title: Powered exoskeletons for bipedal locomotion after spinal cord injury.
abstract: Powered exoskeletons promise to increase the quality of life of people with lower-body paralysis or weakened legs by assisting or restoring legged mobility while providing health benefits across multiple physiological systems. Here, a systematic review of the literature on powered exoskeletons addressed critical questions: What is the current evidence of clinical efficacy for lower-limb powered exoskeletons? What are the benefits and risks for individuals with spinal cord injury (SCI)? What are the levels of injury considered in such studies? What are their outcome measures? What are the opportunities for the next generation exoskeletons?
  
  
  
  A systematic search of online databases was performed to identify clinical trials and safety or efficacy studies with lower-limb powered exoskeletons for individuals with SCI. Twenty-two studies with eight powered exoskeletons thus selected, were analyzed based on the protocol design, subject demographics, study duration, and primary/secondary outcome measures for assessing exoskeleton's performance in SCI subjects.
  
  
  
  Findings show that the level of injury varies across studies, with T10 injuries being represented in 45.4% of the studies. A categorical breakdown of outcome measures revealed 63% of these measures were gait and ambulation related, followed by energy expenditure (16%), physiological improvements (13%), and usability and comfort (8%). Moreover, outcome measures varied across studies, and none had measures spanning every category, making comparisons difficult.
  
  
  
  This review of the literature shows that a majority of current studies focus on thoracic level injury as well as there is an emphasis on ambulatory-related primary outcome measures. Future research should: 1) develop criteria for optimal selection and training of patients most likely to benefit from this technology, 2) design multimodal gait intention detection systems that engage and empower the user, 3) develop real-time monitoring and diagnostic capabilities, and 4) adopt comprehensive metrics for assessing safety, benefits, and usability.
authors.affiliation: Laboratory for Non-invasive Brain-Machine Interface Systems, Department of Electrical Engineering, University of Houston, Houston, TX 77204, USA.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Contreras-Vidal
authors.forename: Nikunj
authors.initials: N
authors.lastname: A Bhagat
authors.forename: Justin
authors.initials: J
authors.lastname: Brantley
authors.forename: Jesus G
authors.initials: JG
authors.lastname: Cruz-Garza
authors.forename: Yongtian
authors.initials: Y
authors.lastname: He
authors.forename: Quinn
authors.initials: Q
authors.lastname: Manley
authors.forename: Sho
authors.initials: S
authors.lastname: Nakagome
authors.forename: Kevin
authors.initials: K
authors.lastname: Nathan
authors.forename: Su H
authors.initials: SH
authors.lastname: Tan
authors.forename: Fangshi
authors.initials: F
authors.lastname: Zhu
authors.forename: Jose L
authors.initials: JL
authors.lastname: Pons
mesh_terms: D000293:Adolescent; D000328:Adult; D000067190:Exoskeleton Device; D005260:Female; D006801:Humans; D008124:Locomotion; D008297:Male; D008875:Middle Aged; D010243:Paralysis / Q000523:psychology / Q000534:rehabilitation; D011474:Prosthesis Design; D011788:Quality of Life; D013119:Spinal Cord Injuries / Q000523:psychology / Q000534:rehabilitation*; D016138:Walking; D055815:Young Adult