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

Abstract 

Hofstad CJ, van der Linde H, Nienhuis B, Weerdesteyn V, Duysens J, Geurts AC. High failure rates when avoiding obstacles during treadmill walking in patients with a transtibial amputation.

Objective

To investigate if and to what extent patients with a transtibial amputation are less successful in avoiding unexpected obstacles while walking than healthy adults.

Design

Experimental 2-group design.

Setting

Dutch rehabilitation center.

Participants

Eleven patients with a transtibial amputation and 14 healthy controls.

Interventions

Not applicable.

Main Outcome Measures

Subjects walked on a treadmill at .56m/s. In 2 series of 12 trials each, an obstacle was dropped in front of the prosthetic or the nonprosthetic leg of the amputation group and the left leg of the control group at different phases during the step cycle. It was noted which avoidance strategy was used (a long step strategy [LSS] or a short step strategy [SSS]) and whether the obstacle was avoided successfully or not. These data were expressed as a percentage of the total number of trials completed by each subject.

Results

With either leg, the amputation group made significantly more errors than the control subjects (prosthetic leg, 24%±17%; nonprosthetic leg, 21%±17% vs 2%±2% for the control group). Highest failure rates were in the amputation group when time pressure was high, requiring an SSS, especially on the prosthetic side. An LSS under time pressure, however, nearly always resulted in failure for both the prosthetic and nonprosthetic legs. Subjects with the longest time since amputation were most successful in avoiding unexpected obstacles.

Conclusions

Under time pressure, patients with a lower-leg prosthesis perform best when they use their nonprosthetic leg as the lead limb in an SSS. The fact that some subjects with the longest time since amputation made no errors suggests that over many years it is possible to relearn the appropriate avoidance reactions sufficiently fast.

Key Words:  Artificial limbs , Gait , Leg prosthesis , Rehabilitation