Plain English Summary
Background and study aims
In knee replacement surgery (knee arthroplasty), all or part of a damaged knee joint is replaced with metal and/or plastic components. Various approaches to knee replacement surgery are used and different designs are available. It was not clear which works better or is safer. The aim of this study is therefore to answer three questions. Should the back surface of the knee cap routinely be resurfaced with an additional plastic part? Should the metal and plastic parts of the knee replacement be firmly fixed together (fixed bearing), or should the plastic part be mobile to allow more normal knee movement (mobile bearing)? Should the part of the knee replacement that attaches to the shin bone (the tibial component), be all plastic or plastic with a metal backing?
Who can participate?
Patients undergoing knee replacement surgery
What does the study involve?
Participants can take part in one or two of the four study comparisons depending on the extent and type of disease in their knee. In each comparison participants are randomly allocated to one of two knee operations (i.e., knee cap resurfacing or no resurfacing; fixed bearing or mobile bearing; all plastic or plastic-and-metal tibial component; partial or total knee replacement). All participants are asked to complete postal questionnaires after three months and annually thereafter up to 20 years after the surgery. The postal questionnaires ask about knee function, general quality of life and healthcare costs. Information is also collected about any complications and further hospital admissions and operations.
What are the possible benefits and risks of participating?
Participants may not benefit personally from taking part in the study but they will be helping doctors to assess which operations are best and safest. We do not think there are any additional risks or disadvantages to participants. Whichever group they are allocated, their operation will be performed by an experienced orthopaedic surgeon. Steps are always taken to make sure that any possible risks are minimised. As part of routine care, participants will be well informed of potential risks.
Where is the study run from?
University of Oxford (UK)
When is the study starting and how long is it expected to run for?
December 1998 to June 2023
Who is funding the study?
Health Technology Assessment Programme (UK)
Who is the main contact?
Prof. David Murray
david.murray@ndos.ox.ac.uk
Trial website
Contact information
Type
Scientific
Primary contact
Prof David Murray
ORCID ID
Contact details
Nuffield Orthopaedic Centre
University of Oxford
Windmill Road
Headington
Oxford
OX3 7LD
United Kingdom
+44 (0)1865 227457
david.murray@ndos.ox.ac.uk
Type
Scientific
Additional contact
Dr Suzanne Breeman
ORCID ID
Contact details
University of Aberdeen
Health Services Research Unit
Health Sciences Building
Foresterhill
Aberdeen
AB25 2ZD
United Kingdom
-
s.breeman@abdn.ac.uk
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
HTA 95/10/01
Study information
Scientific title
A randomised controlled trial of different knee prostheses
Acronym
KAT (Knee Arthroplasty Trial)
Study hypothesis
A UK wide network of clinical centres will be established to conduct randomised partial factorial trials on current practice of knee replacement. Independent management by health services research units is a feature of the application. Individual surgeons will be invited to consider areas of uncertainty concerning current knee prosthetic and participate in randomisation between certain design aspects of knee replacement systems which are otherwise similar in all other respects.
The project will require two phases, each of six years. At end of first phase, the trial will demonstrate short to medium-term variations in costs and outcome relating to the four management options. The second phase is necessary in order to demonstrate prosthesis design-related adverse events. This trial will produce authoritative data to inform purchasers, providers, consumers and clinicians about this very commonly performed procedure in the NHS.
More details can be found at:
1. http://www.nets.nihr.ac.uk/projects/hta/951001
2. http://w3.abdn.ac.uk/HSRU/CHART/public/trials/TrialDetails.aspx?page=current-trials&tid=15
Protocol can be found at: http://www.nets.nihr.ac.uk/__data/assets/pdf_file/0003/53724/PRO-95-10-01.pdf
Ethics approval
Multi-centre Research Ethics Committee for Scotland, 30/11/1998, ref: MREC/98/0/100
Study design
Randomised controlled trial
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Hospitals
Trial type
Treatment
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Condition
Primary knee replacement surgery
Intervention
Current interventions as of 23/01/2009:
The trial is evaluating four aspects of knee replacements:
1. Metal backing of the tibial component compared with a single high density polyethylene component (350 participants)
2. Patellar resurfacing compared with no resurfacing (1400 participants)
3. A polyethylene mobile bearing component between the tibia and femur compared with a fixed bearing arthroplasty (350 participants)
4. Uni-compartmental arthroplasty compared with total knee replacement (350 participants)
Individual patients can participate in a maximum of two comparisons and then only if the surgeon responsible for care is substantially uncertain about these particular aspects.
Previous interventions:
The four management options are:
1. Metal versus non-metal backing of the tibial component
2. Whether to resurface the patella
3. Unicompartmental versus total knee arthroplasty
4. Mobile versus fixed bearing
Intervention type
Other
Phase
Not Applicable
Drug names
Primary outcome measure
Current primary outcome measures as of 23/01/2009:
Oxford Knee Score (postal questionnaire) at 3 months and then annually thereafter.
Previous primary outcome measures:
Outcomes will be in terms of complications and patient-assessed pain and function, principally conducted by post.
Costings include those relating to
1. Early complications expected immediately post operatively from medical effects
2. Medium-term complications such as dislocation and infection
3. Late complications of wear, loosening and infection.
Secondary outcome measures
Added as of 23/01/2009:
Complications and patient-assessed pain and function, assessed principally by postal questionnaires including:
1. SF-12
2. EQ-5D
3. Questions about any further hospital admissions and surgery
4. Costings:
4.1. Early complications expected immediately post-operatively from medical effects
4.2. Medium-term complications such as dislocation and infection
4.3. Late complications of wear, loosening and infection
Questionnaires are completed at 3 months and then annually thereafter.
Overall trial start date
31/12/1998
Overall trial end date
30/06/2023
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
Added as of 23/01/2009:
1. A decision has been made to have primary knee replacement surgery
2. The surgeon has no clear preference for a specific option in at least one of the comparisons
3. Both males ane females, no age limits
Participant type
Patient
Age group
Other
Gender
Both
Target number of participants
2,450
Participant exclusion criteria
Does not meet inclusion criteria
Recruitment start date
01/07/1999
Recruitment end date
31/12/2002
Locations
Countries of recruitment
United Kingdom
Trial participating centre
University of Oxford
Oxford
OX3 7LD
United Kingdom
Trial participating centre
University of Aberdeen
Health Services Research Unit
Aberdeen
AB25 2ZD
United Kingdom
Sponsor information
Organisation
Department of Health (UK)
Sponsor details
Quarry House
Quarry Hill
Leeds
LS2 7UE
United Kingdom
-
Sheila.Greener@doh.gsi.gov.uk
Sponsor type
Government
Website
Funders
Funder type
Government
Funder name
Health Technology Assessment Programme
Alternative name(s)
NIHR Health Technology Assessment Programme, HTA
Funding Body Type
government organisation
Funding Body Subtype
Federal/National Government
Location
United Kingdom
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
2009 results in http://www.ncbi.nlm.nih.gov/pubmed/19122088
2012 cost-effectiveness analysis results in http://www.ncbi.nlm.nih.gov/pubmed/22290396
2014 results in http://www.ncbi.nlm.nih.gov/pubmed/24679222
Publication citations
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Results
Murray DW, MacLennan GS, Breeman S, Dakin HA, Johnston L, Campbell MK, Gray AM, Fiddian N, Fitzpatrick R, Morris RW, Grant AM, , A randomised controlled trial of the clinical effectiveness and cost-effectiveness of different knee prostheses: the Knee Arthroplasty Trial (KAT)., Health Technol Assess, 2014, 18, 19, 1-235, vii-viii, doi: 10.3310/hta18190.
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, Johnston L, MacLennan G, McCormack K, Ramsay C, Walker A, The Knee Arthroplasty Trial (KAT) design features, baseline characteristics, and two-year functional outcomes after alternative approaches to knee replacement., J Bone Joint Surg Am, 2009, 91, 1, 134-141, doi: 10.2106/JBJS.G.01074.
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Dakin H, Gray A, Fitzpatrick R, Maclennan G, Murray D, , Rationing of total knee replacement: a cost-effectiveness analysis on a large trial data set., BMJ Open, 2012, 2, 1, e000332, doi: 10.1136/bmjopen-2011-000332.