The M.U.S.T. Pedicle screws system is intended for posterior non-cervical pedicle fixation (T1-S2/ilium) and non-pedicle fixation, or anterolateral fixation (78-L5). These devices are indicated as an adjunct to fusion for all of the following indications: degenerative disc disease (defined as back pain of discogenic origin with degeneration of the disc confirmed by history and radiographic studies); spondylolisthesis; trauma (i.e., fracture or dislocation); spinal stenosis; curvatures (i.e., scoliosis, kyphosis, and/or lordosis); tumor; pseudoarthrosis; and failed previous fusion in skeletally mature patients.

Device Description

The M.U.S.T. Midline Cortical (MC) Screw System is intended to be used as part of the M.U.S.T. Pedicle Screw system (K12115, K132878, K141988, K153664, K162061, K171170, K171758, K193365) for the stabilization and the fusion of the lumbar and thoracic spine. The M.U.S.T. pedicle screw system includes cannulated or non-cannulated poly-axial pedicle screws (K121115, K132878, K153664), cannulated or non-cannulated mono-axial pedicle screws (K132878), set screws (K121115, K171758), straight and pre-bent rods (K12115, K141988, K162061), lateral connectors (K162061) and cross connectors (K132878, K193365). The M.U.S.T. pedicle screw system also includes the enhanced screws and rods designed for percutaneous surgery (K141988).

The M.U.S.T. Midline Cortical (MC) Screw System introduce new polyaxial screws and reduction screws (solid and cannulated), developed with a focus on Midline Cortical Trajectory approach. The devices subject of this submission are:

M.U.S.T. MC polyaxial screws Solid
M.U.S.T. MC polyaxial screws Cannulated
M.U.S.T. MC polyaxial reduction screws Solid
M.U.S.T. MC polyaxial reduction screws Cannulated

Intended purpose and the performance specification of the devices are equivalent to the ones of the current US cleared portfolio: polyaxial screws are already used in the MUST implant construct.

The M.U.S.T. Midline Cortical (MC) Screws and the Inlay are manufactured from Ti-6Al-4V ELI (ISO 5832-3 Implants for surgery -Metallic materials - Part 3: Wrought titanium 6-vanadium alloy + ASTM F136 Standard Specification for Wrought Titanium-4Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications (UNS R56401); the Tulip and the Setscrew are made of Co-Cr-Mo alloy according to ISO 5832-12:2019, Implants for Surgery - Metallic materials -Part 3: Wrought cobalt-chromium-molybdenum alloy, the same material of the previous cleared M.U.S.T. Pedicle Screw (K153664, K121115, K171170).

AI/ML Overview

Here's an analysis of the provided text regarding the acceptance criteria and study for the M.U.S.T. Midline Cortical (MC) Screw System:

1. Table of acceptance criteria and the reported device performance:

The provided document does not explicitly state specific quantitative acceptance criteria for many of its tests. Instead, it describes various tests performed and implies that the results of these tests met the necessary standards for substantial equivalence. For instance, mechanical evaluations were conducted "according to ASTM F1717-18" without specifying the pass/fail thresholds. The "geometrical analysis" was performed "to ensure that the implant has sufficient fixation" and "in comparison to approved and marketed implants," implying an acceptance of similarity or non-inferiority.

To create a table, I will infer the performance reported based on the conclusion of substantial equivalence.

Evaluation/Test	Acceptance Criteria (Inferred)	Reported Device Performance/Outcome
Non-Clinical Studies
DESIGN VALIDATION
Wetlab (Surgical Technique)	Satisfactory performance and usability by experienced surgeons according to the MUST MC surgical technique.	Performed by 3 experienced surgeons according to MUST MC surgical technique; implies satisfactory validation.
Geometrical Analysis (Implant Fixation)	Sufficient fixation in bone, comparable to approved and marketed implants, concerning important thread dimensions.	Performed in comparison to approved and marketed implants to ensure sufficient fixation; implies comparable and sufficient fixation.
PERFORMANCE TESTING
Worst Case Definition for ASTM F1717	Identification of appropriate implant types and sizes representing the "worst case" for mechanical testing.	Worst case defined for mechanical testing of the spinal construct in a vertebrectomy model.
Mechanical Evaluation (Static Compression Bending)	Compliance with ASTM F1717-18 standard test methods for spinal implant constructs in a vertebrectomy model. (Implicitly meeting or exceeding predicate's performance or standard thresholds).	Performed according to ASTM F1717-18; implies compliance and satisfactory mechanical performance.
Mechanical Evaluation (Dynamic Compression Bending)	Compliance with ASTM F1717-18 standard test methods for spinal implant constructs in a vertebrectomy model. (Implicitly meeting or exceeding predicate's performance or standard thresholds).	Performed according to ASTM F1717-18; implies compliance and satisfactory mechanical performance.
Mechanical Evaluation (Static Torsion)	Compliance with ASTM F1717-18 standard test methods for spinal implant constructs in a vertebrectomy model. (Implicitly meeting or exceeding predicate's performance or standard thresholds).	Performed according to ASTM F1717-18; implies compliance and satisfactory mechanical performance.
PYROGENICITY
Endotoxins-Mediated Pyrogenicity Assessment (Implants)	Assessment indicating acceptable pyrogenicity levels as per documented reports. (Implicitly non-pyrogenic).	"ENDOTOXINS-MEDIATED PYROGENICITY ASSESSMENT REPORT FOR: 'MUST PEDICLE SCREWS IMPLANTS SURGICAL KITS'" (TF VI-PS-01, RAS-01.008.141 Rev. 5, Dated: October 17 2020) was provided.
Endotoxins-Mediated Pyrogenicity Assessment (MC Modular	Assessment indicating acceptable pyrogenicity levels as per documented reports. (Implicitly non-pyrogenic).	"ENDOTOXINS-MEDIATED PYROGENICITY ASSESSMENT FOR: 'MUST MC MODULAR TAP'" (TF VS-PS-01, RAS-01.008.260 Rev. 0, Dated: February 18 2020) was provided.

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

Sample Size:
- Wetlab (Surgical Technique): The "cadaver labs were performed by 3 experienced surgeons." This refers to the number of users of the devices, not a number of distinct device units or anatomical samples tested. The number of cadavers used is not specified.
- Geometrical Analysis: Not specified, but it would involve measurements of the (new) M.U.S.T. MC implants and approved/marketed implants.
- Mechanical Performance Testing (ASTM F1717): Not specified. ASTM F1717 standards generally define specific sample sizes (e.g., minimum of 5 samples per test condition for static tests, 3-6 for dynamic fatigue). The document states "Worst Case definition... for mechanical testing," implying specific samples were chosen.
- Pyrogenicity Assessment: Not specified, but would align with standard biological testing protocols.
Data Provenance (Country of Origin, Retrospective/Prospective): Not explicitly stated. These were non-clinical studies conducted for regulatory submission. Given the manufacturer is Medacta International SA (Switzerland) and its US counterpart Medacta USA, the testing could have been conducted in any accredited lab globally. They are prospective tests conducted on the device components and system.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience):

Number of Experts: 3 experienced surgeons were used for the wetlab (surgical technique validation).
Qualifications of Experts: They are described as "experienced surgeons." No further detailed qualifications (e.g., years of experience, specific sub-specialty) are provided in this document.

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

The document mentions "3 experienced surgeons" performed the wetlab. However, it does not describe an adjudication method for their observations or findings. It simply states the lab was performed "according to MUST MC surgical technique," implying their use was for validation of the technique and device performance, not necessarily for a consensus-driven "ground truth" establishment in the typical sense of diagnostic accuracy.

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, an MRMC comparative effectiveness study was NOT done.
This device is a medical implant (spinal screw system), not an AI/software device that assists human readers. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply to this submission.

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

No, a standalone (algorithm only) performance study was NOT done.
As explained above, this is a physical medical implant, not a software algorithm.

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

For the non-clinical studies:

Wetlab: "Performance by 3 experienced surgeons according to MUST MC surgical technique" implies the ground truth for surgical technique validation was established through expert application/observation and adherence to predefined protocols.
Geometrical Analysis: Ground truth was the geometric properties of approved and marketed implants used for comparison, and engineering specifications.
Mechanical Testing (ASTM F1717): Ground truth was defined by the requirements and methodologies of the ASTM F1717-18 standard and comparisons to the mechanical characteristics of the predicate device.
Pyrogenicity: Ground truth was established by standard biological assessment methods for endotoxins, validated against established limits.

8. The sample size for the training set:

Not applicable. This device is a physical medical implant, not an AI/machine learning model that requires a training set.

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

Not applicable. (See point 8).

Summary

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April 20, 2021

Image /page/0/Picture/1 description: The image shows the logo of the U.S. Food and Drug Administration (FDA). On the left is the Department of Health & Human Services logo. To the right of that is the FDA logo, which consists of the letters "FDA" in a blue square, followed by the words "U.S. FOOD & DRUG ADMINISTRATION" in blue text. The logo is simple and professional, and it is easily recognizable.

Medacta International SA % Mr. Christopher Lussier Senior Director, Quality & Regulatory Medacta USA 3973 Delp Street Memphis. Tennessee 38118

Re: K210427

Trade/Device Name: M.U.S.T. Midline Cortical (MC) Screw System Regulation Number: 21 CFR 888.3070 Regulation Name: Thoracolumbosacral Pedicle Screw System Regulatory Class: Class II Product Code: NKB, KWQ, KWP Dated: February 9, 2021 Received: February 11, 2021

Dear Mr. Lussier:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies.combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807): labeling (21 CFR Part

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801); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

for

Colin O'Neill, M.B.E. Assistant Director DHT6B: Division of Spinal Devices OHT6: Office of Orthopedic Devices Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known)

K210427

Device Name

M.U.S.T. Midline Cortical (MC) Screw System

Indications for Use (Describe)

Type of Use (Select one or both, as applicable)
☒ Prescription Use (Part 21 CFR 801 Subpart D)	☐ Over-The-Counter Use (21 CFR 801 Subpart C)

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510(k) Summary

I. Submitter

Medacta International SA Strada Regina 6874 Castel San Pietro (CH) Switzerland Phone (+41) 91 696 60 60 Fax (+41) 91 696 60 66 Contact Person: Stefano Baj, Regulatory and Compliance Director, Medacta International SA Applicant Correspondent: Chris Lussier, Senior Director of Quality and Regulatory, Medacta USA Date Prepared: February 9, 2021 Date Revised: April 12, 2021

II. Device

Device Proprietary Name:	M.U.S.T. Midline Cortical (MC) Screw System
Common or Usual Name:	Pedicle screw spinal system
Classification Name:	Thoracolumbosacral pedicle screw system
Primary Product Code:	NKB
Secondary Product Code:	KWQ, KWP
Regulation Number:	21 CFR 888.3070, 21 CFR 888.3060, 21 CFR 888.3050
Device Classification:	II

III. Predicate Device

Substantial equivalence is claimed to the following devices:

Primary predicate device:

M.U.S.T. Pedicle Screw System, K171170, Medacta International SA ●
Additional predicate devices:
M.U.S.T. Pedicle Screw System, K121115, Medacta International SA
M.U.S.T. Pedicle Screw System, K153664, Medacta International SA ●
M.U.S.T. Combined Set Screws, K171758, Medacta International SA ●
Valeo Pedicle Screw System, K072022, Amedica Corp.

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IV. Device Description

M.U.S.T. MC polyaxial screws Solid ●
M.U.S.T. MC polyaxial screws Cannulated ●
M.U.S.T. MC polyaxial reduction screws Solid ●
M.U.S.T. MC polyaxial reduction screws Cannulated

Intended purpose and the performance specification of the devices are equivalent to the ones of the current US cleared portfolio: polyaxial screws are already used in the MUST implant construct.

V. Indications for Use

The M.U.S.T. Pedicle screws system is intended for posterior non-cervical pedicle fixation (T1-S2/ilium) and non-pedicle fixation, or anterolateral fixation (T8-L5). These devices are indicated as an adjunct to fusion for all of the following indications: degenerative disc disease (defined as back pain of discogenic origin with degeneration of the disc confirmed by history and radiographic studies); spondylolisthesis; trauma (i.e., fracture or dislocation); spinal stenosis; curvatures (i.e., scoliosis, and/or lordosis); tumor; pseudoarthrosis; and failed previous fusion in skeletally mature patients.

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VI. Comparison of Technological Characteristics

The new M.U.S.T. Midline Cortical (MC) Screws and the predicate devices (K153664, K12115, K171170) share the following characteristics:

indication for use; ●
screw shaft dimensions; ●
screw and inlay material (Ti6Al4V ELI);
tulip and setscrew material (CoCrMo) ●
setscrew (cleared through K171758) ●
through hole diameter (applicable to cannulated versions);
biocompatibility;
. device usage;
sterility;
shelf life;
packaging. ●

The difference between the M.U.S.T. Midline Cortical (MC) Screws and the predicate devices are:

Tulip dimensions;
Screw thread, Spherical Head dimensions and recess.

VII. Performance Data

The introduction of the M.U.S.T. Midline Cortical (MC) Screw components into M.U.S.T. - Pedicle Screw System portfolio was evaluated by risk analysis to identify any new risks associated with the change. Based on the risk analysis, design verification was conducted to written protocols with predefined acceptance criteria. The protocols and pre-defined acceptance criteria were based on the standards, FDA guidance, and comparison to the predicate device system.

The following validation and tests are being provided in support of the substantial equivalence determination:

Non-Clinical Studies

DESIGN VALIDATION
- o A wetlab has been performed to validate the MUST MC implants and related instruments. The cadaver labs were performed by 3 experienced surgeons according to MUST MC surgical technique

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Geometrical Analysis MUST MC implants: To ensure that the implant has sufficient O fixation in the bone, a geometrical analysis was performed in comparison to approved and marketed implants, related to the most important dimensions of the threads.

PERFORMANCE TESTING ●

Worst Case definition for ASTM F1717 testing: discussion of implant types and sizes, chosen O as the worst case for mechanical testing of the spinal construct in a vertebrectomy model.
Mechanical evaluation under static compression bending to ASTM F1717-18 o Standard test methods for Spinal Implants Construct in a Vertebrectomy model
Mechanical evaluation under dynamic compression bending according to ASTM F1717-18 O Standard test methods for Spinal Implants Construct in a Vertebrectomy model
Mechanical evaluation under static torsion according to ASTM F1717-18 Standard test о methods for Spinal Implants Construct in a Vertebrectomv model
PYROGENICITY ●
- o ENDOTOXINS-MEDIATED PYROGENICITY ASSESSMENT REPORT FOR: "MUST PEDICLE SCREWS IMPLANTS SURGICAL KITS" TF VI-PS-01, RAS-01.008.141 Rev. 5, Dated: October 17 2020
- ENDOTOXINS-MEDIATED PYROGENICITY ASSESSMENT FOR: "MUST MC o MODULAR TAP" TF VS-PS-01, RAS-01.008.260 Rev. 0, Dated: February 18 2020.

Clinical Studies:

No clinical studies were conducted. ●

Conclusion VIII.

Based on the above information, the M.U.S.T. Midline Cortical (MC) Screws are substantially equivalent to the identified predicate devices.

Substantial equivalence has been demonstrated through a comparison of intended use, design and technological characteristics, as well as performance evaluations.

Regulation Number and Section

§ 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.