Margins of stability in young adults with traumatic transtibial amputation walking in destabilizing environments

Abstract

Understanding how lower-limb amputation affects walking stability, specifically in destabilizing environments, is essential for developing effective interventions to prevent falls. This study quantified mediolateral margins of stability (MOS) and MOS sub-components in young individuals with traumatic unilateral transtibial amputation (TTA) and young able-bodied individuals (AB). Thirteen AB and nine TTA completed five 3-minute walking trials in a Computer Assisted Rehabilitation ENvironment (CAREN) system under three each of three test conditions: no perturbations, pseudo-random mediolateral translations of the platform, and pseudo-random mediolateral translations of the visual field. Compared to the unperturbed trials, TTA exhibited increased mean MOS and MOS variability during platform and visual field perturbations (p < 0.010). Also, AB exhibited increased mean MOS during visual field perturbations and increased MOS variability during both platform and visual field perturbations (p < 0.050). During platform perturbations, TTA exhibited significantly greater values than AB for mean MOS (p < 0.050) and MOS variability (p < 0.050); variability of the lateral distance between the center of mass (COM) and base of support at initial contact (p < 0.005); mean and variability of the range of COM motion (p < 0.010); and variability of COM peak velocity (p < 0.050). As determined by mean MOS and MOS variability, young and otherwise healthy individuals with transtibial amputation achieved stability similar to that of their able-bodied counterparts during unperturbed and visually-perturbed walking. However, based on mean and variability of MOS, unilateral transtibial amputation was shown to have affected walking stability during platform perturbations.

Does unilateral transtibial amputation lead to greater metabolic demand during walking?

“…There are several examples in which servicemembers who participated in intensive rehabilitation programs and had access to regular prosthetic care demonstrated smaller deficits than previously reported. For example, they have performed similarly to their nondisabled counterparts in areas such as activity performance, gait biomechanics, and walking stability [34][35][36][37][38][39][40][41]. It is important to recognize that the similarities observed here and elsewhere, while encouraging, do not represent an absence of dysfunction or the full restoration of function in all people or across all aspects of life.…”

Dynamic stability of superior vs. inferior body segments in individuals with transtibial amputation walking in destabilizing environments

“…The experimental protocol is described in detail elsewhere (Beltran et al, 2014; Beurskens et al, 2014). Briefly, all subjects walked on a 2m x 3m treadmill in a Computer Assisted Rehabilitation Environment (CAREN) virtual reality system (Motek, Amsterdam, Netherlands) (Fig.…”

“…When subjected to side to side mechanical (walking platform) perturbations, subjects with amputation exhibited greater variability of step widths and trunk (C7) kinematics than controls (Beurskens et al, 2014). These subjects with amputation also exhibited larger mean lateral margins of stability (Beltran et al, 2014). Larger mean stability margins might suggest these subjects were more stable (Hof et al, 2005; Hof et al, 2007) when perturbed.…”

“…Interestingly, when young highly active individuals with and without transtibial amputation were subjected to mediolateral perturbations, subjects in both groups took shorter and wider steps (Beurskens et al, 2014), thus increasing their bases of support (Beltran et al, 2014). Likewise, all subjects exhibited greatly increased stepping variability and trunk kinematic variability when perturbed (Beurskens et al, 2014).…”

“…Larger mean stability margins might suggest these subjects were more stable (Hof et al, 2005; Hof et al, 2007) when perturbed. However, these patients also exhibited greater step to step variability in their margins of stability, which could indicate they still exhibited an increased likelihood of experiencing steps with very small or possibly negative margins of stability (Beltran et al, 2014). However, these patients did not exhibit increased local or orbital instability of their trunk (C7) movements compared to healthy controls (Beurskens et al, 2014).…”