Intra- and Inter-Examiner Reliability of Kinovea for Hip Flexion Angle Measurement During Straight Leg Raise Test

Abstract

The accurate and reliable measurement of hip flexion angles during the Straight Leg Raise (SLR) test is essential for clinical and research purposes. Despite the widespread use of motion analysis tools, few studies have examined the reliability of affordable, open-source software 0.9.5 like Kinovea for this application. This study aimed to evaluate the intra- and inter-examiner reliability of Kinovea for measuring the hip flexion angle during the SLR test in individuals with and without low back pain (LBP). An observational study was conducted involving 53 participants (38 with LBP and 15 asymptomatic controls). Each participant underwent two SLR test sessions conducted by two examiners with varying levels of experience. The hip flexion angles were measured using Kinovea software based on video recordings. Intra- and inter-examiner reliability were assessed using the Intraclass Correlation Coefficient (ICC), Standard Error of Measurement (SEM), and Minimal Detectable Change (MDC). The effects of examiner experience and patient group were also analyzed. Kinovea demonstrated excellent intra- and inter-examiner reliability for measuring hip flexion angles, with ICC values ranging from 0.985 to 0.998. The SEM values were low (0.5°–1.5°), and the MDC values at 95% confidence ranged from 1.3° to 4.0°. No significant differences were found between the examiners’ experience or the patient groups. Thus, Kinovea offers a reliable, cost-effective, and user-friendly method for measuring hip flexion angles during the SLR test. Its consistency and precision, even across examiners with differing experience levels, highlight its potential to standardize assessments and improve diagnostic and therapeutic applications. Future research should explore its use in more complex movement analyses and diverse clinical populations to further validate its utility.