Training for users of myoelectric multigrip hand prostheses: a scoping review

Assessing the effectiveness of serious game training designed to assist in upper limb prothesis rehabilitation

Introduction

Controlling a myoelectric upper limb prosthesis is difficult, therefore training is required. Since training with serious games showed promising results, the current paper focuses on game design and its effectivity for transfer between in-game skill to actual prosthesis use for proportional control of hand opening and control of switching between grips. We also examined training duration and individual differences.

Method

Thirty-six participants were randomly assigned to one of three groups: a task-specific serious game training group, a non-task-specific serious game training group and a control group. Each group performed a pre-test, mid-test and a post-test with five training sessions between each test moment. Test sessions assessed proportional control using the Cylinder test, a test designed to measure scaling of hand aperture during grabbing actions, and the combined use of proportional and switch control using the Clothespin Relocation Test, part of the Southampton Hand Assessment Procedure and Tray Test. Switch control was assessed during training by measuring amplitude difference and phasing of co-contraction triggers.

Results

Differences between groups over test sessions were observed for proportional control tasks, however there was lack of structure in these findings. Maximum aperture changed with test moment and some participants adjusted maximum aperture for smaller objects. For proportional and switch control tasks no differences between groups were observed. The effect of test moment suggests a testing effect. For learning switch control, an overall improvement across groups was found in phasing of the co-contraction peaks. Importantly, individual differences were found in all analyses.

Conclusion

As improvements over test sessions were found, but no relevant differences between groups were revealed, we conclude that transfer effects from game training to actual prosthesis use did not take place. Task specificity nor training duration had effects on outcomes. Our results imply testing effects instead of transfer effects, in which individual differences played a significant role. How transfer from serious game training in upper limb prosthesis use can be enhanced, needs further attention.

Economic evaluation of upper limb prostheses in the Netherlands including the cost-effectiveness of multi-grip versus standard myoelectric hand prostheses

PURPOSE

To investigate the costs, quality of life, and user experiences associated with upper limb prosthesis use, and to evaluate the cost-effectiveness of multi-grip compared to standard myoelectric hand prostheses (MHPs/SHPs).

MATERIALS AND METHODS

The EQ-5D-5L to assess the quality of life, the patient-reported outcome measure to assess the preferred usage features of upper limb prosthesis (PUF-ULP), and a cost questionnaire (societal perspective) were completed by 242 prosthesis users (57% men; mean age = 58 years). Incremental cost-utility and cost-effectiveness ratios (ICUR/ICER) with respectively the EQ-5D-5L and PUF-ULP were calculated to compare MHPs with SHPs. Statistical uncertainty was estimated using bootstrapping. Netherlands Trial Registry number: NL7682.

RESULTS

The mean yearly total costs related to prosthesis use of MHPs (€54 112) and SHPs (€23 501) were higher compared to prostheses with tools/accessories (€11 977), body-powered (€11 298), and cosmetic/passive prostheses (€10 132). EQ-5D-5L and PUF-ULP scores did not differ between prosthesis types. ICUR was €-728 833 per quality-adjusted life year; ICER was €-187 798 per PUF-ULP point gained.

CONCLUSIONS

Myoelectric prostheses, especially MHPs, were most expensive compared to other prostheses, while no differences in quality of life and user experiences were apparent. MHPs were not cost-effective compared to SHPs. When prescribing MHPs, careful consideration of advantages over SHPs is recommended.

Progressive unsupervised control of myoelectric upper limbs

Objective.Unsupervised myocontrol methods aim to create control models for myoelectric prostheses while avoiding the complications of acquiring reliable, regular, and sufficient labeled training data. A limitation of current unsupervised methods is that they fix the number of controlled prosthetic functions a priori, thus requiring an initial assessment of the user's motor skills and neglecting the development of novel motor skills over time.Approach.We developed a progressive unsupervised myocontrol (PUM) paradigm in which the user and the control model coadaptively identify distinct muscle synergies, which are then used to control arbitrarily associated myocontrol functions, each corresponding to a hand or wrist movement. The interaction starts with learning a single function and the user may request additional functions after mastering the available ones, which aligns the evolution of their motor skills with an increment in system complexity. We conducted a multi-session user study to evaluate PUM and compare it against a state-of-the-art non-progressive unsupervised alternative. Two participants with congenital upper-limb differences tested PUM, while ten non-disabled control participants tested either PUM or the non-progressive baseline. All participants engaged in myoelectric control of a virtual hand and wrist.Main results.PUM enabled autonomous learning of three myocontrol functions for participants with limb differences, and of all four available functions for non-disabled subjects, using both existing or newly identified muscle synergies. Participants with limb differences achieved similar success rates to non-disabled ones on myocontrol tests, but faced greater difficulties in internalizing new motor skills and exhibited slightly inferior movement quality. The performance was comparable with either PUM or the non-progressive baseline for the group of non-disabled participants.Significance.The PUM paradigm enables users to autonomously learn to operate the myocontrol system, adapts to the users' varied preexisting motor skills, and supports the further development of those skills throughout practice.