pattern of left-right ilio-femoral length asymmetry associated with sacral alar height asymmetry, and (2) bilateral anomalous lengthening of the tibia relative to the foot. The findings are consistent with the hypothesis that at the time of diagnosis of AIS in girls there are anomalies of skeletal proportions associated with a predisposition to curve progression; these proportions are in three dimensions--left-right, cephalo-caudal in the trunk (proximo-distal in the lower limbs), and front-back in the trunk. The origin of these anomalies is unknown but possible causes, and of the associated AIS, are genetic and environmental factors acting in embryonic life not expressed phenotypically until years after birth.