Training prosthesis users to switch between modes of a multi-articulating prosthetic hand.

PURPOSE: Producing triggers to switch between modes of myoelectric prosthetic hands has proven to be difficult. We evaluated whether digital training methods were feasible in individuals with an upper limb defect (ULD), whether myosignals in these individuals differ from those of non-impaired individuals and whether acquired skills transfer to prosthesis use. MATERIALS AND METHODS: Two groups participated in a 9-day pre-test-post-test design study with seven 45-minute training sessions. One group trained using a serious game, the other with their myosignals digitally displayed. Both groups also trained using a prosthesis. The pre- and post-tests consisted of an adapted Clothespin Relocation Test and the spherical subset of the Southampton Hand Assessment Procedure. After the post-test, the System Usability Scale (SUS) was administered. Clinically relevant performance measures and myosignal features were analysed. RESULTS: Four individuals with a ULD participated. SUS-scores deemed both training methods feasible. Three participants produced only a few correct triggers. Myosignals features indicated larger variability for individuals with a ULD compared to non-impaired individuals (previously published data [1]). Three participants indicated transfer of skill. CONCLUSIONS: Even though both training methods were deemed feasible and most participants showed transfer, seven training sessions were insufficient to learn reliable switching behaviour.Trial registration: The study was approved by the medical ethics committee of the University Medical Center Groningen (METc 2018.268).Implications for rehabilitationSwitching between pre-programmed modes of a myoelectric prosthetic hand can be learned, however it does require training.Serious games can be considered useful training tools for trigger production in early phases of myoelectric prosthesis control training.In order to evoke transfer of skill from training to daily life both task-specificity and focus of attention during training should be taken into account.

Repeatability and Safety of the Functional Capacity Evaluation-One-Handed for Individuals with Upper Limb Reduction Deficiency and Amputation.

Purpose To assess repeatability and safety of the functional capacity evaluation-one-handed (FCE-OH), a FCE-OH individuals, consisting of eight items. Method The FCE-OH protocol was administered twice to 23 individuals with upper limb absence (87% male; median age 46 years; median 2 days between sessions). To examine repeatability, test-retest reliability and agreement were assessed with the intraclass correlations coefficient (ICC) and limits of agreement (LoA), respectively. Reliability was considered acceptable when ICC-values were ≥0.75. Widths of LoA of four tests were compared with those of healthy adults. Safety and pain response were assessed with a questionnaire. Results After controlling for stability of construct, ICC-values ranged between 0.23 and 0.96, and widths of LoA ranged between 16 and 79%. Intertrial (learning) effects were present in three test items. No serious adverse reactions were reported. A pain response was reported by 30% of the participants. Conclusion Good or excellent reliability was observed in five tests, while three items showed poor or moderate test-retest reliability. Interpretation of agreement was possible for four tests, of which three showed widths of LoA similar to those reported in healthy adults. Learning effects were present; therefore, interpretation at the individual level should be performed with care. As the CI of several items were wide, confirmation of results in a larger sample is warranted. Safety was confirmed.

Functional Capacity Evaluation in Upper Limb Reduction Deficiency and Amputation: Development and Pilot Testing.

Purpose To develop and pilot test a functional capacity evaluation (FCE) for individuals with upper limb absence (ULA) due to reduction deficiency or amputation, and to examine the relationship between FCE results and presence of musculoskeletal complaints (MSC). Method Five tests (overhead lifting, overhead working, repetitive reaching, fingertip dexterity, and handgrip strength) were selected and adapted if necessary. The newly developed FCE, called FCE-One-Handed (FCE-OH), was pilot tested in 20 adults individuals with ULA, and 20 matched controls. MSC were assessed via a questionnaire. Results Adaptations were considered necessary for all tests, except the handgrip strength test. The repetitive overhead lifting test of the non-affected limb was added. On the overhead lifting test, individuals with above-elbow ULA (ten males), performed similar to controls using one hand. When lifting bimanually using the prosthesis, a trend for lower lifting capacity of individuals with below-elbow ULA (seven males, three females) was observed compared to controls. On the overhead working test, individuals with above-elbow ULA performed worse compared to controls. Other tests showed no significant differences between groups. Relationships between FCE results and presence of MSC were non-significant. Conclusion The FCE-OH can be used to test functional capacity of one-handed individuals. Individuals with ULA generally showed similar functional capacity as two-handed individuals. FCE results were not related to MSC. It was discussed that a higher physical load on the non-affected limb might reflect a relative deficit of functional capacity.

Flexible and static wrist units in upper limb prosthesis users: functionality scores, user satisfaction and compensatory movements.

BACKGROUND: The current study examines the relevance of prosthetic wrist movement to facilitate activities of daily living or to prevent overuse complaints. Prosthesis hands with wrist flexion/extension capabilities are commercially available, but research on the users' experiences with flexible wrists is limited. METHODS: In this study, eight transradial amputees using a myoelectric prosthesis tested two prosthesis wrists with flexion/extension capabilities, the Flex-wrist (Otto Bock) and Multi-flex wrist (Motion Control), in their flexible and static conditions. Differences between the wrists were assessed on the levels of functionality, user satisfaction and compensatory movements after two weeks use. RESULTS: No significant differences between flexible and static wrist conditions were found on activity performance tests and standardized questionnaires on satisfaction. Inter-individual variation was remarkably large. Participants' satisfaction tended to be in favour of flexible wrists. All participants but one indicated that they would choose a prosthesis hand with wrist flexion/extension capabilities if allowed a new prosthesis. Shoulder joint angles, reflecting compensatory movements, showed no clear differences between wrist conditions. CONCLUSIONS: Overall, positive effects of flexible wrists are hard to objectify. Users seem to be more satisfied with flexible wrists. A person's needs, work and prosthesis skills should be taken into account when prescribing a prosthesis wrist. TRIAL REGISTRATION: Nederlands Trial Register NTR3984 .

The effect of the height to which the hand is lifted on horizontal curvature in horizontal point-to-point movements.

In point-to-point reaching movements, the trajectory of the fingertip along the horizontal plane is not completely straight but slightly curved sideward. The current paper examines whether this horizontal curvature is related to the height to which the finger is lifted. Previous research suggested that the height to which the hand is lifted might be a determinant of horizontal curvature. We asked participants to make point-to-point movements in three conditions: constrained movements (i.e., fingertip keeps contact with table top) over vertically curved surfaces that differed in height, constrained movements over a flat surface, and unconstrained movements (i.e., fingertip lifted from table top). In constrained movements, we found a strong relation between horizontal curvature and lifted height of the finger. Interestingly, for unconstrained movements, the relation between horizontal curvature and height to which the finger was lifted was weak. This demonstrates that the height to which the finger was lifted relates to horizontal curvature in some, but not in all conditions. This suggests that the height to which the hand is lifted should be included, in particular for constrained movements, when giving a full account of horizontal curvature in point-to-point movements.

Improving obstacle detection by redesign of walking canes for blind persons.

This paper describes an experiment in which the performance of cane walkers with the traditional straight long cane and a redesigned cane, the curved cane, was compared. The curved cane has a curve where the tip touches the ground. Participants were 18 experienced cane walkers who were totally blind. The aspects of cane walking that were investigated included obstacle detection, drop-off (slope) detection and walking speed. The performance with both canes was investigated in two different ways: (1) by means of constructed courses in which objective measures of cane walking were derived; and (2) by means of more qualitative measures based on the participants' experiences with the curved cane during a 3-week try-out period. Results showed that obstacle-detection was significantly better with the curved cane, whereas drop-off detection and walking speed were comparable for the two canes. The participants' experiences mirrored these results.