Effect of the Atalante Exoskeleton on Standing and Walking in Individuals With Paraplegia: A Prospective Controlled-Environment Study in a Rehabilitation Context

This clinical study aims to evaluate the feasibility, safety, and acceptability of the Atalante robotic exoskeleton, developed by Wandercraft, within a functional rehabilitation protocol for individuals with complete paraplegia. Unlike re-education, which focuses on restoring impaired functions, rehabilitation seeks to promote long-term autonomy despite persistent impairments.

The study would involve adult participants with complete spinal cord injury-induced paraplegia. Each participant would follow an intensive program of 60 sessions over six weeks, including phases of verticalization, postural stabilization, and assisted locomotion. The protocol would include three evaluation domains: (1) biomedical safety (orthostatic tolerance, adverse events, metabolic load), (2) techno-functional usability (setup time, technical incidents), and (3) user-perceived trust (comfort, sense of safety, satisfaction).

The primary objective would be to determine whether the Atalante exoskeleton can be safely and repeatedly used by individuals with complete paraplegia without requiring manual support. The study would also aim to identify potential barriers to its integration into an intensive rehabilitation protocol. The expected outcomes could guide clinical practices and help define optimal inclusion criteria for the safe and effective use of this technology.

Background and Rationale Complete paraplegia, resulting from spinal cord injury, is a major neurological condition involving irreversible loss of lower limb function. Given the limitations of neuromotor re-education in such contexts, rehabilitation aims to restore autonomy and social participation by leveraging residual capacities and assistive technologies. Robotic exoskeletons represent a promising technological innovation in this domain by offering assisted locomotion that compensates for loss of mobility.

Among these devices, Atalante (Wandercraft, Paris, France) is a next-generation, self-stabilizing exoskeleton designed to enable dynamic walking without manual support, through a fully motorized lower limb system. Unlike conventional devices that require crutches or canes, Atalante provides active stabilization, offering new perspectives in terms of autonomy, safety, comfort, and quality of life.

While the potential benefits of exoskeletons in motor recovery have been explored, their use in a functional rehabilitation context remains under-investigated. This project therefore aims to evaluate the Atalante exoskeleton as an assistive tool for autonomy within a structured intensive protocol in a safe clinical environment.

Primary Objective To evaluate the feasibility, safety, and acceptability of intensive use of the Atalante exoskeleton in a functional rehabilitation context among adults with chronic complete paraplegia.

Secondary Objectives To determine the number of sessions required to reach operational familiarization with the exoskeleton.

To describe technical incidents and their impact on comfort and perceived safety.

To assess the energy cost of assisted locomotion.

To identify potential bone contraindication criteria based on bone mineral density (T-score).

To measure the evolution of user satisfaction throughout the protocol.

Investigational Device: Atalante Exoskeleton

The Atalante exoskeleton is an active robotic system with 12 powered degrees of freedom symmetrically distributed across both lower limbs (3 at the hip, 1 at the knee, 2 at the ankle). It enables:

Biomimetic joint movements,

Active postural control,

Self-stabilized dynamic walking without external support.

Its hybrid control system (continuous/discrete time) is based on Hybrid Zero Dynamics algorithms, which optimize movement trajectories and ensure real-time dynamic balance. The user interface allows switching between multiple modes (sit-to-stand, walk, stop) via remote control. Inertial sensors, angular encoders, and pressure sensors detect the user's intention to move.

Study Design Type: Prospective, single-center, longitudinal, non-randomized study.

Intervention duration: 6 weeks (60 sessions per participant).

Location: Centre de Médecine Physique et Réadaptation APAJH, Pionsat (France).

Safety setup: Overhead rail system with active fall protection, non-interfering with device operation.

Population Participants will be adults with complete paraplegia (ASIA A), lesion level ≤ T6, with stabilized spinal cord injury. They must present anthropometric parameters compatible with the exoskeleton (height, weight, joint mobility). Selection will be based on strict eligibility criteria (see "Eligibility" section).

Intervention Protocol

Each participant will undergo:

2 sessions/day, 5 days/week for 6 weeks.

Each session includes:

Assisted verticalization (sit-to-stand),

Orthostatic stabilization (upright stance without support),

Assisted locomotion (stabilized walking).

Sessions will be supervised by trained professionals. A session will be considered valid if the participant completes a 40-meter round trip without incident. The intensity of the program is designed to simulate realistic sustained home use.

Evaluation Domains

1. Biomedical Safety

   Monitoring of adverse events (major and minor): fractures, skin abrasions, orthostatic hypotension, pain.

   Metabolic analysis (VO₂, cost of transport, perceived exertion via Borg scale) during sessions 21 and 60.

   Exploratory contraindication: T-score \< -3.5 at the hip (severe osteoporosis).
2. Techno-Functional Usability

   Donning and doffing times (sessions 1 to 60),

   Number and type of technical incidents: unexpected stops, deviations, backward perturbations, software bugs.

   Functional familiarization assessment (Elbow Curve method).
3. Perceived Confidence and Acceptability

Session-end assessments via:

Visual analog scales (VAS): general comfort, thoracic harness comfort, safety while standing, walking, and during transitions.

QUEST 2.0 questionnaire at the end of the protocol.

Data Analysis Methodology Quantitative data will be expressed as means ± standard deviation or medians (interquartile ranges).

Intra-subject pre/post comparisons: Student's t-test for parametric data, Wilcoxon test otherwise.

Longitudinal follow-up: progression curves for donning time, technical incidents, and VAS scores.

Effect size and significance thresholds: p \< 0.05; 95% confidence intervals.

Ethics The study will be conducted in accordance with the principles of the Declaration of Helsinki. It has received approval from the Ethics Committee (CPP) and the French Medicines Agency (ANSM). All participants will sign informed consent. French CPP : 2016-A01221-50.

Expected Outcomes

The results of this study could:

Confirm the relevance of Atalante in a functional rehabilitation approach,

Provide practical recommendations for safe clinical use,

Prepare future multicenter studies in real-life environments (home, urban spaces),

Contribute to the development of eligibility criteria for prescribing exoskeletons as assistive mobility devices.

Eligibility Criteria:
Inclusion Criteria:

* Complete spinal cord injury (ASIA A classification)
* Lesion level at or below T6
* Injury occurred more than 6 months prior to enrollment (chronic/stabilized injury)
* Ability to maintain upright posture without symptomatic orthostatic hypotension
* Joint range of motion compatible with wearing the exoskeleton
* Anthropometric dimensions compatible with the device, including:
* Body weight less than 90 kg

Exclusion Criteria:

* Spasticity greater than 3 on the Modified Ashworth Scale
* Joint limitations incompatible with exoskeleton use
* Spinal instability
* Cognitive or psychiatric disorders affecting protocol adherence
* Recent dermatological conditions
* History of fragility fractures in the lower limbs within the past 2 years
* Presence of 5 or more fracture risk factors according to Craven et al., including:

  * Injury older than 10 years
  * Thoracic-level lesion
  * Absence of regular weight-bearing activity
  * Low spasticity
  * Body Mass Index (BMI) \< 20
* Cardiopulmonary contraindications to physical effort
* Pregnancy or breastfeeding