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

Abstract

BackgroundThe 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.MethodsThe 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.Results30MW 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.ConclusionsThough 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.

Outcome Measures in Clinical Practice: Five Questions to Consider When Assessing Patient Outcome

“…Equations were developed taking into account sex, age, height, and weight, which were determined to be important factors accounting for roughly 40 % of the variance in distance walked. Similar reference values have been found in more recent studies in healthy individuals [5,25,26].…”

Manipulating walking path configuration influences gait variability and six-minute walk test outcomes in older and younger adults

“…Due to its simplicity and close relation to activities of daily living, the 6MWT has been used to represent functional capacity in chronic obstructive pulmonary disease and total knee arthroplasty patients and older individuals [1][2][3]. Conversely, measures of gait variability are more specific indicators of the neural control of gait [4] and have been used to discriminate between older fallers and nonfallers and to predict older adults at risk of falling, a major health hazard in this population [5,6].…”

Influence of Preoperative Physical Function on Gait 1 Month After Total Knee Arthroplasty

“…The TUG test has acceptable concurrent validity for measuring dynamic balance and high repeatability in patients awaiting TKA 18) . Similarly, Ko et al 33) found that TUG test predicted physical activity and WOMACFunction scores. The association between TUG test and postoperative gait speed may be due to their sit-to-stand element; TUG test performance depends on a combination of neuromuscular components (walking ability, lower limb strength, and balance) that also play important roles in gait speed.…”

“…Along with gait speed, the 6MWT is commonly used to evaluate ambulatory capacity because it is a simple and clinically relevant measure of exercise endurance. The 6MWT has been shown as a robust measurement of functional mobility during the long-term recovery of patients after TKA 33) and is a highly reliable measurement tool in patients who underwent primary TKA 34) . Here, we found that preoperative BMI was the most powerful predictor of postoperative gait endurance in the first month following TKA.…”