ASB 2024

Minimum Foot Clearance (mFC) Visualizations

Animation of Minimum Foot Clearance Method: 3D Scan + Inertial Measurement (IMU) Trajectory. Maroon point is true lowest point on shoe during swing. Orange point = toe, yellow point = heel, gray point = center of IMU.

Minimum Foot Clearance Gaussian Heatmaps with Histograms: each representing location on foot of lowest point during late-swing in last minute of 6MWT. Key provided for density heatmap at far right of figure.

Probability of Minimum Foot Clearance (mFC) Occurrence in Forefoot Region: In contrast to IFC, mFC reveals single lowest point in a forward swing, then averaged over all forward swings per minute, then participant and intervention. This answers the question, “On average, how often did the lowest point during swing occur in the Forefoot Region?” Both interventions significantly lowered probability of mFC occurring in the Forefoot Region vs NI (p<0.001). cfAFO and FES did not differ from eachother.

In bold: mFC averaged across participants by minute; lighter lines represent individual subject data with mFC averaged by minute for each intervention.

Timing of mFC within Forward swing (with forward swing expressed as 0-100% for duration): Each line represents a single stride’s IFC’s throughout forward swing, with mFC as a single dot. Heatmap representation shows earlier strides as lighter, later strides as darker colors.

Both interventions had a significant impact of the timing of mFC, moving the occurrence of the single lowest point within each forward swing later by around 5%. The cfAFO showed the greatest consistency of timing of mFC, through a much smaller coefficient of variation than FES or NI.

Subject 8, IFC stride by stride, divided by each minute of 6-minute walk test: No Intervention (left), cfAFO (right). Each line represents a single stride. Values at and below zero likely represent scuffs. Profile of lowest point height appears to differ with intervention.

Clinical Test Results

PIADS Subscores: Difference from FES to cfAFO subscores shown. Preference for FES indicated by Participants 1,4,8,10, otherwise cfAFO. With the exception of Participant 2 and Adaptability subscore for Participant 4, PIADS Subscores differences match with device preference (positive score on chart indicates higher/better Subscore for FES, negative indicates higher/better for cfAFO). MDC of 2.1 or higher met only in Participant 4, Competence and Adaptability.

MSWS Score Differences Between Interventions: Lower scores are more favorable. Changes meeting meaningful change 0f 8 are highlighted in red.

*https://journals-sagepub-com.ezproxy.library.wisc.edu/doi/10.1177/2055217315596993

MFIS Scores: Lower scores are more favorable. Only participant 11 met the MDC, when comparing cfAFO either Basline or FES. This aligns with participant 11 preference for cfAFO.

Functional Gait Assessment (FGA) Score Differences Between Interventions: Higher scores are more favorable. Changes meeting MCID of at least 4 are highlighted in red.

Total 6MWT Distances: Preference for FES indicated by Participants 1,4,8,10, otherwise cfAFO.

Participant Preferences: Under each test (column header), best intervention for each subject listed. Color highlight added when best intervention matched participant preference. KEY: self-EDSS = self-Expanded Disability Status Scale (self-rating of perceived walking disability for individuals with Multiple Sclerosis, higher score is worse), DWI = Distance Walked Index, AFC = Average Foot Clearance (Average of instantaneous foot clearances over each forward swing), AFC-delta = min1 – min6 AFC, FGA = Functional Gait Assessment, MFIS = Modified Fatigue Impact Scale, MSWS = Multiple Sclerosis Walking Scale, PIADS = Psychosocial Impact of Assistive Devices Scale.