Minimally invasive reconstruction of fractures and joints; Adjuvant for osteosynthesis in complex joint fractures; Multifragment joint fractures; Simple metaphyseal fractures of the wrist, ankle, elbow, and shoulder, Condylar fractures; Osteochrondriis dissecans, Ostero-Chondral Fractures, Ligament avulsion injuries, Ligament fixation, Other small fragment, cancellous bone fractures, Small joint fusion. Areas where accurate sorew placement is vital. Metatarsal and phalangeal osteotomies; Fractures of the tarsals, metatarsals and other fractures of the foot; Avulsion fractures and fractures of metatarsal V; Tarso-metatarso-phalangeal arthrodesis; Tarsal Fusions; Calcaneal and talar fractures, Subtalar arthrodesis. Ankle arthrodesis. Fractures of small joints, such as: Ankle fractures, Fractures of the fibula, malleolus, and calcaneus, Distal tibia and pilon fractures, Acetabular fractures of the pelvic ring; Fractures of the femoral head and neck, Supracondylar femoral fractures, Slipped capital femoral epiphyses, An adjunct to DHIS in basilar neck fractures, Intractures, Intracapsular fractures of the hip, Fractures of the distal femur and proximal tibia, Patellar fractures. Small fragments of the hand and wrist, Fractures of the carpals and metacarpals, Carnal and metacarpal arthrodesis. Scaphoid fracture and other fractures of the hand, Phalangeal and interphalangeal fractures of the ulna and radius. Radial head fractures. Fractures of the olecranon and distal humeral head fractures, Ligament fixation at the proximal humerus, Glenoid fractures.

Device Description

The S4 Screw System is collection of cannulated, headless screws having fenestrations on the head and within the thread pitch.

AI/ML Overview

This document, a 510(k) Summary for the S4 Screw System, does not describe a study that uses AI or machine learning technology. It pertains to a physical medical device (bone screws) and its mechanical properties.

Therefore, many of the requested elements regarding acceptance criteria for an AI/ML device and the details of a study proving its performance (e.g., sample size for test/training sets, expert ground truth, MRMC studies) are not applicable to the content provided.

The document focuses on non-clinical performance testing (bench tests) and comparisons to predicate devices for substantial equivalence, which is typical for Class II devices like bone screws.

Here's an analysis based on the information provided in the document, framed by what would be relevant if it were an AI/ML device, to highlight why the full set of questions cannot be answered:

Based on the provided FDA 510(k) Summary for the S4 Screw System (K191995), the following information can be extracted regarding its acceptance criteria and the study proving it meets them:

Note: This submission does not involve an AI/ML device. Therefore, the concepts of a "test set," "training set," "ground truth experts," "adjudication methods," or "MRMC studies" as they apply to software-based diagnostic or prognostic devices are not relevant or described in this document. The "study" mentioned refers to non-clinical bench testing of the physical screw system.

1. Table of Acceptance Criteria and Reported Device Performance:

For a physical device like a bone screw, "acceptance criteria" are typically defined by engineering standards to ensure its mechanical integrity and safety. "Performance" refers to the results of tests against these standards.

Acceptance Criterion (Standard)	Reported Device Performance (Summary)
Mechanical Performance:
ASTM F543 (Standard Specification and Test Methods for Metallic Medical Bone Screws)	Tested per ASTM F543.
- Torsional Properties	Testing performed. (Specific values/pass criteria not detailed in the summary, implied to meet standard requirements).
- Insertion and Removal Torque	Testing performed. (Specific values/pass criteria not detailed).
- Pullout Strength	Testing performed. (Specific values/pass criteria not detailed).
Biocompatibility/Material Composition:
ASTM F136-13 (Ti-6Al-4V ELI)	Material specified to meet this standard.
ASTM F899-12b (Stainless Steel)	Material specified to meet this standard.
ASTM F1185-03 (Hydroxyapatite)	Material specified to meet this standard; information referenced in Master File.
Sterilization Efficacy:
ISO 11137-1:2017 (Radiation Sterilization)	Sterilization validation study completed. (Implied to meet standard requirements).
Packaging Integrity:
Packaging Performance Study	Packaging performance study completed to validate packaging performance. (Implied to meet standard requirements).
Risk Assessment:
(FMEA for modified intended use, additional sizes, HA coating)	Analysis determined modifications resulted in an acceptable low risk category.

2. Sample Size Used for the Test Set and Data Provenance:

Sample Size (Test Set): Not explicitly stated in terms of number of screws tested for each mechanical property. For bench testing, samples are typically specific numbers of manufactured devices.
Data Provenance: The studies are non-clinical, bench-top laboratory tests conducted by the manufacturer, Subchondral Solutions, Inc. No information regarding country of origin of data (beyond the company's US location) or retrospective/prospective nature is applicable in the context of human clinical data.

3. Number of Experts Used to Establish Ground Truth and Their Qualifications:

Not applicable. For a physical device, "ground truth" is established through adherence to national/international engineering standards and validated test methods, not by expert interpretation of data or images.

4. Adjudication Method for the Test Set:

Not applicable. This concept relates to resolving disagreements among human readers or annotators for ground truth in AI/ML performance studies.

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

No, this was not done. MRMC studies are specific to evaluating the clinical performance of diagnostic or screening devices, often involving human readers and potentially AI assistance. This submission is for a physical orthopedic implant.

6. Standalone (Algorithm Only) Performance:

Not applicable. This refers to the performance of an AI algorithm without human intervention. The S4 Screw System is a physical device, not an algorithm.

7. Type of Ground Truth Used:

For this physical device, "ground truth" is defined by engineering specifications, material science standards, and established mechanical test methodologies (e.g., ASTM F543). It is not derived from expert consensus, pathology, or outcomes data in the way an AI/ML diagnostic would be.

8. Sample Size for the Training Set:

Not applicable. There is no "training set" as this is not an AI/ML device.

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

Not applicable. No training set exists for this type of device.

In summary, the provided document details the mechanical, material, and sterilization validation of a bone screw system (S4 Screw System) through non-clinical bench testing against established industry standards for similar devices. It does not contain any information relevant to the development, validation, or performance of an AI/ML driven medical device.

Summary

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April 18, 2020

Image /page/0/Picture/1 description: The image contains the logo of the U.S. Food and Drug Administration (FDA). On the left, there is a symbol representing the Department of Health & Human Services - USA. To the right of this symbol, there is the FDA logo, which includes the letters 'FDA' in a blue square, followed by the words 'U.S. FOOD & DRUG' and 'ADMINISTRATION' in blue text.

Subchondral Solutions, Inc. Michael Kolber Consultant 147 Hillbrook Drive Los Gatos, California 95032

Re: K191995

Trade/Device Name: S4 Screw System Regulation Number: 21 CFR 888.3040 Regulation Name: Smooth Or Threaded Metallic Bone Fixation Fastener Regulatory Class: Class II Product Code: HWC Dated: July 19, 2019 Received: July 26, 2019

Dear Michael Kolber:

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

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requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 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 (OS) 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 mediation-emitting products, including information about labeling regulations, please see Device Advice (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,

Shumaya Ali, MPH Assistant Director DHT6C: Division of Restorative, Repair and Trauma 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) K191995

Device Name S4 Screw SystemTM

Indications for Use (Describe)

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

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510(k) Summary

510(k) Number K191995

Submitter Name and Address

Name:	Subchondral Solutions, Inc.
Contact:	Michael Kolber
	Consultant, Regulatory Affairs
Address:	147 Hillbrook Drive
	Los Gatos, CA 95032
Telephone:	408-505-6626
Date Prepared:	April 16, 2020

General Device Information

Product Name:	S4 Screw System™
Common Name:	Bone Screw System
Classification:	21CFR888.3040, Smooth or threaded bone fixation fastener
Device Class:	Class II
Product Code:	HWC

Predicate Devices

Primary Predicate:	Subchondral Solutions, Inc. S4 Screw System (K162171)
Additional Predicates:	Acumed Cannulated Screw System (K123890)Medacta International M.U.S.T. Sacral Iliac Screw and Pelvic TraumaSystem (K171595)
Reference Devices:	Newclip Technics (K160617)Tyber Medical, Trauma Screw (K153575)

Device Description

The S4 Screw System is collection of cannulated, headless screws having fenestrations on the head and within the thread pitch.

Intended Use (Indications)

The S4 Screw System consists of screws and accessories and is generally intended for fixation of fracture, fusion and osteotomies of large and small bones appropriate for size of device. These large and small bones may include the following:

Minimally invasive reconstruction of fractures and joints; Adjuvant for osteosynthesis in complex joint fractures: Multifragment joint fractures; Simple metaphyseal fractures of the wrist, ankle, elbow, and shoulder, Condylar fractures; Osteochrondritis dissecans, Ostero-Chondral Fractures, Ligament avulsion injuries, Ligament fixation, Other small fragment, cancellous bone fractures. Small joint fusion. Areas where accurate screw placement is vital. Metatarsal and phalangeal osteotomies; Fractures of the tarsals, metatarsals and other fractures of the foot; Avulsion fractures and fractures of metatarsal V; Tarso-metatarsal and metatarso

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phalangeal arthrodesis; Tarsal Fusions; Calcaneal and talar fractures, Subtalar arthrodesis, Ankle arthrodesis. Fractures of small joints, such as: Ankle fractures, Navicular fractures of the fibula, malleolus, and calcaneus, Distal tibia and pilon fractures, Acetabular fractures. Other fractures of the pelvic ring; Fractures of the femoral head and neck, Supracondylar femoral fractures, Slipped capital femoral epiphyses, An adjunct to DHIS in basilar neck fractures, Intercondylar femur fractures, Intracapsular fractures of the hip, Fractures of the distal femur and proximal tibia, Patellar fractures, Tibial plateau fractures. Small fragments of the hand and wrist, Fractures of the carpals and metacarpals, Carnal and metacarpal arthrodesis, Scaphoid fracture and other fractures of the hand, Phalangeal and interphalangeal fractures of the ulna and radius. Radial head fractures . Fractures of the olecranon and distal humerus, Humeral head fractures, Ligament fixation at the proximal humerus, Glenoid fractures.

Comparison of Technology

The S4 Screw System (subject device) has a modified intended use compared to the predicate device, but identical to the Acumed Cannulated Screw System.

Also, additional sizes have been added (reference devices Newclip Technics, K160617 and Tyler Medical, K153575), as well as the optional addition of hydroxyapatite (HA) coating (additional predicate device Medacta Intl., K171595). The purpose of the additional sizes is to enable to repair larger bones, as appropriate for the size of the device. The purpose of the HA coating is to improve bone growth.

Summary of Non-Clinical Performance Testing Bench Test

Mechanical testing of the S4 Screw System was performed, per ASTM F543. The selected tests include Torsional Properties, Insertion and Removal Torque, and Pullout Strength. In addition, information about the hydroxyapatite-coating is referenced in the Master File.

Packaging and Sterilization

A packaging performance study was completed to validate packaging performance. Also, a sterilization validation study was also completed.

Risk Assessment/Analysis

A Failure Modes and Effects Analysis (FMEA) was used to assess changes made to the subject S4 Screw System compared to the predicate S4 Screw System with regard to the modified intended use, as well as the additional sizes and HA coating. The analysis determined that the modifications resulted in an acceptable low risk category.

Referenced Standards

ASTM F136-13 -	Standard Specification for Wrought Titanium-6Aluminum-4Vanadium ELI(Extra Low Interstitial) Alloy for Surgical Implant Applications (UNSR56401)
ASTM F899-12b -	Standard Specification for Stainless Steel for Surgical Instruments.
ASTM F1185-03 -	Standard Specification for Composition of Hydroxyapatite for SurgicalImplants

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Standard Specification and Test Methods for Metallic Medical Bone ASTM F543-17 -Screws
ISO 11137-1:2017 Sterilization of health care products Radiation Part 1: Requirement for device validation and routine control of a sterilization process for medical devices

Statement of Equivalence

Based on similarities in indications for use and technological characteristics, as well as nonclinical performance testing, we believe the S4 Screw System is substantially equivalent to the predicate devices.

Regulation Number and Section

§ 888.3040 Smooth or threaded metallic bone fixation fastener.

(a)
Identification. A smooth or threaded metallic bone fixation fastener is a device intended to be implanted that consists of a stiff wire segment or rod made of alloys, such as cobalt-chromium-molybdenum and stainless steel, and that may be smooth on the outside, fully or partially threaded, straight or U-shaped; and may be either blunt pointed, sharp pointed, or have a formed, slotted head on the end. It may be used for fixation of bone fractures, for bone reconstructions, as a guide pin for insertion of other implants, or it may be implanted through the skin so that a pulling force (traction) may be applied to the skeletal system.(b)
Classification. Class II.