Attempted symmetry affects dynamic gait stability in individuals with lower-limb amputation

Abstract

Background: Gait in people with lower limb amputation (LLA) is typically asymmetrical. Reducing this asymmetry is often attempted to minimise the impact of secondary health issues. However, temporal-spatial asymmetry in gait of people with LLA has also been shown to underpin dynamic stability.

Research question: The current study aimed to identify the effects of acute attempts to achieve temporal-spatial symmetry on the dynamic stability of people with unilateral transtibial amputation (UTA). The secondary aim of this study was to identify the corresponding biomechanical adaptations during attempted symmetrical gait.

Methods: Eleven people with UTA walked along a 15 m walkway in four different conditions: normal (NORM), attempted symmetrical step length and step frequency (SYM_SL+SF) attempted symmetrical step length (SYM_SL) and attempted symmetrical step frequency (SYM_SF). Dynamic stability was measured using the backward (BW) and medio-lateral (ML) margins of stability (MoS).

Results: Results indicate that attempting SYM_SF had a positive effect on gait stability in BW and ML directions, while attempting SYM_SL had a potentially negative effect, although these results did not appear to be significant. The absence of clustering in principal component analysis, supported the lack of significant results, indicating no features differentiating between conditions of attempted symmetry. Conversely, there was clustering by limbs which were associated with differences in knee and ankle joint angles between the prosthetic and non-prosthetic limbs, and clustering by individuals highlighting the importance of patient-specific analysis.

Conclusion: The data suggests that attempted symmetrical gait reduces asymmetry but also affects dynamic stability.

Keywords: Asymmetry; Dynamic stability; Margin of stability; Principal component analysis; Transtibial amputation.