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The STIWELL med4 is a neuromuscular electronic stimulator indicated for use under medical supervision for adjunctive therapy in the treatment of medical diseases and conditions.

As a powered muscle stimulator the STIWELL med4 is indicated for the following conditions:

• Relaxation of muscle spasm
• Prevention or retardation of disuse atrophy
• Increasing local blood circulation
• Muscle re-education
• Immediate post-surgical stimulation of calf muscles to prevent venous thrombosis
• Maintaining or increasing range of motion

As a transcutaneous electrical nerve stimulator for pain relief the STIWELL med4 is indicated for the following conditions:

• Symptomatic relief and management of chronic (long-term), intractable pain
• Adjunctive treatment in the management of post-surgical pain and post traumatic acute pain

As a biofeedback device the STIWELL med4 is indicated for the following conditions:

• Biofeedback, relaxation and muscle re-education purposes

As an external functional neuromuscular stimulator the STIWELL med4 is indicated for the following conditions:

• Helps to relearn voluntary motor functions of the extremities

As a nonimplanted electrical continence device the STIWELL med4 is indicated for the following conditions:

• Acute and ongoing treatment of stress, urge or mixed urinary incontinence and where the following results may improve urinary control: Inhibition of the detruser muscles through reflexive mechanisms and strengthening of pelvic floor muscles
• Incontinence treatment for assessing EMG activity of the pelvic floor and accessory muscles such as the abdominal and the gluteus muscles

The STIWELL med4 is powered by rechargeable batteries. It has four stimulation channels and two EMG measurement channels.

The STIWELL med4 is intended for stationary use in a hospital as well as home use by the patient. The physician/therapist has the flexibility to adjust the programs and monitors the progress of the therapy. Statistics regarding the completed treatments can be retrieved from the STIWELL med4 and from the PC.

The provided document is a 510(k) premarket notification for the STIWELL med4, a neuromuscular electronic stimulator. It focuses on establishing substantial equivalence to predicate devices rather than proving performance against specific acceptance criteria through clinical studies. Therefore, much of the requested information regarding clinical study design, performance metrics, and expert adjudication is not present in this type of submission.

Here's an analysis based on the available information:

Acceptance Criteria and Reported Device Performance

The acceptance criteria for this device are primarily based on demonstrating substantial equivalence to legally marketed predicate devices, meaning the new device has the same intended use and the same technological characteristics as the predicate device, or has different technological characteristics but does not raise different questions of safety and effectiveness and is as safe and effective as a legally marketed device.

The document provides extensive tables comparing the STIWELL med4's technical characteristics across various stimulation programs (Functional Electrical Stimulation, Incontinence, TENS, Biofeedback) with its predicate devices. The "performance" in this context is the successful demonstration that these characteristics are similar enough to existing devices to not introduce new safety or effectiveness concerns.

Summary Table of Equivalence (Acceptance Criteria are inferred from predicate device characteristics):

Detailed Study Information from the Provided Text:

This submission is a 510(k) Premarket Notification, which primarily relies on demonstrating substantial equivalence to predicate devices already on the market. It typically does not involve prospective clinical trials to prove efficacy or performance against specific, pre-defined quantitative acceptance criteria in the same way a PMA (Premarket Approval) application would.

Therefore, many of the specific details requested below regarding clinical studies (sample size, data provenance, expert adjudication, MRMC studies, standalone performance, training sets) are generally not part of a 510(k) submission unless there are significant technological differences requiring new clinical data to establish safety and effectiveness. The document itself states, "Tests have been carried out according to the following standards," referring to various IEC and ISO standards for electrical safety, EMC, and environmental testing, confirming that the primary testing was focused on meeting recognized standards and comparing technical specifications.

1. A table of acceptance criteria and the reported device performance:

   • See the table above for inferred acceptance criteria (based on predicate device characteristics) and the STIWELL med4's reported performance against those. The "acceptance criteria" here are implicitly defined by the technical specifications and safety features of the predicate devices.

2. Sample sized used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective):

   • Not Applicable (N/A) for clinical data. This document outlines a 510(k) submission based on substantial equivalence and engineering/safety testing, not new clinical trials.
   • The "test set" primarily refers to the device itself being tested in a lab setting against various electrical and environmental standards. The document mentions tests according to IEC standards for general safety, EMC, nerve/muscle stimulators, environmental conditions (transport, cold, dry heat, damp heat, vibration), and 21 CFR 898 for electrode lead wires and patient cables.
   • Data Provenance: The standards listed implicitly suggest the testing was done by the manufacturer (Otto Bock Healthcare Product GmbH, Austria) or a contracted lab to meet international and US regulatory requirements for device safety and performance according to engineering specifications.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience):

   • N/A. The "ground truth" in this context is defined by the technical specifications of the predicate devices and the requirements of the international safety and performance standards listed (e.g., IEC 60601 series). Compliance is assessed through engineering tests, not expert clinical evaluation.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

   • N/A. Adjudication methods like 2+1 or 3+1 are used in clinical trials to establish ground truth or resolve discrepancies in expert interpretation of clinical data. This type of study was not performed as part of this 510(k) submission.

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:

   • N/A. The STIWELL med4 is an electrical stimulator and biofeedback device, not an AI-assisted diagnostic or therapeutic tool. Therefore, MRMC studies comparing human readers with and without AI assistance are irrelevant and were not performed.

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done:

   • N/A. This device is hardware for neuromuscular electrical stimulation and biofeedback. It does not have a "standalone algorithm" in the sense of a software-only diagnostic or therapeutic AI. Its performance is defined by its electrical output characteristics and biomechanical sensing capabilities as verified by engineering and safety testing.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

   • Engineering Specifications and Regulatory Standards. The "ground truth" for this 510(k) submission is that the device's technical specifications and safety features meet or are equivalent to those of legally marketed predicate devices, and that it complies with relevant electrical and medical device safety standards (e.g., IEC 60601 series, 21 CFR 898).

8. The sample size for the training set:

   • N/A. There is no "training set" in the context of a machine learning model. The STIWELL med4 is a physical medical device whose design and manufacturing processes are validated, not "trained" on data.

9. How the ground truth for the training set was established:

   • N/A. As there is no training set, this question is not applicable.

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