78-year-old female with acute pain in the right forearm and elbow after a fall on an outstretched arm with dorsiflexion of the wrist. The patient experienced a sudden sharp pain in the forearm immediately after trauma.
Ultrasound examination of the elbow demonstrates fluid and swelling in the humeroradial joint and beneath the annular ligament of the radius. Additional fluid is visible in the olecranon fossa, consistent with intra-articular elbow effusion.
At the radial neck, a cortical interruption with step-off deformity is visible. The appearance is suspicious for a radial neck fracture. The radial head appears anatomically positioned. There is no sonographic evidence of radial head dislocation.
The suspected radial neck fracture was subsequently confirmed on radiographic imaging.
1. Final diagnosis
Traumatic radial neck fracture with intra-articular elbow effusion, detected on ultrasound and later confirmed radiographically. The radial head is anatomically positioned, without clear dislocation or luxation.
2. Differential diagnosis
The primary diagnosis is a non-displaced or minimally displaced radial neck fracture, involving the radial head-neck region after a fall on an outstretched hand. Differential diagnoses include occult radial head injury, capsuloligamentous elbow injury, humeroradial joint contusion, and associated intra-articular synovial reaction. Persistent pain, restricted motion, mechanical blocking, or pain during pronation and supination should prompt further assessment of the radial head, radial neck, and humeroradial joint.
3. Teaching points
Elbow effusion after acute trauma is an important indirect sign of intra-articular injury. Ultrasound can detect joint fluid in the humeroradial joint and olecranon fossa and may directly demonstrate cortical interruption or step-off deformity at the radial head or neck. Dynamic and comparative assessment can help evaluate radial head position, but radiographs or CT remain important for confirmation and fracture classification.
4. Injury/disease information
Radial neck fractures often occur after a fall on an outstretched hand, with axial load transmitted through the wrist and forearm to the elbow. Non-displaced or minimally displaced fractures without mechanical block are often managed with short-term immobilization for pain control followed by early, gentle mobilization to reduce the risk of elbow stiffness. Displacement, instability, mechanical block, neurovascular symptoms, or uncertainty about fracture extension may require specialist trauma or orthopedic evaluation and, when indicated, CT imaging.
Marc is founder of, and trainer at, SonoSkills. SonoSkills is an organization dedicated to MSK ultrasound education. He's also an MSK Sonographer at EchoConsult in Roermond, the Netherlands.
More Cases from Marc Schmitz
