## 3 Results  
### Sample Data  
The participants were asked about general data, such as their gender, age, country, degree of amputation or congenital disorder and cause of amputation (if applicable). They were also asked about the dominant hand before amputation (if applicable), the dominant hand after amputation (if applicable) and affected hand(s). A total of 18 participants (7 males and 11 females, aged 32.9 \(\pm\) 11.8 years; 15 Spanish, 1 Mexican, 1 American, 1 Japanese) completed the questionnaire. Figure 1 displays bar plots. They illustratethe responses to specific questions, including (A) the reported degree of amputation or congenital disorder and (B) the cause of amputation. All of the participants reported a change in their handedness after amputation. The participants who were right-handed and had right hand amputations became left-handed, and vice versa. In a case with amputations of both hands, the participant did not change their handedness and remained right-handed. The participants were also asked about their current and past prosthetic use statuses. Of the 18 participants, 12 were currently using prosthetics (one for both hands), 4 had discontinued using them and 2 had never used them. The individuals who never used prosthetics or abandoned them were requested to specify their reasons. The reported reasons are listed in Table 1 after distinguishing between the participants who never used prosthetics and those who had discontinued their use. Additional data were obtained from current users: the prosthesis type, the manufacturing method and the duration required to achieve comfort in controlling their prosthesis. Of the current users, 15.38% reported employing mechanical prostheses, while 84.62% reported using electrical/myoelectrical ones. In terms of the average period of familiarization with prostheses, most participants reported a period of only a few days. However, the individual with a double amputation reported still being in the learning process. \begin{table}
\begin{tabular}{c c} \hline \hline
**Never Used** & **Abandoned Prosthetics (4 Participants)** \\ \hline \hline \multirow{4}{*}{Learned to perform *ADLs without prosthesis} & The prosthesis appeared non-functional with shoulder \\  & disarticulation; it merely served a cosmetic purpose. \\ \cline{2-3}  & The prosthesis appeared non-functional with a damaged \\  & brachial plexus; it merely served a cosmetic purpose and \\  & hindered the performance of ADLs rather than \\  & helping them. \\ \hline \hline \multirow{4}{*}{Rejection in childhood; learned to perform ADLs without prosthesis} & The prosthesis was rejected after a period of use in \\  & childhood. The individual felt that the prosthesis restricted \\  & elbow movement. They learned to perform ADLs without \\ \cline{2-3}  & It was abandoned after a challenging adaption period \\ \cline{2-3}  & because the individual was capable of performing all ADLs \\ \cline{2-3}  & without the need for a prosthesis. \\ \hline \hline \end{tabular} \({}^{*}\)ADLs = activities of daily living.  
\end{table} 
Table 1: Reported reasons for prostheses abandonment. Figure 1: Bar plots illustrating the responses to the following: (**A**) the degree of amputation or congenital disorder and (**B**) the cause of amputation. The current users were also asked about socket materials, those in contact with a limb, the socket fixing system, socket sensorization, the manufacturing method and the anthropometric measurement system. All of the prostheses used by the participants were commercially available. Their socket materials included rigid polymers (52.94%), soft polymers (29.41%), fabrics (11.76%) and metal (5.88%). The materials in contact with the residual limb were rigid polymers (50%), soft polymers (42.86%) and fabrics (7.14%). The socket fixing systems were rigid structures (46.1%), Velcro(r) straps (15.4%), silicone/suspension structures (15.4%), elastic straps (7.7%), harnesses (7.7%) and mechanical fixing systems (7.7%).