Quantification of Motor Compensation Following Biomechanical, Proprioceptive and Physiological Alterations Post-lower Limb Amputation.

Lower limb amputation causes segmental loss that alters locomotor organization. The human body, designed to function in a multisegmental manner, must adapt to this new configuration where segments are missing, depending on the level of amputation. These adaptations are directly linked to the biomechanical, physiological and proprioceptive alterations caused by the loss of the amputated segments. Without mechanoreceptive afferents essential for regulating locomotion, the sensory system uses alternative information to maintain efficient locomotor function. The prosthesis partially compensates, but remains limited on the biomechanical and proprioceptive levels. Current prosthetic technologies, inspired by biomimicry, aim to imitate evolutionary solutions to restore walking, although current algorithms do not allow real-time modulation. This research aims to characterize post-amputation locomotor adaptations through biomechanical, physiological and proprioceptive exploration to develop a "locomotor characterization" model.

The study authors hypothesize that the post-amputation alterations are exacerbated in contexts of continuous and discontinuous constraints (e.g., ascent/descent and destabilization), and that the addition of a prosthesis, although inspired by biomimicry, only restores partial compensation of locomotor functions.


Eligibility Criteria:
Inclusion Criteria:

* The patient must have given their free and informed consent and signed the consent form
* The patient must be a member or beneficiary of a health insurance plan
* Persons with unilateral transtibial or transfemoral amputees followed in the MPR department at the Nîmes University Hospital, RRL department, Grau du Roi University Rehabilitation Hospital.
* All etiologies: vascular, traumatic and septic.
* Adapted equipment validated by the rehabilitation doctor.
* Able to walk for 5 minutes on a treadmill without technical assistance

Inclusion criteria specific to healthy volunteers:

* Adults (\>18 years old) and under 40 years old
* Able to walk for 5 minutes on a treadmill without technical assistance.
* Body mass index between 18 and 25

Exclusion Criteria:

* The patient is participating in an interventional or a drug/medical device study, or is in a period of exclusion determined by a previous study
* The patient unable to express consent
* It is impossible to give the patient informed information
* The patient is under safeguard of justice or state guardianship
* Patient who has already been included in this study.
* Pregnant, parturient or breastfeeding patient.
* Appearance of a stump wound during the study requiring unloading.
* Patient for whom the implementation of vibration stimulation is not possible

Exclusion criteria for amputee patients:

* Patient suffering from uncorrected or untreated visual disorders.
* Patient with major cognitive disorders (MoCA \<23).
* Patient with vestibular disorders or uncontrolled epilepsy.
* Patient with an unhealed amputation stump.
* Patient with a weight \> 135kg or \< 20kg
* Patients with a FAC of 1 (i.e. patients who need firm and continuous assistance from a person to support their weight and maintain balance) or less.
* Sensory impairment that makes it impossible to perceive stimulation
* Significantly reduced bone density
* Patient in whom it is impossible to correctly adjust the GRAIL System harness to the corresponding body part due to:

  * Body shape
  * Colostomy bags
  * Skin lesions that cannot be adequately protected.
  * Any other reason that prevents a good, painless adjustment of the harness.
* Patient in whom it is impossible to correctly adjust the CON-TREX System:

  * Body shape
  * Colostomy bags
  * Skin lesions that cannot be adequately protected.
  * Any other reason that prevents a good, painless adjustment of the support systems.

Exclusion criteria for healthy volunteers:

* History of significant injury or surgery affecting the lower limbs (such as hip or knee replacement or knee/ankle ligament reconstruction) that could impact walking
* History of neurological or psychiatric disorders that could affect locomotion or the processing of sensorimotor information.
* Drug treatments affecting locomotion: drugs likely to alter walking or balance, such as sedatives, muscle relaxants or neuroleptics.