Validation of IMU against optical reference and development of open-source pipeline: proof of concept case report in a participant with transfemoral amputation fitted with a Percutaneous Osseointegrated Implant.
Kirstin Ahmed, Shayan Taheri, Ive Weygers and 1 others
PMID 39085954WHAT IT FOUND
In one person with a surgically bone-anchored prosthesis and one without amputation, wearable sensors estimated lower-limb joint motion close enough to lab cameras to be considered clinically acceptable.
This is a measurement proof of concept, not evidence that gait training works.
Key findings
01For the participant with transfemoral amputation, the average absolute difference between inertial and optical joint angle estimates was 2.35° on the amputated side and 3.59° on the intact side, and no difference exceeded 5.98° on either side.
02For the non-amputated participant, the average absolute difference was 2.26°, and no difference exceeded 5.46°.
03Waveform similarity between the systems was above 0.92 for the amputated side, above 0.89 for the intact side, and above 0.88 for the non-amputated participant.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included one participant with transfemoral amputation and one non-amputated participant, so it cannot show how the pipeline performs across POI users or prosthetic socket users. The non-amputated participant was not a matched control: she differed in age, sex, height, weight, and mobility. The comparison was between measurement systems during structured gait trials, not between treatments or clinical outcomes. The authors report remaining model inaccuracies, calibration pose errors, anatomical landmark variability, soft tissue artefacts, IMU weight and band effects, real-world unknowns, and drift error. The pipeline produced range-of-motion inputs intended to enable Gait Deviation Index calculation in future work; this paper did not report GDI outcomes. The participant sessions were not conducted at the same time.
Declared interests
Funding was provided by Stiftelsen Promobilia and Chalmers University of Technology. The supplied text does not report author conflicts of interest.
The easy way to misread this
Do not conclude that wearable sensors are validated for clinical gait assessment in all people with transfemoral amputation. The accuracy was shown in one participant with a bone-anchored implant, and the paper did not test whether the measurements improve diagnosis or treatment.