The EXp Acetabular Shell Liner is intended for use in reconstruction of the articulating surface of the acetabular portion of the hip that is severely disabled and/or very painful resulting from: 1. Non-inflammatory degenerative joint disease including osteoarthritis and avascular necrosis. 2. Rheumatoid arthritis. 3. Correction of functional deformity. 4. Treatment of non-union, femoral neck fracture, and trochanteric fractures of the proximal femur with head involvement, unmanageable using other techniques. 5. Revision of previously failed total hip Arthroplasty. Cemented and Uncemented Applications
Device Story
Acetabular shell liner component for total hip arthroplasty; manufactured from Vitamin E-blended GUR 1020 UHMWPE; compression molded and gamma-irradiated. Used in conjunction with acetabular shell, femoral head (Biolox forte, Biolox Delta, or CoCr alloy), and femoral stem. Implanted by orthopedic surgeons in clinical settings. Vitamin E additive provides oxidative resistance and maintains mechanical properties post-aging. Device functions as articulating surface to restore hip joint function; reduces wear and oxidation compared to conventional UHMWPE. Available in hooded and non-hooded configurations.
Clinical Evidence
Bench testing only. No clinical data. Testing included: tensile, impact, compressive, and small punch strength; thermal properties; oxidation resistance (ASTM F2102/F2003); hip simulator wear (ISO 14242-1, 5 million cycles); rim impingement (ASTM F2582); GC-MS/LC-MS for Vitamin E elution; and biocompatibility (mutagenicity, irritation, sensitization, cytotoxicity). Results showed EXp material maintained mechanical properties and oxidation resistance after accelerated aging, whereas conventional GUR 1050 material showed significant degradation.
Indicated for patients with severe hip disability/pain due to non-inflammatory degenerative joint disease (osteoarthritis, avascular necrosis), rheumatoid arthritis, functional deformity, non-union, femoral neck/trochanteric fractures, or revision of failed total hip arthroplasty. For use in cemented and uncemented applications.
Regulatory Classification
Identification
A hip joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis is a device intended to be implanted to replace a hip 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 has a femoral component made of a cobalt-chromium-molybdenum (Co-Cr-Mo) alloy or a titanium-aluminum-vanadium (Ti-6Al-4V) alloy and an acetabular component composed of an ultra-high molecular weight polyethylene articulating bearing surface fixed in a metal shell made of Co-Cr-Mo or Ti-6Al-4V. The femoral stem and acetabular shell have a porous coating made of, in the case of Co-Cr-Mo substrates, beads of the same alloy, and in the case of Ti-6Al-4V substrates, fibers of commercially pure titanium or Ti-6Al-4V alloy. The porous coating has a volume porosity between 30 and 70 percent, an average pore size between 100 and 1,000 microns, interconnecting porosity, and a porous coating thickness between 500 and 1,500 microns. The generic type of device has a design to achieve biological fixation to bone without the use of bone cement.
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# 510(k) Summary
| Manufacturer: | StelKast, Inc.<br>200 Hidden Valley Road<br>McMurray, PA 15317 | MAR 2 4 2011 |
|--------------------|------------------------------------------------------------------------------------------------------------------------------------|--------------|
| Device Trade Name: | EXp Acetabular Shell Liner | |
| Contact: | Mr. Donald A. Stevens<br>Vice Chairman<br>(888) 273-1583 | |
| Prepared by: | Musculoskeletal Clinical Regulatory Advisers, LLC<br>1331 H Street, NW, 12th Floor<br>Washington, DC 20005<br>Phone: (202)552-5800 | |
| Date Prepared: | March 14, 2011 | |
| Common Name: | Acetabular Shell Liner | |
| Classification: | 21 CFR 888.3358, Hip joint metal/polymer/metal semiconstrained<br>porous-coated uncemented prosthesis | |
| Class: | II | |
| Product Codes: | OQG, OQH, OQI, LPH, LWJ, JDI, MAY, LZO | |
#### Indications For Use:
The EXp Acetabular Shell Liner is intended for use in reconstruction of the articulating surface of the acetabular portion of the hip that is severely disabled and/or very painful resulting from:
- 1. Non-inflammatory degenerative joint disease including osteoarthritis and avascular necrosis.
- 2. Rheumatoid arthritis.
- 3. Correction of functional deformity.
- 4. Treatment of non-union, femoral neck fracture, and trochanteric fractures of the proximal femur with head involvement, unmanageable using other techniques.
- 5. Revision of previously failed total hip Arthroplasty.
Cemented and Uncemented Applications
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## Device Description:
The EXp Acetabular Shell Liner is made of polyethylene to which Vitamin E has been added. It is available in both hooded and non-hooded options. The liner is part of a complete total hip system and will be used in conjunction with an acetabular shell, femoral head and femoral stem in total hip arthroplasty. The femoral heads which are to be mated with the EXp Liner are made of Biolox forte, Biolox Delta, or CoCr alloy.
## Predicate Devices:
#### Liners
Comparative information presented in the 510(k) supports the substantial equivalence of the EXp Acetabular Liner with respect to its indications for use, design, materials, and function.
This 510(k) demonstrates the substantial equivalence of the EXp Acetabular Liner to the following predicate devices: Acetabular Liners in the Stelkast Provident Hip System (K935484) and the Stelkast ProForm Hip System (K950827); Biomet RingLoc Acetabular Component with ArCom Polyethylene (K032396 and K970501). Previously cleared polyethylene acetabular liners to which Vitamin E has been added include the Biomet E-Poly (Vitamin E) Acetabular Liners (K050327).
All of these acetabular liners have the same intended use, have the same general design and available sizes, and are made of UHMWPE.
Non-clinical testing was performed on the EXp Acetabular Liner to determine tensile strength, impact strength, compressive strength, small punch strength, thermal properties, free radical concentration. oxidation resistance, swell ratio, hip simulator wear under normal and abrasive conditions, wear particle characterization, rim impingement, liner push-out, lever-out, and torque-out resistance, GCMS analysis of hexane extract postwear testing, fusion defect characterization, fatigue crack propagation, trans-vinylene index, and biocompatibility (i.e., mutagenicity, irritation, sensitization, and cytotoxicity testing).
The results of the performed tests demonstrate that the EXp Acetabular Liner is substantially equivalent to legally marketed predicate devices.
## Femoral Heads
The StelKast Biolox Delta Ceramic Femoral heads are substantially equivalent to previously cleared Biolox Delta Ceramic Femoral Heads: Smith & Nephew (K083762); Biomet (K073102); Zimmer (K071535); and Howmedica Osteonics (K051588). The StelKast Biolox forte Ceramic Femoral Heads were approved for use with StelKast femoral stems in P040051. The CoCr Femoral Heads were cleared for use with StelKast femoral stems in K934162.
Testing in support of the ceramic femoral heads includes static burst strength, fatigue, post-fatigue burst strength, pull-off, and rotational stability.
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# Claims for the EXp Liner
Oxidative Stability and Mechanical Performance of the EXp material
- 1) EXp is more resistant to oxidation than conventional UHMWPE and its ultimate load, as measured per ASTM F2183, does not decrease during oxidative aging per ASTM F2003, The EXp UHMWPE is a compression molded GUR 1020 blended with Vitamin E. crosslinked with gamma irradiation and terminally sterilized using ethylene oxide. For comparison, a well recognized industry standard material, conventional GUR 1050 material, sterilized using 25kGy in an inert environment was tested in parallel. The EXp UHMWPE demonstrated resistance to oxidation, as measured using ASTM F2102, after aging per ASTM F2003. Specifically, after four weeks of aging per ASTM F2003, the maximum ASTM F2102 oxidation index increased from 0.1 ± 0.02 to 0.2 for the EXp material and from 0.1 ± 0.04 to 3.8 ± 0.2 for the conventional GUR1050 material.
Consistent with the oxidation index data, the resulting mechanical performance of the materials, as determined using the ASTM F2183 small punch test. showed that the EXp material retained its mechanical performance while that of the 25kGv GUR 1050 material decreased. Specifically, the ultimate load for the EXp material remained relatively constant. 63.3 ± 8.9 N and 73.1 ± 5.2 N. for the non-aged and 4-week-aged material, respectively. The ultimate load for the conventional material decreased from 71.5 ± 3.0 N for the non-aged material to an embrittled condition in which no small punch sample could be machined. For reference, the ultimate load after two weeks of aging had reduced to 45.7 ± 5.9 N.
All EXp samples were machined from GUR1020- E. which is blended by percentage weight with Vitamin E. compression molded, crosslinked with gamma irradiation, and subsequently ethylene oxide sterilized. All conventional samples were machined from GUR1050, ram extruded UHMWPE and subsequently gamma sterilized using 25-40 kGv in an inert environment. Bench testing is not necessarily indicative of clinical performance.
- 2) The morphology of the EXp UHMWPE is consistent with conventional UHMWPE. Material samples of both the EXp UHMWPE and 25kGy GUR 1050 material were subjected to freeze fracture analysis. Both materials demonstrated no consolidation defects or voids when imaged at high magnification under scanning electron microscopy.
All EXp samples were machined from GUR1020- E, which is blended by percentage weight with Vitamin E, compression molded, crosslinked with gamma irradiation, and subsequently ethylene oxide sterilized. All conventional samples were machined from GUR1050, ram extruded UHMWPE and subsequently gamma sterilized using 25-40 kGy in an inert environment. Bench testing is not necessarily indicative of clinical performance.
- 3) The vitamin E blended into the EXp UHMWPE does not elute from the EXp material during hexane extraction or isopropanol (IPA) extraction. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography -mass spectrometry (LC-MS) analysis of hexane solvent used for extraction of the EXp material confirmed that no Vitamin E was extracted from the material when refluxed at 74°C for 24 hours. GC-MS and LC-MS analysis of IPA solvent used for extraction of the EXp material confirmed
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that no Vitamin E was extracted from the material when soaked at room temperature for 18 hours. The GC-MS and LC-MS technique have detection limits of 50-250 ppb and 1000 ppm, respectively.
All EXp samples were machined from GUR1020- E. which is blended by percentage weight with Vitamin E, compression molded, crosslinked with gamma irradiation, and subsequently ethylene oxide sterilized. Bench testing is not necessarily indicative of clinical performance.
Oxidative Stability and Mechanical Performance of the EXp Liners
- 4) EXpremains resistant to oxidation after 5 million cycles of wear testing and artificial aging. Wear testing followed by accelerated aging provides a method to assess the possibility that repeated loading experienced during wear testing may change the distribution or content of the Vitamin E in the EXp material; leaving the material susceptible to oxidation. Testing was conducted per ISO 14242-1 using an AMTI hip simulator with 20g/L bovine serum lubricant to a total cycle count of 5.0 million cycles. All samples were tested in their final sterilized form. Following wear testing, the EXp Liners were aged in an oxidative environment per ASTM F2003 for 4 weeks. The EXp Liners demonstrated a resistance to oxidation, as measured using ASTM F2102. Specifically, the maximum oxidation index increased from 0.1 ± 0.02 for the non-aged EXp material to 0.2 ± 0.02 for the four-week-aged EXp material.
EXp samples were machined from GUR1020- E, which is blended by percentage weight with Vitamin E, compression molded, crosslinked with gamma irradiation, and subsequently ethylene oxide sterilized. Bench testing is not necessarily indicative of clinical performance.
- 5) The EXp liners experienced no failures as a result of dynamic impingement testing. Dynamic impingement testing, per ASTM F2582, confirmed that artificially aged EXp liners demonstrated a resistance to rim fracture under fatigue loading conditions to 1.0MC. Specifically, three liners were loaded to engage the liner rim with the femoral neck at moments equal to 4.6 Nm (70% of the static peak dislocation moments). All three samples reached run-out equal to 1.0MC and no fractures of the liners were observed throughout testing nor did the locking mechanism fail.
All EXp samples were machined from GUR1020- E, which is blended by percentage weight with Vitamin E, compression molded, crosslinked with gamma irradiation, and subsequently ethylene oxide sterilized. Bench testing is not necessarily indicative of clinical performance.
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Image /page/4/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo features a stylized eagle with three curved lines representing its wings. The words "DEPARTMENT OF HEALTH & HUMAN SERVICES USA" are arranged in a circular pattern around the eagle.
Food and Drug Administration 10903 New Hampshire Avenue Document Control Room -WO66-G609 Silver Spring, MD 20993-0002
StelKast, Inc. % Mr. Donald A. Stevens Vice Chairman 200 Hidden Valley Road McMurray, Pennsylvania 15317
MAR 2 4 2011
Re: K094035 Trade/Device Name: EXp Acetabular Shell Liner Regulation Number: 21 CFR 888.3358 Regulation Name: Hip Joint metal/polymer/metal semi-constrained porous-coated uncemented prosthesis Regulatory Class: Class II Product Code: OQG, OQH, OQI, LPH, LWJ, JDI, MAY, LZO Dated: March 15, 2011 Received: March 17, 2011
Dear Mr. Stevens:
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 includions 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, Drig, 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, inte re 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 maching.
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 devine 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.
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Page 2 - Mr. Donald A. Stevens
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 not 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 Issing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting (reporting of medical device-related adverse events) (21 CFR 803), good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 100-100.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please go to http://www.fda.gov/AboutFDA/CentersOffices/CDRH/CDRHOffices/ucm115801.html for the Center for Devices and Radiological Health's (CDRH's) Office of Cochilian 1962.1000 roll note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR 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.h1m for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.
You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll the (800) 638-2041 or (301) 796-7100 or at its Internet address http://www.fda.gov/MedicalDevices/Resourcesfor You/Industry/default.htm.
Sincerely yours,
Aty B. Ruter
for
Mark N. Melkerson Director Division of Surgical, Orthopedic and Restorative Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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# Indications for Use
510(k) Number (if known):
Device Name: EXp Acetabular Liner
Indications for Use:
- 1. Non-inflammatory degenerative joint disease including osteoarthritis and avascular necrosis.
- 2. Rheumatoid arthritis.
- 3. Correction of functional deformity.
- 4. Treatment of non-union, femoral neck fracture, and trochanteric fractures of the proximal femur with head involvement, unmanageable using other techniques.
- 5. Revision of previously failed total hip Arthroplasty.
Cemented and Uncemented Applications
Prescription Use **YES** AND/OR Over-The-Counter Use **NO**
(Part 21 CFR 801 Subpart D) (21 CFR 801 Subpart C)
(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED)
Concurrence of CDRH, Office of Device Evaluation (ODE)
for M. Mulkerson
(Division Sign-Offy Division of Surgical, Orthopedic, and Restorative Devices
510(k) Number K094035 Page j of 1
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.