Changes in lower limb biomechanics when following floor-projected foot placement visual cues for gait rehabilitation

Background: Lately, the projection of foot placement visual cues onto the floor has been considered for use in gait rehabilitation. While promising, this approach needs further basic assessment to ensure proper uses. Research question: Does following floor-projected foot placement visual cues of one's natural walking pattern induce gait mechanics changes immediately or after a practice period? Methods: Gait mechanics data from fifteen healthy individuals (7 female, 25.4 +/- 5.0 years, 21.5 +/- 1.68 kg/m(2)) was collected during normal walking without visual cues, and during two testing phases (immediate and after 45-60 min of practice) of walking with floor-projected visual cues depicting their normal spatial parameters. Magnitudes and variabilities of spatial gait parameters and sagittal plane lower limb kinematics and kinetics were compared between the three testing phases using repeated measures ANOVA and post-hoc paired ttests. Results: Compared to normal walking without foot placement visual cues, there was a statistically significant (p < 0.05) increase in stride length (maximum change of 0.01 +/- 0.01 m), stance phase knee flexion (2.0 +/- 2.5 degrees), and swing phase hip flexion (1.2 +/- 1.3 degrees) in both immediate and post-practice testing phases, along with an increase in terminal stance hip (0.28 +/- 0.38 %BW*Ht) and knee (0.25 +/- 0.25 %BW*Ht) flexion moments in the immediate testing phase. All of these changes between testing phases were smaller than their corresponding normal gait smallest real differences (SRD). With the addition of visual cues, variability was statistically significantly decreased in spatial parameters and increased in knee flexion angle at heel strike and knee flexion moment in terminal stance. Significance: While biomechanical changes were observed, their magnitudes were small enough to suggest that floor-projected visual cues can be used in gait retraining without introducing unintended gait changes. Furthermore, the results suggested that lengthy practice periods are not necessary. The validity of these observations will, however, need to be confirmed in cases of severe impairments.