Role of sonography in the evaluation of unstable os acromiale

Os acromiale is a relatively common anatomic variation in which the acromial apophysis fails to completely fuse with the scapula.^1-4 Although typically regarded as an incidental finding, os acromiale may produce symptoms arising from the hypermobile nonunion site itself or as a result of downward impingement on the underlying rotator cuff.^1,5,6 Identifying symptomatic os acromiale can be clinically challenging when a patient has shoulder pain, resulting in delayed diagnosis.^5,7,8 This report highlights the use of sonography to identify symptomatic unstable os acromiale in an 18-year-old multisport athlete with refractory posttraumatic shoulder pain.