Imaging description

Loose bodies in the elbow are most commonly found in the anterior aspect of the joint within the coronoid fossa/recess (Figure 26.1). The second most common location is within the olecranon fossa/recess, posteriorly. On radiographs, ossified loose bodies can be seen as a typically round or ovoid osseous fragment (Figure 26.1). Non-ossified loose bodies (as well as ossified loose bodies) can be seen on CT arthrography or MRI. Ossified loose bodies on MRI can have fatty signal similar to fatty marrow. In general, loose bodies are seen as filling defects on CT arthrography. They can also be seen easily on MRI if there is fluid within the joint space of the elbow. In regard to imaging, CT arthrography has the best combined sensitivity (between 90–99%) and specificity (60–70%) for detecting elbow loose bodies. Radiographs have a similar specificity (but lower sensitivity) while MRI has a similar sensitivity (but lower specificity). Ultrasound (US) arthrography has also been reported to be more accurate than conventional US in the detection of loose bodies in the elbow.

Importance

Medical imaging plays an important role in the evaluation of the patient with limited range of motion of unknown etiology. One of the causes of this is the presence of an intra-articular loose body. Radiography is the initial imaging test of choice. If this is non-contributory and a loose body is clinically suspected, then CT arthrography would be the most helpful in accurately identifying a loose body. If the reason for the loss of range of motion is unknown, then MR would typically be the best imaging study (after radiography) given its overall utility in better identifying multiple different causes of elbow pathology (relative to US or CT arthrography).