(215 days)
The SensorWalk is intended to lock the knee joint during the stance phase and to unlock the knee joint during the swing phase when walking forward on level surfaces. It is intended solely for the orthotic fitting of the lower limbs of patients who are community ambulators and who:
- Exhibit knee instability in the sagittal plane while bearing weight during the stance phase of their gait cycle;
- Have hip extensor strength of at least grade 3 (against gravity);
- Have the muscle strength in their torso or pelvis required to swing the SensorWalk forward while they are walking;
- Have a gait in which the step length on level ground exceeds the length of the opposing foot;
- Weigh 300 pounds or less; and
- Are able to understand and carry out the instructions.
The Sensor Walk is a microprocessor-controlled Knee Ankle Foot Orthosis (KAFO) designed to help wearers achieve a safer, more physiologically correct gait. It does this by unlocking the knee joint when the wearer is ready for swing phase and locking it again for stability during stance phase.
The Sensor Walk system includes an onboard microprocessor, a clutch spring knee joint, foot pressure sensors, a knee angle sensor, a battery, and a battery charger. When the sound limb has been loaded during walking and the affected side is about to enter swing phase (with the toe still on the ground) the microprocessor reads signal information from the foot and knee sensors and allows the knee to go into flexion. When the orthosis begins to extend again, the knee will enter a stable phase, preventing any flexion while allowing full extension for stance phase. The Sensor Walk will support the wearer if they load it at any point while it is extending, offering them exceptional stability. Wearers can disengage the knee joint, such as for sitting, simply by pressing the manual release switch.
The Sensor Walk offers 12 hours of continuous use before it needs to be recharged, and contains an audible warning to alert the use if the battery is running low.
When the Sensor Walk is turned off, it offers the stability of a traditional locked KAFO throughout the gait cycle.
The Sensor Walk has Manual Release Function. A control collar at the knee joint can be manually pushed back to temporarily override the locking mechanism and put the joint into free swing mode. As soon as the collar is reling meetialism und be able to lock.
To override the Sensor Walk's locking mechanism for a longer period, a Manual Release Rocker Switch can be pressed to lock the control collar in the free swing mode. When the Manual Release Rocker Switch is pressed and the joint is in free-swing mode, the switch will show an amber dot to indicate that caution should be used. In normal operating mode, the switch will show a green dot indicating that the locking feature will function normally.
The Sensor Walk™ is comprised of the following parts: a traditional, doubleupright KAFO with a free-articulating medial knee joint; a lateral mechanical clutch, 6 spring knee joint, microprocessor-controlled electronics, foot sensors, a battery, and a battery charger.
The foot sensor plate includes 4 sensors arranged in a straight line on the bottom of the foot plate. They are numbered from 1 to 4, beginning with the most posterior. The sensors overlap by 3/8 inch (10mm), and are wired to a sensor selection switch located in the electronics of the Sensor Walk. The Sensor Walk comes delivered with sensors 1 and 2 activated, but, if necessary, other sensors can be selected to optimize patient fitting.
The Sensor Walk is delivered with the following components:
- Fabricated KAFO with Sensor Walk (17B500) knee joint and foot sensor (520E500)
- Battery (517B20) and Charger (517L20)
- Sensor Walk Instructions for Use
The Sensor Walk comes in either a right or left, laminated or thermoplastic. The Order Numbers are as follows:
- 17B500 == R-L300 == Laminated Right
- 17B500 = L-L300 Laminated Left
- 17B59() = R-T300 Thermoplastic Right
- 178500 -- L-T300 -- Thermoplastic Left
The provided text describes the "Sensor Walk" device, a microprocessor-controlled Knee Ankle Foot Orthosis (KAFO). However, it is a 510(k) summary for a medical device and not a study proving the device meets acceptance criteria.
The 510(k) summary focuses on demonstrating "substantial equivalence" to a legally marketed predicate device (OTTO BOCK FreeWalk), not on reporting specific performance against acceptance criteria from a standalone study. Therefore, the requested information about acceptance criteria, detailed study parameters, sample sizes, ground truth establishment, expert involvement, and comparative effectiveness is largely not present in the provided document.
Here's a breakdown of what can and cannot be answered based on the provided text:
1. A table of acceptance criteria and the reported device performance:
This information is not provided in the document. The 510(k) summary focuses on comparing the Sensor Walk to a predicate device and outlining its intended use and technological characteristics, rather than reporting performance against specific, quantifiable acceptance criteria.
2. Sample size used for the test set and the data provenance (e.g., country of origin of the data, retrospective or prospective):
This information is not provided. The document does not describe any specific test set or study conducted for the Sensor Walk. It mentions that "None of the differences [between Sensor Walk and FreeWalk] raise any new questions of safety or effectiveness that have not been addressed by the developers (OTTO BOCK and Mayo Clinic)," which implies reliance on existing knowledge or internal assessments rather than a specific clinical trial detailed here.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
This information is not provided. No test set is described, so no ground truth establishment by experts is detailed.
4. Adjudication method (e.g., 2+1, 3+1, none) for the test set:
This information is not provided. No test set is described, so no adjudication method is mentioned.
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
This is not applicable as the Sensor Walk is a physical orthotic device, not an AI diagnostic or image analysis tool that would involve human readers.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
This is not directly applicable in the context of a standalone algorithm performance in the way it's usually asked for AI/software devices. The entire device is the "standalone" unit in terms of its function (microprocessor-controlled KAFO). However, no specific performance metrics for the device are reported that could be compared to typical "standalone algorithm" evaluations.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
This information is not provided. As no specific test data or study with ground truth is described, the type of ground truth used is unknown.
8. The sample size for the training set:
This information is not provided. The document does not mention any training set for an algorithm. While the device is microprocessor-controlled, the text does not describe a machine learning algorithm that undergoes a training phase.
9. How the ground truth for the training set was established:
This information is not provided. As no training set is mentioned, the method of establishing its ground truth is also not described.
Summary of what is available from the document (related to acceptance/testing):
- The device (Sensor Walk) aims to provide a safer, more physiologically correct gait by unlocking the knee joint for swing phase and locking it for stability during stance phase.
- Intended Use & Indications for Use: These outline the specific conditions and patient characteristics for which the device is designed. These act as high-level "acceptance criteria" for the device's application.
- Intended Use: Orthotic fitting of lower limbs, for community ambulators, forward walking on level surfaces, with power turned on. Not for sports or aggressive use.
- Indications for Use (Patient Criteria):
- Knee instability in the sagittal plane during stance phase.
- Hip extensor strength of at least grade 3 (against gravity).
- Muscle strength in torso/pelvis to swing KAFO forward.
- Gait where step length on level ground exceeds length of opposing foot.
- Weigh 300 pounds or less.
- Able to understand and carry out instructions.
- Functional Features: The document describes the device's operation (e.g., 12 hours continuous use, audible low battery warning, manual release function). Implied "acceptance" is that these features function as described.
- Substantial Equivalence: The key "study" or basis for clearance is the demonstration of substantial equivalence to the OTTO BOCK FreeWalk, a Class I exempt device. This comparison focuses on technological characteristics and intended use rather than specific endpoint performance data from a clinical trial. The developers (OTTO BOCK and Mayo Clinic) have attested that differences do not raise new safety or effectiveness questions.
Therefore, while the document explains the purpose and features of the Sensor Walk, it does not provide the detailed study information typically requested when evaluating acceptance criteria for a device, particularly one involving advanced algorithms or diagnostic capabilities. The 510(k) process for this Class I device relied on demonstrating similarity to a legally marketed predicate, rather than an independent clinical performance study with defined acceptance criteria.
§ 890.3475 Limb orthosis.
(a)
Identification. A limb orthosis (brace) is a device intended for medical purposes that is worn on the upper or lower extremities to support, to correct, or to prevent deformities or to align body structures for functional improvement. Examples of limb orthoses include the following: A whole limb and joint brace, a hand splint, an elastic stocking, a knee cage, and a corrective shoe.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter, subject to the limitations in § 890.9. The device is also exempt from the current good manufacturing practice requirements of the quality system regulation in part 820 of this chapter, with the exception of § 820.180, regarding general requirements concerning records and § 820.198, regarding complaint files.