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 has been performed for over 40 years as last resort treatment of arthritis and damaged knee joints. A knee replacement aims to reduce pain, stiffness and immobility. The most common measures of success in joint replacement surgery to date has been the rate at which a revision is required (further surgery to replace worn out components etc). The success of an implant can also be determined using validated patient reported outcome measures (PROMs) which are defined as validated measures to assess any aspect of health which come from the patient themselves.
The Medial Rotation Knee (MRK) from MatOrtho Limited is a total knee replacement system that was CE marked in 1994. It has proven to be a very successful design of knee replacement and shows the best revision rates at only 1.83% in 7 years from the UK. This study will compare two types of knee replacement implants (all-polyethylene tibia medial rotation knee implant vs metal-backed tibial medial rotation knee).

Who can participate?
Adult patients undergoing total knee arthroplasty for any indication.

What does the study involve?
Participants will be allocated to one of the two groups: 75 will receive metal-backed MRK implants and 75 will receive all-polyethylene tibia MRK implants. They will then be followed up over a 2 year period, during which they will be asked to complete various PROMs questionnaires, before and after the operation.

What are the possible benefits and risks of participating?
Taking part in the study will not impose any further risks on to the patient. The patients will be asked to attend an extra follow up appointment 2 years post-operatively and travel expenses will be offered to the patients to minimise any inconvenience. The potential risks of the surgery will remain the same regardless of whether the patient takes part or not, this will be fully explained to the patient during the consent process.

Where is the study run from?
The study is run by the Robert Jones & Agnes Hunt Orthopaedic Hospital NHS Foundation Trust and he patients will be recruited from 3 NHS sites across the UK.

When is the study starting and how long is it expected to run for?
July 2014 to December 2018 (updated 03/07/2019, previously: July 2018)

Who is funding the study?
MatOrtho Ltd.

Who is the main contact?
Dr Catherine Whitall

Trial website

Contact information



Primary contact

Dr Catherine Whittall


Contact details

The Arthritis Research Centre
Robert Jones & Agnes Hunt Orthopaedic Hospital
SY10 7AG
United Kingdom
+44 (0)1691404139



Additional contact

Dr Laura Richards


Contact details

MatOrtho Limited
13 Mole Business Park
KT22 7BA
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Medial Rotation Knee Randomised Controlled Trial Allpolyethylene versus Metal backed tibia


MRK Poly Vs Metal

Study hypothesis

There is no difference in range of motion between the all-polyethylene tibia and metal-backed tibial medial rotation knee implants.

Ethics approval

NRES Committee North West - Greater Manchester South, 26/02/2015, ref: 15/NW/0005

Study design

Multi-centre randomised controlled imterventional study

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


Patients undergoing total knee arthroplasty for any indication.


Participants in the study will all be undergoing total knee arthroplasty, group A will receive the all-polyethylene tibia medial rotation knee implant whereas group B will receive the metal-backed tibial medial rotation knee.

Intervention type



Drug names

Primary outcome measure

Compare the mean range of motion (ROM) of the all-polyethylene tibia MRK to the metal-backed tibia MRK. A difference of means in ROM of 5 degrees or more will be used to determine if there is a difference in the clinical outcome of the all-polyethylene tibia and the metal-backed tibia.

Secondary outcome measures

Patient reported outcome measures will be compared for the two treatment arms, including the Oxford Knee Score, the EQ-5D, Modified Forgotten Joint Score, and the UCLA Activity score.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Primary total knee arthroplasty (for any indication)
2. Informed consent to participate in the study provided by the patient
3. Patients aged over 18
4. Able to understand and respond to Patient-reported outcome measures (PROMs) for the duration of the study period

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Severe muscular, neurological or vascular deficiencies which compromise the affected extremity
2. Bone deficiency or deficient bone quality likely to compromise the implant (as determined by surgical team on pre-operative radiographs)
3. Severe ligament instability
4. Hypersensitivity to the materials used
5. Alcoholism or other addictive disorders
6. Sepsis
7. Osteomyelitis
8. Osteomalacia
9. Severe osteoporosis – clinical judgement
10. Metabolic disorders which may impair bone formation
11. Patients lacking capacity to provide consent
12. Those whose prospects for a recovery to independent mobility would be compromised by known pre-existing medical conditions
13. Patients who have their contralateral knee already in the study

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Robert Jones & Agnes Hunt Orthopaedic Hospital NHS Foundation Trust
SY10 7AG
United Kingdom

Sponsor information


MatOrtho Limited

Sponsor details

13 Mole Business Park
KT22 7BA
United Kingdom

Sponsor type




Funder type


Funder name

MatOrtho Limited

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

To be confirmed at a later date

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

The following changes were made to the trial record: 1. The recruitment end date was changed from 07/01/2016 to 31/12/2018. 2. The overall end date was changed from 06/07/2018 to 31/12/2021. 3. The intention to publish date was added. 4. The plain English summary was updated to reflect these changes. 30/03/2016: Ethics approval information added.