Patellofemoral OsteoarthritisNCT04772625
Failure Analysis of Patellofemoral Arthroplasty
An observational study of Patellofemoral Osteoarthritis and Arthroplasty Complications, run by Anders Odgaard at 1 site in Denmark.
Trial summary
The purpose of the retrospective cohort study is 1) to determine preoperative risk factors for revision af patellofemoral arthroplasty, and 2) to provide a detailed description of indications for revision after patellofemoral arthroplasty. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Patellofemoral Osteoarthritis, Arthroplasty Complications, Knee Osteoarthritis
- What is being tested?
- Patellofemoral arthroplasty
- Type of treatment
- Medical device
- How many people
- 550 participants
- Where
- 1 siteDenmark
- Study dates
- 1 Jan 2019to 1 Apr 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: Patients operated with patellofemoral arthroplasty for patellofemoral osteoarthritis.
Who may be able to join
- Patellofemoral arthroplasty
- Primary procedure performed between Jan 1 2008 and Dec 31 2015
- Primary procedure performed in Denmark
Who cannot join
- Patella-nail syndrome
- Dislocating tendon following patellectomy.
Trial locations and contacts
1 site in 1 country.
About this study
The purpose of the retrospective cohort study is 1) to determine preoperative risk factors for revision af patellofemoral arthroplasty, and 2) to provide a detailed description of indications for revision after patellofemoral arthroplasty. All patients operated with patellofemoral arthroplasty in Denmark from January 1, 2008 to December 31, 2015, will be included in the cohort.
Read the detailed description
Approx. 11,000 operations with the insertion of a knee arthroplasty (knee prosthesis) are performed annually DK. The durability and quality of the treatment are assessed with prosthesis survival, that expresses the proportion of prostheses that are still functional after a given number of years (eg the 10-year prosthesis survival for all types of knee prostheses in DK is approximately 94%).
Unicompartmental implants are increasingly used, so that only the worn part of the knee is replaced. Especially for osteoarthritis between the patella and the femur, a patellofemoral prosthesis (PFA - patellofemoral alloplasty) can be inserted, which is much smaller than the traditional full prosthesis (TKA - total knee arthroplasty).
PFA operations are controversial. A recently published Danish study (double-blind RCT) comparing TKA and PFA has shown that PFA patients achieve greater satisfaction, better knee function and greater quality of life than TKA patients. A recent study has also demonstrated that the cost of a PFA procedure is less than that of a TKA. As a paradox to this clear RCT finding, all national implant registers (Sweden, England, New Zealand, Denmark, etc.) show a significantly poorer prosthesis survival for PFA compared with TKA.
It is important for the future treatment of patients with severe osteoarthritis between the patella and femur to understand the cause of the discrepancy between RCT and registry results. The discrepancy gives rise to a number of questions regarding. indications, techniques, competences, postoperative regimens etc.
The divergence between the RCT and registry studies can only be clarified by a study that 1) examines the influence of preperative factors (patient history, physical findings, radiology etc.) on outcome, and that 2) attempts a causal analysis for each reoperation. The investigators intend to do this though a cohort study including all cases of patellofemoral arthroplasty performed in Denmark from January 1, 2008 until December 31, 2015.
The purpose is to determine preoperative risk factors for revision after PFA and to provide a detailed description of indications for revision after PFA.
- Being tested
- Patellofemoral arthroplasty
- Keywords
- Patellofemoral arthroplasty, Knee revision surgery, Indication
- Medical subject headings
- Osteoarthritis, Knee
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Patellofemoral arthroplastyDevice
Also called Artificial joint between knee cap and thigh bone
Insertion of an artificial joint between the front of the femur and the back of the patella. The femoral component consists of a metal implant, and the patellar component is a polyethylene implant. The two components replace the original articular cartilage of the patellofemoral joint.
| Study group | Role | What they receive |
|---|---|---|
| PFA | The cohort consists of all patients operated with patellofemoral arthroplasty for isolated patellofemoral osteoarthritis in Denmark from Jan 1 2008 to Dec 31 2015. The number of patients is expected to be around 500. A patellofemoral arthroplasty is defined as an arthroplasty consisting of a metal trochlear component and a polyethylene patella component. The definition of isolated patellofemoral osteoarthritis in the study is pragmatic and given by the operating surgeon. Receives: Device: Patellofemoral arthroplasty |
What is being measured
The primary outcome is the main question the study is designed to answer.
Implant revision and reoperation rates
The proportion of revised and reoperated patients
Measured: 10-year
Secondary outcomes (1)
The 6-year cumulative revision rate
The 6-year cumulative revision rate of patellofemoral arthroplasties in a target trial comparing two groups of surgeons: 1) those surgeons, who were a part of a randomised clinical trial comparing PFA and TKA, and 2) other surgeons. In addition to this, the 6-year cumulative reoperation rate (other than revision) and the 6-year cumulative mortality rate will also be reported.
Measured: 6 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Feb 2021
- Study start1 Jan 2019
- Primary completion9 Nov 2022
- Study completion1 Apr 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (6)Papers the sponsor has linked to this study.
- Other trials for Patellofemoral OsteoarthritisStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Retrospective
- Enrolment
- 550 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Anders Odgaard
- Sponsor type
- University, hospital or other
- Collaborators
- Stryker Orthopaedics
- Responsible party
- Sponsor-investigator, Anders Odgaard, Copenhagen University Hospital, Rigshospitalet
- Investigators
- Anders Odgaard, MD, DMSc, Principal investigator, Copenhagen University Hospital, Rigshospitalet
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04772625
- Sponsor's protocol ID
- PFA_Failure_06
- Status last verified
- Jul 2025
- First submitted
- 24 Feb 2021
- Last updated
- 30 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- Undecided
Publications
Odgaard A, Madsen F, Kristensen PW, Kappel A, Fabrin J. The Mark Coventry Award: Patellofemoral Arthroplasty Results in Better Range of Movement and Early Patient-reported Outcomes Than TKA. Clin Orthop Relat Res. 2018 Jan;476(1):87-100. doi: 10.1007/s11999.0000000000000017.
PubMed 29529622Bendixen NB, Eskelund PW, Odgaard A. Failure modes of patellofemoral arthroplasty-registries vs. clinical studies: a systematic review. Acta Orthop. 2019 Oct;90(5):473-478. doi: 10.1080/17453674.2019.1634865. Epub 2019 Jul 1.
PubMed 31259645Odgaard A, Eldridge J, Madsen F. Patellofemoral Arthroplasty. JBJS Essent Surg Tech. 2019 Apr 24;9(2):e15. doi: 10.2106/JBJS.ST.18.00094. eCollection 2019 Jun 26.
PubMed 31579533Fredborg C, Odgaard A, Sorensen J. Patellofemoral arthroplasty is cheaper and more effective in the short term than total knee arthroplasty for isolated patellofemoral osteoarthritis: cost-effectiveness analysis based on a randomized trial. Bone Joint J. 2020 Apr;102-B(4):449-457. doi: 10.1302/0301-620X.102B4.BJJ-2018-1580.R3.
PubMed 32228074Odgaard A, Kappel A, Madsen F, Kristensen PW, Stephensen S, Attarzadeh AP. Patellofemoral Arthroplasty Results in Better Time-weighted Patient-reported Outcomes After 6 Years than TKA: A Randomized Controlled Trial. Clin Orthop Relat Res. 2022 Sep 1;480(9):1707-1718. doi: 10.1097/CORR.0000000000002178. Epub 2022 Mar 21.
PubMed 35315804Rasmussen LE, Hoffmann AG, Blanche P, Espersen F, Justesen TF, Rasmussen LE, Hangaard S, Christensen R, Odgaard A. Surgeon Training and Revision Rates After Patellofemoral Arthroplasty. JAMA Netw Open. 2025 Jun 2;8(6):e2517825. doi: 10.1001/jamanetworkopen.2025.17825.
PubMed 40577013
Study at a glance
From the registry record, last updated by the sponsor on 30 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Failure Analysis of Patellofemoral Arthroplasty
- ClinicalTrials.gov ID
- NCT04772625
- Acronym / sponsor ID
- PFA_Failure_06
- Keywords
- Patellofemoral arthroplasty, Knee revision surgery, Indication
- Study type
- Observational
- Recruitment status
- Active, not recruiting
- Enrolment
- 550 participants (estimated)
- Lead sponsor
- Anders OdgaardUniversity, hospital or other
- Collaborators
- Stryker Orthopaedics
- Study start
- 1 Jan 2019 (actual)
- Primary completion
- 9 Nov 2022 (actual)
- Study completion
- 1 Apr 2026 (estimated)
- First posted
- 26 Feb 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of the retrospective cohort study is 1) to determine preoperative risk factors for revision af patellofemoral arthroplasty, and 2) to provide a detailed description of indications for revision after patellofemoral arthroplasty. All patients operated with patellofemoral arthroplasty in Denmark from January 1, 2008 to December 31, 2015, will be included in the cohort.
Detailed description
Approx. 11,000 operations with the insertion of a knee arthroplasty (knee prosthesis) are performed annually DK. The durability and quality of the treatment are assessed with prosthesis survival, that expresses the proportion of prostheses that are still functional after a given number of years (eg the 10-year prosthesis survival for all types of knee prostheses in DK is approximately 94%).
Unicompartmental implants are increasingly used, so that only the worn part of the knee is replaced. Especially for osteoarthritis between the patella and the femur, a patellofemoral prosthesis (PFA - patellofemoral alloplasty) can be inserted, which is much smaller than the traditional full prosthesis (TKA - total knee arthroplasty).
PFA operations are controversial. A recently published Danish study (double-blind RCT) comparing TKA and PFA has shown that PFA patients achieve greater satisfaction, better knee function and greater quality of life than TKA patients. A recent study has also demonstrated that the cost of a PFA procedure is less than that of a TKA. As a paradox to this clear RCT finding, all national implant registers (Sweden, England, New Zealand, Denmark, etc.) show a significantly poorer prosthesis survival for PFA compared with TKA.
It is important for the future treatment of patients with severe osteoarthritis between the patella and femur to understand the cause of the discrepancy between RCT and registry results. The discrepancy gives rise to a number of questions regarding. indications, techniques, competences, postoperative regimens etc.
The divergence between the RCT and registry studies can only be clarified by a study that 1) examines the influence of preperative factors (patient history, physical findings, radiology etc.) on outcome, and that 2) attempts a causal analysis for each reoperation. The investigators intend to do this though a cohort study including all cases of patellofemoral arthroplasty performed in Denmark from January 1, 2008 until December 31, 2015.
The purpose is to determine preoperative risk factors for revision after PFA and to provide a detailed description of indications for revision after PFA.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| PFA | – | Device: Patellofemoral arthroplastyThe cohort consists of all patients operated with patellofemoral arthroplasty for isolated patellofemoral osteoarthritis in Denmark from Jan 1 2008 to Dec 31 2015. The number of patients is expected to be around 500. A patellofemoral arthroplasty is defined as an arthroplasty consisting of a metal trochlear component and a polyethylene patella component. The definition of isolated patellofemoral osteoarthritis in the study is pragmatic and given by the operating surgeon. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Patients operated with patellofemoral arthroplasty for patellofemoral osteoarthritis.
Key inclusion criteria (3 listed)
- Patellofemoral arthroplasty
- Primary procedure performed between Jan 1 2008 and Dec 31 2015
- Primary procedure performed in Denmark
Key exclusion criteria (2 listed)
- Patella-nail syndrome
- Dislocating tendon following patellectomy.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Patellofemoral arthroplastyAlso: Artificial joint between knee cap and thigh boneInsertion of an artificial joint between the front of the femur and the back of the patella. The femoral component consists of a metal implant, and the patellar component is a polyethylene implant. The two components replace the original articular cartilage of the patellofemoral joint. | Device | PFA |
Primary outcome
Implant revision and reoperation rates
Time frame: 10-year
The proportion of revised and reoperated patients
1 secondary outcome
The 6-year cumulative revision rate
Time frame: 6 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Jul 2025.
- Background: PubMed 29529622Odgaard A, Madsen F, Kristensen PW, Kappel A, Fabrin J. The Mark Coventry Award: Patellofemoral Arthroplasty Results in Better Range of Movement and Early Patient-reported Outcomes Than TKA. Clin Orthop Relat Res. 2018 Jan;476(1):87-100. doi: 10.1007/s11999.0000000000000017.
- Background: PubMed 31259645Bendixen NB, Eskelund PW, Odgaard A. Failure modes of patellofemoral arthroplasty-registries vs. clinical studies: a systematic review. Acta Orthop. 2019 Oct;90(5):473-478. doi: 10.1080/17453674.2019.1634865. Epub 2019 Jul 1.
- Background: PubMed 31579533Odgaard A, Eldridge J, Madsen F. Patellofemoral Arthroplasty. JBJS Essent Surg Tech. 2019 Apr 24;9(2):e15. doi: 10.2106/JBJS.ST.18.00094. eCollection 2019 Jun 26.
- Background: PubMed 32228074Fredborg C, Odgaard A, Sorensen J. Patellofemoral arthroplasty is cheaper and more effective in the short term than total knee arthroplasty for isolated patellofemoral osteoarthritis: cost-effectiveness analysis based on a randomized trial. Bone Joint J. 2020 Apr;102-B(4):449-457. doi: 10.1302/0301-620X.102B4.BJJ-2018-1580.R3.
- Background: PubMed 35315804Odgaard A, Kappel A, Madsen F, Kristensen PW, Stephensen S, Attarzadeh AP. Patellofemoral Arthroplasty Results in Better Time-weighted Patient-reported Outcomes After 6 Years than TKA: A Randomized Controlled Trial. Clin Orthop Relat Res. 2022 Sep 1;480(9):1707-1718. doi: 10.1097/CORR.0000000000002178. Epub 2022 Mar 21.
- Background: PubMed 40577013Rasmussen LE, Hoffmann AG, Blanche P, Espersen F, Justesen TF, Rasmussen LE, Hangaard S, Christensen R, Odgaard A. Surgeon Training and Revision Rates After Patellofemoral Arthroplasty. JAMA Netw Open. 2025 Jun 2;8(6):e2517825. doi: 10.1001/jamanetworkopen.2025.17825.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Anders Odgaard, MD, DMSc principal investigator
Copenhagen University Hospital, Rigshospitalet
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Patellofemoral Osteoarthritis and Arthroplasty Complications, run by Anders Odgaard at 1 site in Denmark.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 30 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Denmark. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Implant revision and reoperation rates (time frame: 10-year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04772625, which also lists 6 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Jul 2025.