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OsteoarthritisNCT04358601

All-poly Versus Metal-backed

A study testing Triathlon PS Knee System with all-polyethylene tibial components and Triathlon PS Knee System with metal-backed modular components in people with Osteoarthritis, run by Region Skane.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

The primary objective is the assessment of prosthetic migration results after two years of the Triathlon PS Knee System with all-polyethylene tibial components compared to the Triathlon PS Knee System with metal-backed modular components by means of Roentgen Stereophotogrammetry. Read more about this study

Who is it for?
Ages 40 to 75 years
Conditions the study is for
Osteoarthritis
What is being tested?
Triathlon PS Knee System with all-polyethylene tibial components and Triathlon PS Knee System with metal-backed modular components
Type of treatment
Medical device
Could I receive a placebo?
No, everyone receives an active treatment
How many people
60 participants
Where
No sites listed yet
Study dates
1 Nov 2014to 10 Jun 2026
Phase
Interventional
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 40 to 75 years
  • All sexes
  • No healthy volunteers
  • Adult, Older adult
  1. The subject is morbidly obese, defined as Body Mass Index (BMI) of > 40. 2. Patient has a flexion contracture of 15° and more. 3. Patient has a varus/valgus contracture of 15° and more. 4. Patients with a pre-operative knee score of >70. 5. The subject has a history of total or unicompartmental reconstruction of the affected joint. 6. The subject will be operated bilaterally. 7. Patients who had a Total Hip Arthroplasty (THA) on contralateral and/or ipsilateral side within the last year that is considered to have an unsatisfactory outcome (Patients with contralateral and/or ipsilateral THA > 1 year ago with good outcome can be included in the study). 8. Patients who had a Total Knee Arthroplasty (TKA) on contralateral side within the last 6 months that is considered to have an unsatisfactory outcome. (Patients with contralateral TKA > 6 months ago with good outcome can be included in the study). 9. The subject has an active or suspected latent infection in or about the knee joint. 10. Osteomyelitis 11. Sepsis 12. Patient who is expected to need lower limb joint replacement for another joint within one year. 13. The subject has a neuromuscular or neurosensory deficiency, which would limit the ability to assess the performance of the device. 14. The subject has a systemic or metabolic disorder leading to progressive bone deterioration. 15. The subject is immunologically suppressed or receiving steroids in excess of normal physiological requirements. 16. The subject's bone stock in compromised by disease or infection which cannot provide adequate support and/or fixation to the prosthesis. 17. The subject has had a knee fusion to the affected joint. 18. Female patients planning a pregnancy during the course of the study. 19. The patient is unable or unwilling to sign the Informed Consent specific to this study

About this study

Official title: Migration and Survival of All-polyethylene Tibial Components Compared to the Metal-backed Modular Components of the Triathlon PS Total Knee System. A RSA Study

The primary objective is the assessment of prosthetic migration results after two years of the Triathlon PS Knee System with all-polyethylene tibial components compared to the Triathlon PS Knee System with metal-backed modular components by means of Roentgen Stereophotogrammetry.

Read the detailed description

The secondary objective will be the prediction of the long-term survival based on the two-year migration patterns combined with clinical factors and radiographic aspects. In order to identify other clinical parameters besides the fixation of the prosthesis components, clinical scores and radiographic aspects will be correlated with the RSA outcome.

Conditions
Osteoarthritis
Being tested
Triathlon PS Knee System with all-polyethylene tibial components, Triathlon PS Knee System with metal-backed modular components
Medical subject headings
Osteoarthritis

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Triathlon PS Knee System with all-polyethylene tibial componentsDevice

    Also called Stryker Orthopaedics

    Primary Total Knee Replacement

  • Triathlon PS Knee System with metal-backed modular componentsDevice

    Also called Stryker Orthopaedics

    Primary Total Knee Replacement

Study groups in NCT04358601
Study groupRoleWhat they receive
All-polyethylene tibial componentsExperimentalTriathlon PS Knee System with all-polyethylene tibial components
Receives: Device: Triathlon PS Knee System with all-polyethylene tibial components
Metal-backed modular componentsActive comparatorTriathlon PS Knee System with metal-backed modular components
Receives: Device: Triathlon PS Knee System with metal-backed modular components

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Migration, measured by means of RSA

    Migration (MTPM in mm) of the prosthesis with respect to the host bone measured by means of roentgen stereophotogrammetric analysis (RSA)

    Measured: 2 years

Secondary outcomes (6)

  1. Migration, measured by means of RSA

    Migration (MTPM in mm) of the prosthesis with respect to the host bone measured by means of roentgen stereophotogrammetric analysis (RSA)

    Measured: 10 years

  2. Investigation of clinical performance and patient outcome with the Knee Society Score (KSS)

    The Knee Society Clinical Rating System is comprised of two distinct sub-scores: one for pain, range of motion (ROM) and joint stability, and one for functional parameters. Sub-scores range from a potential minimum score of 0 to a maximum score of 100 points. Although the specific scores are not distinguished as "excellent," "good," "fair," or "poor," a higher value represents a better outcome.

    Measured: pre-operative, 3 months, 1, 2, 5, 7 and 10 years

  3. Investigation of clinical performance and patient outcome with the Knee Injury and Osteoarthritis Outcome Score (KOOS) patient questionnaire

    KOOS consists of 5 subscales: Pain, other symptoms, function in daily living , function in sport and recreation and knee related quality of life (QOL). The previous week is the time period considered when answering the questions. Standardized answer options are given (5 Likert boxes) and each question is assigned a score from 0 to 4. A normalized score (100 indicating no symptoms and 0 indicating extreme symptoms).

    Measured: pre-operative, 3 months, 1, 2, 5, 7 and 10 years

  4. Investigation of clinical performance and patient outcome with EuroQuol-5 dimension (EQ-5D) patient questionnaire

    The EQ-5D health questionnaire provides a simple descriptive profile and a single index value for health status.

    Measured: pre-operative, 3 months, 1, 2, 5, 7 and 10 years

  5. Investigation of clinical performance and patient outcome with the Forgotten Joint Score (FJS) patient questionnaire.

    The FJS consists of 12 questions and focuses on the patients' awareness of their joint replacement during a range of day to day and recreational activities. The score has a range of 0-100.questionnaire

    Measured: pre-operative, 3 months, 1, 2, 5, 7 and 10 years

  6. Investigation of patient outcome with radiographic analysis

    Plain radiographs will be obtained for assessment of fixation of the device.

    Measured: pre-operative, 3 months, 1, 2, 5, 7 and 10 years

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted24 Apr 2020
  2. Study start1 Nov 2014
  3. Primary completion17 Sep 2017
  4. Study completion10 Jun 2026 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Enrolment
60 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04358601
Sponsor's protocol ID
Allpoly Triathlon PS
Status last verified
May 2026
First submitted
20 Apr 2020
Last updated
11 May 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A study testing Triathlon PS Knee System with all-polyethylene tibial components and Triathlon PS Knee System with metal-backed modular components in people with Osteoarthritis, run by Region Skane.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

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 11 May 2026. Status can change between updates, so confirm with the study contact before making plans.

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?

Migration, measured by means of RSA (time frame: 2 years). 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 NCT04358601.

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 11 May 2026; AzTrials last refreshed its copy on 2 Nov 2026.

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