Uses of Phantom Sensations Induced by Global and Local Modifications of the Prosthetic Socket as Somatosensory Feedback During Walking in Lower Limb Amputees

NCT07191795 | Recruiting DMC

• 2 other identifiers: 2022-A01647-36ANR-23-CE17-0067-02
• Study Type: interventional
• Target: 228
• Locations: 1 country
• Sites: 1

Brief Summary

Following lower-limb amputation, the loss of somatosensory information from the missing limb renders walking less automatic, more cognitively demanding, and often asymmetric, which can lead to secondary pathologies. Hypothesis: This study is based on the hypothesis that phantom limb sensations (PLS), when coherent with the prosthetic device's movements and the phases of the gait cycle, can compensate for the loss of somatosensory feedback and thereby improve locomotion for individuals with amputation. It is further hypothesized that it is possible to artificially induce these coherent and useful sensations, notably through "referred sensations" elicited by stimulation of the residual limb (e.g., via the prosthetic socket). Objectives: The project aims to:

• Determine whether the natural presence of phantom limb sensations during walking impacts gait parameters.
• Confirm in a larger patient population that modifications to the prosthetic socket can induce or enhance phantom sensations that are perceived as useful for walking.
• Investigate whether these perceptual changes (induced or enhanced) are associated with objective, measurable improvements in gait quality.

Conditions

Lower Limb Amputation

Keywords

Phantom Limb Sensation; Referred Sensation; Somatosensory Feedback; Lower Limb Prosthesis; Prosthetic Gait

Outcome Measures

Primary Outcomes (8)

• Characterization of phantom limb sensations

  A composite assessment of phantom limb sensations will be conducted via a semi-structured interview. Data collected will include: * Type of sensation (e.g., tingling, pain, movement). * Location (toes, heel, calf). * Intensity (Mild, Strong, Very Strong).

  The first day of the study

• Walking speed under laboratory conditions

  The participant's average walking speed, measured in meters per second (m/s). The measurement will be collected using inertial measurement units (IMUs) and/or a Vicon motion capture system while the participant walks on hard ground or on a treadmill at their self-selected speed.

  The first day of the study for the control group and the second day of the study for participants with amputation

• Step length symmetry index.

  Gait symmetry will be calculated based on the stride length of the affected (or corresponding) limb and the healthy limb. The symmetry index is a unitless ratio (or percentage) that quantifies the difference between the two limbs. A value of 1 (or 100%) indicates perfect symmetry. Measured using inertial measurement units or the Vicon system.

  The first day of the study for the control group and the second day of the study for participants with amputation

• Changes in the surface area of sensory maps referred to the residual limb

  The total surface area capable of triggering phantom sensations will be measured. For each type of stimulation (brush, pressure, point, electrical), the number of 3x3 cm areas causing a sensation will be counted. The total surface area (in cm²) will be calculated by multiplying this number by 9. A map will be generated for each stimulation modality.

  2nd or 3rd day of the study depending on whether the participant with an amputation was included in phase 2 or not and during the 6-month follow-up visit.

• Change in the average intensity of reported phantom sensations.

  When each reactive area is stimulated, the participant will rate the intensity of the phantom sensation perceived on a 6-point Numerical Rating Scale (NRS), ranging from 0 (no sensation) to 5 (maximum intensity imaginable). The average intensity of the reactive areas will be calculated for each type of stimulation.

  2nd or 3rd day of the study depending on whether the participant with an amputation was included in phase 2 or not and during the 6-month follow-up visit.

• Localization of the cortical source of somatosensory evoked potentials (SEPs) during stimulation of referred sensation areas

  The recorded EEG activity will be used to model and locate the source of the maximum cortical response. The primary outcome measure will be the coordinates (e.g., in the MNI or Talairach atlas) of the center of activation in the somatosensory cortex. The objective is to compare the source localization obtained during ecological gait after each demanding walking situation.

  The second day of the study for participants with amputation

• Participant's subjective preference for one of the four socket conditions tested.

  At the end of the four test sessions, participants will be asked to rank the four conditions (rigidity A/B, with/without focal pressure) from most to least conducive to walking. The primary outcome will be the condition ranked first by the largest number of participants.

  Day 7 of the study

• Change in the spatiotemporal parameters of walking in ecological situations

  Several key walking parameters (speed in m/s, cadence in steps/min, step symmetry index) will be measured using inertial sensors during the outdoor walk. The analysis will compare the average values of these parameters between the four socket conditions.

  Days 4 to 7 to the study

Secondary Outcomes (12)

• Walking pace under laboratory conditions

  The first day of the study for the control group and the second day of the study for participants with amputation

• Analysis of muscle co-activation in the lower limbs and trunk during walking.

  The first day of the study for the control group and the second day of the study for participants with amputation

• Maximum vertical reaction force during walking.

  The first day of the study for the control group and the second day of the study for participants with amputation

• Assessment of mental workload during walking using the NASA-TLX questionnaire

  The first day of the study for the control group and the second day of the study for participants with amputation

• Analysis of brain activity related to cognitive load during walking

  The second day of the study for participants with amputation

Study Arms (3)

TT

EXPERIMENTAL

People with transtibial amputation

Other: Gait analysis; Other: Mapping of referred sensations.; Other: Phantom limb interview

TF

EXPERIMENTAL

People with transfemoral amputation

Other: Gait analysis; Other: Mapping of referred sensations.; Other: Exploration of the areas of the brain activated during referred sensations; Other: Evaluation of the effects of socket modifications on phantom sensations and walking; Other: Phantom limb interview

Control

EXPERIMENTAL

Asymptomatic people

Other: Gait analysis; Other: Exploration of the areas of the brain activated during referred sensations

Interventions

Gait analysis OTHER

Participants with unilateral amputations and a control group will undergo a comprehensive walking analysis. In a lab setting (on a treadmill or floor), their gait will be recorded using inertial sensors, EMG, force plates, and motion capture, while an EEG cap and a NASA-TLX questionnaire will assess cognitive load. Capable participants will also perform a walking test on a real-world outdoor course with varied terrain. The data will be analyzed to compare walking patterns between groups (amputees vs. controls, and amputees with vs. without phantom limbs). Finally, participants will describe any interactions they perceived between their phantom sensations and walking during the tests.

Control; TF; TT

Mapping of referred sensations. OTHER

Participants reporting referred sensations in gait analysis phase will undergo further testing. The study will investigate whether prosthesis pressure or a specific socket interaction causes these sensations. A 3x3 cm grid will be drawn on the residual limb to systematically map referred sensations using various stimuli (brush, pressure tip, electrical stimulation). Participants will rate the intensity and describe the location of any resulting phantom sensations. This mapping will be repeated after 6 months to assess the stability of these sensations over time, with the ultimate goal of potentially using them to provide sensory feedback for prosthesis users. The session will last approximately 2 hours.

TF; TT

Exploration of the areas of the brain activated during referred sensations OTHER

Unilateral transfemoral amputees with detailed referred sensation maps will have their brain activity recorded using a 64-electrode EEG cap. Non-invasive stimuli will be applied to four specific sites: an area on the residual limb that elicits a referred sensation, the corresponding location on the intact foot, a neutral area on the residual limb, and its corresponding location on the intact thigh. This process, involving 400 total stimulations, will be repeated after 6 months to track cortical changes. Non-amputee participants will also be tested as a control group to check for symmetry in brain responses to thigh stimulation. Each session lasts about 2 hours.

Control; TF

Evaluation of the effects of socket modifications on phantom sensations and walking OTHER

This phase will evaluate how socket modifications affect phantom sensations and walking in 10 transfemoral amputees. First, the best material to comfortably induce referred sensations will be determined in a small sub-study. Then, each participant will be tested under four conditions: their usual socket and a socket with different rigidity, both with and without a specific local pressure point added inside. The location of this pressure point is based on the user's sensation map. Participants' walking will be analyzed in both lab and real-world environments for each condition, and they will provide feedback on their sensations and which setup they find most helpful. The evaluation involves 4 sessions over 2-3 months

TF

Phantom limb interview OTHER

A semi-structured interview will be conducted to ask participants to describe their phantom limb sensations (type, location, intensity) under three conditions: without their prosthesis, while standing with it, and while walking with it. This aims to identify factors influencing these sensations. Additionally, a brief physical examination of the residual limb will be performed to see if touch in specific areas triggers any referred sensations.

TF; TT

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Participants with amputations:
• Major lower limb amputation
• Understand and be able to express oneself in the French language (for semi-structured interviews)
• Affiliated with a social security scheme
• Asymptomatic volunteer participants:
• No major surgery on the lower limbs for at least 3 years
• No minor injury to the trunk, lower or upper limbs that could influence walking for at least 1 year
• Understand and be able to express oneself in the French language
• Affiliated with a social security scheme

You may not qualify if:

• History of psychiatric disorders
• Pregnant or breastfeeding woman
• Minor
• Adult subject to a legal protection measure
• Person under guardianship or conservatorship
• Person under a judicial protection order
• Pain affecting walking (trunk, residual limb, phantom limb, contralateral limb)
• Medical treatment incompatible with walking

Sponsors & Collaborators

• Union de Gestion des Etablissements des Caisses d'Assurance Maladie - Nord Est: lead
• Clinique Chantecler: collaborator
• Centre Orthopédique Maguelone: collaborator
• Centre Helio Marin: collaborator
• Institut universitaire de réadaptation Valmante Sud: collaborator
• Institut des Sciences du Mouvement: collaborator

Study Sites (1)

Institut Régional de Médecine Physique et de Réadaptation

Nancy, 54000, France

RECRUITING

MeSH Terms

Interventions

Gait Analysis; Walking

Intervention Hierarchy (Ancestors)

Gait; Physical Examination; Diagnostic Techniques and Procedures; Diagnosis; Physical Functional Performance; Physical Fitness; Health; Population Characteristics; Locomotion; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Exercise; Motor Activity

Study Officials

• Amelie A Touillet

  Institut Régional de Médecine Physique et de Réadaptation

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Jonathan J Pierret, PhD

CONTACT

+33383526761; jonathan.pierret@ugecam.assurance-maladie.fr

Christelle C Requena

CONTACT

christelle.requena@ugecam.assurance-maladie.fr

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: HEALTH SERVICES RESEARCH
• Intervention Model: SEQUENTIAL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 21, 2025
• First Posted: September 25, 2025
• Study Start: September 16, 2024
• Primary Completion (Estimated): September 30, 2028
• Study Completion (Estimated): September 30, 2030
• Last Updated: September 25, 2025

Record last verified: 2025-09

Locations

FR (1)