Transtibial amputee joint motion has increased attractor divergence during walking compared to non-amputee gait

Shane R. Wurdeman, Sara A. Myers, Nicholas Stergiou

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The amputation and subsequent prosthetic rehabilitation of a lower leg affects gait. Dynamical systems theory would predict the use of a prosthetic device should alter the functional attractor dynamics to which the system self-organizes. Therefore, the purpose of this study was to compare the largest Lyapunov exponent (a nonlinear tool for assessing attractor dynamics) for amputee gait compared to healthy non-amputee individuals. Fourteen unilateral, transtibial amputees and fourteen healthy, non-amputee individuals ambulated on a treadmill at preferred, self-selected walking speed. Our results showed that the sound hip (p = 0.013), sound knee (p = 0.05), and prosthetic ankle (p = 0.023) have significantly greater largest Lyapunov exponents than healthy non-amputees. Furthermore, the prosthetic ankle has a significantly greater (p = 0.0.17) largest Lyapunov exponent than the sound leg ankle. These findings indicate attractor states for amputee gait with increased divergence. The increased attractor divergence seems to coincide with decreased ability for motor control between the natural rhythms of the individual and those of the prosthetic device. Future work should consider the impact of different prostheses and rehabilitation on the attractor dynamics.

Original languageEnglish (US)
Pages (from-to)806-813
Number of pages8
JournalAnnals of biomedical engineering
Issue number4
StatePublished - Apr 2013


  • Dynamic stability
  • Dynamical system
  • Gait
  • Lyapunov exponent
  • Nonlinear dynamics
  • Rehabilitation
  • Stride-to-stride fluctuations

ASJC Scopus subject areas

  • Biomedical Engineering


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