Morphometric analysis of thoracic pedicles in Chinese patients with adolescent idiopathic scoliosis: A study based on the 3-dimensional CT reconstruction

Abstract

Objective To investigate morphology of thoracic pedicles of Chinese patients with adolescent idiopathic scoliosis,and to find if the differences exist compared with other races and provide a reference for the pedicle screw placement.Methods Data of 56 adolescent idiopathic scoliosis patients who underwent CT scan and 3-dimensional reconstruction in our hospital from July 2007 to June 2012 were retrospectively analyzed.There were 10 males and 46 females,aged from 10 to 18 years (average,14.8 years).According to the Lenke classification,there were 28 cases of type Ⅰ,12 cases of type Ⅱ,14 cases of type Ⅲ and 2 cases of type Ⅳ.The average Cobb angle was 55° (range,36° to 90°) before operation.Based on 3-dimensional CT reconstruction,following parameters were measured:pedicle width and pedicle angle in sagittal plane,minimum pedicle diameter in coronal plane,chord length,pedicle width and pedicle angle in transverse plane.After concluding the regular pattern of variation of pedicle morphology,a comparison with other races was conducted.Results Compared with the convex side,the pedicle width and pedicle angle on the concave side of the main thoracic curve were smaller,while the chord length was longer.In sagittal plane,the pedicle width increased from head end to tail end,ranging from 0.68 to 1.36 cm.The pedicle width in transverse plane ranged from 0.30 to 0.70 cm.In coronal plane,the minimum pedicle diameter ranged from 0.28 to 0.67 cm.Conclusion Compared with the western patients,the pedicle width is smaller in Chinese patients with adolescent idiopathic scoliosis.It is difficult and high risk to implant screws on the concave side of the apical vertebra region.So we suggest that pedicle screw with a diameter of 3.5 mm should be used to avoid complications. Key words: Scoliosis; Adolescent; Thoracic vertebrae; Tomography, spiral computed