Intra and inter-rater reliability of the projection of the body’s center of mass obtained via photogrammetry

ABSTRACT For optimal postural control, the center of mass (COM) of the body is a variable that is projected vertically between the legs, over a support base. This study had as aim assessing the inter- and intra-rater reliability of the projection of the COM over the support base, measured with the aid of the Postural Evaluation Software (SAPO). Fifty-seven volunteers were evaluated and all were subjected to photographic records taken from the anterior, left and right lateral views, at the same time. The pictures were handed over to two raters, who then used SAPO to analyze them. For the statistical analysis, the intra-class correlation coefficient (ICC) was used, and to estimate the minimum detectable change (MDC), the standard error (SE) was used. The results showed excellent levels of inter and intra-rater reliability for asymmetries in the frontal and sagittal planes, and for the projection of the center of gravity in the frontal and lateral planes (ICC>0.90; 95%CI>0.95; MDC between 2.16 - 4.87). The results of the study showed that the analysis of the COM obtained with SAPO had good inter- and intra-rater reliability.

摘要：为实现最优姿势控制，人体质心（center of mass, COM）是一个在支撑基底部垂直投射于双腿之间的变量。本研究旨在评估借助姿势评估软件（Postural Evaluation Software, SAPO）测得的质心在支撑基底部投射的评定者间与评定者内信度。研究共纳入57名志愿者，同时采集其前位、左侧位及右侧位的影像记录。将获取的图像交由两名评定者，使用SAPO完成分析。统计分析采用组内相关系数（intra-class correlation coefficient, ICC），并通过标准误（standard error, SE）估算最小可检测变化（minimum detectable change, MDC）。结果显示，额状面与矢状面的不对称性、以及额状面与侧平面的质心投射均表现出极佳的评定者间与评定者内信度（ICC>0.90；95%置信区间>0.95；MDC介于2.16~4.87之间）。本研究结果表明，通过SAPO获取的质心分析具备良好的评定者间与评定者内信度。