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NCT Number: NCT07831707

The Role of Visual Attention and Environmental Complexity in Real-world Mobility for People With Lower Limb Amputation

Despite high medical expenses (>$500K/patient), mobility improvements achieved during rehabilitation for people with lower limb amputation (LLA) fail to translate into improved real-world outcomes. Even with advances in prosthesis technology enabling faster gait speed, greater walking endurance, and improved mobility confidence, people with LLA report persistent dissatisfaction with real-world mobility, limited ability to walk in the community, and difficulty achieving recommended physical activity levels.

Real-world walking requires thinking and moving simultaneously (e.g., cognitive-motor dual-tasking), visually attending to the environment, and navigating varying terrain. In contrast, clinical mobility assessments are usually performed without additional visual or cognitive demands, in controlled environments, and on level surfaces. Current clinical tools used to assess ambulation progression during rehabilitation do not adequately assess these changes in people who have experienced LLA.

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Key information

Conditions

Lower Limb Amputation

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Virginia Commonwealth University

Richmond, Virginia, 23239, United States

Location status: Recruiting

Location contact

Paul Kline

CONTACT

[email protected]

804-828-4483

Paul Kline

PRINCIPAL_INVESTIGATOR

About this study

A step toward rectifying a critical gap in care for those with LLA by quantifying the effect of vision-based and non-vision-based cognitive-motor dual-tasking and high and low complexity terrain on gait speed and gaze behavior. Cognitive-motor dual-task assessment paradigms are well-established in other populations and often used to better approximate real-world walking demands. However, the type of cognitive task used is an important factor. The most common methods for dual-task assessment in people with LLA are limited to cognitive tasks lacking overt visual attention (e.g., serial subtraction - performing repeated subtractions from a given starting number).Although walking while performing non-vision-based cognitive tasks results in slower gait speed than single-task walking, this type of task has limited ecological validity and the observed dual-task performances have not been associated with real-world walking outcomes.

Performing vision-based cognitive-motor dual-tasks is particularly important for people with LLA. Due to lost somatosensory input from the amputated limb, the central nervous system increases dependence on visual input for sensorimotor integration. As a result, people with LLA report needing to "concentrate on every step", and affix their gaze on each subsequent step compared to 3 steps ahead like adults without LLA.

Current clinical assessments fail to detect impairments during mobility tasks requiring visual attention in complex environments. The lack of understanding of the interaction between visual attention and complex environment precludes a comprehensive mobility assessment, allows undetected impairments to persist, and limits translation of rehabilitation gains into improved real-world mobility outcomes.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • unilateral transtibial LLA of either dysvascular (diabetes, peripheral vascular disease, and/or infection) or traumatic etiology
  • 18 years old minimum
  • able to ambulate 2 minutes without rest
  • 9 months since LLA
  • fitted with terminal prosthesis
  • 20/60 vision or better (with or without glasses/contacts)

Exclusion criteria

  • congenital or cancer-related LLA
  • ankle-level or above LLA on the contralateral limb
  • residual limb wound or contralateral foot ulcer
  • unstable heart condition (including unstable angina, uncontrolled cardiac dysrhythmia, acute myocarditis, hypertension, and acute pericarditis)
  • acute systemic infection
  • prisoner
  • inability to follow a 3-step command
  • concussion/brain injury in the past 12 months
  • active cancer treatment
  • preexisting neurological condition (i.e., multiple sclerosis, Parkinson's disease)
  • participating in prosthetic rehabilitation
  • color-blindness
  • history of seizure(s)
  • inability to read and communicate in English.

Participants in the control group must meet the non-amputation-related criteria noted above, be within ±2 years and the same biological sex as their paired participants with LLA.

Treatment and study plan

Comprehensive assessment of walking patterns and functional mobility

Other

Assessment of accelerometry: Daily duration (minutes) of sitting, standing, stepping, Daily step count, Daily walking bouts stepping cadence, Timed Up and Go and Two-minute Walk Test

Comprehensive assessment of eye movements during walking

Other

Comprehensive assessment of eye movements during walking including Target Fixation Time (seconds; %) and Number of fixations

Questionnaire Assessments completed

Other

The following assessments will be completed: World health organization disability assessment schedule 2.0 (WHODAS), and Activities Specific Balance Confidence Scale.

Primary outcomes

  1. Gait Analysis-Walking Speed

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Measure walking speed meters/second. Captured during dual-task and single-task walking, it is used to measure motor performance. Normal Speed: Healthy adults usually walk at 1.2 to 1.4 meters per second.Fall Risk: A speed below 1.0 meter per second shows a higher risk for falls.Frailty Warning: A speed below 0.6 to 0.8 meters per second suggests a high risk of functional decline or disability.

  2. Gait Analysis-Stride Length

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Measure the stride length in meters. stride length is the total distance covered during one full cycle of walking or running with the same foot. It measures the space from where one foot touches the ground to when that exact same foot touches the ground again.

  3. Gait Analysis-Stride length asymmetry

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Assess Stride length asymmetry is an imbalance where the distance covered by the right and left steps differs. Symmetry Index (SI): Compares spatial step metrics or temporal single-limb support times between limbs.Percentage difference: Calculated by contrasting mean left and right step values; values exceeding 10% typically indicate notable dysfunction.

  4. Cognitive Task Performance Cognitive Task Performance

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Accuracy (percentage correct) of each cognitive task. This reflects cognitive performance and is measured in both dual-task and single-task conditions.

  5. Cognitive Task Performance

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Measure Response time (milliseconds)

  6. Functional Mobility (Two-minute Walk Test)

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Two-minute Walk Test measures the total distance a person can walk on a flat, hard surface within two minutes. It evaluates functional mobility, submaximal endurance, and self-paced walking capacity in adults. Recorded to the nearest meter or foot using a measuring wheel, and lap count.

  7. Functional Mobility (Timed Up and Go)

    Time frame: Visit 1

    Timed Up and Go (TUG) test measures functional mobility, dynamic balance, and fall risk by timing how fast a person stands from a chair, walks 3 meters (10 feet), turns around, walks back, and sits down. Under 10-12 seconds: Normal, independent mobility with low fall risk.12-20 seconds: Moderate risk of falling or subtle mobility issues; requires further evaluation.Over 14-20 seconds: High risk for falls; often indicates difficulty moving outside alone or a need for assistive devices.

  8. Eye Tracking (Target Fixation Time)

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Target Fixation Time (seconds; %), The length of time the eye remains relatively still on a target to process detail, reflecting visual attention.

  9. Eye Tracking (Number of fixations)

    Time frame: Visit 1 and visit 2 (which will take place 10-14 days after visit 1)

    Number of fixations is a core metric measuring how many times a person's eyes pause and focus on a specific area or object. High Fixation Count: indicates frequent attention on an area or element. Low Fixation Count: Means an element was quickly passed over, easily understood, or ignored.

  10. Patient Reported Outcomes (Houghton Scale)

    Time frame: Visit 1

    The Houghton Scale assesses a person's confidence and ability in using their prosthesis safely and effectively during everyday mobility tasks. The Houghton Scale is a self-administered, 4-item questionnaire used to assess the functional use of a prosthesis by individuals with lower-limb amputations.It measures how often a patient wears their prosthesis, the types of activities they perform with it, and their perceived stability in various outdoor environments. Total scores range from 0 to 12, with higher scores indicating greater prosthesis use and independence

  11. Patient Reported Outcomes (PEQ - Mobility subscale)

    Time frame: Visit 1

    PEQ - Mobility subscale is the The Prosthesis Evaluation Questionnaire - Mobility subscale, captures a person's self reported ability to move and perform daily activities while using their prosthesis. It uses a 5-point ordinal scale (0-4). 0: Not able or hardly able to 4: No problem or almost fully able. The total scale ranges from 0 to 48. A higher score indicates greater mobility.

  12. Patient Reported Outcomes (WHODAS)

    Time frame: Visit 1

    WHODAS The World health organization disability assessment schedule 2.0 (WHODAS) evaluates how health conditions impact a person's functioning and participation across major life domains over the past 30 days. Items are rated on a 5-point Likert scale: None (0), Mild (1), Moderate (2), Severe (3), and Extreme or Cannot Do (4). While no universal "cut-off" exists, scores placing a patient in the top 10% of the population distribution-roughly >10 for the 12-item simple score or >41 for the 36-item version-likely indicate significant impairment.

  13. Patient Reported Outcomes (Activities Specific Balance Confidence Scale)

    Time frame: Visit 1

    Activities Specific Balance Confidence Scale is a self-report instrument used to measure an individual's confidence in maintaining balance while performing 16 various daily activities. Unlike performance-based tests, it captures the patient's perceived ability to avoid falling or becoming unsteady.Patients rate their confidence for each item on a scale from 0% (no confidence) to 100% (complete confidence). The higher the score,the higher the function and physical activity (range > 80% high function, 50% - 80% moderate function and < 50% low function.

  14. Accelerometry (Daily duration of sitting, standing, stepping)

    Time frame: Between Visit 1 and 2 (which is 10-14 days after visit 1)

    Daily duration (minutes) of sitting, standing, and stepping reported as an aggregate mean.

  15. Accelerometry (Daily step count)

    Time frame: Between Visit 1 and 2 (which is 10-14 days after visit 1)

    Daily step count will be measured and reported as an aggregate mean.

  16. Accelerometry (Daily walking bouts stepping cadence)

    Time frame: Between Visit 1 and 2 (which is 10-14 days after visit 1)

    Daily walking bouts stepping cadence will be reported as an aggregate mean

Study contacts

Contact information is provided by the study sponsor or research team.

Paul Kline

CONTACT

[email protected]

804-828-4483

Sponsors and collaborators

Lead sponsor

Virginia Commonwealth University

Other

Registry information

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Sep 21, 2026
Registry last updated
Sep 21, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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