Diabetic peripheral neuropathy (DPN) is increasingly common among older Americans, with a prevalence approaching 15%, and is a potent risk factor for falls. Previous work has shown that older persons with DPN have functionally significant impairments in lower extremity sensory and motor function that impacts postural control. An irregular surface, which challenges postural control, is a common source of falls in this population. Moreover, measures of gait variability on an irregular surface more effectively differentiate between older persons with DPN and those without, and between older persons with DPN who fall and those who do not, than similar measures on a smooth surface. We hypothesize that feedback loop delay in ankle joint force output in response to a perturbation, related primarily to a DPN-associated impairment in rate of strength generation, is the mechanism by which DPN leads to postural instability, which in turn results in increased gait variability and fall risk. Therefore the aims of this research are: 1) To measure feedback loop delay in ankle joint force output in a group of 40 subjects (30 DPN, stratified by severity, and 10 healthy old) and determine its ability to predict postural responses to discrete perturbations, provided by a novel shoe, under the medial and lateral forefoot using kinematic and force plate data;2) To further evaluate the effect of feedback loop delay, utilizing the same subjects, by determining its ability to predict measures of gait variability on smooth and irregular surfaces;3) To investigate the extent to which measures of gait variability, determined separately on smooth and irregular surfaces, predict the incidence of falls and fall-related injuries observed prospectively over one year in a group of 100 subjects with DPN. The resulting research will provide insights into the mechanism by which DPN impairs recovery from surface irregularities and identify the gait measure best able to predict falls and fall-related injuries in this high risk population.

Public Health Relevance

Walking as a form of exercise is a common and important treatment of adult onset diabetes mellitus. However, many older patients with diabetes have nerve damage in their feet and legs that causes them to fall, particularly when walking on irregular surfaces. This research will identify the reasons that such patients fall, and which patients are at greatest risk of falling and being injured. This information will lead to strategies for making such patient safer while walking.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG026569-05
Application #
8277271
Study Section
Musculoskeletal Rehabilitation Sciences Study Section (MRS)
Program Officer
Joseph, Lyndon
Project Start
2008-05-01
Project End
2013-10-31
Budget Start
2012-05-01
Budget End
2013-10-31
Support Year
5
Fiscal Year
2012
Total Cost
$288,789
Indirect Cost
$93,713
Name
University of Michigan Ann Arbor
Department
Physical Medicine & Rehab
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Richardson, James K (2017) Imbalanced: The Confusing Circular Nature of Falls Research…and a Possible Antidote. Am J Phys Med Rehabil 96:55-59
Richardson, James K; Eckner, James T; Allet, Lara et al. (2017) Complex and Simple Clinical Reaction Times Are Associated with Gait, Balance, and Major Fall Injury in Older Subjects with Diabetic Peripheral Neuropathy. Am J Phys Med Rehabil 96:8-16
Richardson, James K (2016) Imbalanced: The Confusing Circular Nature of Falls Research… and a Possible Antidote. Am J Phys Med Rehabil :
Nnodim, Joseph O; Kim, Hogene; Ashton-Miller, James A (2016) Dual-task performance in older adults during discrete gait perturbation. Exp Brain Res 234:1077-84
Donaghy, Alex; DeMott, Trina; Allet, Lara et al. (2016) Accuracy of Clinical Techniques for Evaluating Lower Limb Sensorimotor Functions Associated With Increased Fall Risk. PM R 8:331-339
Zurales, Katie; DeMott, Trina K; Kim, Hogene et al. (2016) Gait Efficiency on an Uneven Surface Is Associated with Falls and Injury in Older Subjects with a Spectrum of Lower Limb Neuromuscular Function: A Prospective Study. Am J Phys Med Rehabil 95:83-90
Nnodim, Joseph O; Yung, Raymond L (2015) Balance and its Clinical Assessment in Older Adults - A Review. J Geriatr Med Gerontol 1:
Richardson, James K; Demott, Trina; Allet, Lara et al. (2014) Hip strength: ankle proprioceptive threshold ratio predicts falls and injury in diabetic neuropathy. Muscle Nerve 50:437-42
Allet, Lara; Kim, Hogene; Ashton-Miller, James et al. (2014) Step length after discrete perturbation predicts accidental falls and fall-related injury in elderly people with a range of peripheral neuropathy. J Diabetes Complications 28:79-84
Nnodim, Joseph O; Kim, Hogene; Ashton-Miller, James A (2013) Effect of a vocal choice reaction time task on the kinematics of the first recovery step after a sudden underfoot perturbation during gait. Gait Posture 37:61-6

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