Evaluation of an adjustable ankle-foot orthosis impact on walking stability during gait transitional phases. (February 2022)

• Record Type: Journal Article
• Authors: Mahmood, Imran; Raza, Anam; Dehghani-Sanij, Abbas A.
• Is Part Of: Medical engineering & physics. Volume 100(2022)
• Publication Date: 2022-02
• Subjects: Gait -- Walking stability -- Loading and unloading phases -- Ankle-foot orthosis -- Model identification -- Nyquist and Bode methods -- Wearable devices; AFO ankle-foot orthosis -- BoS base of support -- DRT dorsiflexion resistive torque -- DPRT dorsi-plantarflexion resistive torque -- DRR dorsiflexion ROM restriction -- DPRR dorsi-plantarflexion ROM restriction -- GM gain margin -- GRF ground reaction force -- HC heel contact -- I/P input -- LTI linear time-invariant -- MoS margin of stability -- N&B Nyquist and Bode -- O/I output/input -- O/P output -- PCA principal component analysis -- PM phase margin -- R2 coefficient of determinant -- ROM range of motion -- Std. standard deviation -- TF transfer function -- TO toe-off -- XCoM extrapolated CoM; Biomedical engineering -- Periodicals; Biomedical Engineering -- Periodicals; Physics -- Periodicals; Génie biomédical -- Périodiques; Biomedical engineering; Electronic journals; Periodicals; 610.28
• DOI: 10.1016/j.medengphy.2021.10.010
• Languages: English
• ISSNs: 1350-4533

Abstract

Highlights: This study introduces method to quantify walking stability during gait transitions. Nyquist and bode methods are introduced to quantify walking stability. Proposed methods investigate impacts of adjustable orthosis on walking stability. Results showed significant effect of wearable orthoses on walking stability. A moderate to severe AFO restrictions are essential to achieve normal stability. Abstract: Walking stability evaluation during gait transitional phases (loading and unloading) has been remained indistinct mainly due to methodological limitations and multiple biomechanical signals being used. This study introduces Nyquist and Bode methods using resultant neuromechanical output/input (O/I) responses to evaluate gait transitional stabilities. The centre of pressure and ground reaction force data are recorded experimentally as output and somatosensory input responses by the neuromotor. Six different walking conditions are simulated by wearing an adjustable orthosis using eleven healthy subjects. The rate of change in O/Is are modelled in time and frequency domains applying linear regression and stability margins are quantified applying N&B methods. Results from outputs showed loading phase as stable and unloading phase as unstable gait phases whereas the margins quantified from inputs showed unstable response during both phases. Stability margins quantified from outputs are decreased ( p < 0.05) and instability margins are increased ( p < 0.05) on applying ankle-foot restrictions. Overall, the neuromotor output stability margins are greater than the instabilities quantified from inputs. Furthermore, a strong interlimb negative correlation ( p < 0.001) was found between loading and unloading phases computed from outputs. This study introduces new stability assessment methods with applications like evaluating lower limb impairments, varying terrains, and stability impacts of wearable devices.