High Failure Rates When Avoiding Obstacles During Treadmill Walking in Patients With a Transtibial Amputation

The positions of the toe marker and the obstacle are shown after transformation from treadmill walking to overground walking. The bold line illustrates the actual trajectory of the toe marker; the thin line illustrates the extrapolated trajectory of the toe marker that would have occurred without an avoidance reaction. The grey rectangle represents the obstacle, which started to fall at 0ms. The duration between this moment and the moment at which the extrapolated toe would have crossed the front of the obstacle is defined as the available response time. In this trial, the available response time was 350ms and a short step strategy was used to avoid the obstacle. Abbreviation: ART, available response time.

Mean ± SD (A) step length, (B) relative stance time, and (C) maximum vertical heel displacement for the left leg of the control group, and for the prosthetic and nonprosthetic legs of the amputation group. *P<.05.

(A) Mean ± SD percentage of failures for the left leg of the control group and for the nonprosthetic and prosthetic legs of the amputation group. (B) Failure rates per available response time category for the left leg of the control group and for the 2 legs of the amputation group.

The mean percentage of total shortening (left side of the graphs) and lengthening steps (right side of the graphs) for the control leg (C) and for the nonprosthetic (NP) and prosthetic (P) legs. The black parts of the bars indicate the mean percentages of failures. (A) All available response time categories (range, 150–800ms); (B) the trials with available response times higher than 250ms; and (C) the trials with available response times lower than 250ms.

A scatterplot of the failure rate against the time since amputation for the prosthetic leg of the amputation group.