Dynamic Surface Topography Data for Assessing Intra- and Interindividual Variation of Vertebral Motion
This data set provides dynamic surface topography (ST) measurements to assess the intra- and interindividual variation of vertebral motion during gait sequences. Surface topography is also known as video rasterstereography. The orientation of all vertebral levels from vertebra prominens (VP) down to L4 as well as the pelvis were acquired while the test persons were walking at different speed levels (2 km/h, 3 km/h, 4 km/h). Ten gait cycles were recorded in each test sequence. In total, 12 volunteers, 10 males and 2 females in the age between 20 and 70, participated in the study. Only asymptomatic and pain free volunteers were included, i.e. individuals without self-reported spinal problems. The BMI had to be below 30 due to a limitation of the used ST system. Additionally, it was required that the test person was able to walk without problems on the treadmill at each addressed motion speed. On the one hand, this setup allows to figure out the consistency of spinal motion during the gait sequences for the particular individuals even when the speed levels changed. On the other hand, this intra-individual consistency can be compared with the variation which occurs between the individuals. A first analysis of the data was provided in Haimerl et al. Comprehensive visualization of spinal motion in gait sequences based on surface topography. Human Movement Science. 2022 Feb;81:102919. In this paper, it was demonstrated how the variation in motion characteristics can be visualized in an intuitive way. This was achieved by a separation of the signals into the particular vertebrae and gait cycles. Subsequently, juxtaposition and superimposition techniques were utilized to provide visual representations of the particular types of variation. It was demonstrated that the average vertebral orientation remained highly consistent even when the test persons were walking at different speed levels. Contrary, this orientation varied substantially between the individuals. Thus, the average vertebral orientation represents individual motion characteristics. It constitutes some kind of neutral profile of the spine. The motion caused by the gait cycles oscillates around these neutral positions. The provided data contains the entire set of test data in this study, including all postural measurements available in the dynamic ST recordings. The utilization of ten gait cycles per test sequence allows a comprehensive processing and analysis of the motion patterns. Thus, the measurements can be utilized for further analysis steps regarding individual characteristics of spinal motion during gait sequences.
Steps to reproduce
The data were obtained using the ST system DIERS 4D motion® Lab / DIERS formetric 4D system (Version 3.10.1, Diers International GmbH, Schlangenbad, Germany). The system was combined with a treadmill for ensuring a consistent walking speed. Additionally, the pedogait component was included for identifying the particular steps / gait cycles. In particular, the starting and end point of a step was identified according to the contact of the particular foot to the ground. The pedogait component is a 1 meter long capacitive pressure plate with 48x112 sensors, which measures the foot pressure reaction forces while walking. The frequency of the camera recordings was 60 Hz and the frequency of the pedogait system 100 Hz. Each individual had to perform test sequences at three different speed levels (i.e. 2, 3, and 4 km/h). Each test sequence contained 10 full gait cycles including left and right steps. The acquisition time for each test sequence was approximately 20 seconds. Before starting the recordings, the test persons were equipped with the standard measurement equipment of the DIERS 4D motion® Lab system, as defined in the system’s manual. Reflective markers were attached to specific anatomical landmarks, including vertebra prominens and both dimples. A habituation phase was included to familiarize the test persons with the system. Within the habituation phase, the speed was incrementally increased to prevent tripping. All further measurement steps were performed as specified by the software. For each test person, the recordings took place on a single day in Nov 2018. All data were stored in a fully anonymized way. No further demographic data was recorded, e.g. mean age or BMI. The complete data set consists of 36 test sequences. Overall, a full set of speed levels were recorded for 11 test persons. For one test person, the speed level was incorrectly assigned in some of the cases. For this test person, one speed level (3 km/h) is not available. The overall data set, including all test sequences, is stored comprehensively in the Excel file ‘RawData_ST gait analysis data_2022-01-27_overall.xlsx’. Additionally, csv files are provided in which the data set is split into the particular test sequences. For each test person / ID (e.g. 9002) and speed level (SL), a separate csv file is provided. This information is encoded in the file name as ‘RawData_ST gait analysis data_2022-01-27_ID_SL.txt’ where ID and SL have to be replaced by the corresponding values. For example, this yields ‘RawData_ST gait analysis data_2022-01-27_9002_2.txt’ for test person 9002 and speed level 2 km/h.