## 3 Results
### Assessment Methods of Usability in the LUse of Rehabilitative Exoskeletons
It consisted of a semi-structured protocol for individual interviews, divided into three themes of investigation, such as capabilities, which can be compensated for or improved with a lower-limb exoskeleton (i.e., behavior capabilities, motor activity capabilities, and protection and resistance capabilities); life habits, which can be improved with a lower-limb exoskeleton (i.e., nutrition, personal care, housing, mobility, responsibility, interpersonal relationships, community life, education, employment, and recreation); and expected technical characteristics of a lower-limb exoskeleton (i.e., appearance, adjustments, comfort, cost, dimensions, durability, effectiveness, installation, weight, repairs and servicing, safety, stigmatization/reaction of others, and usefulness/simplicity of use). The QUEST instrument was used as a reference for the development of the interview protocol. In addition, the transcribed text data were analyzed through thematic analysis with parallel coding to mitigate the subjectivity of interpretation. On this basis, this method was assigned a score of 7 out of 17 in our critical appraisal checklist. _Think-Aloud protocol._ Reported by one of the selected studies [25], this method was deployed to assess the usability of a hand/wrist rehabilitative exoskeleton during the prototype development of the system. It consisted of the user thinking aloud while using the robotic device and reporting potentially relevant issues in terms of usability. The think-aloud protocol lacks evidence of both validity and reliability. However, its findings were positively correlated to other methodologies' results. On this basis, this method was assigned a score of 6 out of 17 in our critical appraisal checklist. Quantitative and Objective Assessment Methods of Usability in the Use of Rehabilitative ExoskeletonsQuantitative and objective assessment methods are those providing a measurement in the form of an amount or count and intended to measure concrete and observable phenomena or qualities [23]. _Toronto Rehabilitation Institute Hand Function Test (TRI-HFT)_. Reported by one of the selected studies [36], this instrument was originally developed to assess the gross motor function of the hands of patients with motor impairments, and can be deployed to assess the usability of hand robotic exoskeletons for rehabilitation purposes. The test focuses on two main dimensions, namely ability to manipulate and grasp strength. The TRI-HFT is reported to show good values of validity and reliability indices, such as construct validity, content validity, and inter-rater reliability. On this basis, this method was assigned a score of 11 out of 17 in our critical appraisal checklist. _Experimental Characterization_. Reported by one of the selected studies [43], this method consists of a procedure that entails the probing and measurement of a system's properties and characteristics, and can be deployed to gauge the usability of a rehabilitative exoskeleton in terms of the torque and speed of the patients' movements. No evidence for validity nor reliability was provided. This method was assigned a score of 6 out of 17 in our critical appraisal checklist. Mixed Types of Assessment Methods of Usability in the Use of Rehabilitative ExoskeletonsMixed types of assessment methods are those deploying both quantitative and qualitative, as well as both objective and subjective, measurements. _Framework of Usability for Robotic Exoskeletal Orthoses (FluREO)_. Reported by one of the selected studies [44], FUREO encompasses six modules (i.e., functional applications, personal factors, device factors, external factors, activities, and health outcomes), each of them corresponding to a set of metrics and measures to assess the usability of current and/or future robotic exoskeletal orthoses for medical motor rehabilitation purposes. Functional applications include community-level mobility, household-level mobility, exercise, and ambulation training.