ABSTRACT•

The objective of this review was to conduct athree-dimensional biomechanical analysis of the skeleton in subjects with adolescent idiopathic scoliosis (AIS).Over 200 subjects with AIS and 64 controls underwent lowdose biplanar X-rays in the free-standing position with 3D reconstructions of the skeleton.

Results have shown that the scoliotic deformity is corre-lated in the three planes, especially in thoracic curvatures. However, these correlations could not fully explain the defor- mities in a single plane. In addition, we have found that pa- tients with severe morphological deformities of the rib cage can be classified depending on : high gibbosity, high volu- metric spine penetration index (VSPI) or both. Gibbosity was correlated to the frontal and horizontal deformities, while VSPI was correlated to the sagittal deformity. Moreover, the lowered side of the pelvis exhibited a decreased acetabular abduction and an increased external hip coverage angle. Both sides of the hip showed decreased anterior coverage as well as increased acetabular anteversion. These changes were determined by the pelvic tilt. This three-dimensional approach allows to better under-stand the morphological deformities of the skeleton and helps in better decision-making in the treatment of AIS.

Keywords :adolescent idiopathic scoliosis ; spine ; rib cage ;hip ; lower limbs ; three-dimensional analysis.