(255 days)
The xvision Spine System, with xvision System Software, is intended as an aid for precisely locating anatomical structures in either open or percutaneous spine procedures. Their use is indicated for any medical condition in which the use of stereotactic surgery may be appropriate, and where reference to a rigid anatomical structure, such as the spine, can be identified relative to CT imagery of the anatomy. This can include the spinal implant procedures, such as Posterior Pedicle Screw Placement in the thoracic and sacro-lumbar region.
The Headset of the xvision Spine System displays 2D stereotaxic screens and a virtual anatomy screen. The stereotaxic screen is indicated for correlating the tracked instrument location to the registered patient imagery. The virtual screen is indicated for displaying the virtual instrument location to the virtual anatomy to assist in percutaneous visualization and trajectory planning.
The virtual display should not be relied upon solely for absolute positional information and should always be used in conjunction with the displayed stereotaxic information.
The xvision Spine (XVS) system is an image-guided navigation system that is designed to assist surgeons in placing pedicle screws accurately, during open or percutaneous computer-assisted spinal surgery. The system consists of a dedicated software, Headset, single use passive reflective markers and reusable components. It uses wireless optical tracking technology and displays to the surgeon the location of the tracked surgical instruments relative to the acquired intraoperative patient's scan, onto the surgical field. The 2D scanned data and 3D reconstructed model, along with tracking information, are projected to the surgeons' retina using a transparent near-eye-display Headset, allowing the surgeon to both look at the patient and the navigation data at the same time.
The provided text describes the performance data and testing conducted for the xvision Spine system, particularly focusing on its accuracy in guiding pedicle screw placement.
Here's an analysis of the acceptance criteria and the study proving the device meets them, based on the provided document:
1. Acceptance Criteria and Reported Device Performance
The core acceptance criteria for the xvision Spine system relate to its positional and trajectory angle accuracy. The document implicitly sets these criteria by comparing the device's performance to the predicate device and by reporting the mean errors and 99% Upper Bound Limits (UBLs).
| Metric | Acceptance Criteria (Implied) | Reported Device Performance (Phantom Study) | Reported Device Performance (Cadaver Study) |
|---|---|---|---|
| Overall Positional Error | ≤ 2.0 mm (Mean) | 0.63 - 0.954 mm (Mean) | 1.98 mm (Mean) |
| ≤ 1.12 mm (99% UBL) | 2.22 mm (99% UBL) | ||
| Overall Trajectory Angle Error | ≤ 2° (Mean) | 0.468 - 0.683° (Mean) | 1.3° (Mean) |
| ≤ 1.08° (99% UBL) | 1.47° (99% UBL) |
Note: The document explicitly states: "Thus, the system has demonstrated performance in 3D positional accuracy with a mean error statistically significantly lower than 3mm and in trajectory angle accuracy with a mean error statistically significantly lower than 3 degrees, in phantom and cadaver studies." However, the "System Accuracy Requirement" for the device, as listed in the comparison table with the predicate, is 2.0mm positional error and 2° trajectory error. The reported performance is compared to this requirement rather than a broader 3mm/3degree standard. Therefore, the "Acceptance Criteria" column above reflects the stricter "System Accuracy Requirement" from the comparison table.
2. Sample Size Used for the Test Set and Data Provenance
- Phantom Study: The sample size for the phantom study is not explicitly stated in terms of the number of measurements or trials. However, it involved testing under "different conditions simulating clinical conditions such as: Headset mounted statically and Headset moving above the markers, different distances between the Headset and the markers, and different angles" and using two Z-link markers (Z1 and Z2).
- Cadaver Study: The sample size is not explicitly stated for the cadaver study either, but it involved positioning pedicle screws percutaneously in "thoracic and sacro-lumbar vertebrae." The number of cadavers or screws tested is not provided.
- Data Provenance:
- Phantom Study: The data provenance is laboratory bench testing. The country of origin is not specified, but the applicant company is located in Israel (Augmedics Ltd.).
- Cadaver Study: The data provenance is from a cadaver study. The country of origin is not specified. This would be considered a prospective study as it involves active experimentation.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
- The document does not specify the number of experts or their qualifications for establishing ground truth in either the phantom or cadaver studies.
- For the cadaver study, the ground truth for positional error was derived from "the post-op scan," and for trajectory error, it was a "recorded planned/virtual trajectory." It implies an objective measurement rather than expert consensus on anatomical landmarks.
4. Adjudication Method for the Test Set
- The document does not describe any adjudication method (e.g., 2+1, 3+1, none) for the test sets. The ground truth appears to be based on direct measurements and pre-defined plans rather than subjective assessments requiring adjudication.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- A Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not conducted. The studies focused on the accuracy of the device itself (standalone performance and cadaver-assisted performance), not on the improvement in human reader performance with or without AI assistance. The device is a navigation system, assisting surgeons during procedures, not an AI-assisted diagnostic tool for human readers.
6. Standalone (Algorithm Only) Performance
- Yes, the performance data presented primarily focuses on the standalone performance of the xvision Spine system, particularly its accuracy. The "Bench testing" results demonstrate the algorithm's accuracy in a controlled environment, and the "cadaver study" validates this accuracy in a more realistic anatomical setting, demonstrating the system's ability to guide screw placement. The focus is on the precision of the stereotaxic instrument, not on human interpretation or analysis.
7. Type of Ground Truth Used
- Phantom Study: The ground truth was established through known mechanical positions and precisely defined settings within the phantom, allowing for objective measurement of error from a pre-defined ideal.
- Cadaver Study: The ground truth for positional error was derived from the post-operative scan (objective imaging data), and for trajectory error, it was compared to the recorded planned/virtual trajectory (pre-defined objective plan).
8. Sample Size for the Training Set
- The document does not provide any information regarding a training set or its sample size. This is a medical device for surgical guidance, not a machine learning model that typically requires a separate training set. The descriptions focus on the validation of the system's accuracy and performance.
9. How the Ground Truth for the Training Set Was Established
- Since no training set is mentioned or implied for this type of medical device validation, there is no information on how ground truth for a training set was established.
§ 882.4560 Stereotaxic instrument.
(a)
Identification. A stereotaxic instrument is a device consisting of a rigid frame with a calibrated guide mechanism for precisely positioning probes or other devices within a patient's brain, spinal cord, or other part of the nervous system.(b)
Classification. Class II (performance standards).