Using Surface Topography to Visualize Spinal Motion During Gait-Examples of Possible Applications and All Tools for Open Science

Abstract

Precise segmental spinal analysis during gait has various implications for clinical use and basic research. Here, we report the use of Surface Topography (ST) to analyze three-dimensional spinal segment movements, in combination with foot pressure measuring, to describe individual vertebral bodies' motion relative to specific phases of gait. Using Statistical Analysis System (SAS) scripts, single files were merged into one raw data table and were used to generate a standardized gait cycle (SGC) for each measurement, including all measured gait cycles for each individual patient, with a spline function to obtain smooth curve progressions. Graph templates from Statistical Package for the Social Sciences create detailed visualizations of the SGCs. Previously obtained measurements from healthy participants were used to demonstrate possible applications of our method. An impressive inter-individual variability as well as intra-individual consistency of spinal motion is shown. The transformation into an SGC facilitates intra- and inter-individual comparisons for qualitative and quantitative analyses. In future studies, we want to use this method to distinguish between physiologic and pathologic spinal motion. Artificial intelligence-based analysis can facilitate this process. All tools and visualizations used are freely available in repositories to enable the replication and validation of our findings.

Keywords: graph-based representation; motion analysis; rasterstereography; spine biomechanics; surface topography.

Figure 1

Dynamic Surface Topography measuring setup. Participant walking on a treadmill with an integrated foot pressure measuring plate while structured light is projected on the textile-free back. System generates a 3D image of the surface and then calculates the corresponding 3D movements for each spinal segment.

Figure 2

Visual representation for all segments of graph Nr.641 [50]. Positive values show rotation to the left, and negative values show rotation to the right. Observation number is displayed on the abscissa, always starting with Initial Contact of the right foot. Durations of right stance phases are delineated with a vertical black line.

Figure 3

Illustration of all segments of graph Nr.622 [50]. Beginning at the pelvis, rhythmic movements superimpose the curve progressions of all vertebral bodies upward. Durations of right stance phases are delineated with a vertical black line.

Figure 4

Visual representation of graph Nr.615 [50] depicting a rarely seen reverse pattern. Most parts of the spine are rotating nearly in phase. Durations of right stance phases are delineated with a vertical black line.

Figure 5

Visual representation of graph Nr.608 [50] depicting a shift of rotation to the right for the entire thoracic spine. Durations of right stance phases are delineated with a vertical black line.

Figure 6

Illustration of all segments of graph Nr.641 SGC [47]. Near sinusoidal wave form, a further specified identification of maxima (rotation to the left) for all vertebral bodies occurred.

Figure 7

Illustration of all segments of graph Nr.622 SGC [47]. Superimposed oscillation as an individually characteristic feature is still visible; maxima identification nevertheless much more precise.

Figure 8

Illustration of all segments of graph Nr.613 SGC [47]. Isolated rotation in the phase of the lumbar and middle thoracic spine, as the individual feature becomes more apparent after transformation in SGC.

Figure 9

Illustration of all segments of graph Nr.608 SGC [47]. The isolated thoracic rotation shift to the right, with T12 being the point of intersection, is now easier to recognize.