Transfemoral Socket Design and Muscle Function

Not Applicable

Completed

Conditions: Amputation

Interventions: Device: Northwestern University Flexible Sub-Ischial Suction Socket (NU-FlexSIS)

Registration Number: NCT04212299

Lead Sponsor: University of Illinois at Chicago

Brief Summary: The objective of this pilot research project is to evaluate the effect of prosthetic socket design on amputated limb hip muscle strength and endurance in Service members, Veterans, and civilians who use above-the-knee prostheses. Traditional above-the-knee socket designs provide pelvic support that interferes with hip motion. They may also reduce the effort required from amputated limb hip muscles to stabilize the hip and amputated limb, risking further loss of muscle mass and strength beyond that due to amputation. Long-standing use of above-the-knee sockets with pelvic support may therefore intensify amputated limb muscle loss and weakness, leading to challenges with walking and balance, increasing the effort required to walk, and contributing to degenerative changes in the hips and knees. Alternative socket designs that lessen the loss of muscle mass and strength are therefore required.

The investigators have developed a new socket without pelvic support for above-the-knee prosthesis users called the Northwestern University Flexible Sub-Ischial Suction (NU-FlexSIS) Socket. This new socket design increases user comfort and is often preferred by users over sockets with pelvic support. This new socket does not lessen the mechanical function of the socket, or walking and balance performance. Our recent research suggests that walking with this new socket may also increase amputated limb hip muscle size. However, more research is needed to demonstrate that this new socket design improves amputated limb hip muscle strength and endurance, leading to better function.

A socket design that increases amputated limb hip muscle strength and endurance would provide a simple way to restore amputated limb hip muscle weakness in above-the-knee prosthesis users. Despite a considerable decrease in hip muscle size and strength due to amputation surgery, amputated limb hip muscles are expected to compensate for the loss of knee and ankle function by providing stability and propulsion during walking. Walking in the new socket design without pelvic support is expected to increase amputated limb hip muscle strength and endurance, providing an appealing alternative to traditional resistance training in order to retain hip muscle strength. Unlike traditional resistance training, using this new socket design would not require additional time or equipment, and may be effective just by walking in the home, community, or workplace. Due to existing infrastructure (e.g., ongoing clinical adoption of the NU-FlexSIS Socket, existing instructional materials and courses for fabrication and fitting of the NU-FlexSIS Socket, as well as a continuing partnership with Chicago's largest provider of prosthetic clinical care), the investigators anticipate being able to translate our research results to clinical practice by the end of the project period.

The investigators expect the results of the proposed pilot research project to directly and positively benefit the health and well-being of Service members, Veterans, and civilians who are above-the-knee prosthesis users. Benefits of increasing amputated limb hip muscle strength and endurance may include: i) improved control over the prosthesis, ii) better balance, iii) reduced effort to walk, and iv) protection against joint degeneration. For Service members these benefits could improve their performance on challenging and/or uneven ground, and increase the distance and speed they can walk or run. For Veterans, these benefits could lead to greater independence during activities of daily living, and fewer falls, reducing the physical and emotional burden on family members and caregivers.

Detailed Description: Not available

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 5

Inclusion Criteria

worn an ischial containment socket for ≥ 2 years, able to walk short distances (10 meters), ability to read, write, and speak English, ≥ 2 years using a liner-based suspension, and a residual limb length ≥ 5".

Exclusion Criteria

amputation of a second leg, contralateral complications (e.g., hip replacement), or other major neuromusculoskeletal or cardiovascular conditions (e.g., heart failure).

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Baseline ischial containment to subischial socket	Northwestern University Flexible Sub-Ischial Suction Socket (NU-FlexSIS)	-

Primary Outcome Measures

Name	Time	Method
Residual Limb Hip Muscle Peak Torque at Baseline	Baseline	Hip flexor, extensor, adductor and abductor muscle strength will be measured in transfemoral prosthesis users using a motor-driven isokinetic dynamometer. Muscular strength will be assessed via average peak torque (i.e., highest torque) across the first three repetitions of 12.
Residual Limb Hip Muscle Peak Torque at 8-weeks	8 weeks after intervention	Hip flexor, extensor, adductor and abductor muscle strength will be measured in transfemoral prosthesis users using a motor-driven isokinetic dynamometer. Muscular strength will be assessed via average peak torque (i.e., highest torque) across the first three repetitions of 12. Comparison will be made to baseline measure.
Residual Limb Hip Muscle Peak Torque at 42-weeks	42 weeks after intervention	Hip flexor, extensor, adductor and abductor muscle strength will be measured in transfemoral prosthesis users using a motor-driven isokinetic dynamometer. Muscular strength will be assessed via average peak torque (i.e., highest torque) across the first three repetitions of 12. Comparison will be made to baseline measure.
Residual Limb Hip Muscle Endurance at Baseline	Baseline	Hip flexor, extensor, adductor and abductor muscle endurance will be measured in transfemoral prosthesis users using a motor-driven isokinetic dynamometer. Muscular endurance will be assessed via a fatigue index, calculated as a percentage of the difference between total work performed during the first and last 3 repetitions divided by total work over the first 3 repetitions. A higher fatigue index will be taken as evidence of reduced muscular endurance.
Residual Limb Hip Muscle Endurance at 8-weeks	8 weeks after intervention	Hip flexor, extensor, adductor and abductor muscle endurance will be measured in transfemoral prosthesis users using a motor-driven isokinetic dynamometer. Muscular endurance will be assessed via a fatigue index, calculated as a percentage of the difference between total work performed during the first and last 3 repetitions divided by total work over the first 3 repetitions. A higher fatigue index will be taken as evidence of reduced muscular endurance. Comparison will be made to baseline measure.
Residual Limb Hip Muscle Endurance at 42-weeks	42 weeks after intervention	Hip flexor, extensor, adductor and abductor muscle endurance will be measured in transfemoral prosthesis users using a motor-driven isokinetic dynamometer. Muscular endurance will be assessed via a fatigue index, calculated as a percentage of the difference between total work performed during the first and last 3 repetitions divided by total work over the first 3 repetitions. A higher fatigue index will be taken as evidence of reduced muscular endurance. Comparison will be made to baseline measure.
Residual Limb Hip Muscle Duration at Baseline	Baseline	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The duration of time each hip muscle was active during a stride was calculated as the percentage of the gait cycle (i.e., heel-strike to heel-strike) for which that EMG signal was above a baseline value (min: 0%, max: 100%). The larger the percentage of the gait cycle that a muscle was deemed to be active, the greater its duration.
Residual Limb Hip Muscle Duration at 8-weeks	8 weeks after intervention	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The duration of time each hip muscle was active during a stride was calculated as the percentage of the gait cycle (i.e., heel-strike to heel-strike) for which that EMG signal was above a baseline value (min: 0%, max: 100%). The larger the percentage of the gait cycle that a muscle was deemed to be active, the greater its duration.
Residual Limb Hip Muscle Duration at at 42-weeks	42 weeks	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The duration of time each hip muscle was active during a stride was calculated as the percentage of the gait cycle (i.e., heel-strike to heel-strike) for which that EMG signal was above a baseline value (min: 0%, max: 100%). The larger the percentage of the gait cycle that a muscle was deemed to be active, the greater its duration.
Residual Limb Hip Muscle Integrated Area at Baseline	Baseline	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The total amount of hip muscle activity was calculated as the integrated area under the EMG signal during a gait cycle (i.e., heel-strike to heel-strike). Each EMG signal was normalized (i.e., divided by its maximum value across all the gait cycles and multiple by 100. The integrated areas is therefore reported as a percentage of that maximum (min: 0%, max: 100%). The larger the integrated area the more the muscle was deemed to be active.
Residual Limb Hip Muscle Integrated Area at 8-weeks	8 weeks after intervention	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The total amount of hip muscle activity was calculated as the integrated area under the EMG signal during a gait cycle (i.e., heel-strike to heel-strike). Each EMG signal was normalized (i.e., divided by its maximum value across all the gait cycles and multiple by 100. The integrated areas is therefore reported as a percentage of that maximum (min: 0%, max: 100%). The larger the integrated area the more the muscle was deemed to be active.
Residual Limb Hip Muscle Integrated Area at 42-weeks	42 weeks after intervention	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The total amount of hip muscle activity was calculated as the integrated area under the EMG signal during a gait cycle (i.e., heel-strike to heel-strike). Each EMG signal was normalized (i.e., divided by its maximum value across all the gait cycles and multiple by 100. The integrated areas is therefore reported as a percentage of that maximum (min: 0%, max: 100%). The larger the integrated area the more the muscle was deemed to be active.
Peak Residual Limb Hip Muscle Activity at Baseline	Baseline	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The highest level of hip muscle activity was calculated as the peak of the EMG signal during a gait cycle (i.e., heel-strike to heel-strike). Each EMG signal was normalized (i.e., divided by its maximum value across all the gait cycles recorded during baseline). The peak EMG is therefore typically reported as a value between 0 and 1. However, if the peak value during assessments increases relative to baseline, the value of the peak activity will exceed 1. The larger the peak value the greater the activation of that muscle.
Peak Residual Limb Hip Muscle Activity at 8 Weeks	8 weeks after intervention	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The highest level of hip muscle activity was calculated as the peak of the EMG signal during a gait cycle (i.e., heel-strike to heel-strike). Each EMG signal was normalized (i.e., divided by its maximum value across all the gait cycles recorded during baseline). The peak EMG is therefore typically reported as a value between 0 and 1. However, if the peak value during assessments increases relative to baseline, the value of the peak activity will exceed 1. The larger the peak value the greater the activation of that muscle.
Peak Residual Limb Hip Muscle Activity at 42 Weeks	42 weeks after intervention	Electromyographic (EMG) signals were recorded from transfemoral prosthesis users' residual limb muscles while walking. The highest level of hip muscle activity was calculated as the peak of the EMG signal during a gait cycle (i.e., heel-strike to heel-strike). Each EMG signal was normalized (i.e., divided by its maximum value across all the gait cycles recorded during baseline). The peak EMG is therefore typically reported as a value between 0 and 1. However, if the peak value during assessments increases relative to baseline, the value of the peak activity will exceed 1. The larger the peak value the greater the activation of that muscle.

Secondary Outcome Measures

Name	Time	Method
Four Square Step Test at Baseline	Baseline	A test of dynamic balance and coordination that assesses the participant's ability to step over objects forward, sideways, and backwards. Test was administered and scored as the best time (i.e., fastest) of two trials.
Four Square Step Test at 8 Weeks	8-weeks after intervention	A test of dynamic balance and coordination that assesses the participant's ability to step over objects forward, sideways, and backwards. Test was administered and scored as the best time (i.e., fastest) of two trials.
Four Square Step Test at 42 Weeks	42-weeks after intervention	A test of dynamic balance and coordination that assesses the participant's ability to step over objects forward, sideways, and backwards. Test was administered and scored as the best time (i.e., fastest) of two trials.
One Leg Stance Test at Baseline	Baseline	A test of static balance that assesses the participant's ability to remain upright on one leg. Test was administered and scored as the best time (i.e., longest) of two trials. Longer times imply better static balance.
One Leg Stance Test at 8 Weeks	8 weeks after intervention	A test of static balance that assesses the participant's ability to remain upright on one leg. Test was administered and scored as the best time (i.e., longest) of two trials. Longer times imply better static balance.
One Leg Stance Test at 42 Weeks	42 weeks after intervention	A test of static balance that assesses the participant's ability to remain upright on one leg. Test was administered and scored as the best time (i.e., longest) of two trials. Longer times imply better static balance.
10-Meter Walk Test at Baseline	Baseline	The 10MWT assesses walking speed in meters per second over a short duration. A faster speed is consider better walking performance. The fastest of 2 trials was used.
10-Meter Walk Test at 8 Weeks	8 weeks after intervention	The 10MWT assesses walking speed in meters per second over a short duration. A faster speed is consider better walking performance. The fastest of 2 trials was used.
10-Meter Walk Test at 42 Weeks	42 weeks after intervention	The 10MWT assesses walking speed in meters per second over a short duration. A faster speed is consider better walking performance. The fastest of 2 trials was used.
2-Minute Walk Test at Baseline	Baseline	The 2-Minute Walk Test is a measurement of waking endurance that assesses walking distance over two minutes. A longer distance walked indicates greater walking endurance.
2-Minute Walk Test at 8 Weeks	8-weeks after intervention.	The 2-Minute Walk Test is a measurement of waking endurance that assesses walking distance over two minutes. A longer distance walked indicates greater walking endurance.
2-Minute Walk Test at 42 Weeks	42-weeks after intervention.	The 2-Minute Walk Test is a measurement of waking endurance that assesses walking distance over two minutes. A longer distance walked indicates greater walking endurance.
Volume of Physical Activity at Baseline	2 weeks prior to intervention (baseline)	To assess the volume of physical activity, transfemoral prosthesis users wore a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from the step count data. The volume of physical activity will be quantified by the mean number of steps per activity bout. Higher values will be taken as evidence of greater physical activity.
Volume of Physical Activity at 8 Weeks	8-weeks after intervention	To assess the volume of physical activity, transfemoral prosthesis users wore a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from the step count data. The volume of physical activity will be quantified by the mean number of steps per activity bout. Higher values will be taken as evidence of greater physical activity.
Volume of Physical Activity at 42 Weeks	42-weeks after intervention	To assess the volume of physical activity, transfemoral prosthesis users wore a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from the step count data. The volume of physical activity will be quantified by the mean number of steps per activity bout. Higher values will be taken as evidence of greater physical activity.
Frequency of Physical Activity at Baseline	2 weeks prior to intervention (baseline)	To assess the frequency of physical activity, transfemoral prosthesis users will wear a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from step count data. The frequency of physical activity will be quantified by the mean number of activity bouts per day. Higher values will be taken as evidence of greater physical activity.
Frequency of Physical Activity at 8 Weeks	8 weeks after intervention	To assess the frequency of physical activity, transfemoral prosthesis users will wear a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from step count data. The frequency of physical activity will be quantified by the mean number of activity bouts per day. Higher values will be taken as evidence of greater physical activity.
Frequency of Physical Activity at 42 Weeks	42 weeks after intervention	To assess the frequency of physical activity, transfemoral prosthesis users will wear a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from step count data. The frequency of physical activity will be quantified by the mean number of activity bouts per day. Higher values will be taken as evidence of greater physical activity.
Duration of Physical Activity at Baseline	2 weeks prior to intervention (baseline)	To assess the duration of physical activity, transfemoral prosthesis users will wear a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from step count data. The duration of physical activity will be quantified by the mean time (in minutes) of activity bouts per day. Higher values will be taken as evidence of greater physical activity.
Duration of Physical Activity at 8 Weeks	8 weeks after intervention	To assess the duration of physical activity, transfemoral prosthesis users will wear a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from step count data. The duration of physical activity will be quantified by the mean time (in minutes) of activity bouts per day. Higher values will be taken as evidence of greater physical activity.
Duration of Physical Activity at 42 Weeks	42 weeks after intervention	To assess the duration of physical activity, transfemoral prosthesis users will wear a StepWatch4 activity monitor (Modus Health, Edmonds, WA) for a 2-week period. Activity bouts, or periods of time in which steps occur in successive 10-second intervals, will be derived from step count data. The duration of physical activity will be quantified by the mean time (in minutes) of activity bouts per day. Higher values will be taken as evidence of greater physical activity.