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When intended for pedicle screw fixation from TI-S1, the indications include immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion in the treatment of the following acute and chronic instabilities or deformities of the thoracic, lumbar, and sacral spine: degenerative disc disease (defined as discogenic back pain with degeneration of the disc confirmed by history and radiographic studies), degenerative spondylolisthesis with objective evidence of neurologic impairment, fracture, dislocation, deformities or curvatures (i.e. scoliosis, and/or lordosis), tumor, and failed previous fusion.

As a pedicle screw system placed between L3 and S1, the indications include Grade 3 or Grade 4 spondylolisthesis, when utilizing autograft or allograft, when affixed to the posterior lumbosacral spine, and intended to be removed after solid fusion is established.

The purpose of this 510(k) submission is to modernize the existing PathFinder Pedicle Screw System. A set of percutaneous insertion rods and new instrumentation have been included for minimally invasive procedures.

The Zimmer Spine PathFinder II system consists of polyaxial cannulated screws and rods and is intended to provide temporary stabilization following surgery to fuse the spine. A range of spinal rod lengths included in this system allows the surgeon to place polyaxial pedicle screws through an open or mini-open procedure. This system is intended only to provide stabilization during the development of a solid fusion with autograft or allograft. These implants are intended to be removed after the development of a solid fusion mass.

The Zimmer Spine PathFinder® II Minimally Invasive Pedicle Screw System is indicated for pedicle screw fixation from T1-S1 for immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion for various spinal instabilities or deformities. Additionally, for placement between L3 and S1, it is indicated for Grade 3 or Grade 4 spondylolisthesis.

Here's an analysis of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance:

2. Sample Size and Data Provenance:

• Test Set Sample Size: Not explicitly stated in the provided text for the mechanical tests. The document mentions "the proposed PathFinder II system and predicate Sequoia Pedicle Screw system" as the subjects of the tests, implying full systems were tested, but the number of individual components or systems tested is not specified.
• Data Provenance: The mechanical tests were performed by Zimmer Spine, Inc. The location of these tests and the nationality of the data are not specified. The tests are non-clinical, meaning they were likely conducted in a laboratory setting. This is a retrospective evaluation as it's part of a 510(k) submission for a device based on pre-existing technology and a predicate.

3. Number of Experts and Qualifications for Ground Truth:

• Not applicable directly. This information is typically relevant for studies involving human interpretation (e.g., imaging devices, diagnostic algorithms). For this device, the "ground truth" for mechanical performance is established by standardized testing protocols (ASTM F1717) and engineering principles, rather than expert consensus on a data set. The FDA's review and determination of substantial equivalence act as the ultimate "expert" validation in this regulatory context.

4. Adjudication Method for the Test Set:

• Not applicable directly. Adjudication methods (like 2+1, 3+1) are used to resolve disagreements among human experts when establishing ground truth. In this case, the evaluation relies on objective mechanical test results compared against established standards. The FDA's review process itself can be seen as a form of adjudication in determining regulatory acceptance based on the submitted data.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:

• No, an MRMC comparative effectiveness study was not done. This type of study is typically performed to assess the impact of a device or AI on human reader performance, especially in diagnostic or screening contexts. The Zimmer Spine PathFinder® II is a spinal implant, and its performance is evaluated through mechanical testing, not through human reader interpretation of images or data.

6. Standalone (Algorithm Only) Performance Study:

• Yes, in a sense, a standalone performance was done for the mechanical aspects. The mechanical tests (static and dynamic axial compression bending, static torsion) were performed on the device itself, functioning independently of human interaction during the test. The "performance" here refers to the device's physical response to simulated forces as measured against a standard, not an algorithm's output.

7. Type of Ground Truth Used:

• Standardized Mechanical Test Results/Engineering Principles. The "ground truth" for this device's performance is derived from the objective measurements obtained during mechanical testing in accordance with ASTM F1717 and the comparison of these results to those of the predicate device. The performance is deemed acceptable if it meets or exceeds the predicate's performance under these standardized conditions.

8. Sample Size for the Training Set:

• Not applicable. This device is a physical medical implant, not an AI/machine learning algorithm that requires a "training set" of data. The "training" for such devices involves design, engineering, and manufacturing processes informed by established biomechanical principles and material science.

9. How Ground Truth for the Training Set Was Established:

• Not applicable. As explained above, there is no "training set" in the context of an AI algorithm for this physical device. The design and validation of the device rely on engineering specifications, material testing, and the performance of previous or predicate devices.

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