title: Coupling between 3D displacements and rotations at the glenohumeral joint during dynamic tasks in healthy participants.
abstract: BACKGROUND
  Glenohumeral displacements assessment would help to design shoulder prostheses with physiological arthrokinematics and to establish more biofidelic musculoskeletal models. Though displacements were documented during static tasks, there is little information on their 3D coupling with glenohumeral angle during dynamic tasks. Our objective was to characterize the 3D glenohumeral displacement-rotation couplings during dynamic arm elevations and rotations.
  
  
  METHODS
  Glenohumeral displacements were measured from trajectories of reflective markers fitted on intracortical pins inserted into the scapula and humerus. Bone geometry was recorded using CT-scan. Only four participants were recruited to the experiment due to its invasiveness. Participants performed dynamic arm abduction, flexion and axial rotations. Linear regressions were performed between glenohumeral displacements and rotations. The pin of the scapula of one participant moved, his data were removed from analysis, and results are based on three participants.
  
  
  RESULTS
  The measurement error of glenohumeral kinematics was less than 0.15mm and 0.2°. Maximum glenohumeral displacements were measured along the longitudinal direction and reached up to +12.4mm for one participant. Significant couplings were reported especially between longitudinal displacement and rotation in abduction (adjusted R(2) up to 0.94).
  
  
  CONCLUSIONS
  The proposed method provides the potential to investigate glenohumeral kinematics during all kinds of movements. A linear increase of upward displacement during dynamic arm elevation was measured, which contrasts with results based on a series of static poses. The systematic investigation of glenohumeral displacements under dynamic condition may help to provide relevant recommendation for the design of shoulder prosthetic components and musculoskeletal models.
authors.affiliation: Laboratoire de simulation et de modélisation du mouvement, Département de kinésiologie, Université de Montréal, 1700, rue Jacques Tétreault, Laval, QC H7N 0B6, Canada. Electronic address: fabien.dalmaso@gmail.com.
authors.forename: Fabien
authors.initials: F
authors.lastname: Dal Maso
authors.affiliation: École Polytechnique de Montréal, 6079, Succursale, Centre Ville, Montréal, QC H3C 3A7, Canada.
authors.forename: Maxime
authors.initials: M
authors.lastname: Raison
authors.affiliation: Karolinska Institute, Stockholm, Sweden.
authors.forename: Arne
authors.initials: A
authors.lastname: Lundberg
authors.affiliation: Karolinska Institute, Stockholm, Sweden; The Swedish School of Sport and Health Sciences, Stockholm, Sweden.
authors.forename: Anton
authors.initials: A
authors.lastname: Arndt
authors.affiliation: Laboratoire de simulation et de modélisation du mouvement, Département de kinésiologie, Université de Montréal, 1700, rue Jacques Tétreault, Laval, QC H7N 0B6, Canada.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Begon
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D006801:Humans; D006811:Humerus / Q000502:physiology; D016014:Linear Models; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D012540:Scapula / Q000502:physiology; D012785:Shoulder Joint / Q000502:physiology*; D014057:Tomography, X-Ray Computed
keywords: 3D kinematics; CT-scan; Intracortical pin; Kinematic model; Shoulder prosthesis