(121 days)
The StimSox™ System is indicated to temporarily increase local blood circulation in healthy leg muscles and immediate post-surgical stimulation of calf muscles to prevent venous thrombosis.
The StimSox™ System is comprised of a battery powered electrical stimulator, disposable gel electrodes, two left foot boots, two right foot boots, and three AAA batteries.
The provided document is a 510(k) premarket notification for the StimSox™ System. It focuses on demonstrating substantial equivalence to predicate devices, rather than presenting a standalone clinical study with detailed acceptance criteria and performance data for a new device.
Therefore, the information requested regarding acceptance criteria, study design, sample sizes, expert ground truth, adjudication methods, MRMC studies, and ground truth establishment for training sets is largely Not Applicable or Not Provided in this type of submission.
Here's a breakdown based on the available information:
1. Table of Acceptance Criteria and Reported Device Performance
This document does not present a table of specific acceptance criteria in numerical terms (e.g., sensitivity, specificity, or improvement percentage) for a clinical outcome, nor does it explicitly report the StimSox™ System's performance against such criteria. The "performance data" mentioned focuses on safety, electrical standards, and biocompatibility, which are part of demonstrating substantial equivalence, not clinical effectiveness in the way a diagnostic AI might be evaluated.
The relevant section, "VIII. CLINICAL EVALUATION," discusses peer-reviewed journal articles for the predicate technology, not a direct study of the StimSox™ System itself. The overall conclusion states that these studies "demonstrated that stimulation on sole of the foot can lead to a temporary increase in local blood circulation in calf muscles. This increase in blood flow may help reduce the risk of venous thrombosis." This reflects the claimed benefit of the technology, broadly, rather than specific performance metrics for this device against pre-defined acceptance criteria.
2. Sample Sizes used for the test set and data provenance
- Sample Size for Test Set: Not applicable / Not provided. The submission refers to existing peer-reviewed articles on the technology itself, not a new clinical trial for the StimSox™ System with a "test set."
- Data Provenance: The document refers to peer-reviewed journal articles (Czyrny JJ, et al. 2010; Kaplan RE, et al. 2002). Specific details about the country of origin of the data or whether they were retrospective or prospective studies are not provided within this 510(k) summary.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
Not applicable / Not provided. This type of detail would be found in a clinical study report for a new device, which is not what this 510(k) summary contains. The "ground truth" for the claims cited from the predicate literature would be the clinical outcomes and measurements reported in those studies, as interpreted by the authors and peer reviewers.
4. Adjudication method for the test set
Not applicable / Not provided. As there's no "test set" for a new clinical study of the StimSox™ System in this document, no adjudication method is described.
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
Not applicable. The StimSox™ System is a powered muscle stimulator, not an AI-assisted diagnostic tool for "human readers." Therefore, an MRMC comparative effectiveness study is irrelevant to this device.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
Not applicable. The StimSox™ System is a physical medical device, not a standalone algorithm. Its performance is evaluated through electrical safety, biocompatibility, and by referencing the clinical effectiveness of similar technology as demonstrated in published literature.
7. The type of ground truth used
The "ground truth" for the clinical claims (increased local blood circulation, prevention of venous thrombosis) is based on the findings of peer-reviewed scientific literature related to electrical foot stimulation. These studies would have used clinical measures and outcomes data to establish their findings. For example, Czyrny JJ, et al. concluded "electrical foot stimulation is at least as effective as knee-high intermittent pneumatic compression in increasing popliteal and femoral blood flow velocity," which implies measurements of blood flow velocity as the basis for their conclusions.
8. The sample size for the training set
Not applicable / Not provided. The StimSox™ System is not an AI/ML algorithm that requires a "training set" in the context of machine learning. The term "training set" is not relevant to its development as described here.
9. How the ground truth for the training set was established
Not applicable. See point 8.
§ 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).