An Assessment of the Utility and Functionality of Wearable Head Impact Sensors in Australian Football

Objectives: To assess the utility and functionality of the X-Patch as a measurement tool to study head impact exposure in Australian Football. Accuracy, precision, reliability and validity were examined.

Designs: Laboratory tests and prospective observational study.

Methods: Laboratory tests on X-Patch were undertaken using an instrumented Hybrid III head and neck and linear impactor. Differences between X-Patch and reference data were analysed. Australian Football players wore the X-Patch devices and games were video-recorded. Video recordings were analysed qualitatively for head impact events and these were correlated with X-Patch head acceleration events. Wearability of the X-Patch was assessed using the Comfort Rating Scale for Wearable Computers.

Results: Laboratory head impacts, performed at multiple impact sites and velocities, identified significant correlations between headform-measured and device-measured kinematic parameters (p<0.05 for all). On average, the X-Patch-recorded peak linear acceleration (PLA) was 17% greater than the reference PLA, 28% less for peak rotational acceleration (PRA) and 101% greater for the Head Injury Criterion (HIC). For video analysis, 118 head acceleration events (HAE) were included with PLA ≥30g across 53 players. Video recordings of X-Patch-measured HAEs (PLA ≥30g) determined that 31.4% were direct head impacts, 9.3% were indirect impacts, 44.1% were unknown or unclear and 15.3% were neither direct nor indirect head impacts. The X-Patch system was deemed wearable by 95-100% of respondents.

Conclusions: This study reinforces evidence that use of the current X-Patch devices should be limited to research only and in conjunction with video analysis.