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

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

Interventions

OTHER

Gait analysis

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.

OTHER

Mapping of referred sensations.

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.

OTHER

Exploration of the areas of the brain activated during referred sensations

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.

OTHER

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

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

OTHER

Phantom limb interview

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.

Sponsors & Collaborators

• Clinique Chantecler

  collaborator UNKNOWN

• Centre Orthopédique Maguelone

  collaborator UNKNOWN

• Centre Helio Marin

  collaborator UNKNOWN

• Institut universitaire de réadaptation Valmante Sud

  collaborator UNKNOWN

• Institut des Sciences du Mouvement

  collaborator UNKNOWN

• Union de Gestion des Etablissements des Caisses d'Assurance Maladie - Nord Est

  lead OTHER

Principal Investigators

• Amelie A Touillet · Institut Régional de Médecine Physique et de Réadaptation

Study Design

Allocation

NON_RANDOMIZED

Purpose

HEALTH_SERVICES_RESEARCH

Masking

NONE

Model

SEQUENTIAL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2024-09-16

Primary Completion

2028-09-30

Completion

2030-09-30

Countries

• France

Study Locations