Role of sonography and magnetic resonance imaging in detecting deltoideal acromial enthesopathy: an early finding in the diagnosis of spondyloarthritis and an under-recognized cause of posterior shoulder pain.

The acromial origin of the deltoid is a target structure of ankylosing spondylitis and related spondyloarthritis, which are often overlooked and underdiagnosed as causes of posterior shoulder pain. The objective of this article is to review the roles of sonography and magnetic resonance imaging in detecting deltoideal acromial enthesopathy and their importance for optimizing management in individuals with posterior shoulder pain. Adequate awareness of such enthesopathy as a potential manifestation of inflammatory rheumatic disorders is critical for early diagnosis of spondyloarthritis.