PTOTOtherJournal of physical therapy science2022

Reliability of Bluetooth inertial sensors for assessing lower limb segment angles and stride length during gait.

Jessica Pitts, Shuaijie Wang, Tanvi Bhatt

PMID 36118656

WHAT IT FOUND

A custom Bluetooth sensor system tracked leg angles and stride length with moderate agreement to lab cameras.

It missed the mark on stride length and shank angles, especially when the foot landed. Use it for spotting general movement patterns, not for precise clinical measurement.

Key findings

01Agreement between the Bluetooth sensors and motion capture was moderate for thigh angles but poor for stride length and shank angles at foot contact.

02The sensor system consistently underestimated the shank angle when the foot touched down, with a bias of nearly 9 degrees.

03Data loss from Bluetooth connection issues occurred in almost every trial, though most trials had less than 5% loss and remained usable.

STILL TO COME

How it was doneWhat they foundWhat it means for PTsWhat it means for OTs

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What it does not show

The study used healthy young adults, so the reliability in patients with neurological or musculoskeletal disorders is unknown. Only the right leg was assessed, assuming symmetry which may not hold in clinical populations. A large number of trials (36 out of 128) were excluded due to data loss or sensor errors, raising questions about real-world usability. This was a secondary analysis of previously collected data, not a primary validation study designed specifically for this sensor system. The Bluetooth system had significant errors in measuring stride length and shank angles at foot contact, limiting its use for precise kinematic analysis.

Declared interests

The authors declared no funding or conflicts of interest.

The easy way to misread this

Do not assume this Bluetooth sensor system is accurate enough to replace clinical gait analysis for precise measurements. The study found poor agreement for stride length and significant errors in shank angles at foot contact, meaning it can only reliably detect general movement patterns, not subtle kinematic impairments.

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