MRCP2-4545

A 63-year-old man presents with a week of right-sided shoulder pain. He denies any trauma and denies radiation of the pain. There is no associated weakness or numbness. The pain is more noticeable at the extremities of movement and is affecting activities of daily living. His past medical history includes type 2 diabetes mellitus and asthma.

Upon examination, the affected shoulder is painful and restricted, with both active and passive movement. External rotation is most severely limited. Pain is elicited when applying direct pressure to the coracoid process.

What is the most appropriate next step given the most likely diagnosis?