Assessment of dynamic orthotic upper-limb rehabilitation by means of on-board sensors

Introduction This study presents the application of a pseudoelastic orthosis for upper-limb repositioning in hemiplegic patients. The focus of the present contribution is on the possibility to evaluate the dynamic interaction between the patient and the orthotic device during set motor tasks by means of sensors mounted on-board the orthosis. Materials and methods Six hemiplegic patients (age 56.16±7.22 years, > 6 months after event) were enrolled for the study, and were prescribed a custom-made dynamic orthosis with pseudoelastic elements to e worn at least 6 hours a day for a month. The orthosis was equipped with an electro-goniometer (elbow joint axis) and a tri-axial accelerometer (lateral upper arm). Measurements were conducted at the beginning (T0) and at the end of the study (T1) during three standardised tasks: Reaching Foreward (RF) Hand-to-Mouth (HM), Timed Upand- Go (TUG). Data acquired from 15 healthy volunteers were used as baseline for comparisons. Results The recordings indicate the evolution of elbow flexion-extension angle during the execution of the motor tasks, and the accelerations of the upper arm. Timecourses were segmented to the level of movement repetitions and sub-movement phases. In general, patients' acceleration curves are less smooth than those for the healthy volunteers indicating uncertainties in limb space positioning and controlling, and the presence of involuntary jerks (cloni). Those effects are promptly separable using spectral analysis. In the time domain, movement phase duration can be measured, adding information about sub-movements (e.g. for the TUG task). Direct comparison with normality curves can help visualise motor deficits and the use of compensatory strategies including the shoulder. Discussion and conclusions This preliminary study shows that adding wearable sensors to a dynamic orthosis has a potential for connecting therapy monitoring to treatment. Future works could lead to exploit these technologies for the development of advanced home-based rehabilitation protocols.