510(k) · Cleared
ClearedStem Extension Line (USTAR II System)
Data to Oct 25, 2026 (FDA decisions) Oct 12, 2026 (recalls) Sep 30, 2026 (MAUDE) refreshed weekly
United Orthopedic Corporation · KRO Prosthesis, Knee, Femorotibial, Constrained, Cemented, Metal/Polymer
Cleared on Aug 22, 2025 as substantially equivalent to K190100 (United Orthopedic Corporation, 2019) after a 29-day review. Its family tree reaches back 8 generations to 1994.
- Decided
- Aug 22, 2025
- Review
- 29 days
- Class
- Class II
- Product code
- KRO
- Recalls
- None
- Predicates
- 1
Its longest line of descent runs back 8 generations to K921308 (1994). 54 ancestors in all, the oldest K864671 (1987). No later device cites it as a predicate yet.
- Root · 8 generations backK921308 HG Multilock Hip Prosthesis W/ TI-NidiumZimmer, Inc. · 1994 · Recalled
- 7 generations backK972893 Partnership Revision Femoral StemsHowmedica Corp. · 1997
- 6 generations backK983404 Type 3 Femoral ComponentsHowmedica Corp. · 1998 · Recalled
- 5 generations backK013106 2 Piece Modular Hip StemHowmedica Osteonics Corp. · 2002 · Recalled
- 4 generations backK022549 Restoration Modular SystemHowmedica Osteonics Corp. · 2002 · Recalled
- 3 generations backK090757 Biomet Modular Femoral Revision SystemBiomet, Inc. · 2009 · Recalled
- 2 generations backK130063 Arcos Trochanter ButtonBiomet, Inc. · 2013
- 1 generation backK190100 USTAR II SystemUnited Orthopedic Corporation · 2019 · Recalled
- This deviceK252303 Stem Extension Line (USTAR II System)United Orthopedic Corporation · 2025
View FIG. 1 as a table
Line of descent and top descendants
| Generation | Number | Device | Applicant | Decided | Recalls |
|---|---|---|---|---|---|
| −8 | K921308 | HG Multilock Hip Prosthesis W/ TI-Nidium | Zimmer, Inc. | 1994 | 1 |
| −7 | K972893 | Partnership Revision Femoral Stems | Howmedica Corp. | 1997 | — |
| −6 | K983404 | Type 3 Femoral Components | Howmedica Corp. | 1998 | 1 |
| −5 | K013106 | 2 Piece Modular Hip Stem | Howmedica Osteonics Corp. | 2002 | 37 |
| −4 | K022549 | Restoration Modular System | Howmedica Osteonics Corp. | 2002 | 3 |
| −3 | K090757 | Biomet Modular Femoral Revision System | Biomet, Inc. | 2009 | 18 |
| −2 | K130063 | Arcos Trochanter Button | Biomet, Inc. | 2013 | — |
| −1 | K190100 | USTAR II System | United Orthopedic Corporation | 2019 | 5 |
| 0 (this device) | K252303 | Stem Extension Line (USTAR II System) | United Orthopedic Corporation | 2025 | — |
Other ancestors by year cleared
| Year cleared | Devices | With a Class I recall |
|---|---|---|
| 1987 | 1 | 0 |
| 1992 | 1 | 0 |
| 1994 | 2 | 0 |
| 1995 | 7 | 0 |
| 1996 | 7 | 0 |
| 1997 | 2 | 0 |
| 1999 | 1 | 0 |
| 2000 | 6 | 0 |
| 2001 | 1 | 0 |
| 2002 | 3 | 0 |
| 2003 | 2 | 0 |
| 2004 | 1 | 0 |
| 2005 | 4 | 0 |
| 2006 | 1 | 0 |
| 2007 | 1 | 0 |
| 2008 | 1 | 0 |
| 2010 | 3 | 0 |
| 2011 | 1 | 0 |
| 2013 | 1 | 0 |
Sources: FDA 510(k) database (decision fields), the FDA summary (predicates and indications), FDA recall and enforcement reports, and MAUDE; processed by 510(k) Report. Verify on FDA.gov · Methodology and accuracy.
Planning a device in KRO? A 510(k) Report weighs predicate choices, recall history and review times for a new device like this one.
Top candidate predicates for a new KRO device
- #1 K251665 Triathlon® Hinge Knee Systemscore 19.0 · 12 generations · no Class I recall
- #2 Held for the reportin the report
- #3 Held for the reportin the report
What was it cleared against? (1)
Devices the submitter claimed this one is substantially equivalent to (*), and reference devices cited for a specific test or feature (†), as written in the FDA summary.
| Type | Number | Device | Decided |
|---|---|---|---|
| * | K190100 | USTAR II SystemSummary page 5…KRO, KWL, LPH, LWJ, LZO, OQI Legally Marketed Predicate Devices Predicate Predicate Trade Name Product Code K190100 USTAR II System KRO, LPH, LWJ, KWL Device Description “United” USTAR II System… | 2019 |
What descends from it?
No later submission names this one as a predicate yet.
Has anything in its family been recalled? (0 Class I)
No FDA recall names this device.
No ancestor or descendant has a Class I recall.
What does this lineage say?
- The line of descent spans 31 years and passes through 5 companies; a new generation was cleared every 3.7 years on median.
- 31 of the 54 ancestors have a recall of any class.
- 1 other device also cites its predicate K190100.
How does its category compare?
All KRO devicesKRO Prosthesis, Knee, Femorotibial, Constrained, Cemented, Metal/Polymer: FDA decisions, review times, recalls and adverse event reports over 20 years. 2025, this device’s year, is highlighted.
FDA decisions per year · KRO
3in 2025
2026 to Oct 25, outlined.
Median 510(k) review, days · KRO
56in 2025
Receipt to decision; years with fewer than 3 clearances left blank.
Recalls per year · KRO
14so far in 2026, the most since 2007
Class I (0 since 2007) Class II/III not classified
Adverse event reports per year · KRO
915in 2025
MAUDE reports naming product code KRO, not matched to any one device; reports are not rates.
View these four charts as a table
| Year | Decisions | Median 510(k) review, days | Recalls (Class I) | MAUDE reports |
|---|---|---|---|---|
| 2007 | 1 | — | 1 | 37 |
| 2008 | 3 | 126 | 3 | 44 |
| 2009 | 3 | 86 | 8 | 66 |
| 2010 | 1 | — | 0 | 110 |
| 2011 | 2 | — | 1 | 119 |
| 2012 | 2 | — | 1 | 173 |
| 2013 | 3 | 189 | 2 | 194 |
| 2014 | 2 | — | 0 | 406 |
| 2015 | 6 | 113 | 1 | 333 |
| 2016 | 3 | 148 | 5 | 369 |
| 2017 | 1 | — | 4 | 543 |
| 2018 | 0 | — | 1 | 614 |
| 2019 | 3 | 244 | 0 | 759 |
| 2020 | 1 | — | 0 | 749 |
| 2021 | 3 | 57 | 1 | 770 |
| 2022 | 1 | — | 0 | 892 |
| 2023 | 4 | 148 | 0 | 746 |
| 2024 | 3 | 87 | 0 | 855 |
| 2025 | 3 | 56 | 1 | 915 |
| 2026 | 1 | — | 14 | — |
What is it indicated for?
1. Metastatic tumor (i.e. osteosarcoma, chondrosarcoma, giant cell tumor or osteoma) where massive resection and transplantation are needed. 2. Severe knee joint damage resulting from trauma where massive resection and transplantation are needed. 3. Non-inflammatory degenerative joint disease such as avascular necrosis, osteoarthritis, or traumatic arthritis. 4. Revision of previously failed total joint arthroplasty, osteotomy, or arthrodesis. 5. Joint…
Read the full statement (139 words)
1. Metastatic tumor (i.e. osteosarcoma, chondrosarcoma, giant cell tumor or osteoma) where
massive resection and transplantation are needed.
2. Severe knee joint damage resulting from trauma where massive resection and transplantation are
needed.
3. Non-inflammatory degenerative joint disease such as avascular necrosis, osteoarthritis, or
traumatic arthritis.
4. Revision of previously failed total joint arthroplasty, osteotomy, or arthrodesis.
5. Joint instability resulting from excessive bone resection
For Femoral component, Hinged/ Tibial baseplate, Hinged/ Cemented tibial stem/ Cemented
Straight stem, RHS, non coated/ Cemented Curved stem, RHS, non coated/ Cemented Straight
stem, RHS/ Cemented Curved stem, RHS/ Tibial Augment: These devices are single use implant
and intended for cemented use only.
For Distal Femoral Component, RHS/ Proximal Tibial Component, RHS/ Tibial stem/ Segment Part,
RHS/ Segment Part, RHS, Bridge: These devices are single use implant and intended for
cementless use only.
Indications for use as stated in the FDA summary.
https://510kreport.com/device/K252303 · printed Nov 5, 2026
Cite this page
510(k) Report. “K252303: Stem Extension Line (USTAR II System).” Lineage record from FDA 510(k) data and the FDA summary. Updated Nov 3, 2026. Accessed Nov 5, 2026. https://510kreport.com/device/K252303
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Record history
- FDA decision record loaded May 2, 2026
- Summary read Oct 13, 2026 (extraction version 9eaa42aa01ed)
- Lineage and recalls computed Nov 3, 2026
- Page last updated Nov 3, 2026