Failure Analysis of Patellofemoral Arthroplasty

July 25, 2025 updated by: Anders Odgaard
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.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

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 Type

Observational

Enrollment (Estimated)

550

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Denmark
      • Copenhagen, Denmark, 2100
        • Rigshospitalet

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients operated with patellofemoral arthroplasty for patellofemoral osteoarthritis.

Description

Inclusion Criteria:

  • Patellofemoral arthroplasty
  • Primary procedure performed between Jan 1 2008 and Dec 31 2015
  • Primary procedure performed in Denmark

Exclusion Criteria:

  • Patella-nail syndrome
  • Dislocating tendon following patellectomy.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
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.
Device: Patellofemoral arthroplasty
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.
Other Names:
  • Artificial joint between knee cap and thigh bone

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Implant revision and reoperation rates
Time Frame: 10-year
The proportion of revised and reoperated patients
10-year

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The 6-year cumulative revision rate
Time Frame: 6 years
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.
6 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Anders Odgaard

Collaborators

Stryker Orthopaedics

Investigators

  • Principal Investigator: Anders Odgaard, MD, DMSc, Rigshospitalet, Denmark

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 1, 2019

Primary Completion (Actual)

November 9, 2022

Study Completion (Estimated)

April 1, 2026

Study Registration Dates

First Submitted

February 24, 2021

First Submitted That Met QC Criteria

February 24, 2021

First Posted (Actual)

February 26, 2021

Study Record Updates

Last Update Posted (Actual)

July 30, 2025

Last Update Submitted That Met QC Criteria

July 25, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • PFA_Failure_06

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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