Sibylle B Thies, Laurence PJ Kenney, Mohammad Sobuh, Adam Galpin, Peter Kyberd, Rebecca Stine, Matthew J Major. (2017)
Skill assessment in upper limb myoelectric prosthesis users: Validation of a clinically feasible method for characterising upper limb temporal and amplitude variability during the performance of functional tasks, Medical Engineering & Physics,47,137-143
Abstract
Upper limb myoelectric prostheses
remain challenging to use and are often abandoned. A proficient user
must be able to plan/execute arm movements while activating the residual
muscle(s), accounting for delays and unpredictability in prosthesis
response. There is no validated, low cost measure of skill in performing
such actions. Trial-trial variability of joint angle trajectories
measured during functional task performance, linearly normalised by
time, shows promise. However, linear normalisation of time introduces
errors, and expensive camera systems are required for joint angle
measurements.
This study investigated whether
trial-trial variability, assessed using dynamic time warping (DTW) of
limb segment acceleration measured during functional task performance,
is a valid measure of user skill. Temporal and amplitude variability of
forearm accelerations were determined in (1) seven myoelectric
prosthesis users and six anatomically-intact controls and (2) seven
anatomically-intact subjects learning to use a prosthesis simulator over
repeated sessions.
(1): temporal variability showed clear group differences (p<0.05).
(2): temporal variability considerably increased on first use of a
prosthesis simulator, then declined with training (both p<0.05).
Amplitude variability showed less obvious differences. Analysing
forearm accelerations using DTW appears to be a valid low-cost method
for quantifying movement quality of upper limb prosthesis use during
goal-oriented task performance.