title: Motion analysis of axial rotation and gait stability during turning in people with Parkinson's disease.
abstract: BACKGROUND
  Axial rigidity and postural instability in people with Parkinson's disease (PD) may contribute to turning difficulty. This study examined the rotation of axial segments and gait instability during turning in people with PD.
  
  
  METHODS
  Thirteen PD and twelve age-matched healthy adults were recruited. Participants performed the timed Up-and-Go test and were recorded by a 3D motion capture system. Axial rotation was evaluated by the rotation onset of the head, thorax and pelvis. Gait stability was evaluated by the center of mass and center of pressure inclination angle. Turning performance was evaluated by turning time and turning steps.
  
  
  RESULTS
  During turning, PD adults rotated the head, thorax and pelvis simultaneously, whereas healthy adults rotated in a cranial to caudal sequence. Further, PD adults had a smaller sagittal inclination angle (p<0.001) but larger frontal inclination angle (p=0.006) than healthy adults. PD adults also turned slower (p=0.002) with a greater number of steps (p<0.001) than healthy adults. Last, PD adults showed a significant correlation between the sagittal inclination angle and turning steps (Spearman's ρ=-0.63), while healthy adults showed a significant correlation between frontal inclination angle and turning steps (Spearman's ρ=-0.67).
  
  
  CONCLUSIONS
  This study demonstrated the axial rigidity in PD adults during turning may reduce forward progression and increase lateral instability. The reduced progression is associated with extra turning steps and the increased lateral instability may result in great fall risk.
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Wen-Chieh
authors.initials: WC
authors.lastname: Yang
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Hsu
authors.affiliation: Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Ruey-Meei
authors.initials: RM
authors.lastname: Wu
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Tung-Wu
authors.initials: TW
authors.lastname: Lu
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Physical Therapy, Tzu Chi University, Hualien, Taiwan. Electronic address: khlin@ntu.edu.tw.
authors.forename: Kwan-Hwa
authors.initials: KH
authors.lastname: Lin
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006257:Head / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*; D010388:Pelvis / Q000502:physiology; D012399:Rotation; D013909:Thorax / Q000502:physiology
keywords: Axial rigidity; Parkinson's disease; Postural stability; Turning