When the loose piece of cartilage lies anteriorly, flexion is quite limited, the fragment catching between the anterior aspect of the humerus and the tip of the coronoid process.
The cartilaginous fragments do not have an osseous nucleus and therefore do not show on radiography.
The left illustration is a tomography.
It usually cannot be reduced by manipulation but limitation of flexion, unless gross, is not of major concern.The alternatives then are: arthroscopic or surgical removal or nothing.