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?
Who is the main contact?
Dr Catherine Whitall
Dr Catherine Whittall
The Arthritis Research Centre
Robert Jones & Agnes Hunt Orthopaedic Hospital
Dr Laura Richards
13 Mole Business Park
Medial Rotation Knee Randomised Controlled Trial Allpolyethylene versus Metal backed tibia
MRK Poly Vs Metal
There is no difference in range of motion between the all-polyethylene tibia and metal-backed tibial medial rotation knee implants.
NRES Committee North West - Greater Manchester South, 26/02/2015, ref: 15/NW/0005
Multi-centre randomised controlled imterventional study
Primary study design
Secondary study design
Randomised controlled trial
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.
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
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
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
Trial participating centre
Robert Jones & Agnes Hunt Orthopaedic Hospital NHS Foundation Trust
13 Mole Business Park
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)