WITHDRAWN: Quantitative assessment of middle deltoid elasticity during different shoulder abduction using shear wave elastography: A preliminary study

Abstract

Background: To measure the middle deltoid (MD) muscle elasticity during different shoulder abduction in healthy participants using shear wave elastography (SWE) and analyze the factors that may affect the MD elasticity, and then to establish the reference ranges of the normal MD elasticity during different shoulder abduction. Methods: Mean shear wave velocity (SWV) of the MD in 70 healthy participants were evaluated at left and right shoulder 0° and 90° abduction (L0°, R0°, L90°, R90°) using SWE, and potential factors that may affect MD elasticity including gender, MD thickness, age, body mass index were analyzed. Normal reference ranges of MD elasticity were calculated using normal distribution method. Results: Mean SWV was statistically significantly higher at L90° than L0°, higher at R90° than R0°, higher at R0° than L0°, and higher at R90° than L90° (all p< 0.0001). Mean SWV was significantly higher in males at both L0° (p< 0.05) and R0° (p< 0.01) than in females. Neither MD thickness, age nor body mass index influenced MD elasticity. Normal reference ranges of the MD elasticity were 2.4-3.1 m/s in males and 2.2-2.9 m/s in females at L0° and 2.5-3.3 m/s in males and 2.4-3.2 m/s in females at R0°, and were 4.9-6.7 m/s at L90°, 5.2-7.1 m/s at R90° for both males and females. Conclusions: Our results suggest that the normal MD elasticity at L0°, R0°, L90°, R90° are different and gender should be considered when determining the reference ranges of normal MD elasticity at L0° and R0° with SWE. These values may provide quantitative baseline measurements for assessment of the normal MD elasticity.