Evaluation of Human Factors for the User-centered Design of Powered Robotic Transfemoral Prostheses: A Survey of Transfemoral Amputee Experience and Priorities
Authors: Fanciullacci Chiara , McKinney Zach , Monaco Vito , Milandri Giovanni , Davalli Angelo , Sacchetti Rinaldo , Laffranchi Matteo , Michieli Lorenzo De , Baldoni Andrea , Mazzoni Alberto , Paternò Linda , Rosini Elisa , Reale Luigi , Trecate Fabio , Crea Simona , Vitiello Nicola , Gruppioni Emanuele 
Published: September 2020

Abstract
BACKGROUND: Transfemoral amputees experience a complex host of physical, psychological, and social challenges, compounded by the functional limitations of current transfemoral prostheses. However, the specific relationships between human factors and prosthesis design and performance characteristics have not yet been adequately investigated. The present study aims to address this knowledge gap. METHODS: A comprehensive single-cohort survey of 114 unilateral transfemoral amputees addressed a broad range of demographic and clinical characteristics, functional autonomy, satisfaction and attitudes towards their current prostheses, and design priorities for an ideal transfemoral prosthesis, including the possibility of active assistance from a robotic knee unit. The survey was custom-developed based on several standard questionnaires used to assess motor abilities and autonomy in activities of daily living, prosthesis satisfaction, and quality of life in lower-limb amputees. Survey data are summarized with descriptive statistics applied separately to users of transfemoral prostheses with versus without microprocessor-controlled knee units (MPKs and NMPKs, respectively). RESULTS: The cohort featured predominantly younger (< 50 yrs.) traumatic male amputees with respect to the general transfemoral amputee population, with pronounced differences in age distribution and amputation etiology (traumatic vs. non-traumatic) between MPK and NMPK groups. These differences were further reflected in user experience, with MPK users reporting markedly greater functional autonomy, satisfaction, and sense of prosthesis ownership than those with NMPKs, in conjunction with a decreased incidence of instability and falls. Across all subjects, the leading functional priorities for an ideal transfemoral prosthesis were overall stability, adaptability to variable walking velocity, and lifestyle-related functionality, while the highest-prioritized general characteristics were reliability, comfort, and weight, with highly variable prioritization of cost. CONCLUSIONS: This study’s findings support the understanding that when appropriately prescribed according to patient characteristics and needs, advanced transfemoral prostheses promote patient mobility, autonomy, and overall health. Survey data indicate overall stability, modularity, and versatility as key design priorities for the continued development of transfemoral prosthesis technology. Finally, observed associations between prosthesis type, user experience, and attitudes concerning prosthesis ownership suggest both that prosthesis characteristics influence device acceptance and functional outcomes, and that psychosocial factors should be specifically and proactively addressed during the rehabilitation process.