Condition category
Musculoskeletal Diseases
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims:
Total knee replacement (TKR) is the established way to treat end-stage osteoarthritis of the knee (when other treatment modalities have been exhausted). Currently more than 50,000 knee replacements are implanted every year in the UK. Over the past 30 years many new versions of knee replacements have been introduced with the development of technology supposedly leading to improvement in the function of the implant and hence the outcome for the patient. In current orthopaedic practise several different versions of TKR are in common use in the UK, and outcome studies using knee pain and functional scoring systems show similar results for most types of implants - around 90% survivorship at 10 years and generally good functional results. We are performing a study to compare the outcome of a new type of knee replacement implant (Triathlon) which, it is claimed, allows greater movement of the knee and better function for patients than the standard knee replacement implant we use (Kinemax). Both implants have received approval from the National Authorities and are currently used in this hospital. The surgeons involved in this trial are experienced in using both types of knee replacement but we do not know if one gives better results for patients.

Who can participate?
We will invite patients suffering from osteoarthritis and on the waiting list for primary TKR at our institution to take part in the study.

What does the study involve?
If you take part in this study you will receive one of the two implants (either Kinemax or Triathlon) though you will not know which implant you have received until the trial has finished. All other aspects of your operation and post-operative care will be the same as for those not taking part in this project. There is no technical difference in the surgery and no difference in the nursing care or rehabilitation you will receive. We will be recruiting 220 patients in total who will be randomly allocated to either implant. 110 patients will receive the Kinemax and 110 the Triathlon. You will be assessed at the pre-admission clinic visit (approximately 2 weeks before your surgery) and at 6 weeks, 6 months and then at 1, 3 and 5 years after the operation. The assessor will not know which type of knee has been used. Assessments will constitute questionnaires on issues such as the pain and stiffness in the knee, your general health and daily activities. Additionally we will measure the movement of your knee, leg strength and ability to undertake some simple day to day tasks such as walking up and down stairs, getting up from a chair and walking a measured distance.

What are the possible benefits and risks of participating?
There should be no additional harmful effects caused by participation in this study in addition to those already explained to you by your consultant for those people undergoing knee replacement surgery. Both types of implants have been routinely used by your surgeon. During the assessments you will be asked to perform normal activities of daily life such as climbing stairs which may cause you some knee pain. However, you will be asked to perform those activities in the same way as you would usually do, minimising the pain as much as possible. You can always, at any moment withdraw from the tests. We hope that either treatment will help with your pain and dysfunction. Both implants have been approved for use in the United Kingdom, but we do not know which implant will help you the most and this is why we are undertaking this research. The information we get from this study will help us to plan treatment for future patients with osteoarthritis requiring a knee implant.

Where is the study run from?
University of Edinburgh and NHS Lothian. All operations and follow-up clinics will be carried out via the Royal Infirmary of Edinburgh.

When is the study starting and how long is it expected to run for?
The study will be open to enrol participants between February 2008 and September 2009. Follow-up assessments will continue for 5 years following surgery.

Who is funding the study?
Styrker Orthopeadics UK

Who is the main contact?
Dr David Hamilton

Trial website

Contact information



Primary contact

Mr Paul Gaston


Contact details

Department of Orthopaedics and Trauma
Royal Infirmary of Edinburgh
Little France Crescent
EH16 4SB
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Comparison of outcome in Total Knee Replacement (TKR) using a new design 'single-raduis-of-curvature' implant (TRIathlon) versus a traditional design 'multi-raduis' implant (KineMAX)



Study hypothesis

That a new implant designed based on modern kinematic theory of the knee would demonstrate enhanced functional outcome in comparison to a traditional design of knee prosthesis.

Ethics approval

Lothian Local Research Ethics Committee, 04/12/2006, ref: 06/S1103/50

Study design

Single-centre prospective double-blind randomised controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Osteoarthritis / total knee arthroplasty


Primary total knee arthroplasty - Patients randomised to either Triathlon or Kinemax implants

Intervention type



Not Applicable

Drug names

Primary outcome measures

1. Change in Oxford Knee Score
2. Lower limb extensor mechanism power output (Leg Extensor Power Rig)

Measured pre-op, 6 weeks, 6 months, 12 months, 3 years and 5 years

Secondary outcome measures

1. Knee range of movement (flexion / extension)
2. Battery of timed functional performance tests (timed up-and-go, stairs climb, 8 metre walk)
3. Pain scores (0-10 numerical rating scale)
4. Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index

Measured pre-op, 6 weeks, 6 months, 12 months, 3 years and 5 years

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Diagnosis of osteoarthritis
2. Planned primary total knee arthroplasty with standard implants
3. Capacity to give informed consent

Participant type


Age group




Target number of participants

204 (102 patients per arm)

Participant exclusion criteria

1. Inability to fulfill the inclusion criteria
2. Comorbidities that would affect post operative recovery or subsequent physical performance

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Royal Infirmary of Edinburgh
EH16 4SB
United Kingdom

Sponsor information


University of Edinburgh (UK)

Sponsor details

Queen's Medical Research Institute
47 Little France Crescent
EH16 4JT
United Kingdom

Sponsor type




Funder type


Funder name

Stryker Orthopeadics (UK)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes