(55 days)
The Ekso™ (version 1.1) and Ekso GT™ (version 1.2) are intended to perform ambulatory functions in rehabilitation institutions under the supervision of a trained physical therapist for the following population:
• Individuals with hemiplegia due to stroke (upper extremity motor function of at least 4/5 in at least one arm)
• Individuals with spinal cord injuries at levels T4 to L5 (upper extremity motor function of at least 4/5 in both arms)
• Individuals with spinal cord injuries at levels of C7 to T3 (ASIA D with upper extremity motor function of at least 4/5 in both arms).
The therapist must complete a training program prior to use of the device. The devices are not intended for sports or stair climbing.
The Ekso is a powered motorized orthosis. It consists of a fitted metal brace that supports the legs, feet, and torso. It is worn via straps on the body, legs, and feet. Battery powered motors drive knee and hip joints. It has an integrated solid torso containing the computer and power supply. It has a hand-held user interface to specify settings and initiate steps. The Ekso is used with a cane, crutch, or walker.
Here's an analysis of the acceptance criteria and supporting study for the Ekso™ (version 1.1) and Ekso GT™ (version 1.2) based on the provided document.
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly present a table of numerical acceptance criteria with corresponding device performance metrics in the way one might see for diagnostic accuracy. Instead, the acceptance criteria are implicitly defined by the safety and effectiveness demonstrated in the clinical studies, particularly for the expanded Indications for Use. The core acceptance criterion appears to be: safe and effective ambulation for the specified patient populations, demonstrated by a lack of adverse events.
| Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|
| Safety: Device operation without falls, adverse events, or significant harm during ambulation. | Study 1: 50 out of 54 patients (93%) safely performed ambulatory functions with only one arm to maintain stability. No falls or other adverse events reported. |
| Study 2: 7 out of 8 patients (88%) safely performed ambulatory functions with only one arm to maintain stability. No falls or other adverse events reported. | |
| Overall: "The lack of adverse events over 216 walking sessions in 57 patients demonstrates the safety and effectiveness of the Ekso device..." | |
| Effectiveness (Ambulatory Function): Patients with conditions covered by the expanded indication can ambulate. | Study 1: Focused on patients with hemiplegia due to stroke, specifically those with "upper extremity motor function of less than 4/5 in one arm" (34 patients) and others not recorded (19 patients). The study demonstrated that these patients could "safely performed ambulatory functions with only one arm to maintain stability." |
| Study 2: Focused on patients with hemiplegia due to stroke, "All limited household ambulators at recruitment." Demonstrated that patients could "safely performed ambulatory functions with only one arm to maintain stability." | |
| Indirect Evidence: "The indirect evidence documents that regardless of upper extremity motor function, 23 patients were able to safely perform ambulatory functions in the Ekso device using only one arm to control the assistive device. The ability of such patients to support themselves and recover from a stumble is equivalent to that of a patient who has upper extremity strength of at least 4/5 in only one arm." | |
| Training Effectiveness: Certified therapists can safely and independently operate the device. | The document describes a two-phase training and certification program for therapists, ensuring competence in screening, setup, fitting, operation, safety, and emergency management. The implication is that this training enables safe operation. |
2. Sample Sizes and Data Provenance
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Test Set (Clinical Studies):
- Study 1: 54 subjects total.
- 34 subjects with affected upper extremity (UE) motor function of less than 4/5 in one arm.
- 1 patient with affected UE motor function of 4/5.
- 19 patients with UE motor function not recorded.
- 216 walking sessions across both studies.
- Study 2: 8 subjects total.
- All 8 subjects were limited household ambulators at recruitment.
- Data Provenance: Both studies are described as "Single center, prospective studies." The country of origin is not explicitly stated, but given the FDA submission, it is likely the United States.
- Study 1: 54 subjects total.
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Training Set: Not applicable for this device as it is a physical exoskeleton, not an AI/software device that requires a "training set" in the machine learning sense. The "training" described in the document refers to human therapist training.
3. Number of Experts and Qualifications for Ground Truth
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Ground Truth for Test Set: The "ground truth" here is the clinical assessment of safety and ability to ambulate. This would have been established by the trained physical therapists supervising the sessions and likely by the principal investigator(s) of the studies. The document states the device is used "under the supervision of a trained physical therapist," and the therapists themselves undergo certification. While no specific number of "experts" are listed for establishing ground truth post-hoc, the safety and effectiveness were directly observed and recorded during the prospective studies by qualified clinical personnel. Their qualifications are implied by their role as physical therapists and study investigators.
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Training Set Ground Truth: Not applicable.
4. Adjudication Method for the Test Set
The document does not describe a formal adjudication method (like 2+1 or 3+1 consensus) for the outcome of the clinical studies. The results are presented as direct observations and reports from the prospective studies ("No falls or other adverse events reported"). This implies the safety and functional performance were observed and recorded directly by the study investigators/therapists.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- No, an MRMC comparative effectiveness study was not done. This type of study (comparing human readers with and without AI assistance) is relevant for diagnostic imaging AI. The Ekso device is a physical exoskeleton for rehabilitation, not a diagnostic AI.
6. Standalone (Algorithm Only) Performance
- Not applicable. The Ekso is an exoskeleton requiring human interaction (the patient wearing it, the therapist supervising it). It does not have a "standalone" algorithm performance in the way an AI diagnostic tool would. Its performance is intrinsically linked to the human operator and patient.
7. Type of Ground Truth Used
- Clinical Observation and Outcomes Data:
- The primary ground truth for the clinical studies was the direct clinical observation of patient safety (absence of falls, adverse events) and their ability to perform ambulatory functions while using the device, as assessed by trained physical therapists and study investigators.
- The "results" section directly references "safely performed ambulatory functions" and "no falls or other adverse events reported," which are observed clinical outcomes.
8. Sample Size for the Training Set
- Not applicable. As noted above, this is a physical medical device, not an AI/machine learning algorithm requiring a "training set" of data. The "training" refers to physical therapist training.
9. How the Ground Truth for the Training Set Was Established
- Not applicable. See point 8. The training for therapists involves demonstrating competence in operating the device and supervising patients safely, as evaluated by the "Ekso Bionics Clinical Training Team."
§ 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).