Parameters of upper cervical alignment and their relationship in adolescent idiopathic scoliosis

English Keywords:Adolescent idiopathic scoliosis  Upper cervical alignment  Lenke classification

English Abstract:

  【Abstract】 Objectives: To explore the parameters of upper cervical alignment and their relationship in the adolescent idiopathic scoliosis(AIS), and to clarify the parameters effect on forward-vision balance. Methods: 196 AIS patients who visited our hospital between January 2014 and January 2016 were reviewed. Patients who had incomplete information, spinal disease and spinal treatment history were excluded. Patients with upper thoracic scoliosis extending to cervical segment were also excluded. As a result, a total of 103 patients were studied in this study, including 26 males and 77 females, with an average age of 14.66±2.31 years(range, 10-17 years). The cervical Cobb angle(CCA), occiput-C2 angle, C1-C2 angle, palatum-C2 angle, C2 vertebra contour angle, C1-C7 SVA, T2 sagittal tilt were measured on full-length spinal X-ray. According to the 3 different Lenke thoracic modifiers(modifier ＋, modifier N, modifier －), patients were divided into 3 groups. All parameters were compared among the three groups. Correlation between the parameters was analyzed. Results: The mean values of CCA, occiput-C2 angle, C1-C2 angle, palatum-C2 angle, C2 vertebra contour angle, C1-C7 SVA and T2 sagittal tilt were 10.29°±8.65°, 13.86°±8.33°, 25.61°±9.17°, 12.06°±8.91°, 98.43°±6.75°, 28.41±10.69mm and 10.73°±8.11°, respectively. CCA and T2 sagittal tilt had significant difference(P<0.05) among the groups according to the Lenke thoracic modifier. The occiput-C2 angle, C1-C2 angle, palatum-C2 angle, C1-C7 SVA had significant positive correlations(P<0.01) between each other. Conclusions: T2 sagittal tilt is affected greatly by the kyphosis of T5-T12 in AIS. If cervical sagittal vertical axis decreased, upper cervical will decrease the C1-C2 angle to maintain forward-vision balance. Upper cervical alignment is one of the most important factors for adjusting forward-vision balance.