A new 3D full-body scanner analyzing the sagittal and coronal balance of the adult spine: a preliminary prospective observational study

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BackgroundThe degenerative spondylosis can cause the difficulty in maintaining sagittal and coronal alignment of spine, and X-ray parameters are the gold standard to analyze the malalignment. This study aimed to develop a new 3D full body scanner to analyze the spinal balance and compare it to X-ray parameters.MethodsNinety-seven adult participants who suffer degenerative spondylosis underwent 3D full body scanning, whole spine X-rays, clinical questionnaires and body composition analyses. The 5 inflection points (ear, shoulder, hip, knee, ankle) of the 3D scanner in the sagittal plane were automatically labeled by an AI algorithm. Three concepts are created including “the angle between two points with respect to the plumb line”, “the horizontal distances between two points in the sagittal plane” and “the angle between three points”. For the coronal plane, the shoulder gradient was analyzed. X-ray parameters of cervical, thoracolumbar and whole spine sagittal balance and coronal balances were compared. The body composition data and clinical questionnaire scores were compared to x-ray and 3D scanner parameters.ResultsThe correlation coefficient (C.C.) of dAB_hor (horizontal distance between ear and shoulder in the sagittal plane) and C2-C7 SVA was 0.478 (p-value < 0.001). The C.C. of aAC_sag (sagittal angle of ear-hip from the plumb line) and ODHA was 0.336 (p < 0.001). About coronal balance, the C.C. of shoulder gradient and clavicle angle from x-ray was 0.373 (p < 0.001). The C.C.s were merely affected by body composition data. But in multiple regression analysis, BMI affected 3D scanner data. Clinical symptoms showed correlations with aBCD(shoulder-hip-knee) and aCDE(hip-knee-ankle angle), which may reflect a compensatory pelvic retroversion and knee flexion for positive sagittal imbalance.ConclusionsThis new 3D scanner has some strengths like radiation-free methods, correlation with x-ray parameters and clinical symptoms, independence to body composition data, and possibility of analyzing dynamic spine balance.