Publications
Characteristics of the Upper Trapezius Muscle in Patients with Chronic Shoulder Impingement Syndrome: A Comparative Study
Authors: Chun-Kai Tang 1, Chia-Feng Lu 2, Shin-Yi Chiou 3, Yi-Fen Shih 1
Affiliations:
- Department of Physical Therapy and Assistive Technology, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
Journal: Nature - Scientific Reports - May 2026 (DOI: 10.1038/s41598-026-46757-7)
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Field & Applications:
- Medical
- Musculoskeletal disorder
The upper trapezius (UT) muscle is critical for proper scapular kinematics, yet the role of intrinsic UT muscle characteristics remains unclear. Our study aimed to compare UT muscle quality (echo intensity, EI), morphology (thickness change), and tone and stiffness between patients with CSIS and controls.
This observational study recruited 30 participants with unilateral CSIS (27.5 ± 5.5 years old; pain duration 23.0 ± 19.7 months) and 30 controls (24.4 ± 3.0 years old) from the community. B-mode ultrasound was utilized to measure UT EI and muscle thickness at rest and during maximal contraction. Myotonometry assessed oscillation frequency (tone) and dynamic stiffness at rest and during 60° shoulder flexion. Data were analyzed using analysis of covariance (age).
The CSIS group exhibited greater UT muscle EI than controls on both affected and unaffected sides (p = 0.007, 95% Confidence Interval [CI]: 2.135–12.894). The CSIS group exhibited greater muscle tone and stiffness during 60° shoulder flexion, including elevated oscillation frequency (p = 0.005, 95% CI: 0.351–1.873) and dynamic stiffness (p = 0.006, 95% CI: 10.678–61.782) than the controls.
Our results suggest that patients with CSIS had bilateral deficits in muscle quality and muscle tone during active tasks. These findings provide objective evidence of altered intrinsic muscle characteristics and mechanical properties in the UT of patients with CSIS.
Keywords: ultrasound imaging, myotonometry, echo intensity, muscle quality, muscle thickness, muscle tone
Our study revealed that patients with CSIS showed significant alterations in the intrinsic characteristics of the UT muscle, including greater echo intensity and increased muscle tone and stiffness, particularly during active shoulder movement, compared with healthy controls. Patients with CSIS and neck pain may exhibit a different pattern of muscle thickness changes, which requires further investigation. These findings provide evidence of altered muscle quality and mechanical properties of the UT in patients with CSIS.