Psychometric properties of the 4-meter walk test after total knee arthroplasty

Objective: To determine the reliability, responsiveness, and convergent validity of the Four-Meter Walk Test (4mWT) compared to the Six-Minute Walk Test (6MWT) surrounding total knee arthroplasty (TKA). Design: Secondary analysis of a randomized controlled trial. Setting: Research laboratory. Participants: One hundred sixty-two patients (aged 63.5 ± 7.4 (mean ± sd) years; 89 females) undergoing TKA participated. Main outcome measures: 4mWT (usual and fastest) and 6MWT were measured 1–2 weeks preoperatively, and 1, 2, 3, 6 and 12 months post-operatively. Results: 4mWT demonstrated excellent test-retest reliability with Interclass Correlation Coefficients (ICC’s) ranging from 0.80 to 0.93 s. 4mWT also demonstrated small measurement error with Standard Error of Measurement (SEM) ranging from 0.15 to 0.35 s. 4mWT (fastest) demonstrated similar responsiveness to 6mWT in the first 2 months after surgery and better responsiveness from 2 to 3 months after surgery. Convergent validity between 6MWT and 4mWT (fastest) was high, with Pearson correlation coefficients ranging from 0.73 to 0.81. Conclusions: The 4mWT (fastest) has excellent test-retest reliability, shows high responsiveness sufficient for clinical outcomes in the immediate postoperative time periods, and exhibits high convergent validity with 6MWT. Given space and time requirements to conduct each test, 4mWT may be preferred for routine clinical assessment.IMPLICATIONS FOR REHABILITATIONWalking ability •Walking is an important functional ability for patients who undergo total knee arthroplasty (TKA). •While the Six-Minute Walk Test is a validated measure of walking ability in the TKA population, its clinical utility is limited by the space and time it takes to perform the test. •The Four-Meter Walk Test (fastest speed) is a valid, reliable, and responsive alternative to the 6MWT and is recommended for routine clinical use after TKA.