Three-dimensional reconstructions of Lenke 1A curves

Abstract

Three-dimensional imaging was performed to identify if Lenke 1A curves could be reclassified in subgroups to improved orthopedic or surgical treatment of adolescent idiopathic scoliosis. It seems that multitude of 3D reconstructions can exist in Lenke 1A curves. With his classification Lenke introduces new parameters in radiographic analysis of idiopathic scoliosis like frontal lumbar and thoracic sagittal modifiers. Scoliosis is defined as a three dimensional deformity in frontal, sagittal and horizontal plane. The spine is considered as an heterogeneous beam, and is modeled as a deformable wire along which vertebrae are beads rotating about the wire. Each vertebra can rotate about the 3D spinal curve. 3D spinal curve is compound of plane regions connected together by zones of transition. The 3D spinal curve is uniquely flexed along the plane regions. The objective of this study was to identify if all Lenke 1A curves could have the same 3D representation. Biplanar radiographic examination with successive exposures (frontal and sagittal) or with EOS system, coupled with photogrammetric reconstructions, may be used for reconstructing the 3D spinal curve. In definitive, we obtain the 3D reconstruction and the regional plans with their parameters. To become familiar with the Lenke classification, we classified 223 antero-posterior radiographs and profile then compared our results: 4 independent readers (2 familiar with scoliosis and 2 no). Patient's characteristics, measurements (Cobb angles in the plan region, cervical, thoracic and lumbar sagittal curves, pelvic parameters and election planes characteristics) were recorded. A total of 63 consecutive Lenke 1A patients were included (mean age of 11.3 years for 47 girls and 16 boys). Thoracic Cobb angle was between 14° and 70° (mean 36.5°). Pelvic incidence was between 26° and 78° (mean 52.8°) and pelvic tilt between −6° and 29° (mean 9.8°). In most of cases, we find 4 torsion planes instead in 43% instead of 3 in asymptomatic subjects and the rotation of these was very disparate. Lenke 1A curves could be represented in a multitude of representations. The 3D representations of idiopathic scoliosis have to enter in our daily practice for the analysis and the orthopedic or chirurgical treatment of this one.