The test-retest reliability, concurrent validity and minimal detectable change of the 3-m backward walking test in patients with total hip arthroplasty

Purpose

To determine the test–retest reliability, concurrent validity and minimal detectable change of the 3-m backward walking test (3MBWT) in patients with Total Hip Arthroplasty (THA).

Methods

A total of 29 patients after unilateral primary THA were enrolled in the study. All evaluations were carried out by the same physiotherapist. The test-retest reliability of the 3MBWT was assessed at an hour interval and analyzed by the Intraclass correlation coefficient (ICC). In the concurrent validity analysis, the Spearman correlation coefficient between 3MBWT and Harris Hip Score (HHS) was calculated. In addition, the standard error of measurement (SEM₉₅) and Minimal Detectable Change (MDC₉₅) values were also calculated.

Results

The mean age of the patients was 75.6 ± 10.0 years. The mean time of the second test was 2.41 s better than the first assessment. The ICC score of 3MBWT was 0.983. Test-retest reliability was excellent. SEM₉₅ and MDC₉₅ values were 1.56 and 4.33, respectively. Both test and retest evaluations of the 3MBWT were correlated with the HHS (p < 0.01). The degree of correlations was moderate.

Conclusion

The 3MBWT is a valid and reliable test in patients with primary unilateral THA. The MDC value of 3MBWT provides essential information to clinicians about patients’ clinical progression.