Differences in multigrip myoelectric hands for facilitating activities of daily living
Most transradial amputees are fitted with a prosthetic hand but use it actively for only 50% of activities of daily living (ADLs). Studies with the multigrip Michelangelo hand reported that many patients perceived ADLs easier to perform than with a conventional prosthetic hand and could also demonstrate improvements in objective ADL performance. Other multigrip hands available on the market offer more grip types than the Michelangelo hand but have not yet been subjected to published clinical studies. Thus, it is unknown whether more grip types result in even greater perceived ease of ADLs execution.
Subjects wearing the bebionic or i-limb hands were assessed with the same hybrid questionnaire as used in the previous Michelangelo study. Demographic information on all subjects was also collected. The results were then compared to the historical data collected in the previous Michelangelo study.
Data were available from 36 unilateral subjects with transradial amputations, 10 each wearing a bebionic or i-limb, respectively, and 16 historical datasets of subjects who used a Michelangelo and conventional hand, respectively.
Means for ease scores and “useful” ratings across 23 ADLs did not differ between the multigrip hands but were better than those for the conventional hands. There were no statistical differences between the 3 multigrip hands. The mean numbers of ADLs by usefulness and method of use (prosthesis actively used to grasp, prosthesis passively used to stabilize, assistance of residual limb, sound hand alone) rating were also similar.
Analyzing the ease of individual activities, Michelangelo mean ease scores for several activities showed modest positive differences compared to conventional myoelectric hands. In contrast, the bebionic profile indicates fewer activities that were scored easier than conventional myoelectric compared with Michelangelo profile, but the difference in the scores for several activities were much greater than for the Michelangelo hand. For the i-limb, there were also several activities for which differences in the mean scores compared to conventional myoelectrics were much greater than that for Michelangelo.
In conclusion, all multigrip myoelectric hands may reduce the difficulty for performing ADLs vs. conventional hands. However, the availability of more grip types in a hand does not necessarily result in greater ease of performance of ADLs in general. Interestingly, the 3 multigrip hands studied showed different activity profiles that they facilitate. For some activities, there was a clear advantage for some hands over others. Thus, clinicians’ knowledge of the patients’ functional needs and the differential features of the available multigrip hands is crucial for selecting the best suitable hand for an individual patient. In addition, this study also highlights the need for more sophisticated control (e.g. pattern recognition) that facilitates easier and more intuitive access to a greater number of grips in a prosthetic hand than the current 2-channel myoelectric control.