Influence of standardized activities on validity of Assessment of Capacity for Myoelectric Control

The Assessment of Capacity for Myoelectric Control (ACMC) is an observation-based clinical tool that evaluates ability to control a myoelectric prosthetic hand during bimanual activities. Two validity aspects were investigated: potential bias interaction between prosthesis users and activities performed during assessment, and potential bias interaction between activities and different user characteristics (sex or prosthetic side). Six activities were standardized for the ACMC. Upper-limb myoelectric prosthesis users (47 congenital, 11 acquired; 31 male, 27 female, average age 19.9 yr) performed three standardized activities, each on one occasion. Bias-interaction analysis in the many-facet Rasch model identified inconsistent patterns in the interactions of individual users and activity facets and between activities and user characteristics. The standardized activities had no significant influence on measures of user ability. The activities functioned similarly across both sexes (p-value greater than or equal to0.12) and across both prosthetic sides in persons with upper-limb reduction deficiency (p-value greater than or equal to0.50) and persons with acquired amputation (p-value greater than or equal to0.13). The results provide evidence for the validity of the ACMC across the standardized activities and support use of the ACMC in prosthesis users of both sexes and prosthetic sides. The newly standardized activities are recommended for future ACMC use.