1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

O-36
HIGH FAILURE RATES WHEN AVOIDING UNEXPECTED OBSTACLES WHILE
WALKING IN PATIENTS WITH A TRANS-TIBIAL AMPUTATION
Hofstad, Cheriel J., MSc 1,3, Van der Linde, Harmen, MD, PhD 1, Nienhuis, Bart, Med Eng1,
Weerdesteyn, Vivian, MSc 1,3, Duysens, Jacques, MD, PhD 1,2,3, Geurts, Alexander C, MD,
PhD 1,2,3
1 Sint Maartenskliniek Research Development & Education, Nijmegen, the Netherlands, 2
Department of Rehabilitation Medicine, University Medical Center St. Radboud, Nijmegen,
the Netherlands, 3 IFKB (Institute for Fundamental and Clinical Human Movement Sciences),
the Netherlands
Conclusions
Patients with a lower leg prosthesis show significantly higher failure rates than control subjects
when avoiding sudden obstacles. Under time pressure, the patients perform best when they use
their non-prosthetic leg as the lead limb in a short step strategy (SSS). Some of the more
experienced prosthesis users made no errors at all, which suggests that over many years it is
still possible to relearn the appropriate avoidance reactions sufficiently fast.
Figure 1. Schematic diagram of experimental set-up. An electromagnet was attached
to a bridge over the front of the treadmill. Two reflective markers were placed on the
most posterior and most anterior end of the (right) foot and to the closest end of the
obstacle.
Introduction
Individuals with a lower leg prosthesis due to a trans-tibial amputation have no muscle control
about the artificial ankle and suffer from absent propriocepsis from the ankle joint and lower
leg muscles as well as from absent exterocepsis from the foot sole. Individuals with a transtibial
amputation may experience difficulties not only with unperturbed standing and walking,
but especially with avoiding obstacles [1] which increases their risk of falling. In daily life,
obstacles often occur suddenly requiring fast, more or less automatic responses. In this
perspective, we addressed the question if and under what circumstances patients with a transtibial
amputation are less successful in avoiding unexpected obstacles. Because of the higher
fall risk in patients with a trans-tibial amputation [1] , it was hypothesized that this group of
patients would indeed be less successful than a group of healthy adults when avoiding
unexpected obstacles, particularly under time pressure.
Statements of clinical significance
To understand why patients with a lower leg amputation fall more easily, it is necessary to
study their ability to avoid obstacles. The acquired information about obstacle avoidance
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