(277 days)
The StimSox™ System is indicated to temporarily increase local blood circulation in healthy leg muscles.
The StimSox™ System is comprised of a battery powered electrical stimulator, disposable gel electrodes, two left foot boots, two right foot boots, three AAA batteries and user manual. The StimSox™ Stimulator software is embedded firmware written for a microcontroller. The software in the StimSox™ Stimulator is for input controls and output display. There is no operating system. It is a real-time loop that is event driven based on the three buttons on the box.
The provided text describes a 510(k) premarket notification for the StimSox™ System, a powered muscle stimulator. The document focuses on demonstrating substantial equivalence to a predicate device, the AMD 6605 TENS/NMES Stimulator.
Here's an analysis of the acceptance criteria and supporting study information, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly present a table of "acceptance criteria" for the StimSox™ System in terms of performance metrics like sensitivity, specificity, or AUC, as might be found for a diagnostic AI device. Instead, it demonstrates "substantial equivalence" to a predicate device by comparing technological characteristics and showing compliance with relevant safety and performance standards. The "performance" is largely demonstrated through these comparisons and a validation study mentioned for current increments.
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Safety: | |
| Biocompatibility of patient-contacting materials | Gel electrodes non-cytotoxic, non-irritating, non-sensitizing per ISO 10993. Boots made of medical grade Nylon Fabric. |
| Electrical Safety (IEC 60601-1-6/A1:2013, IEC 62366/A1:2014, IEC | Complied with IEC 60601-1-6/A1:2013, IEC 62366/A1:2014, IEC 60602-1-11:2010, IEC 60601-1-2:2007 (Ed. 3.0), IEC 60601-2-10: 2012. |
| 60602-1-11:2010, IEC 60601-1-2:2007, IEC 60601-2-10: 2012) | |
| Electromagnetic Compatibility (EMC) (IEC 60601-1-2:2007) | Complied with IEC 60601-1-2:2007 (Ed. 3.0). |
| Risk Analysis | Satisfactory risk analysis results demonstrating acceptable potential and mitigated hazards. |
| No DC component in waveform (IEC 60601-2-10) | Biphasic waveform, ensuring no DC component. |
| Effectiveness (Substantial Equivalence): | |
| Ability to temporarily increase local blood circulation in healthy | Indicated to temporarily increase local blood circulation in healthy leg muscles. Clinical data review suggests limited output is sufficient. Validation study demonstrated 1.0mA increments were safe and effective in achieving a small contraction of plantar muscles and desired clinical response. |
| leg muscles | |
| Performance of 1mA current steps to achieve clinical response | A validation study demonstrated that the 1.0mA increments were safe and effective in achieving the desired clinical response (small contraction of the plantar muscles of the foot). |
| Software Verification | Software verification provided. |
2. Sample Size Used for the Test Set and Data Provenance
The document mentions a "StimSox validation study" which "demonstrated that the 1.0mA increments were safe and effective in achieving the desired clinical response." However, it does not provide specific details on the sample size used for this test set, nor the data provenance (e.g., country of origin, retrospective/prospective nature).
It also references "one study (Thrombosis and Haemostasis. Kaplan RE et al., Throm Haemost 2002;88:2004)" for electrode placement differences, stating it found foot electrodes more comfortable and effective. This study was "not conducted with the predicate," and details about its sample size or provenance are not given in the context of the StimSox validation.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This information is not provided in the document. The nature of the device (powered muscle stimulator) and its intended use (increasing local blood circulation) would likely involve physiological measurements rather than expert image interpretation for ground truth.
4. Adjudication Method for the Test Set
This information is not provided in the document. Given the nature of a muscle stimulator, the "ground truth" would likely be objective physiological measurements (e.g., blood flow, muscle contraction), rather than subjective expert assessment requiring adjudication.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
An MRMC study is typically performed for diagnostic devices where human readers interpret medical images or data. For a powered muscle stimulator, an MRMC study comparing human reader improvement with and without AI assistance is not applicable and was not performed/reported.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
The StimSox™ System is a hardware device with embedded firmware for input controls and output display. It is not an AI algorithm that provides diagnostic or predictive outputs in a standalone manner. Therefore, a standalone performance study in the context of "algorithm only" is not applicable and was not performed/reported as it would be for an AI/ML-based diagnostic device. The device's "performance" is its ability to deliver electrical stimulation as intended for its physiological effect.
7. Type of Ground Truth Used
Based on the nature of the device and the brief mention of the validation study:
- The "desired clinical response" for the StimSox validation study (a "small contraction of the plantar muscles of the foot") suggests physiological measurements or direct observation of muscle response would constitute the ground truth.
- The indication ("temporarily increase local blood circulation") would imply ground truth established by physiological measurements of blood flow (e.g., Doppler ultrasound, plethysmography).
8. Sample Size for the Training Set
The StimSox™ System uses "embedded firmware written for a microcontroller" with a "real-time loop that is event driven." This indicates traditional microcontroller programming, not a machine learning model that requires a distinct "training set." Therefore, the concept of a "training set" sample size is not applicable to this device in the same way it would be for an AI/ML system.
9. How the Ground Truth for the Training Set Was Established
As there is no indication of a machine learning model or a "training set" in the context of AI, this question is not applicable. The device's functionality is based on programmed logic rather than learned patterns from data.
§ 890.5850 Powered muscle stimulator.
(a)
Identification. A powered muscle stimulator is an electrically powered device intended for medical purposes that repeatedly contracts muscles by passing electrical currents through electrodes contacting the affected body area.(b)
Classification. Class II (performance standards).