Presentation Title

Transtibial amputee prosthesis preference is related to the change in stride-to-stride fluctuations

Advisor Information

Nicholas Stergiou

Location

Milo Bail Student Center Omaha Room

Presentation Type

Oral Presentation

Start Date

8-3-2013 3:45 PM

End Date

8-3-2013 4:00 PM

Abstract

Currently there are no performance metrics that relate to an amputee's prosthesis preference, a possible result of these measures failing to account for stride-to-stride relationships. The purpose of this study was to determine if changes in stride-to-stride fluctuations during amputee walking with two different prostheses is correlated with preference between the prostheses. Thirteen unilateral, transtibial amputees walked non-stop on a treadmill for three minutes at a self-selected speed in two different prostheses while motion of the lower limb segments was recorded. After walking, subjects marked their degree of preference on a continuous visual analog scale. The flexion/extension angle of the intact and prosthetic leg’s ankle, knee, and hip joint from a three minute interval for each prosthesis was embedded within its reconstructed state space. From this, the largest Lyapunov exponent (LyE) was calculated to measure the temporal organization of the stride-to-stride fluctuations. The change in LyE between prostheses was then correlated with the preference between prostheses. The change in LyE at the prosthetic ankle was found to be strongly correlated with the preference between prostheses (r=0.629, P=0.021). In conclusion, the temporal organization of stride-to-stride fluctuations seems to reflect neuromuscular organization of the motor output. The stride-to-stride fluctuations that occur with a prosthesis are altered from the fluctuations that would naturally occur in a non-amputee. Thus, the subjects seem to have an affinity towards a prosthesis that best promotes return to natural stride-to-stride fluctuations. These results are the first to find an objective measure strongly correlated to prosthesis preference.

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Mar 8th, 3:45 PM Mar 8th, 4:00 PM

Transtibial amputee prosthesis preference is related to the change in stride-to-stride fluctuations

Milo Bail Student Center Omaha Room

Currently there are no performance metrics that relate to an amputee's prosthesis preference, a possible result of these measures failing to account for stride-to-stride relationships. The purpose of this study was to determine if changes in stride-to-stride fluctuations during amputee walking with two different prostheses is correlated with preference between the prostheses. Thirteen unilateral, transtibial amputees walked non-stop on a treadmill for three minutes at a self-selected speed in two different prostheses while motion of the lower limb segments was recorded. After walking, subjects marked their degree of preference on a continuous visual analog scale. The flexion/extension angle of the intact and prosthetic leg’s ankle, knee, and hip joint from a three minute interval for each prosthesis was embedded within its reconstructed state space. From this, the largest Lyapunov exponent (LyE) was calculated to measure the temporal organization of the stride-to-stride fluctuations. The change in LyE between prostheses was then correlated with the preference between prostheses. The change in LyE at the prosthetic ankle was found to be strongly correlated with the preference between prostheses (r=0.629, P=0.021). In conclusion, the temporal organization of stride-to-stride fluctuations seems to reflect neuromuscular organization of the motor output. The stride-to-stride fluctuations that occur with a prosthesis are altered from the fluctuations that would naturally occur in a non-amputee. Thus, the subjects seem to have an affinity towards a prosthesis that best promotes return to natural stride-to-stride fluctuations. These results are the first to find an objective measure strongly correlated to prosthesis preference.