Evaluation of a Modified Running-specific Prosthetic Foot

University of Washington

Status: Completed

Conditions: Transtibial Amputation

Treatments: Device: Energy storing foot (ESF); Device: Modified running specific foot (mRSF)

Study type: Interventional

Funder types: Other

Identifiers

NCT02440711

49150

Details and patient eligibility

About

The goal of this study is to evaluate endurance, walking performance, mobility, and perceived exertion of transtibial prosthesis users (i.e., study participants) walking with a conventional energy storing prosthetic foot (ESF) and a novel modified running-specific prosthesis (mRSF). A randomized cross-over study will be conducted to determine if the mRSF provides superior performance to the ESF, which is commonly prescribed to most active individuals with lower limb amputation.

Full description

Amputation of a limb is a life-altering event with profound physical, psychological, and social implications. To address their functional, vocational, and recreational needs, people with lower limb amputation (LLA) are often provided with a prosthesis or artificial leg. While use of a prosthesis can allow an individual to achieve a basic level of functional mobility, absence of an anatomical foot and ankle still impairs their physical performance. As a result, people with LLA regularly exhibit decreased walking speeds, diminished endurance, and restricted ability to participate in desired life situations.

Over the past three decades, increasingly sophisticated prosthetic foot designs have been developed by the prosthetics industry to replace amputated structures in the leg. Contemporary, energy storing feet (ESF) employ advanced materials and unique geometric designs to improve walking performance and endurance of their users. Although prosthetic limbs with ESF allow people with LLA the potential to return to an active lifestyle, even the most advanced ESF do not significantly reduce the increased energy demands required for walking when compared to conventional prosthetic feet.

Commercially-available running-specific feet (RSF) like the Össur Cheetah (Össur, Reykjavik, Iceland) allow people with LLA to participate in athletic activities and sporting events. RSF provide significantly enhanced performance, compared to traditional ESF, by extending the length and increasing the stiffness of the prosthetic keel (forefoot). RSF also do not include a heel, as they are used only for running activities. Although transtibial runners with RSF exhibit endurance levels similar to non-amputees, the RSF design does not allow the biomechanical movements or provide the stability needed to use the foot for walking (over level or uneven terrain).

A novel modified running-specific foot (mRSF) has been developed to integrate the performance of a RSF with the utility of an ESF. The mRSF combines the running keel (forefoot) of a RSF with the walking heel of a ESF. The mRSF can then be used for walking, running, and other routine daily activities. Preliminary feedback on the mRSF suggests that users experience improved overall function and high satisfaction with the device. However, empirical evidence is needed to support prescription of this prosthetic foot at other clinical facilities.

The goal of this study is therefore to evaluate endurance, walking performance, mobility, and perceived exertion of transtibial prosthesis users (i.e., study participants) walking with a conventional ESF and the mRSF. Results will be compared to determine if the mRSF provides superior performance to the ESF, which is commonly prescribed to most active individuals with LLA.

Enrollment: 36 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• unilateral or bilateral, transtibial (below-knee) amputation from non-dysvascular causes
• Medicare functional classification level (K-level) 3 or higher (unlimited community ambulatory)
• prosthetic user for > 1 year
• scheduled to receive a mRSF prosthesis
• able and willing to participate in the study protocol (e.g., treadmill walking, overground walking, respond to survey questions, able to read and write English)

Exclusion criteria

• contralateral lower or upper limb involvement
• any health condition that would limit participation in the study procedures (e.g., skin breakdown, heart disease)

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: None (Open label)

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36 participants in 2 patient groups

mRSF-ESF

Experimental group

Description:

Study participants in Arm 1 will first receive the Modified running specific foot (mRSF) and then the Energy storing foot (ESF). Outcomes will be assessed (in each condition) after 1 month of use. Order of interventions will be randomly assigned.

Treatment:

Device: Modified running specific foot (mRSF)

Device: Energy storing foot (ESF)

ESF-mRSF

Experimental group

Description:

Study participants in Arm 2 will first receive the Energy storing foot (ESF) and then the Modified running specific foot (mRSF). Outcomes will be assessed (in each condition) after 1 month of use. Order of interventions will be randomly assigned.

Treatment:

Device: Modified running specific foot (mRSF)

Device: Energy storing foot (ESF)