(109 days)
The ReWalk ReStore is intended to be used to assist ambulatory functions in rehabilitation under the supervision of a trained therapist for people with hemiplegia/hemiparesis due to stroke who can ambulate at least 1.5m (5ft) with no more than minimal to moderate levels of assistance. The trained therapist must successfully complete a training program prior to operating the device. The device is not intended for sports or stair climbing.
The ReWalk ReStore™ ("ReStore™") device is a lightweight, wearable, battery-powered soft orthotic exosuit is intended to be used to assist ambulatory functions in rehabilitation institutions under the supervision of a trained therapist for people with hemiplegia/hemiparesis due to stroke.
The ReStore™ device is designed to provide plantarflexion (PF) and dorsiflexion (DF) assistance to the paretic ankle during walking by transferring mechanical forces from two motors mounted on a Waistpack through Bowden cables to attachment points worn on the calf and insole. Through a set of gears, the motors actuate the Bowden cables to provide plantarflexion and dorsiflexion forces. Forces are transferred through the Bowden cables by pulling an inner cable within an outer sheath. The distal end of the outer sheath is fixed at an attachment point worn on the Calf Wrap, and the distal end of the inner cable is fixed at an attachment point worn on an insole made of flexible plastic that is worn within the shoe on the paretic foot. The relative motion that occurs between these two points when the inner cable is moved results in torques being applied across the ankle joint. The placement of the attachment points anterior and posterior to the ankle joint result in corresponding torques to provide assistance during dorsiflexion and plantarflexion, respectively. Load cells attached to the cables provide force feedback allowing control of the level of assistance provided to the patient. Sensors attached to the shoes are used to detect gait events during walking to inform timing of the assistance from the ReStore™ device. Specifically, inertial measurement units (IMUs) are attached to shoes on both legs to provide signals corresponding to events within the gait cycle, such as heel-strike or toeoff, in order to determine the appropriate timing of assistance from ReStore™.
The ReStore™ is designed to provide adjustable levels of assistance to the patient's paretic leg. It does not constrain or provide assistance to the patient's non-paretic leg. The device enables the therapist to individually modify the level of assistance provided during plantarand dorsiflexion as appropriate for each individual patient. The timing of assistance is based on data collected from the motion sensors on both the paretic and non-paretic feet, which determines the patient's orientation within their gait cycle.
Plantarflexion assistance occurs during the late stance and toe-off portion of the paretic leg gait cycle. This level of assistance targets a desired cable force, which can be adjusted from 0% to 25% of the patient's body weight. Dorsiflexion assistance occurs during the swing and heel-strike phase of the paretic gait cycle. This level of assistance targets a desired cable travel, which can be adjusted from 0 cm to 5 cm. Plantarflexion and dorsiflexion assistance levels are determined by the therapist based on visual evaluation of the patient's gait symmetry, the therapeutic goals of the walking session or the ability of the patient to achieve consistent ground clearance or heel-strike landing patterns with their paretic foot. The ReStore™ device includes apparel-like components, mechanical components, electrical components, cables, sensors and a handheld controller.
The ReWalk Restore device is a soft orthotic exosuit intended to assist ambulatory functions in rehabilitation for individuals with hemiplegia/hemiparesis due to stroke.
1. Table of Acceptance Criteria and Reported Device Performance:
The document primarily focuses on demonstrating the safety and effectiveness of the ReWalk Restore device against a predicate device (Indego®) through clinical and non-clinical studies. While explicit "acceptance criteria" in a quantitative sense for performance metrics are not clearly defined as pass/fail thresholds in the provided text, the successful completion of the clinical trial demonstrating safety and efficacy, alongside meeting all design requirements and compliance with standards, serves as the basis for acceptance. The performance is reported in terms of safety outcomes and improvements in walking parameters.
| Acceptance Criteria (Implied) | Reported Device Performance (ReWalk Restore) |
|---|---|
| Device Safety (no device-related serious adverse events or falls) | PASS: Zero device-related serious adverse events and zero device-related falls in the 44-subject multi-site clinical trial and engineering studies. |
| Manageable Adverse Events | PASS: Initial adverse event rate of 13.5% in early study phase, reduced to 1.3% after retraining on donning/fitting. Majority were minor. |
| Improved Walking Speed (Comfortable) | PASS: In subjects completing all 7 visits (n=36), 86.1% increased comfortable walking speed with ReStore™. |
| Improved Walking Speed (Maximal) | PASS: In subjects completing all 7 visits (n=36), 80.6% increased maximal walking speed with ReStore™. |
| Increased Walking Distance (2-minute walk test) | PASS: Average walking distance increased by 47.9 ft. during walking with assistance (Assist mode) compared to without assistance (Slack mode). |
| Device Reliability | PASS: Not explicitly quantified with a threshold, but assessed as a secondary endpoint and implied by successful study completion. |
| Device Safety for Physical Therapist | PASS: Not explicitly quantified with a threshold, but assessed as a secondary endpoint and implied by successful study completion. |
| Compliance with Design Requirements/Standards | PASS: Met all design inputs and specifications, and complied with applicable standards (e.g., ANSI/AAMI ES60601-1, IEC 60601-1-2, ISO 10993-1/5/10). |
2. Sample Size and Data Provenance for Test Set:
- Sample Size for Clinical Trial: 44 subjects for the multi-site clinical trial.
- Sample Size for Engineering Studies: 35 unique participants across two ongoing engineering studies (with 10 participants enrolled in both).
- Sample Size for Clinical Validation Substudy: 9 participants.
- Total Unique Participants: 79 individuals.
- Data Provenance: The multi-site clinical trial was conducted across 5 study sites, and the engineering studies were conducted at the Wyss Institute at Harvard University (Cambridge, MA). The country of origin is the USA for the engineering and clinical validation studies, and likely includes multiple sites/countries for the "multi-site clinical trial" but specific country details are not provided beyond the Wyss Institute location for some studies. All studies were prospective as they were IRB-approved and conducted according to Good Clinical Practice (GCP) principles.
3. Number of Experts and Qualifications for Ground Truth:
The document does not detail the number of experts used to establish the ground truth for specific performance metrics in the way one might see in an image classification study. Instead, the "ground truth" for the device's safety and effectiveness is established through a clinical trial involving trained therapists supervising patients. Their observations and assessments during the trials, along with objective measurements of walking parameters, form the basis of evaluating the device's performance. The document states, "The trained therapist must successfully complete a training program prior to operating the device," indicating a level of qualification for the individuals involved in using and assessing the device. Specific qualifications like "radiologist with 10 years of experience" are not applicable to this type of device and study.
4. Adjudication Method for the Test Set:
The document does not describe "adjudication methods" in the context of expert consensus (e.g., 2+1, 3+1). The primary endpoints for the clinical trial are device safety (frequency and severity of device-related adverse events, falls) and exploratory endpoints for efficacy (walking speed, distance). These are assessed through direct observation and measurement during the study, rather than through expert consensus on qualitative events. Adverse event reporting and management would involve a clinical team review rather than an adjudication panel for "ground truth."
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not conducted. This type of study is more relevant to diagnostic imaging interpretation (where multiple readers interpret cases). The ReWalk Restore is a therapeutic and assistive device, and its effectiveness is measured by direct patient outcomes and performance improvements in ambulation, not by human reader interpretation.
6. Standalone (Algorithm Only) Performance:
No, a standalone (algorithm only) performance study was not done. The ReWalk Restore device is inherently human-in-the-loop, designed to provide assistance to a person with hemiparesis/hemiplegia during ambulation. Its function is to augment human movement, not to perform independently. The performance is always assessed with the human user.
7. Type of Ground Truth Used:
The ground truth for device safety was based on the occurrence and severity of device-related adverse events and falls as reported and managed during the clinical trials. For efficacy, the ground truth was based on objective physiological and functional outcome measures such as 10-meter walk tests (comfortable and maximal speeds) and 2-minute walk distances, directly measured from the subjects during their walking assessments.
8. Sample Size for the Training Set:
The document does not explicitly mention a "training set" in the context of machine learning. The studies described are for clinical validation and engineering development. If any machine learning components are part of the device's control system, the data used for their development/training is not detailed in this summary. The 79 individuals who participated in the various studies represent the subjects on whom the device was tested and refined, rather than a distinct "training set" for an AI algorithm in the traditional sense of a diagnostic or predictive model.
9. How the Ground Truth for the Training Set Was Established:
As there is no clearly defined "training set" for an AI algorithm in the provided text, the method for establishing ground truth for such a set is not described. The studies focused on validating the device's safety and effectiveness through direct clinical assessment and objective measures in human participants.
§ 890.3480 Powered lower extremity exoskeleton.
(a)
Identification. A powered lower extremity exoskeleton is a prescription device that is composed of an external, powered, motorized orthosis that is placed over a person's paralyzed or weakened limbs for medical purposes.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Elements of the device materials that may contact the patient must be demonstrated to be biocompatible.
(2) Appropriate analysis/testing must validate electromagnetic compatibility/interference (EMC/EMI), electrical safety, thermal safety, mechanical safety, battery performance and safety, and wireless performance, if applicable.
(3) Appropriate software verification, validation, and hazard analysis must be performed.
(4) Design characteristics must ensure geometry and materials composition are consistent with intended use.
(5) Non-clinical performance testing must demonstrate that the device performs as intended under anticipated conditions of use. Performance testing must include:
(i) Mechanical bench testing (including durability testing) to demonstrate that the device will withstand forces, conditions, and environments encountered during use;
(ii) Simulated use testing (
i.e., cyclic loading testing) to demonstrate performance of device commands and safeguard under worst case conditions and after durability testing;(iii) Verification and validation of manual override controls are necessary, if present;
(iv) The accuracy of device features and safeguards; and
(v) Device functionality in terms of flame retardant materials, liquid/particle ingress prevention, sensor and actuator performance, and motor performance.
(6) Clinical testing must demonstrate a reasonable assurance of safe and effective use and capture any adverse events observed during clinical use when used under the proposed conditions of use, which must include considerations for:
(i) Level of supervision necessary, and
(ii) Environment of use (
e.g., indoors and/or outdoors) including obstacles and terrain representative of the intended use environment.(7) A training program must be included with sufficient educational elements so that upon completion of training program, the clinician, user, and companion can:
(i) Identify the safe environments for device use,
(ii) Use all safety features of device, and
(iii) Operate the device in simulated or actual use environments representative of indicated environments and use.
(8) Labeling for the Physician and User must include the following:
(i) Appropriate instructions, warning, cautions, limitations, and information related to the necessary safeguards of the device, including warning against activities and environments that may put the user at greater risk.
(ii) Specific instructions and the clinical training needed for the safe use of the device, which includes:
(A) Instructions on assembling the device in all available configurations;
(B) Instructions on fitting the patient;
(C) Instructions and explanations of all available programs and how to program the device;
(D) Instructions and explanation of all controls, input, and outputs;
(E) Instructions on all available modes or states of the device;
(F) Instructions on all safety features of the device; and
(G) Instructions for properly maintaining the device.
(iii) Information on the patient population for which the device has been demonstrated to have a reasonable assurance of safety and effectiveness.
(iv) Pertinent non-clinical testing information (
e.g., EMC, battery longevity).(v) A detailed summary of the clinical testing including:
(A) Adverse events encountered under use conditions,
(B) Summary of study outcomes and endpoints, and
(C) Information pertinent to use of the device including the conditions under which the device was studied (
e.g., level of supervision or assistance, and environment of use (e.g., indoors and/or outdoors) including obstacles and terrain).