Characterizing Everyday Locomotion Behaviors in Persons with Lower Limb Loss: A Month-Long Wearable Sensor Study

Abstract

Monitoring mobility outcomes in real-world environments can provide a distinct perspective compared to traditional outcome measures obtained in laboratory or clinical settings, which may be limited by environmental factors or behavioral modification. Here, we present an ecologically valid framework for collecting mobility outcomes in everyday life by utilizing prosthesis-mounted wearable sensors. The custom sensor suite, consisting of five inertial measurement units, GPS, and environmental sensors, was worn by 14 individuals with unilateral transtibial amputation for approximately 4 weeks each. Across the monitoring period, 49,577 ± 30,468 (mean ± SD) strides were identified per participant (~10.2 sensor-hours per day). Strides were characterized according to walking bout duration, with most walking observed in relatively short walking bouts (<30 s) at slow walking speeds (~0.5 m/s). Turns were identified and characterized by magnitude, direction, strides, and time taken to complete. The percentage of prosthetic-inside turns was around 50% for less than 90° turns, but higher turn angles showed bias toward prosthetic-outside turns, on average. Most individual participants showed bias toward one direction or the other. Participants also averaged ~28.3 stair-steps per sensor-day. Stair-steps were biased toward upstairs (vs. downstairs) walking and toward step-over-step (vs. step-by-step) strategies. Collectively, these data provide a uniquely detailed evaluation of locomotion behaviors among persons with lower limb loss in everyday living. Future work could utilize the ecological framework described here for establishing functional benchmarks, assisting with device prescription, and otherwise guiding long-term care for optimizing mobility outcomes and quality of life after lower limb loss.