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The Freedom Spinal Cord Stimulator (SCS) System is intended as the sole mitigating agent, or as an adjunct to other modes of therapy used in a multidisciplinary approach for chronic, intractable pain of the trunk and/or lower limbs, including unilateral or bilateral pain.

The Freedom-8A Trial Lead Kit is only used in conjunction with the Freedom-8A Stimulator Receiver Kit, and the Freedom-4A Trial Lead Kit is used for either the Receiver Kit Freedom-4A or the Receiver Kit Freedom-8A Stimulator. The trial devices are solely used for trial stimulation (no longer than 30 days) to determine efficacy before recommendation for a permanent (long term) device.

The Stimwave Technologies Incorporated (Stimwave) Freedom Spinal Cord SCS System (System) is used for spinal column stimulation to provide therapeutic relief for chronic. intractable pain of the trunk and and/or lower limbs including unilateral or bilateral pain. The therapy utilizes pulsed electrical current to create an energy field that acts on nerves near the spinal column. The System is comprised of an implantable stimulator (Freedom-8A/4A Stimulator), receiver component (Receiver), and an externally worn transmitter (Wearable Antenna Assembly (WAA)) to power the device. The System is implanted only following a successful trial period with the Freedom-8A/4A Trial Lead.

This document describes the Stimwave Freedom Spinal Cord Stimulator (SCS) System, which is intended for chronic, intractable pain of the trunk and/or lower limbs. The submission (K182720) is identical to K180981 but includes updates to widen the available range of stimulation parameters for repetition rate (5 Hz to 10 kHz) and pulse width (30 us to 1000 us). No design modifications were made. The document leverages performance testing from prior submissions (K180981 and others) to demonstrate substantial equivalence to the predicate device.

Here's an analysis of the acceptance criteria and study information:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't present a specific table of "acceptance criteria" for performance that the device must meet in terms of a benchmark metric (e.g., Sensitivity, Specificity, Accuracy for a diagnostic device). Instead, it implicitly defines acceptance criteria through compliance with design requirements and various international standards. The "device performance" is primarily demonstrated through passing these tests and showing substantial equivalence to a predicate device.

The two key parameters that were updated in this submission are:

• Repetition Rate: Increased from 5 to 1500 Hz (predicate) to 5 to 10,000 Hz (subject device).
• Pulse Width: Increased from 50 to 500 microseconds (predicate) to 30 to 1000 microseconds (subject device).

The "performance" of the device is described in terms of its ability to pass a series of non-clinical tests and, to some extent, a clinical non-inferiority study for efficacy.

2. Sample size used for the test set and the data provenance

Test Set Sample Size: The clinical study was a multicenter, prospective, randomized controlled study. The document does not explicitly state the sample size of subjects enrolled in this clinical study (test set). However, it does refer to "the percentage of subjects who responded" indicating a cohort of patients.

Data Provenance:

• Country of Origin: Not explicitly stated but implied to be US-based given the FDA submission.
• Retrospective or Prospective: The clinical study was prospective.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

Not applicable. This device is a neurostimulator for pain relief, not a diagnostic device with "ground truth" established by experts in the typical sense for imaging algorithms. The clinical endpoints (pain relief as measured by VAS, ODI, PGIC scores) are patient-reported outcomes.

4. Adjudication method for the test set

Not applicable for establishing ground truth in the context of this device's function. The clinical study was a randomized controlled study comparing two stimulation frequency ranges. The primary and secondary endpoints were measured using established scales (VAS, ODI, PGIC).

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. This is a medical device (Spinal Cord Stimulator), not an AI-based diagnostic tool that assists human readers.

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

The device itself is a standalone implantable stimulator, meaning it functions independently of ongoing human interpretation or algorithmic input for its stimulation delivery. The "algorithm" here refers to the stimulation parameters. The submission confirms the device's performance across an expanded range of these parameters.

The non-clinical performance data (e.g., electrical safety, mechanical robustness, MRI compatibility) are standalone tests of the device's physical and electrical characteristics. The clinical trial compared the efficacy of the device with different stimulation parameter settings (10,000 Hz vs 50-1500 Hz) in patients.

7. The type of ground truth used

The "ground truth" in the clinical study was based on patient-reported outcomes (PROs):

• Visual Analog Scale (VAS) for pain relief and severity.
• Oswestry Disability Index (ODI) scores.
• Patient Global Impression of Change (PGIC) scores.

8. The sample size for the training set

Not applicable. This device is not an AI/ML algorithm that requires a "training set" in the conventional sense. The "learning" aspect is not explicitly mentioned as part of the device's function or development process in this document. The device's operational parameters (repetition rate, pulse width) are pre-defined, although the software restricts them in prior versions. The current submission updates these software restrictions based on prior design and testing.

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

Not applicable, as there is no "training set" for an AI/ML algorithm in this context.

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