Powered Prosthetics for Knee Amputations

Overseen By Levi Hargrove, PhD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Shirley Ryan AbilityLab

Disqualifiers: Weight over 250 pounds, cognitive impairment, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 1 Jurisdiction This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 27

20 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how powered prosthetics can improve walking for individuals with above-knee amputations. Researchers aim to determine if adding power to the knee, the ankle, or both can enhance walking ease and efficiency. Participants will test various prosthetic combinations, including the SRALab Hybrid Knee and SRALab Polycentric Powered Ankle, and receive training to identify the most effective option. Ideal candidates have a transfemoral amputation (above the knee), have used a prosthetic leg for at least six months, and can walk 50 meters unaided.

As an unphased trial, this study allows participants to contribute to innovative research that could enhance mobility for many.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. Please consult with the study team or your doctor for guidance.

What prior data suggests that these powered prosthetics are safe for transfemoral amputees?

Research has shown that powered prosthetic devices, such as the SRALab Hybrid Knee and SRALab Polycentric Powered Ankle, are generally easy for users to handle. In studies where participants tried these devices, researchers found no major safety issues. For instance, one study with a 70-year-old man who had a leg amputation demonstrated that he could use these devices effectively after some training. This suggests they can be safe and manageable with proper guidance.

These devices are part of research aimed at improving walking for people with above-knee amputations. They are not yet approved for widespread use, so researchers continue to closely monitor safety. While some minor discomfort or adjustment issues might occur, major problems are not commonly reported. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the SRALab Hybrid Knee and SRALab Polycentric Powered Ankle because these devices offer dynamic, powered support that closely mimics natural leg movement, unlike current prosthetic options like the Ottobock C-Leg, which primarily offer passive support. The Hybrid Knee's advanced microprocessor technology adjusts in real-time to the user's movement, providing smoother transitions and more natural walking patterns. Meanwhile, the Polycentric Powered Ankle enhances stability and adaptability across various terrains, potentially improving balance and reducing the effort required for walking. These innovations aim to empower users with greater mobility and independence, sparking hope for a significant leap in quality of life for those with knee amputations.

What evidence suggests that these prosthetic devices are effective for improving ambulation in knee amputees?

This trial will evaluate the effectiveness of powered prosthetics, such as the SRALab Hybrid Knee and SRALab Polycentric Powered Ankle, for individuals with knee amputations. Research has shown that these powered prosthetics can greatly improve walking compared to non-powered prosthetics. Participants will be assigned to different arms, receiving either the SRALab devices or other prosthetic combinations like the Ottobock Cleg4 and foot. These devices add strength to the missing joints, helping users walk more naturally and efficiently. Early results suggest that powering both the knee and ankle might further boost walking ability. With focused training on these powered devices, users may experience even greater improvements, leading to better mobility in everyday life. ^{1 3 5 6 7}

Are You a Good Fit for This Trial?

This trial is for K2-level transfemoral amputees, meaning individuals who have had an above-knee amputation and can walk with a cane or crutches. The study aims to understand the impact of powered prosthetic knees and ankles on their walking ability.

Inclusion Criteria

It has been over 6 months since I got my final prosthesis.

I have had one leg amputated above the knee.

Medically cleared by physician to participate in study

Exclusion Criteria

I understand and can follow the study's requirements.

Significant new injury that would prevent use of a prosthesis

Significant other comorbidity

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Baseline Assessment

Baseline data collection with Ottobock Cleg 4/Ottobock foot or clinically prescribed microprocessor knee unit/foot

1 week

1 visit (in-person)

Condition A: CLeg + Polycentric Ankle

Participants are fit with the CLeg + Polycentric Ankle and undergo device tuning and functional outcome assessments

3 weeks

4 visits (in-person)

Condition B: SRALab Hybrid Knee + Passive Ankle

Participants switch to SRALab Hybrid Knee + Passive Ankle and repeat the protocol for device tuning and assessments

3 weeks

4 visits (in-person)

Intensive Training

Participants receive intensive clinical training with the SRALab Hybrid Knee + Polycentric Ankle

8 weeks

16 visits (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

2 visits (in-person)

What Are the Treatments Tested in This Trial?

Interventions

• SRALab Hybrid Knee and SRALab Polycentric Powered Ankle

Trial Overview

The study compares different combinations of prosthetic limbs: a passive microprocessor knee (Ottobock CLeg4) with either an Ottobock foot or polycentric ankle, and a powered knee (SRALAB Hybrid Knee) with either a passive or polycentric powered ankle.

How Is the Trial Designed?

Group I: Transfemoral Amputee participants: SRALAB Hybrid knee + Polycentric Ankle, Ottobock Cleg4 + OB foot Experimental Treatment 2 Interventions

During this arm, participants will receive intensive clinical training with the SRALAB Hybrid knee + Polycentric Ankle twice per week over 8 weeks, lasting 2-3 hours. Training will include patient-driven therapy to achieve participants' individual therapy goals, functional mobility and community skills. At the end of the 8-week training period, subjects will complete the same set of functional outcome measures, biomechanical and metabolic assessments in previous arms. To complete this arm, participants will again complete training and outcome measures with the Ottobock Cleg4/Ottobock or their clinically prescribed microprocessor knee unit/foot over 3 visits.

Group II: Transfemoral Amputee participants: Ottobock CLeg4 + Polycentric Ankle, Hybrid Knee + Passive Ankle Experimental Treatment 2 Interventions

For this arm, transfemoral amputees will participate in an AB/BA randomized crossover study. Before each arm of the cross-over, baseline data will be taken with the Ottobock Cleg 4/Ottobock foot or their clinically prescribed microprocessor knee unit/foot. Condition A is CLeg + Polycentric Ankle Condition B is SRALab Hybrid knee + Passive Ankle Subjects will participate in 2 sessions over 2 weeks, each lasting 2-3 hours to have the device tuned for the specific condition (A or B). On the third week, they will participate in 2 visits to complete functional outcome measures, biomechanical and metabolic assessments. They will then switch conditions, and repeat the protocol for the second condition. There will not be a washout period between conditions, but subjects will complete outcome measures with the Ottobock Cleg 4/Ottobock foot or their clinically prescribed microprocessor knee unit/foot prior to each arm of the crossover to obtain baseline data.

Group III: Transfemoral Amputee participants: Ottobock Cleg4 + Ottobock foot; Hybrid Knee + Polycentric Ankle Active Control 2 Interventions

Participant is fit with the commercially available device (Ottobock Cleg 4/Ottobock foot), they will receive standard of care clinical training for 3-4 sessions over 4 weeks, plus 1 session for outcome assessments. Participant is then fit with the SRALAB Hybrid knee and SRALAB Polycentric Ankle prosthesis, they again will receive clinical training for 3-4 sessions over 4 weeks, plus 1 session for outcome assessments.

SRALab Hybrid Knee and SRALab Polycentric Powered Ankle is already approved in United States for the following indications:

Approved in United States as SRALab Hybrid Knee and SRALab Polycentric Powered Ankle for:

• Transfemoral amputation for K2 level ambulators

Who Is Running the Clinical Trial?

Shirley Ryan AbilityLab

Lead Sponsor

Trials

212

Recruited

17,900+

Published Research Related to This Trial

In a study involving 20 male above-knee amputees fitted with a new UCBL four-bar polycentric knee prosthesis, 16 participants reported benefits from the device, with 7 considering it superior to their previous prosthetics after an average follow-up of 12.3 months.

Most subjects experienced maintained or enhanced functionality, particularly noting improved ease of walking on inclines and increased knee flexion, although some initial mechanical issues were resolved during the study.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Subjective evaluation of the UCBL polycentric knee linkage by active above knee amputees. A prospective trial. Jergesen, HE., Hoaglund, FT., Roberts, RA.[2022]

Three service members with unilateral transfemoral limb loss quickly became proficient with a powered knee-ankle (PKA) prosthesis after just three training sessions, indicating that the device can be effectively learned in a short time frame.

While the PKA prosthesis showed a 4% lower cost of transport at slower speeds, it resulted in greater compensatory movements (like trunk flexion and rotation) compared to standard prostheses, highlighting the need for tailored training to optimize functional outcomes for different populations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Functional Performance Outcomes of a Powered Knee-Ankle Prosthesis in Service Members With Unilateral Transfemoral Limb Loss. Knight, AD., Jayaraman, C., Elrod, JM., et al.[2023]

The Power Knee (PK) prosthetic knee unit generates more power during stair descent compared to the C-Leg, potentially reducing the strain on the nondisabled limb during these activities.

While the PK helps lessen the power needed from the nondisabled knee during stair climbing, it does not outperform the C-Leg in other tasks, indicating that further improvements are needed for optimal function.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Assessment of transfemoral amputees using C-Leg and Power Knee for ascending and descending inclines and steps. Wolf, EJ., Everding, VQ., Linberg, AL., et al.[2019]

Bone-anchored implants are becoming a promising solution for lower-limb amputees, offering significant improvements in function and quality of life, despite concerns about high infection rates.

Emerging technologies like targeted muscle innervation (TMR) and regenerative peripheral nerve interfaces (RPNI) show potential benefits and should be integrated into clinical practices, while increased funding for prosthetic research could enhance the development of effective microprocessor-controlled devices.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Advanced techniques in amputation surgery and prosthetic technology in the lower extremity. Hobusch, GM., Döring, K., Brånemark, R., et al.[2020]

The study developed a new method for configuring powered knee and ankle prostheses that significantly reduces the time needed to set them up for different walking modes, cutting the initial accommodation period by 56% to under 5 hours.

By using modified intrinsic control strategies, only 17% of the configuration parameters needed adjustment for novice users, making it easier for amputees to transition to using these advanced prosthetic devices.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Configuring a powered knee and ankle prosthesis for transfemoral amputees within five specific ambulation modes. Simon, AM., Ingraham, KA., Fey, NP., et al.[2022]

Microprocessor-controlled prosthetic knees (MPKs) can significantly reduce uncontrolled falls by up to 80% and improve fall risk indicators for individuals with transfemoral amputation classified as MFCL-2, based on a review of six studies involving 57 subjects.

Users of MPKs may experience improved walking speeds, with a 14% to 25% increase on level ground, a 20% increase on uneven surfaces, and a nearly 30% faster descent on slopes, suggesting enhanced mobility and safety for limited community ambulators.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Benefits of microprocessor-controlled prosthetic knees to limited community ambulators: systematic review. Kannenberg, A., Zacharias, B., Pröbsting, E.[2022]

In a study involving eight transfemoral amputees, the C-Leg microprocessor-controlled knee did not significantly reduce oxygen cost compared to the Mauch SNS knee at various walking speeds, indicating similar efficiency in terms of energy expenditure.

However, participants walked faster at their self-selected walking speed with the C-Leg compared to the Mauch SNS, suggesting that while the C-Leg may not improve overall energy efficiency, it allows for a more comfortable and faster walking pace without increasing oxygen consumption.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Gait efficiency using the C-Leg. Orendurff, MS., Segal, AD., Klute, GK., et al.[2022]

In a study comparing prosthetic knee systems for U.S. military service members with transfemoral amputations, the Power Knee™ (PK) showed greater peak knee power in the amputated limb during sit-to-stand tasks compared to the C-Leg, suggesting enhanced performance for PK users.

Despite the differences in knee power, both prosthetic systems resulted in greater forces on the intact limb, indicating that while PK may improve certain tasks, it does not significantly reduce impact on the remaining joints compared to the C-Leg.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Comparison of the Power Knee and C-Leg during step-up and sit-to-stand tasks. Wolf, EJ., Everding, VQ., Linberg, AA., et al.[2022]

A case study demonstrated that lightweight powered knee and ankle prostheses can effectively restore natural leg movements for individuals with bilateral above-knee amputations, allowing them to walk and climb stairs with improved gait patterns.

The powered prostheses were able to replicate essential biomechanical functions, such as ankle push-off during walking and knee power generation during stair ascent, which are crucial for enhancing mobility and quality of life.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Powered knee and ankle prostheses enable natural ambulation on level ground and stairs for individuals with bilateral above-knee amputation: a case study. Hood, S., Creveling, S., Gabert, L., et al.[2023]

Advancements in prosthetic technology over the past 15 years have significantly improved the performance of athletes with lower-limb amputations, particularly through the use of dynamic carbon prosthetic feet that enhance sprinting capabilities.

The running gait of athletes with trans-tibial amputation is nearly symmetrical, but those with trans-femoral amputation experience more asymmetry due to the lack of a knee joint, which affects their overall propulsion and load distribution during running.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Evolution in prostheses for sprinters with lower-limb amputation]. Pailler, D., Sautreuil, P., Piera, JB., et al.[2022]

In a clinical trial involving 20 active above-knee amputees, 80% reported positive experiences with the UCBL four-bar polycentric prosthetic knee, with over one-third finding it superior to previous devices.

The prosthetic knee allowed for increased knee flexion, helping to maintain or enhance daily activity levels without significantly altering fundamental gait parameters, indicating its potential effectiveness and safety for users.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The University of California Biomechanics Laboratory four-bar polycentric knee linkage. A clinical trial in 20 active above-knee amputees. Jergesen, HE., Hoaglund, FT., Roberts, RA., et al.[2022]

Citations

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Powered Prosthetics for Knee Amputations

What data supports the effectiveness of the treatment SRALab Hybrid Knee and SRALab Polycentric Powered Ankle for knee amputations? Research on similar ...

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Understanding How Powered Componentry Impacts K2-Level ...

The goal of this study is to understand how providing power at the knee or ankle individually, or providing power at both the knee and ankle, ...

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Amputation Clinical Trials - Policy Lab

A listing of 39 Amputation clinical trials actively recruiting volunteers for paid trials and research studies in various therapeutic areas.

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Evaluation of a Lightweight Powered Leg

We have designed a lightweight powered leg with innovative knee and ankle designs that significantly reduce weight and noise while providing necessary power ...

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frontiersin.org

frontiersin.org/journals/rehabilitation-sciences/articles/10.3389/fresc.2023.1203545/full

Powered knee and ankle prosthesis use with a K2 level ...

Powered prosthetic knees and ankles have the capability of restoring power to the missing joints and potential to provide increased functional mobility to ...

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pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC10300561/

Powered knee and ankle prosthesis use with a K2 level ...

We trained a 70 year old male participant with a unilateral transfemoral amputation to use a powered knee and powered ankle prosthesis.

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sralab.org

sralab.org/clinical-trials/limb-loss-impairment/intuitive-control-hybrid-prosthetic-leg-during-ambulation

Intuitive Control of a Hybrid Prosthetic Leg During Ambulation

The objective of this research is to determine the clinical benefits of an innovative and lightweight powered leg controlled using our intent recognition ...