Obe Wesley Vernon, Simmonite Neil, Reel Sarah, Reidy Selina
Division of Podiatry and Clinical Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK.
Forensic Podiatry Unit, Podiatry Services, Primary and Community Services, Sheffield Teaching Hospitals NHS FT, Jordnathorpe Health Centre, 1 Dyche Close, Sheffield S8 8DJ, UK.
Sci Justice. 2017 Jul;57(4):276-282. doi: 10.1016/j.scijus.2017.03.007. Epub 2017 Apr 3.
Dynamic bare footprints differ from static bare footprints through the presence of additional, lighter markings around the rear of the heel print and apices of the toe print areas. These images can appropriately be described as inner dark and outer ghosting features. To date, the functional cause of both features has not been understood. To gain such an understanding could potentially allow the further development and use of these features in forensic identification. The aim of this project was to investigate the causes of the inner dark and outer ghosting features seen in dynamic bare footprints through an observational, practice-based action research approach within a gait laboratory. Volunteer male participants provided bare footprints on inkless paper taped to a Kistler force plate with video cameras situated either side. Ground reaction force data were collected as the footprints were formed and the event recorded using video cameras to allow these data to be correlated later. The findings suggest that the ghosting at the heel is the result of splaying of the fibro fatty pad, while that at the toes is the result of the distal ends of the toes coming into contact with the ground as the heel is lifted. Footprint, ground reaction force and video data comparisons showed that the inner dark area of the heel print corresponded with the main body of the heel contacting the ground. Outer ghosting corresponded with a backward splaying of the fat pad and the heel strike transient spike in vertical ground reaction force during increased loading. The inner dark area of the toes corresponded with a longer period of toe contact with the ground. Outer ghosting corresponded with the decreasing vertical ground reaction force and shorter contact time as the toes were leaving the ground towards the end of the contact phase of gait. Although the sample size was limited, these are new appreciations which could facilitate the use of the inner dark features in identification to provide additional points for comparison in cases involving dynamic bare footprints. Further work is now indicated to study these features in different populations and under varying conditions.
动态赤脚足迹与静态赤脚足迹不同，其在脚跟印后部和脚趾印区域的顶点周围存在额外的、较浅的印记。这些图像可恰当地描述为内部深色和外部重影特征。迄今为止，这两种特征的功能成因尚未明了。了解其成因可能会推动这些特征在法医鉴定中的进一步发展和应用。本项目的目的是通过在步态实验室中采用基于观察和实践的行动研究方法，探究动态赤脚足迹中内部深色和外部重影特征的成因。男性志愿者参与者在粘贴于奇石乐测力板上的无墨纸上留下赤脚足迹，两侧设有摄像机。在形成足迹时收集地面反作用力数据，并使用摄像机记录该事件，以便之后将这些数据进行关联。研究结果表明，脚跟处的重影是纤维脂肪垫展开的结果，而脚趾处的重影是脚跟抬起时脚趾远端与地面接触的结果。足迹、地面反作用力和视频数据的比较显示，脚跟印的内部深色区域与脚跟接触地面的主体相对应。外部重影与脂肪垫向后展开以及加载增加期间垂直地面反作用力中的脚跟撞击瞬态峰值相对应。脚趾的内部深色区域与脚趾与地面接触的较长时间段相对应。外部重影与步态接触阶段结束时脚趾离开地面时垂直地面反作用力的减小以及较短的接触时间相对应。尽管样本量有限，但这些都是新的认识，有助于在涉及动态赤脚足迹的案件中利用内部深色特征提供额外的比对点。现在需要进一步开展工作，在不同人群和不同条件下研究这些特征。
