Condition category
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
The Figure of 8 Walk (F8W) test was developed to measure both straight and curved path walking in clockwise and counterclockwise directions. Research has shown that it is a valid and reliable test in elderly people and patients with stroke. However, its validity and reliability for patients who have undergone knee replacement surgery are yet to be tested. In addition, to date the F8W test has only been validated in clinical settings under controlled conditions; i.e., with smooth floors and quiet surroundings. This is likely to differ from the environment participants will encounter in daily life and so may not accurately reflect the patient’s advanced walking performance. There is therefore a need for the F8W to be validated in both the participant’s own home environment and for patients who have undergone knee replacement surgery.

Who can participate?
Patients who have undergone knee surgery at least one year ago.

What does the study involve?
Participants will be given the opportunity to choose to have their assessments carried out by a physiotherapist in either their home or in a clinical setting. At the first visit a physiotherapist will carry out the F8W test. A second appointment will then be made between 7-21 days later. This visit will involve two separate tests, once with the same physiotherapist who attended the first appointment and a second test with a different physiotherapist. This will help us to establish the reliability of the test over time and the reliability of the test between different measuring physiotherapists.

What are the possible benefits and risks of participating?
We do not expect any particular benefits for the participants from taking part in this study. All the assessments chosen are used in clinical practice and have been used safely in the past. There are no known particular side effects of the assessments and an experienced physiotherapist will be with the participants throughout to monitor how they are doing and check they are safe. Participants may experience some pain or tiredness whilst carrying out the tests but they will be offered a rest in between each test and they may stop the test at any point should they wish to.

Where is the study run from?
Nuffield Orthopaedic Centre (UK).

When is the study starting and how long is it expected to run for?
From June to November 2015.

Who is funding the study?
NIHR Health Technology Assessment Programme - HTA (UK).

Who is the main contact?
Martha Moore

Trial website

Contact information



Primary contact

Ms Martha Moore


Contact details

Physiotherapy Research Unit
Windmill Road
United Kingdom
+44 (0)1865 737526

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Validity and reliability of the figure of 8 walk test: an observational crossover trial


Fig 8

Study hypothesis

To investigate the validity and reliability of the Figure of 8 Walk Test for participants one year after knee replacement at home and in clinical settings.

Ethics approval

NHS Research and Ethics Committee South West Exeter, 21/05/2015, ref: 15/SW/0138

Study design

Observational crossover trial

Primary study design


Secondary study design

Trial setting


Trial type


Patient information sheet


Knee arthroplasty


Patients who have had a knee replacement a year ago and are eligible to take part will be given the option to have their assessments at home or at the physiotherapy department at the Nuffield Orthopaedic Centre. The initial assessment will involve three physical measures tests including the figure of 8 walk test, the timed up and go and the short physical performance battery. They will also be asked to complete two short paper questionnaires, the Oxford Knee Score and an Outcome Measures Evaluation Form. At the first visit the same physiotherapy researcher will carry out the physical measures. A second appointment will then be made between 7-21 days later. This visit will involve two separate assessments, once with the same research physiotherapist who attended the initial appointment and a second assessment with a different research physiotherapist. During this appointment the initial research physiotherapist will carry out only the Figure of 8 Walk test. The participant will then be given a rest and the second research physiotherapist will carry out the Figure of 8 Walk test once more with the participant.

Intervention type



Drug names

Primary outcome measures

Figure of 8 Walk test – measured at baseline and 7-21 days later at the second assessment. During the second assessment the Fig 8 will be measured twice by two different assessors. To measure the outcome we will record how long it takes to complete the test in seconds, how many steps the participant takes, whether the test was completed within the 2ft boundary and a 3-point smoothness score.

Secondary outcome measures

1. Timed up and Go – measured only at the baseline assessment. Assessed by timing how long it takes to complete the test in seconds.
2. Short Physical Performance Battery – measured only at baseline. Comprises of three different measures, assessed by time taken to complete all three.

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

12 months post total knee replacement

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Further surgery within 12 months
2. Rheumatoid arthritis

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Nuffield Orthopaedic Centre,
Oxford University Hospitals NHS Trust
United Kingdom

Sponsor information


University of Oxford (UK)

Sponsor details

Windmill Road
United Kingdom

Sponsor type




Funder type


Funder name

NIHR Health Technology Assessment Programme - HTA (UK)

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

Stored in repository

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes