Test-retest reliability and minimal detectable change of three-dimensional gait analysis in chronic low back pain patients.

BACKGROUND AND AIM: Three-dimensional gait analysis (3DGA) can provide detailed data on gait impairment in chronic low back pain (CLBP) patients. However, data about reliability and measurement error of 3DGA in this population is lacking. The aim of this study is to investigate test-retest reliability and minimal detectable change of 3DGA in a sample of CLBP patients.

METHODS: A test-retest study was conducted with a sample of 14 CLBP patients that underwent two biomechanical gait assessments with an interval of 7.6 ± 1.8 days. Anthropometric and time-distance parameters, as well as peak values for lower limb and trunk joint angles and moments, were computed. Intraclass Correlation Coefficient (ICC3,k) and their 95% confidence intervals were calculated. Standard error of measurement (SEM), minimal detectable change (MDC) and limits of agreement (LOA) were also estimated.

RESULTS: The obtained ICC values demonstrate high test-retest reliability for most joint angles, with low SEM (< 2.5°) values. Although joint moments showed lower reliability than joint angles, the majority of the ICCs were above 0.7 and the SEM and MDC values were low (≤ 0.06 Nm/kg and ≤ 0.18 Nm/kg). Bland-Altman plots with 95% LOA revealed a good agreement and time-distance parameters were all highly repeatable (ICCs > 0.86).

CONCLUSIONS: The results of this study show high test-retest reliability for lower limb and trunk joint angles, and time-distance parameters during gait in CLBP individuals, together with a low measurement error. These results also support the use of this method in clinical assessments of CLBP patients' gait patterns.