Comparison of Pattern Recognition Control and Direct Control in TMR

Inclusion Criteria: * A upper limb amputation at the transhumeral or shoulder-disarticulation level * Successful TMR surgery * Previous success at operating a myoelectric prosthesis using surface EMG signals from reinnervated muscles (not necessarily current prosthesis usage, although current prosthesis users may be more likely to use their trial prostheses). Exclusion Criteria: * Significant new injury that would prevent use of a prosthesis: The ability to consistently wear a prosthesis and perform activities of daily living and specific performance tasks is necessary to evaluate the relative benefits of the interventions. * Cognitive impairment sufficient to adversely affect understanding of or compliance with study requirements, ability to communicate experiences, or ability to give informed consent: The ability to understand and comply with requirements of the study is essential in order for the study to generate useable, reliable data. The ability to obtain relevant user feedback through questionnaires and informal discussion adds significant value to this study. Of note, all TMR patients to date have normal cognitive function and we are not aware of any new brain injuries that would preclude participation * Significant other co morbidity: Any other medical issues or injuries that would preclude completion of the study, use of the prostheses, or that would otherwise prevent acquisition of useable data by researchers.