Reliability of shear-wave elastography in assessing the stiffness of the nuchal fascia and the thickness of upper cervical muscles

•The ultrasound-based shear-wave elastography may be a reliable tool for assessing the stiffness of the nuchal fascia and the thickness of upper cervical muscles.•The stiffness of nuchal fascia in forward head posture was higher than in neutral posture.•No differences on the stiffness of the nuchal fascia and the thickness of upper cervical muscles between the right and left sides in healthy adults.•No differences on the stiffness of the nuchal fascia between males and females in healthy adults. To determine the reliability of shear-wave elastography (SWE)in assessing the stiffness of the nuchal fascia and the thickness of upper cervical muscles in neutral head posture (NHP) or forward head posture (FHP). Sixteen healthy adults (mean age: 21.69 ± 1.01years, 9 females) were included. SWE mode was chosen to measure the nuchal fascia shear modulus and muscle thickness was measured in B-mode. Measurements were collected by two independent investigators on two different days. The intraclass correlation coefficient (ICC) was used to measure the relative reliability, and the standard error of measurement (SEM) were used to measure the absolute reliability. Intra‑rater (ICC = 0.63-0.89) and inter-rater (ICC = 00.54-0.82) reliability for the nuchal fascia shear modulus were moderate to excellent. Intra‑rater (ICC = 00.64-0.96) and inter-rater (ICC = 00.48-0.86) reliability for upper cervical muscles thickness were moderate to excellent. The SEM percentage oscillated from 3.27% to 13.55%. There were significant differences(P 0.05) were observed between the right and left sides. The upper cervical muscles thickness of males was significantly thicker(P 0.05) on the nuchal fascia shear modulus. Ultrasound-based SWE may be a reliable tool for assessing the stiffness of the nuchal fascia and the thickness of upper cervical muscles in clinical practice. ChiCTR2200055736