Objectives: In the literature, shoulder ultrasound (US) protocols rely on the widely accepted anatomical concept of the infraspinatus tendon (IST) running parallel and posterior to the supraspinatus tendon (SST). To assess the IST, authors currently recommend placing the transducer posteroinferior to the acromion; however the examination of the anterosuperior part of the IST remains problematic. The aim of our study was to apply recent anatomical knowledge to propose a simple protocol to assess the IST over its entire width including its anterosuperior margin.
Materials and methods: Six non-diseased shoulders from four cadavers were assessed in hyperextended internal rotation (HIR) position with US anterosuperolateral approach followed by dissection. Twelve healthy volunteers underwent similar US examination of the shoulder.
Results: The IST is a thin, wide, strap-like tendon. The HIR position exposed the largest area of IST beyond the acromion; combined anterosuperolateral US approach enabled imaging of the IST over its entire width with transverse and longitudinal views. The anterosuperior margin of the IST was distinguishable from the SST.
Conclusion: The anterosuperolateral US approach in HIR position enables an accurate assessment of the IST including the transverse plane. The limit between the SST and IST appears more clearly.
Key points: • The hyperextended internal rotation of the shoulder brings the infraspinatus tendon forward. • The infraspinatus tendon is visible with anterosuperolateral ultrasound approach. • The anterosuperior margin of the infraspinatus tendon is visible with this technique.