Establishing the inter-rater and test–retest reliability of the levator scapulae index in women with chronic mechanical neck pain: a reliability study

The levator scapulae is an important postural muscle that tends to shorten or become tight because of overactivity and bad posture, leading to neck and shoulder pain. Therefore, it is important to measure its length to effectively address dysfunction. The aim of this study was to measure the length of the levator scapulae using the levator scapulae index and examine this tool's inter-rater and test–retest reliability in women with chronic mechanical neck pain. A total of 130 women aged between 18 to 30 years, with a body mass index between 18.5 and 24.9 kg/m2 and experiencing chronic mechanical neck pain, participated in this study. The length of the participants' levator scapulae was measured with a digital Vernier calliper and with the women in a standing position. Measurements were taken twice on the same day in the afternoon, with a 1 hour resting time between trials. The test–retest reliability of the levator scapulae index was measured for each participant. The procedure was repeated by two researchers after a 1-hour interval, and a mean value was obtained. Variability in body height was normalised by using the levator scapulae index (levator scapulae length [cm]/subject's height [cm]×100) Spearman's rank correlation coefficient test was used to establish the test–retest reliability (rho=0.96). Inter-rater reliability was established by intra-class correlation coefficient (rater A: 1.0, rater B: 0.98) with Cronbach's alpha (0.99). The findings demonstrated the excellent reliability of the levator scapulae index for the measurement of levator scapulae length in females with chronic mechanical neck pain. This study helps to establish a reliable method for levator scapulae length measurement, which helps clinicians to plann more efficient treatment protocols for patients with chronic mechanical neck pain.