The Unity™ Total Knee System is intended for use in total knee arthroplasty in skeletally mature patients, to provide increased mobility and reduce pain by replacing the damaged knee joint articulation where there is evidence of sufficient sound bone to seat and support the components. General total knee arthroplasty indications include: • Painful, disabling joint disease of the knee resulting from: degenerative arthritis, rheumatoid arthritis or post-traumatic arthritis • Post-traumatic loss of knee joint configuration and function • Moderate varus, valgus, or flexion deformity in which the ligamentous structures can be returned to adequate function • Revision of previous unsuccessful knee replacement or other procedure, where soft tissue stability is adequate • Fracture of the distal femur and/or proximal tibia that cannot be stabilized by standard fracture management techniques • The posterior stabilized variant is also indicated for PCL instability requiring implant bearing surface geometries with increased anterior-posterior constraint and absent or non-functioning posterior cruciate ligament The Unity™ Total Knee System is indicated for cemented use, single use only.
Device Story
Unity Total Knee System is a fixed-bearing knee prosthesis for total knee arthroplasty. System components include cobalt chromium (CoCr) femoral component, UHMWPE tibial insert, CoCr tibial tray with titanium alloy keel, and optional all-polyethylene patellar component. Variants include cruciate retaining (CR) and posterior stabilized (PS). System includes titanium alloy augments and stem extensions for bone loss management. Used in clinical settings by orthopedic surgeons to replace damaged knee joint articulation, reduce pain, and increase mobility. Components are cemented and for single use. Output is a reconstructed knee joint articulation. Benefits include restoration of joint function and stability in patients with degenerative or traumatic knee conditions.
Clinical Evidence
No clinical data. Substantial equivalence determined via non-clinical bench testing, including torsional assembly, torsional disassembly, cyclic disassembly, and cyclic fretting per ASTM F1814-15, and cyclic testing per ASTM F1800-12. Bacterial Endotoxin Testing (BET) performed using LAL kinetic chromogenic methodology.
Indicated for skeletally mature patients undergoing total knee arthroplasty due to painful, disabling joint disease (degenerative, rheumatoid, or post-traumatic arthritis), post-traumatic loss of function, moderate varus/valgus/flexion deformity, revision of unsuccessful knee replacement, or distal femur/proximal tibia fractures. Posterior stabilized variant indicated for PCL instability or absent/non-functioning PCL. Contraindicated if insufficient bone stock to support components or inadequate soft tissue stability.
Regulatory Classification
Identification
A knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented prosthesis is a device intended to be implanted to replace a knee joint. The device limits translation and rotation in one or more planes via the geometry of its articulating surfaces. It has no linkage across-the-joint. This generic type of device includes prostheses that have a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a tibial component or components and a retropatellar resurfacing component made of ultra-high molecular weight polyethylene. This generic type of device is limited to those prostheses intended for use with bone cement (§ 888.3027).
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January 17, 2018
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 is a blue square with the letters "FDA" in white. To the right of the blue square is the text "U.S. FOOD & DRUG ADMINISTRATION" in blue.
Corin USA Limited Lorraine Mander Regulatory Affairs Associate 12750 Citrus Park Lane Tampa, Florida 33625
Re: K173884
Trade/Device Name: Unity Total Knee System Regulation Number: 21 CFR 888.3560 Regulation Name: Knee Joint Patellofemorotibial Polymer Semi-Constrained Cemented Prosthesis Regulatory Class: Class II Product Code: JWH Dated: December 20, 2017 Received: December 21, 2017
Dear Lorraine Mander:
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. 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 801); medical device reporting of medical device-related adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (OS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
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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 http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.
For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/) and CDRH Learn (http://www.fda.gov/Training/CDRHLearn). 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 (http://www.fda.gov/DICE) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).
Sincerely,
# Katherine D. Kavlock -S
for Mark N. Melkerson Director Division of Orthopedic Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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| DEPARTMENT OF HEALTH AND HUMAN SERVICES | |
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| Food and Drug Administration | |
| <b>Indications for Use</b> | |
| Form Approved: OMB No. | 0910-0120 |
| Expiration Date: | 06/30/2020 |
| See PRA Statement below. | |
| 510(k) Number (if known) | K173884 |
| Device Name | Unity Total Knee System |
| Indications for Use (Describe) | The Unity™ Total Knee System is intended for use in total knee arthroplasty in skeletally mature patients, to provide increased mobility and reduce pain by replacing the damaged knee joint articulation where there is evidence of sufficient sound bone to seat and support the components. |
| General total knee arthroplasty indications include: | |
| • Painful, disabling joint disease of the knee resulting from: degenerative arthritis, rheumatoid arthritis or post-traumatic arthritis | |
| • Post-traumatic loss of knee joint configuration and function | |
| • Moderate varus, valgus, or flexion deformity in which the ligamentous structures can be returned to adequate function | |
| • Revision of previous unsuccessful knee replacement or other procedure, where soft tissue stability is adequate | |
| • Fracture of the distal femur and/or proximal tibia that cannot be stabilized by standard fracture management techniques | |
| • The posterior stabilized variant is also indicated for PCL instability requiring implant bearing surface geometries with increased anterior-posterior constraint and absent or non-functioning posterior cruciate ligament | |
| The Unity™ Total Knee System is indicated for cemented use, single use only. | |
| Type of Use (Select one or both, as applicable) | <div> <label><input checked="checked" type="checkbox"/> Prescription Use (Part 21 CFR 801 Subpart D)</label> </div> <div> <label><input type="checkbox"/> Over-The-Counter Use (21 CFR 801 Subpart C)</label> </div> |
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FORM FDA 3881 (7/17)
Page 1 of 1
PSC Publishing Services (301) 443-6740 EF
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| 1. Applicant/Sponsor:<br>Distributor | Corin USA<br>12750 Citrus Park Lane<br>Suite 120<br>Tampa, Florida 33625<br>Establishment Registration No.: 1056629 |
|--------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 2. Contact Person: | Lorraine Mander<br>Regulatory Affairs Associate<br>Corin Limited<br>+44 1285 884761<br><a href="mailto:lorraine.mander@coringroup.com">lorraine.mander@coringroup.com</a><br>Lucinda Gerber<br>Global Regulatory Affairs Manager<br>Corin Limited / Corin USA<br>1 (772) 321-2478<br><a href="mailto:lucinda.gerber@coringroup.com">lucinda.gerber@coringroup.com</a> |
| 3. Date: | December 20, 2017 |
| 4. Proprietary Name: | Unity™ Total Knee System |
| 5. Common Name: | Knee Prosthesis |
| 6. Product Code(s): | JWH |
| 7. Classification Name: | Knee joint patellofemorotibial polymer/metal/polymer semi- constrained<br>cemented prosthesis (21CFR888.3560) |
# 3. 510(K) SUMMARY
- 8. Legally Marketed Devices to which Substantial Equivalence is claimed:
- Unity™ Total Knee System (K113060) .
# 9. Device Description:
The Unity Knee™ is a fixed bearing total knee replacement system that consists of a cobalt chromium alloy (CoCr) femoral component, a UHMWPE polyethylene tibial insert, a cobalt chromium Alloy (CoCr) tibial tray with a titanium alloy keel extension and all-polyethylene patellar component for use in primary total knee arthroplasty. The Unity Knee™ is provided in two variants, cruciate retaining (CR) and posterior stabilized (PS). The Unity Knee™ CR is intended for use in instances where the posterior cruciate ligament (PCL) is functional. The Unity Knee™ PS variant is utilized when a total knee replacement is indicated, and the posterior cruciate ligament is non-functioning or absent, resulting in joint instability. The
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Unity Knee™ patellar component is optional and is used in situations where replacement of the articular surface of the patella is required. The system also provides titanium alloy augments including femoral augments tibial augments and stem extensions.
The Unity Knee™ is intended for use in total knee arthroplasty in skeletally mature patients, to provide increased mobility and reduce pain by replacing the damaged knee joint articulation where there is evidence of sufficient sound bone to seat and support the components.
The Unity™ Total Knee system was originally cleared in K113060. This submission is for the inclusion of an additional range of femoral and tibial augments. The additional range of augments have the same intended purpose as those cleared in the original 510(k) submission (K113060).
#### 10. Intended Use / Indications:
The Unity™ Total Knee System is intended for use in total knee arthroplasty in skeletally mature patients, to provide increased mobility and reduce pain by replacing the joint articulation where there is evidence of sufficient sound bone to seat and support the components.
General total knee arthroplasty indications include:
- . Painful, disabling joint disease of the knee resulting from: degenerative arthritis, rheumatoid arthritis or post-traumatic arthritis
- . Post-traumatic loss of knee joint configuration and function
- . Moderate varus, valgus, or flexion deformity in which the ligamentous structures can be returned to adequate function
- . Revision of previous unsuccessful knee replacement or other procedure, where soft tissue stability is adequate
- . Fracture of the distal femur and/or proximal tibia that cannot be stabilized by standard fracture management techniques
- The posterior stabilized variant is also indicated for PCL instability requiring implant bearing . surface geometries with increased anterior-posterior constraint and absent or non-functioning posterior cruciate ligament
The Unity™ Total Knee System is indicated for cemented use, single use only.
## 11. Summary of Technologies / Substantial Equivalence:
The Unity™ Total Knee System augments, subject of this submission, are identical in terms of intended use and indications, fixation, compatible components and are manufactured from the same materials as the predicate Unity™ Total Knee augments (K113060).
Additionally, the Unity augments, the subject device, are similar to the predicate (K113606) in terms of design and size range. Based on the similarities, Corin believes that the Unity™ Total Knee System augments are substantially equivalent to the predicate devices.
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#### 12. Non-Clinical Testing:
Non-clinical testing and analysis included torsional assembly, torsional disassembly, cyclic disassembly and cyclic fretting in line with ASTM F1814-15. Cyclic testing has been conducted based on ASTM F1800-12. The results of this testing show that the Unity™ Total Knee System augment is expected to be safe and effective for the proposed indications and is substantially equivalent to the predicate device.
Bacterial Endotoxin Testing (BET) has been conducted on finished, sterilized product, using Limulus Amebocyte Lystate (LAL) kinetic chromogenic methodology.
## 13. Clinical Testing:
Clinical testing was not necessary to determine substantial equivalence between the Unity™ Total Knee System augment and the predicate devices.
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Learn the FDA Browser
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.