title: Step length after discrete perturbation predicts accidental falls and fall-related injury in elderly people with a range of peripheral neuropathy.
abstract: OBJECTIVE
  Distal symmetric polyneuropathy increases fall risk due to inability to cope with perturbations. We aimed to 1) identify the frontal plane lower limb sensorimotor functions which are necessary for robustness to a discrete, underfoot perturbation during gait; and 2) determine whether changes in the post-perturbed step parameters could distinguish between fallers and non fallers.
  
  
  METHODS
  Forty-two subjects (16 healthy old and 26 with diabetic PN) participated. Frontal plane lower limb sensorimotor functions were determined using established laboratory-based techniques. The subjects' most extreme alterations in step width or step length in response to a perturbation were measured. In addition, falls and fall-related injuries were prospectively recorded.
  
  
  RESULTS
  Ankle proprioceptive threshold (APrT; p=.025) and hip abduction rate of torque generation (RTG; p=.041) independently predicted extreme step length after medial perturbation, with precise APrT and greater hip RTG allowing maintenance of step length. Injured subjects demonstrated greater extreme step length changes after medial perturbation than non-injured subjects (percent change = 18.5 ± 9.2 vs. 11.3 ± 4.57; p = .01).
  
  
  CONCLUSIONS
  The ability to rapidly generate frontal plane hip strength and/or precisely perceive motion at the ankle is needed to maintain a normal step length after perturbation, a parameter which distinguishes between subjects sustaining a fall-related injury and those who did not.
authors.affiliation: Department of Physiotherapy, University of Applied Sciences of Western Switzerland, Geneva, Switzerland; Department of Physical Medicine & Rehabilitation, University of Michigan, Ann Arbor, MI, USA; Health Care Directorate, University Hospitals and University of Geneva, Geneva, Switzerland. Electronic address: lara.allet@hesge.ch.
authors.forename: Lara
authors.initials: L
authors.lastname: Allet
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Hogene
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Department of Mechanical Engineering, Biomechanics Research Laboratory, University of Michigan, Ann Arbor, MI, USA.
authors.forename: James
authors.initials: J
authors.lastname: Ashton-Miller
authors.affiliation: Department of Physical Medicine & Rehabilitation, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Trina
authors.initials: T
authors.lastname: De Mott
authors.affiliation: Department of Physical Medicine & Rehabilitation, University of Michigan, Ann Arbor, MI, USA.
authors.forename: James K
authors.initials: JK
authors.lastname: Richardson
mesh_terms: D000058:Accidental Falls; D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000502:physiology; D005684:Gait; D020233:Gait Disorders, Neurologic / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D035002:Lower Extremity; D008875:Middle Aged; D053580:Muscle Strength; D010523:Peripheral Nervous System Diseases / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D011379:Prognosis; D012307:Risk Factors; D016138:Walking / Q000502:physiology*; D014947:Wounds and Injuries / Q000175:diagnosis* / Q000209:etiology*
keywords: Falls; Gait; LP; Lateral Perturbed; MP; MVC; Maximum Voluntary Contraction; Medial Perturbed; Muscle strength; PN; Peripheral Neuropathy; Peripheral neuropathy; Proprioception; RTG; Rate of Torque Generation; SL; SW; Sensorimotor functions; Step length; Step width; UnP; Unperturbed