55-year-old patient presenting with lateral elbow pain and possible mechanical symptoms after a crash with a .Quad where she landed on her elbow. Clinical concern for intra-articular pathology with altered joint mechanics.
Ultrasound examination of the elbow demonstrates signs of intra-articular pathology.
There is increased synovial fluid within the humeroradial joint, visible on the lateral elbow view in proximity to the common extensor tendon. Additional fluid is noted within the olecranon fossa, likely communicating with the humeroulnar joint compartment, consistent with joint effusion.
At the level of the radial head, there is a clinically and sonographically apparent prominence compared to the contralateral side. Ultrasound measurements suggest that the radial head is positioned more superiorly relative to the capitellum than expected.
Dynamic assessment during pronation and supination reveals altered biomechanics, with an increased range of motion of the radial head, particularly in the deep-to-superficial direction. This suggests abnormal joint kinematics and possible instability or incongruity of the radiocapitellar articulation.
These findings raise suspicion for underlying intra-articular pathology, potentially involving ligamentous injury, prior trauma, or subtle radial head subluxation.
1. Final diagnosis
Intra-articular elbow effusion with suspected radiocapitellar incongruity and abnormal radial head biomechanics, possibly reflecting instability or prior injury.
2. Differential diagnosis
Consider radial head subluxation, annular ligament injury, osteochondral lesion of the capitellum, or post-traumatic deformity. MRI or CT may be helpful for further evaluation of intra-articular structures.
3. Teaching points
Joint effusion on ultrasound is an important indicator of intra-articular pathology. Comparison with the contralateral side is valuable when assessing subtle positional abnormalities. Dynamic ultrasound can reveal abnormal joint kinematics that may not be apparent on static imaging.
4. Injury/disease information
Radiocapitellar incongruity may result from trauma, ligamentous injury (e.g., annular ligament), or chronic instability. Altered biomechanics can lead to pain, impaired motion, and long-term joint degeneration if untreated.
Marc is founder of, and trainer at, SonoSkills. SonoSkills is an organization dedicated to MSK ultrasound education. He's also an MSK Sonographer at the Laurentius Hospital in Roermond, the Netherlands.
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