Physiologic Range of Step-by-step Variations in Lower Limb Prosthesis Forces During Walking

Study Overview
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Brief Summary
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In human gait there is a certain amount of variation between steps; some considered physiological and owed to variations in environment or posture, and some severe enough to be indicative of gait instabilities that may lead to stumbling and falling. In users of lower limb prosthetics, such gait instabilities are of especially great interest. The study investigates the correlation between socket alignment quality and gait step-by-step variability in users of trans-tibial-prosthetics. It is hypothesized that a clearly defined range of step-by-step variability exists, and that therefore step-by-step variability is suitable as an outcome variable for the assessment of socket alignment. A sample of ten persons with trans-tibial amputation will be recruited for this pilot study. Subjects will be asked to walk on different natural surfaces while the socket alignment is successively perturbed. Step-by-step variations in horizontal ground reaction forces and torsional moments will be measured and statistically compared.

Official Title
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Physiologic Range of Step-by-step Variations in Lower Limb Prosthesis Forces

Conditions
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Trans-tibial Limb Loss

Intervention / Treatment
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* Procedure: Prosthetic alignment perturbation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: activity classification of K2 to K4 experience in prosthesis use of at least one year stated ability to walk pain free for at least 30 minutes Exclusion Criteria: age of less than 18 years acute or ongoing residual limb pain use of a prosthesis that is not suitable for installation of the load cell (e.g. is too short, or has non-removable cosmesis)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Trans-tibial prosthesis users<br>prosthetic alignment perturbation | Procedure: Prosthetic alignment perturbation<br>* Prosthetic ankle plantar-flexion will be modified in different degrees, devices (prosthetic components) will not be modified from baseline condition<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Step-by-step variability | Peak horizontal ground reaction force (Fx and Fy) as well as peak axial torsion moment (Mz) will be extracted for 10 consecutive intermediary steps for each testing condition. Total range in Newtons over the 10 step sample, as well as maximal difference between consecutive steps in Newtons and percent will be reported for statistical analysis. | 2 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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prosthetics, amputation, gait stability, step variability, load cell