Investigation of axioscapular muscle thickness in individuals with neck pain with and without scapular dysfunction

Background: Scapular downward rotation (SDR) is associated with altered axioscapular muscles, including upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), and levator scapulae (LS). SDR is commonly seen in patients with chronic non-specific neck pain (NP). However, the extent of muscle thickness changes in this population remains unclear. Objectives: To investigate thickness of the axioscapular muscles between individuals with NP with SDR compared to those with NP and controls without scapular dysfunction (SD) Design: A cross-sectional study. Method: Sixty-six female participants were included, with 22 in each of the following groups: NP with SDR, NP without SD, and control without SD. Muscle thickness was taken using ultrasound imaging on the side of neck pain or dominant side, both at rest and during 120 degrees arm flexion with a 1-kg weight. Ratios of the axioscapular muscle thickness were calculated for each condition. Results: The NP with SDR group showed significantly reduced LT thickness, both at rest and during arm elevation compared to the NP without SD and control without SD groups (p < 0.05). The NP without SD group demonstrated greater UT thickness at rest compared to the NP with SDR and control without SD groups (p <= 0.01). There were no differences in SA and LS thickness or in muscle ratios between the groups (p > 0.05). Conclusions: Individuals with NP and SDR exhibited decreased LT thickness and those NP without SD showed greater UT thickness. This may suggest that scapular dysfunction (i.e., SDR) contributes to alterations in axioscapular muscle thickness in patients with NP.