Rehabilitative ultrasound measurement of trapezius muscle contractile states in people with mild shoulder pain.

INTRODUCTION The utility of rehabilitative ultrasound imaging (RUSI) for assessing trapezius muscle contractile characteristics was investigated by examining whether muscle thickness changes during contraction (CT) differed between people with and without mild shoulder pain. METHODS In 18 subjects with mild shoulder pain (aged 28±8 years) and 18 matched controls, trapezius muscle thickness change was measured in prone at rest at 0° and during isometric CTs at 90° and 120° of shoulder abduction. Images were taken at four sites using a real-time ultrasound scanner (7-MHz linear transducer, 40 mm footprint). Percentage change in muscle thickness from rest was calculated. Differences between painful and non-painful shoulders and participant groups were examined by analysis of variance (ANOVA) and t-tests. RESULTS There were no significant differences between groups or sides in trapezius muscle thickness change during CT. There was no significant difference in trapezius muscle resting thickness (RT) between painful and non-painful shoulders in the same subjects. CONCLUSION Contractile ability of the trapezius muscle, assessed using RUSI was not impaired in subjects with mild shoulder pain during the test manoeuvres used. Further research is warranted involving patients with different severity of symptoms, using other test manoeuvres before RUSI can be advocated for assessing scapular muscle dysfunction.