Validity of an Optical Proximity Sensor (OPS) to measure foot clearance during swing.
D. Rafferty, A. Kerr, P. Dall, G. Hendry and E. Hyslop
School of Health and Social Care, Glasgow Caledonian University
Introduction: Current methods for measuring foot clearance are limited by their use of a treadmill, inability to capture multiple steps and confinement to a laboratory. Given that variation in this parameter is considered a factor in the incidence of trip falling it’s measurement in the field over multiple steps would be an important advance. The development of a wireless optical proximity sensor (OPS) has opened up the opportunity for this kind of data collection. Consequently this study aimed to test the validity of an OPS through comparison with a motion capture system. Methods: Following ethical approval 15 subjects aged 33.1 (+/-10) years, height 174 (+/-6.4) cm and weight 75 (+/-12.2) kg walked at three velocities (preferred, slow and fast). An OPS was placed on the medial aspect of shoe, ensuring that the OPS was parallel to the floor, and a reflective marker placed on it’s outer casing. The marker was tracked with a motion analysis system sampling at 50Hz. The lowest point of the foot during the swing phase was recorded from each system and these data compared using ICCs. Results: There was excellent agreement between the two systems. ICCs of 0.925 (all speeds), 0.931 (preferred), 0.966 (slow) and 0.889 (fast) were recorded. Conclusion: These results represent a strong agreement between the two systems in measuring the lowest point during swing. The OPS could thus be used instead of cameras to record foot clearance, opening up opportunities for data collection over long periods of time and in natural settings.
Support
School of Health and Social Care Research fund
References
nil