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The LOADPRO™ Intraoperative Rod Strain Sensor is an intraoperative surgical tool that allows surgeons to measure unidirectional rod microstrain on posterior rods in the sagittal plane when performing spine surgery. This device is an adjunct to surgeon tactile feedback and is not intended to replace a surgeon's clinical judgment.

The LOADPRO™ Intraoperative Rod Strain Sensor is a single use, disposable tool to be used in conjunction with X-Spine Systems Fortex Pedicle Screw System for 5.5mm diameter titanium (ASTM F136) or cobalt chrome (ASTM F1537) rod configurations.

The LOADPRO™ Intraoperative Rod Strain Sensor includes a titanium/zirconia ceramic, single use strain sensing device, which includes radio-frequency identification (RFID) technology (13.56MHz), intended to enable access to strain measurement values, incorporating a passive transponder, inserter, and scanner (Figure 1 and 2). The transponder attaches to X-Spine Systems Fortex Pedicle Screw System using 5.5mm titanium alloy or cobalt chrome rods in corrective spinal surgeries (Figure 3). The transponder is used only to acquire rod microstrain values and a unique device identification code, which is read by the scanner, during the surgical correction.

The LOADPRO™ Intraoperative Rod Strain Sensor is a titanium/zirconia ceramic, ethylene oxide (EtO) sterilized, single use device designed to provide objective readings of the change of mechanical unidirectional strain on a pedicle screw rod. The LOADPRO™ Intraoperative Rod Strain Sensor consists of the following primary components, described in the proceeding sections:

• LOADPROTM Intraoperative Rod Strain Sensor ●
• . Hand Held Reader (scanner)
• . Manual Orthopaedic Surgical Instrumentation

Here's a breakdown of the acceptance criteria and the study information for the LOADPRO™ Intraoperative Rod Strain Sensor, based on the provided text:

Acceptance Criteria and Reported Device Performance

Note: The provided document does not explicitly present a "table of acceptance criteria and the reported device performance" in the format of a direct comparison for all performance metrics. Instead, it describes various tests and their successful outcomes against implied or stated criteria. The table below synthesizes the information available.

Study Details

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

• Rod Durability Testing (Dynamic): Not explicitly stated, but performed on "non-sensored rods and on sensored rods after fifteen (15) LOADPRO™ Intraoperative Rod Strain Sensor installations / removals were performed at the same location."
• Rod Durability Testing (Static): 3 samples per group (non-sensored vs. sensored).
• Sensor Variability Testing: The graph shows 6 different sensors (SN 1, SN 2, SN 4, SN 5, sn 3, SN 9).
• Accuracy and Repeatability Testing: "All tested Sensors" passed (implied multiple sensors). Specific tables for Ti and CoCr show redacted serial numbers, implying multiple units per rod type.
• Usability Study (Table Top): 15 users (orthopedic spine surgeons and fellows).
• Usability Study (Intraoperative): 5 patients/surgeries (one patient had surgery over two separate days, resulting in 6 surgeries), 4 participating surgeons, 13 sensors used.
• Data Provenance: Not explicitly stated (e.g., country of origin). The studies appear to be prospective bench testing and a prospective intraoperative usability study.

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

• Bench Testing (Rod Durability, Sensor Characterization, Accuracy): Ground truth was established by comparing the LOADPRO™ sensor readings to established mechanical testing methods and reference strain gauges. No human experts were involved in establishing the "ground truth" for these physical measurements, as the measurements are objective.
• Usability Testing (Table Top): 15 practicing orthopedic spine surgeons and fellows. Their "feedback" was the ground truth for usability, graded on a modified usability scale.
• Usability Testing (Intraoperative): 4 participating surgeons. Their feedback, related to operative time and blood loss, contributed to the usability assessment.

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

• Bench Testing: Not applicable, as objective physical measurements were taken. Discrepancies would be resolved by re-testing or calibration.
• Usability Testing (Table Top): A specific scoring system was used (1-5 scale converted to 0-100, with an adjusted total score of 70 or greater as acceptable). A score less than 70 would "require a review by the sponsor and adjustment based on the user's feedback." This implies a form of internal review or adjudication if criteria were not met.
• Usability Testing (Intraoperative): The text indicates "surgeon feedback" was used, but does not detail a formal adjudication method for that feedback.

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

• No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This device is an intraoperative strain sensor, not an AI-powered diagnostic tool. It provides objective measurements and is an "adjunct to surgeon tactile feedback," not a replacement or an AI assistance tool for image interpretation. Therefore, discussions of "human readers" or "AI assistance" are not applicable in this context.

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

• Yes, the performance testing for the LOADPRO™ Intraoperative Rod Strain Sensor largely represents standalone performance. The various bench tests (Rod Durability, Sensor Limit, Sensor Variability, Sensor Longevity, Sensor Temperature Variability, Reader Duration, Accuracy and Repeatability) assessed the device's ability to accurately and reliably measure strain and function independently. The usability studies, while involving surgeons, focused on their interaction with the device and the device's impact on the procedure, rather than the device's performance being dependent on their interpretation for its core function. The "algorithm" here is the embedded software that processes strain data, and its direct performance was verified.

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

• Mechanical Performance (Rod Durability, Sensor Characterization, Accuracy, etc.): The ground truth was established through objective physical measurements using established metrology and standards. This typically involves calibrated load cells, reference strain gauges, and standardized test fixtures (e.g., ASTM F1717-13, ASTM F2193-2).
• Software Verification: Ground truth was based on the functional specifications of the software.
• Biocompatibility, EMC, Sterilization, Shelf Life: Ground truth was based on international standards and validated test methods (e.g., ISO 10993-5, EN 60601-1, IEC 60601-1-2, ISO 11135, ASTM F1980-07, AAMI ST79, ISO17665-1).
• Usability Testing: Ground truth was based on end-user (surgeon) feedback against a predefined usability scale and qualitative observations regarding operative time and blood loss.

8. The sample size for the training set

• Not applicable. The LOADPRO™ Intraoperative Rod Strain Sensor is a physical measurement device with embedded software, not a machine learning or AI algorithm that requires a separate "training set" in the conventional sense. The "training" for the device's functionality would be its design, calibration, and manufacturing process.

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

• Not applicable, as there is no "training set" for an AI/ML algorithm. The device's calibration and design are based on fundamental physics and engineering principles, validated through benchmark testing against known physical standards.

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