Email updates

Keep up to date with the latest news and content from BMC Musculoskeletal Disorders and BioMed Central.

Open Access Research article

The six-minute walk test is an excellent predictor of functional ambulation after total knee arthroplasty

Victoria Ko123*, Justine Marie Naylor1234, Ian Andrew Harris1234, Jack Crosbie5 and Anthony ET Yeo4

Author Affiliations

1 South West Sydney Clinical School, University of New South Wales, Sydney, Australia

2 Orthopaedics Department, Liverpool Hospital, Sydney, Australia

3 Whitlam Orthopaedic Research Centre, Sydney, Australia

4 Ingham Institute Applied Medical Research, Sydney, Australia

5 School of Science and Health, University of Western Sydney, Sydney, Australia

For all author emails, please log on.

BMC Musculoskeletal Disorders 2013, 14:145  doi:10.1186/1471-2474-14-145

Published: 24 April 2013

Abstract

Background

The Six-minute walk (6MW) and Timed-Up-and-Go (TUG) are short walk tests commonly used to evaluate functional recovery after total knee arthroplasty (TKA). However, little is known about walking capacity of TKA recipients over extended periods typical of everyday living and whether these short walk tests actually predict longer, more functional distances. Further, short walk tests only correlate moderately with patient-reported outcomes. The overarching aims of this study were to compare the performance of TKA recipients in an extended walk test to healthy age-matched controls and to determine the utility of this extended walk test as a research tool to evaluate longer term functional mobility in TKA recipients.

Methods

The mobility of 32 TKA recipients one year post-surgery and 43 healthy age-matched controls were assessed using the TUG, 6MW and 30-minute walk (30MW) tests. The latter test was repeated one week later. Self-reported function was measured using the WOMAC Index and a physical activity questionnaire.

Results

30MW distance was significantly shorter amongst TKA recipients (mean 2108 m [95% CI 1837 to 2381 m]; Controls 3086 m [2981 to 3191 m], P < 0.001). Test-retest repeatability was high (ICC = 0.97, TKA; 0.96, Controls). Amongst TKA recipients, the 30MW distance correlated strongly with the shorter tests (6MW, r = 0.97, P < 0.001; TUG, r = −0.82, P < 0.001). Multiple regression modeling found 6MW distance to be the only significant predictor (P < 0.001) of 30MW distance, explaining 96% of the variability. The TUG test models were moderate predictors of WOMAC function (55%) and physical activity (36%) and were stronger predictors than 6MW and 30 MW tests.

Conclusions

Though TKA recipients are able to walk for 30 minutes one year post-surgery, their performance falls significantly short of age-matched norms. The 30MW test is strongly predicted by 6MW test performance, thus providing strong construct validity for the use of the 6MW test in the TKA population. Neither a short nor long walk test is a strong predictor of patient-reported function after TKA.

Keywords:
Gait; Self-reported outcomes