Wearable technology for mobility measurement in orthopedics and traumatology: a comparison of commercially available systems

Abstract

Background

Wearable activity sensors offer valuable insights into physical activity and are increasingly used in clinical and rehabilitation settings. However, most are designed for healthy individuals, necessitating a thorough evaluation of their applicability for pathological gait patterns. This study aims to assess the accuracy of commercially available wearables in measuring gait patterns among patients with lower limb injuries compared to healthy individuals.

Methods

A prospective cohort study enrolled 40 participants divided into four groups: Group A (younger patients with lower limb injuries with age < 75y), Group B (younger healthy individuals with age 75y), Group C (elderly patients with lower limb injuries and age 75y), and Group D (elderly healthy individuals with age > 75y). Mobility was assessed in real-world scenarios using four wearable devices (Apple Watch Series 4, Fitbit Charge 3, ActivPal 4, and StappOne Insoles V1.0) across three gait speeds in a gait laboratory, with GAITrite mats and video as gold standards.

Results

Accuracy varied significantly between devices. The accelerometer-based wearables (Apple Watch Series 4, Fitbit Charge 3 and ActivPal 4™) underestimated cumulative step count compared to pressure-based Stappone v1. 0, especially for slow and restricted gait patterns (Groups C and D). Relative Difference of Wearables Measurements to the true numbers of steps (Group C: AW -21.83%, FB -28.99%, AP -20.00% versus SO 0.00% - Group D: AW -8.51%, FB -14.29%, AP -20.00% versus SO 4.55%). Zero measurements occurred frequently with wrist-worn devices, highlighting their limitations in detecting slow or restricted movements. In contrast, pressure-based StappOne Insoles demonstrated superior accuracy, with minimal deviations across all groups and gait speeds. The inaccuracy was exacerbated by factors such as the use of mobility aids, partial weight-bearing, and postoperative restrictions, which altered arm and leg movements.

Conclusions

Accelerometer-based wearables require algorithmic improvements to address the challenges of slow and pathological gait patterns. The frequent occurrence of zero measurements with wrist-worn devices underscores their limited utility in clinical populations. Practical challenges, such as altered movement patterns due to mobility aids and partial weight-bearing, further limit their accuracy. Pressure-based systems, while accurate, face practicality issues for daily use. These findings emphasize the need for tailored wearable technologies for orthopedic and trauma patients.

Level of evidence

Prospective cohort study, Level of Evidence 2.