OS Acromiale

OS Acromiale

The acromion (bony roof) of the shoulder develops from different growth centers made of cartilage. During development, these growth centers grow, transform into bone, and fuse together to form one bone. Occasionally, one or more of these growth centers does not completely fuse with others. The end of the acromion which does not fuse, separated by a layer of cartilage and fibrous tissue from the remainder of the bony acromion and scapula, is a called an os acromiale. The os acromiale, the unfused portion of the bony acromion, is typically asymptomatic (non-painful) and does not require treatment. However, when the os acromiale, is unstable and mobile, which can occur after a traumatic injury, it may pinch the rotator cuff tendon or bursa, causing symptoms of rotator cuff inflammation and pain. When severe enough, these symptoms warrant surgical intervention.