Influence of the malleolar marker position on postural parameters in the sagittal plane

ABSTRACT Photogrammetry is a postural evaluation method that provides information based on the reference of anatomical markers. In the sagittal plane, one of the main evaluations is related to the plumb line; however, the literature shows divergences regarding the placement of the malleolar reference marker. Some argue that it must be placed exactly on the center of the lateral malleolus, while others defend placing it slightly in front of the lateral malleolus. This study aimed to identify whether the modification of the position of the malleolar marker affects the results of the procedure. This is a cross-sectional analytical observational study, with comparative intrasubject design. Forty-four healthy subjects (25 women and 19 men; 27±6 years old; 170±11 cm; 71±15 kg) were evaluated using protocol and software DIPA© for investigation of the variables (plumb line test and pelvic version) in the sagittal plane, with the malleolar marker in two positions: (1) in the center of the lateral malleolus and (2) in front of the lateral malleolus. The analysis was carried out according to descriptive (frequency distribution, mean and standard deviation) and inferential (Shapiro-Wilk test, dependent Student’s t-test, and Wilcoxon test, α=0.05) statistical methods. For both variables, the malleolar marker position presented statistically significant difference (p<0.05) only on the scalar value, not significantly affecting the posture classification. The results suggest that the vertical reference point for photogrammetry, based on the malleolar marker, can be chosen by the evaluator.

摘要：摄影测量法（Photogrammetry）是一种基于解剖标记物参考获取信息的姿势评估方法。在矢状面（sagittal plane）评估中，核心评估维度之一与垂直线相关；但现有文献对外踝（lateral malleolus）参考标记物的放置位置存在分歧。部分学者主张标记物需精准置于外踝中心，另有学者则认为应将其放置于外踝略前方位置。本研究旨在探究踝部标记物位置变更是否会对该评估流程的结果产生影响。本研究为横断面分析观察性研究，采用受试者内比较设计方案。研究纳入44名健康受试者（25名女性、19名男性；年龄27±6岁；身高170±11cm；体重71±15kg），采用DIPA©软件及标准化实验方案，针对矢状面的两项评估变量——垂直线测试与骨盆倾角，设置两种踝部标记物放置位置开展评估：（1）外踝中心位置；（2）外踝前方位置。数据分析采用描述性统计（频数分布、均值与标准差）及推断性统计方法，其中推断性统计包含夏皮罗-威尔克检验（Shapiro-Wilk test）、配对t检验（dependent Student’s t-test）与威尔科克森检验（Wilcoxon test），检验水准设为α=0.05。结果显示，针对两项评估变量，仅在标量数值层面，踝部标记物位置存在统计学显著性差异（p<0.05），但该差异并未对姿势分类结果产生显著影响。本研究结果表明，基于踝部标记物的摄影测量法垂直参考点可由评估者自行选择。