(42 days)
When intended for pedicle screw fixation from T1 -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 pedicle screw system placed between L3 and S1, the indications include Grade 3 or Grade 4 spondylolisthesis, when utilizing autologous bone graft, when affixed to the posterior lumbosacral spine, and intended to be removed after the solid fusion is established.
The existing, commercially available Zimmer Spine PathFinder NXT® system consists of various screws, rods and associated accessories and is intended to provide temporary stabilization following surgery to fuse the spine. PathFinder NXT screws are polyaxial cannulated designs with a range of spinal rod lengths. PathFinder NXT allows the surgeon to place polyaxial pedicle screws either through an open or mini-open procedure. PathFinder NXT is designed to aid in the surgical correction of several types of spinal conditions and intended only to provide stabilization during the development of a solid fusion with a bone graft. These implants are intended to be removed after the development of a solid fusion mass. Additionally, the PathFinder NXT MIS System includes instrumentation to facilitate the implantation of the PathFinder NXT implants. The prior 510(k) for the PathFinder NXT MIS System included both Class I 510(k) exempt instrumentation and those instruments considered to the implant. PathFinder NXT was cleared via 510(k) #K100845 on 21 September 2010.
The Fixed Percutaneous Rod Holder accessory that is the subject of this premarket notification instrument is intended for use with the PathFinder NXT® Pedicle Screw System. This instrument is designed specifically for use with the rod implant component of the PathFinder NXT® Pedicle Screw System and, is considered an accessory to the implant. The Fixed Percutaneous Rod Holder holds and inserts a rod percutaneously through the extender sleeves which are positioned on the implanted screw head.
This 510(k) summary describes a modification to an existing medical device, the PathFinder NXT® Minimally Invasive Pedicle Screw System, specifically an accessory called the Fixed Percutaneous Rod Holder. The submission focuses on demonstrating substantial equivalence to the predicate device, not on proving de novo clinical effectiveness of the entire system.
Here's an analysis of the provided information regarding acceptance criteria and the study that proves the device meets them:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criterion | Reported Device Performance | Comments |
|---|---|---|
| Reliability under anticipated clinical loads | "Design Verification Testing conducted, (1) reliability testing under anticipated clinical loads, ... demonstrated that the proposed device is substantially equivalent to the predicate device." | No specific quantitative metrics or thresholds for "reliability" are provided beyond the statement of substantial equivalence. |
| Fatigue strength under aggressive use simulations (beyond foreseeable misuse) | "...and (2) aggressive use simulations to test the fatigue strength when subjected to excessive loading beyond foreseeable misuse to determine survivability and extent of impact on intended use (function), demonstrated that the proposed device is substantially equivalent to the predicate device." | No specific quantitative metrics or thresholds for "fatigue strength" or "survivability" are provided beyond the statement of substantial equivalence. |
| Material composition | "are both manufactured from the same material (-17-4PH Stainless Steel)" and "the steel utilized for the proposed and unmodified instrument meet the ASTM A-564 'Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes'." | This is a direct comparison to the predicate and a conformity to a recognized standard. |
| Cleaning and Sterilization | "are cleaned and sterilized in the same way with the same parameters" | This is a direct comparison to the predicate. |
| General form and design | "similar designs" and "similar to the predicate version of the instrument in general form" | This is a qualitative comparison to the predicate. |
| Intended Use | "have the same intended use" | This is a direct comparison to the predicate. |
2. Sample Size Used for the Test Set and Data Provenance
This submission does not describe a clinical study with a "test set" in the traditional sense of patient data. The "tests" performed were engineering design verification tests on the device itself. Therefore, the concepts of "sample size for the test set" and "data provenance (e.g., country of origin of the data, retrospective or prospective)" are not applicable to this type of submission.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
There were no human experts used to establish ground truth for a test set of patient data, as this was a device modification and engineering verification testing. The "ground truth" for the performance was established by the physical testing against engineering specifications and comparison to the predicate device. Therefore, this information is not applicable.
4. Adjudication Method for the Test Set
As there was no clinical test set requiring human interpretation or labeling, an adjudication method is not applicable. The "adjudication" in this context would be the internal engineering and regulatory review process by Zimmer Spine, Inc. and ultimately the FDA.
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
This submission does not involve Artificial Intelligence (AI) or reader interpretation of images. It is for a physical medical device (pedicle screw system accessory). Therefore, an MRMC comparative effectiveness study is not applicable.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
This is a physical medical device, not an algorithm or AI system. Therefore, a standalone algorithm performance study is not applicable.
7. The Type of Ground Truth Used
For this device modification, the "ground truth" was established by:
- Engineering Specifications: The design verification tests measured physical properties and performance against defined engineering requirements and tolerances.
- Predicate Device Performance: The primary ground truth for substantial equivalence was the established performance and safety profile of the legally marketed predicate device (PathFinder NXT® Minimally Invasive Pedicle Screw System, #K100845). The modified accessory was deemed equivalent if it performed at least as well as the predicate under specified conditions and did not introduce new safety or effectiveness concerns.
- Industry Standards: Compliance with ASTM A-564 for material specification.
8. The Sample Size for the Training Set
There was no "training set" in the context of machine learning or AI. The design and manufacturing process for a physical device doesn't involve a training set. If interpreted in a broader sense as development and testing, the "samples" would be the prototype devices and test articles subjected to the design verification tests. The exact number of units tested is not specified in the summary but would be detailed in the full design verification report.
9. How the Ground Truth for the Training Set Was Established
As there was no "training set" in the AI sense, this question is not applicable. If referring to the development process of the device itself, the design "ground truth" was established through engineering design processes, material selection based on established standards, and performance goals derived from clinical needs and the performance of the predicate device.
§ 888.3070 Thoracolumbosacral pedicle screw system.
(a)
Identification. (1) Rigid pedicle screw systems are comprised of multiple components, made from a variety of materials that allow the surgeon to build an implant system to fit the patient's anatomical and physiological requirements. Such a spinal implant assembly consists of a combination of screws, longitudinal members (e.g., plates, rods including dual diameter rods, plate/rod combinations), transverse or cross connectors, and interconnection mechanisms (e.g., rod-to-rod connectors, offset connectors).(2) Semi-rigid systems are defined as systems that contain one or more of the following features (including but not limited to): Non-uniform longitudinal elements, or features that allow more motion or flexibility compared to rigid systems.
(b)
Classification. (1) Class II (special controls), when intended to provide 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: severe spondylolisthesis (grades 3 and 4) of the L5-S1 vertebra; degenerative spondylolisthesis with objective evidence of neurologic impairment; fracture; dislocation; scoliosis; kyphosis; spinal tumor; and failed previous fusion (pseudarthrosis). These pedicle screw spinal systems must comply with the following special controls:(i) Compliance with material standards;
(ii) Compliance with mechanical testing standards;
(iii) Compliance with biocompatibility standards; and
(iv) Labeling that contains these two statements in addition to other appropriate labeling information:
“Warning: The safety and effectiveness of pedicle screw spinal systems have been established only for spinal conditions with significant mechanical instability or deformity requiring fusion with instrumentation. These conditions are significant mechanical instability or deformity of the thoracic, lumbar, and sacral spine secondary to severe spondylolisthesis (grades 3 and 4) of the L5-S1 vertebra, degenerative spondylolisthesis with objective evidence of neurologic impairment, fracture, dislocation, scoliosis, kyphosis, spinal tumor, and failed previous fusion (pseudarthrosis). The safety and effectiveness of these devices for any other conditions are unknown.”
“Precaution: The implantation of pedicle screw spinal systems should be performed only by experienced spinal surgeons with specific training in the use of this pedicle screw spinal system because this is a technically demanding procedure presenting a risk of serious injury to the patient.”
(2) Class II (special controls), when a rigid pedicle screw system is intended to provide immobilization and stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion in the treatment of degenerative disc disease and spondylolisthesis other than either severe spondylolisthesis (grades 3 and 4) at L5-S1 or degenerative spondylolisthesis with objective evidence of neurologic impairment. These pedicle screw systems must comply with the following special controls:
(i) The design characteristics of the device, including engineering schematics, must ensure that the geometry and material composition are consistent with the intended use.
(ii) Non-clinical performance testing must demonstrate the mechanical function and durability of the implant.
(iii) Device components must be demonstrated to be biocompatible.
(iv) Validation testing must demonstrate the cleanliness and sterility of, or the ability to clean and sterilize, the device components and device-specific instruments.
(v) Labeling must include the following:
(A) A clear description of the technological features of the device including identification of device materials and the principles of device operation;
(B) Intended use and indications for use, including levels of fixation;
(C) Identification of magnetic resonance (MR) compatibility status;
(D) Cleaning and sterilization instructions for devices and instruments that are provided non-sterile to the end user; and
(E) Detailed instructions of each surgical step, including device removal.
(3) Class II (special controls), when a semi-rigid system is intended to provide immobilization and stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion for any indication. In addition to complying with the special controls in paragraphs (b)(2)(i) through (v) of this section, these pedicle screw systems must comply with the following special controls:
(i) Demonstration that clinical performance characteristics of the device support the intended use of the product, including assessment of fusion compared to a clinically acceptable fusion rate.
(ii) Semi-rigid systems marketed prior to the effective date of this reclassification must submit an amendment to their previously cleared premarket notification (510(k)) demonstrating compliance with the special controls in paragraphs (b)(2)(i) through (v) and paragraph (b)(3)(i) of this section.