title: Individual responses to alignment perturbations in socket reaction moments while walking in transtibial prostheses.
abstract: BACKGROUND
  The alignment of transtibial prostheses has a systematic effect on the mean socket reaction moments in amputees. However, understanding their individual differences in response to alignment perturbations is also important for prosthetists to fully utilize the socket reaction moments for dynamic alignment in each unique patient. The aim of this study was to investigate individual responses to alignment perturbations in transtibial prostheses with solid-ankle-cushion-heel feet.
  
  
  METHODS
  A custom instrumented prosthesis alignment component was used to measure the socket reaction moments while walking in 11 amputees with transtibial prostheses under 17 alignment conditions, including 3° and 6° of flexion, extension, abduction, and adduction of the socket, 5mm and 10mm of anterior, posterior, lateral, and medial translation of the socket, and an initial baseline alignment. Coronal moments at 30% of stance and maximum sagittal moments were extracted for comparisons from each amputee.
  
  
  RESULTS
  In the coronal plane, varus moment at 30% of stance was generally reduced by adduction or medial translation of the socket in all the amputees. In the sagittal plane, extension moment was generally increased by posterior translation or flexion of the socket; however, this was not necessarily the case for all the amputees.
  
  
  CONCLUSIONS
  Individual responses to alignment perturbations are not always consistent, and prosthetists would need to be aware of this variance when addressing individual socket reaction moments during dynamic alignment in clinical setting.
authors.affiliation: Orthocare Innovations, Mountlake Terrace, WA, USA. Electronic address: tkobayashi@orthocareinnovations.com.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Orthocare Innovations, Mountlake Terrace, WA, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Orendurff
authors.affiliation: Interdisciplinary Division of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Orthocare Innovations, Mountlake Terrace, WA, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Boone
mesh_terms: D000328:Adult; D000674:Amputees; D001186:Artificial Limbs; D001696:Biomechanical Phenomena / Q000502:physiology; D002138:Calibration; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D057285:Precision Medicine / Q000379:methods; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D016138:Walking / Q000502:physiology
keywords: Amputation; Direct measurement; Gait; Kinetic; Malalignment; SACH foot