Radiographic analysis of sagittal spino-pelvic alignment in asymptomatic Chinese adults

Objective To describe sagittal pelvic pattern,and to analyze sagittal spino-pelvic alignment in asymptomatic Chinese adults.Methods This was a prospective radiological analysis.Anteroposterior and lateral radiographs of the whole spine were taken in 139 Chinese volunteers,including 94 males and 45 females,aged from 21 to 28 years (average,23.5±1.5 years).By using picture archiving and communication systems,several pelvic and spinal parameters (pelvic incidence,pelvic tilt,sacral slope,lumbar lordosis,thoracic kyphosis,cervical lordosis,sagittal vertical axis,apex of total lumbar lordosis,total lumbar lordosis,upper arc of total lumbar lordosis,lower arc of total lumbar lordosis,junctional level,apex of total thoracic kyphosis,total thoracic kyphosis,total cervical lordosis,and lordosis tilt) were measured and the correlations of all parameters were analyzed.Results The mean value of pelvic incidence was 45.1°±9.6°,which was significantly less than those reported in western and Korean subjects.Total lumbar lordosis has a significant correlation with pelvic incidence,sacral slope,total thoracic kyphosis,cervical lordosis and sagittal vertical axis.The sagittal lumbar-pelvic alignment was classified into 4 types according to position of apex of total lumbar lordosis:type Ⅰ (11 cases),the apex was located in L5 or intervertebral space between L4 and L5; type Ⅱ (61 cases),the apex was located in bottom or middle of L4; type Ⅲ (33 cases),the apex was located in upper part of L4 or in intervertebral space between L3 and L4; type Ⅳ (34 cases),the apex was located at L3 level or more high level.Conclusions The sagittal pelvic pattern of Chinese adults is significantly different from those of western and Korean.Lumbar lordosis plays a critical role in regulating spinal sagittal balance.With upper shift of apex of total lumbar lordosis,the lower lumbar lordosis angle and sacral slope increase,but the lordosis tilt decreases. Key words: Spine;  Pelvis;  Radiography