The SpaceFix Shoulder Spacer is intended for temporary (maximum 180 days) use as part of a two-stage procedure in skeletally mature patients undergoing a total or hemi shoulder arthroplasty revision due to prosthetic joint infection. The device is indicated for use when the infecting organism is sensitive to gentamicin, as the PMMA bone cement includes gentamicin for local antibiotic delivery. Following prosthesis explantation and thorough debridement, the device is implanted in the glenoid cavity and humeral canal. At the conclusion of the temporary implantation period (not to exceed 180 days), the device must be removed and either replaced with a definitive shoulder prosthesis or alternative surgical intervention (e.g., resection arthroplasty, fusion).
Device Story
SpaceFix Shoulder Spacer is a temporary, single-use implant for two-stage shoulder arthroplasty revision; indicated for patients with prosthetic joint infections sensitive to gentamicin. Device consists of PMMA bone cement (G3A formula) reinforced with an AISI 316LVM stainless steel core. Implanted into glenoid cavity and humeral canal following explantation and debridement; provides local antibiotic delivery. Maximum implantation duration is 180 days, after which it must be removed and replaced with a definitive prosthesis or alternative surgical intervention. Device is pre-molded, distinguishing it from intra-operatively molded predicates. Used by orthopedic surgeons in clinical settings to manage infection while maintaining joint space during the interval between revision stages.
Clinical Evidence
No clinical data. Evidence consists of bench testing, including biocompatibility, shelf-life, sterilization validation, pyrogenicity/endotoxin monitoring, gentamicin elution profile, fatigue strength, and package integrity.
Technological Characteristics
Materials: PMMA bone cement (G3A formula) and AISI 316LVM stainless steel reinforcement core. Form factor: Pre-molded spacer available in four sizes (stem/head diameter and stem length). Principle: Local antibiotic delivery via gentamicin-loaded PMMA. Sterilization: Provided sterile. Connectivity: None (standalone).
Indications for Use
Indicated for skeletally mature patients undergoing total or hemi shoulder arthroplasty revision due to prosthetic joint infection. Use restricted to cases where infecting organism is sensitive to gentamicin.
Regulatory Classification
Identification
Polymethylmethacrylate (PMMA) bone cement is a device intended to be implanted that is made from methylmethacrylate, polymethylmethacrylate, esters of methacrylic acid, or copolymers containing polymethylmethacrylate and polystyrene. The device is intended for use in arthroplastic procedures of the hip, knee, and other joints for the fixation of polymer or metallic prosthetic implants to living bone.
Special Controls
*Classification.* Class II (special controls). The special control for this device is the FDA guidance document entitled “Class II Special Controls Guidance Document: Polymethylmethacrylate (PMMA) Bone Cement.”
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FDA U.S. FOOD & DRUG ADMINISTRATION
September 15, 2025
G21 S.r.l
% Barry Sands
President and Founder
RQMIS, Inc.
110 Haverhill Road
Suite 524
Amesbury, Massachusetts 01913
Re: K252443
Trade/Device Name: SpaceFix Shoulder Spacer
Regulation Number: 21 CFR 888.3660
Regulation Name: Shoulder joint metal/polymer semi-constrained cemented prosthesis
Regulatory Class: Class II
Product Code: KWS, MBB
Dated: August 1, 2025
Received: August 4, 2025
Dear Mr. Sands:
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 (the 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 available 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.
U.S. Food & Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
www.fda.gov
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K252443 - Barry Sands
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Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).
Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).
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 (reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting-combination-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 Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.
All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system.
Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 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-devices/medical-device-safety/medical-device-reporting-mdr-how-report-medical-device-problems.
For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medical-devices/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-devices/device-advice-comprehensive-regulatory-
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K252443 - Barry Sands
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assistance/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,
JESSE MUIR-S
Digitally signed by JESSE
MUIR-S
Date: 2025.09.15 12:03:35
-04'00"
Jesse Muir, Ph.D.
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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SpaceFix Shoulder Spacer
Page 12 of 38
| Indications for Use | | |
| --- | --- | --- |
| Please type in the marketing application/submission number, if it is known. This textbox will be left blank for original applications/submissions. | K252443 | ? |
| Please provide the device trade name(s). | | ? |
| SpaceFix Shoulder Spacer | | |
| Please provide your Indications for Use below. | | ? |
| The SpaceFix Shoulder Spacer is intended for temporary (maximum 180 days) use as part of a two-stage procedure in skeletally mature patients undergoing a total or hemi shoulder arthroplasty revision due to prosthetic joint infection.
The device is indicated for use when the infecting organism is sensitive to gentamicin, as the PMMA bone cement includes gentamicin for local antibiotic delivery.
Following prosthesis explantation and thorough debridement, the device is implanted in the glenoid cavity and humeral canal.
At the conclusion of the temporary implantation period (not to exceed 180 days), the device must be removed and either replaced with a definitive shoulder prosthesis or alternative surgical intervention (e.g., resection arthroplasty, fusion). | | |
| Please select the types of uses (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
K252443
# G21's SpaceFix Shoulder Spacer
A. SUBMITTER'S ADDRESS, TELEPHONE NUMBER, CONTACT PERSON
G21 S.r.l.
Filippo Foroni
Via S. Pertini, 8
41039 S. Possidonio (MO) Italy
Phone: +39 0535 30312
Email: filippo.foroni@g-21.it
Author:
Arunkumar Prabhakaran
US Regulatory Submissions Manager
Phone: 978-358-7307
Email: regulatorysubmissions@rqmis.com
Primary Contact:
Barry E. Sands
RQMIS Inc.
110 Haverhill Road, Suite 524
Amesbury, MA 01913
Phone: (978) 358-7307
Email: regulatorysubmissions@rqmis.com
Date Prepared: July 31, 2025
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510(k) summary
## B. SUBJECT DEVICE
Trade/proprietary name of device: SpaceFix Shoulder Spacer
Common or Usual Name: SpaceFix Shoulder Spacer
Classification Name: Shoulder Joint metal/polymer semi-constrained cemented prosthesis
Regulation Number: 21 CFR 888.3660
Classification: Class II
Product Code: KWS, MBB
## C. PREDICATE DEVICES
### Primary Predicate:
- Name: SpaceFlex Shoulder
- 510(k): K202338
- Product code: KWS, MBB
- Regulation: 21 CFR 888.3027
- Classification: Class II
### Additional Predicate:
- Name: Remedy Shoulder Spacer
- 510(k): K152267
- Product code: KWS, MBB
- Regulation: 21 CFR 888.3660
- Classification: Class II
## D. DEVICE DESCRIPTION
The SpaceFix Shoulder Spacer is a temporary shoulder spacer made with PMMA bone cement with Gentamicin and reinforced with a stainless steel core. The subject device is provided sterile, single use and is intended for temporary (maximum 180 days) use as part of a two-stage procedure in skeletally mature patients undergoing total or hemi shoulder arthroplasty revision due to prosthetic joint infection.
## E. INDICATIONS FOR USE
The SpaceFix Shoulder Spacer is intended for temporary (maximum 180 days) use as part of a two-stage procedure in skeletally mature patients undergoing total or hemi shoulder arthroplasty revision due to prosthetic joint infection.
The device is indicated for use when the infecting organism is sensitive to gentamicin, as the PMMA bone cement includes gentamicin for local antibiotic delivery.
Following prosthesis explantation and thorough debridement, the device is implanted in the glenoid cavity and humeral canal. At the conclusion of the temporary implantation period (not to exceed 180 days), the device must be removed and either replaced with a definitive shoulder prosthesis or alternative surgical intervention (e.g., resection arthroplasty, fusion).
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{6}
510(k) summary
## F. TECHNOLOGICAL CHARACTERISTICS
The SpaceFix Shoulder Spacer is available in four different sizes, based on stem and head diameter, and stem length. The bone cement used to mold the SpaceFix Shoulder Spacer is the G3A formula, a low-viscosity bone cement that is already FDA approved. The reinforcement core used within the Spacer is made of stainless steel, as per the AISI 316LVM standard, and is identical to that of the primary predicate, SpaceFlex Shoulder.
## G. PERFORMANCE DATA
Performance data was conducted to demonstrate that the performance of the SpaceFix Shoulder Spacer complies with the recognized consensus standards and G21 acceptance criteria. The tests include biocompatibility testing, shelf-life testing, sterilization validation, pyrogenicity testing/endotoxin monitoring, gentamicin elution profile assessment, fatigue strength testing, package integrity testing, and gentamicin stability. The company conducted the same test as the predicate, and found to be substantially equivalent to the primary predicate.
## H. TECHNOLOGICAL CHARACTERISTICS COMPARISON:
The Subject Device, SpaceFix Shoulder Spacer, is substantially equivalent to the primary predicate, SpaceFlex Shoulder, K202338, in terms of indication and intended use, material and technological characteristics, and additional predicate, Remedy Shoulder Spacer, K152267, regarding molding process. The only difference is that the subject device, is premolded compared to the primary predicate, which is molded in the OR. This difference does not raise any questions of safety or effectiveness since the molding process is same and the performance of the subject device was found to be equivalent to the primary predicate device.
## I. SUBSTANTIAL EQUIVALENCE CONCLUSION
Both the subject device and predicate bone cements are made of polymethylmethacrylate (PMMA) with gentamicin and are used for identical indications (i.e., for revision surgeries). Since there is no significant difference in the technological characteristics between the subject and predicate devices, we conclude that the subject device is substantially equivalent to the Primary Predicate (K202338).
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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.