bubble_chart Overview

The surface of the radial head is covered with cartilage, and its central part is concave, forming a cup-shaped structure that articulates with the capitulum of the humerus. When the elbow is extended, only the anterior half of the radial head makes contact with it. During elbow flexion, the two surfaces fully align. The ulnar side of the cup-shaped surface features a crescent-shaped slope, which contacts the radial edge of the trochlea during pronation. The periphery of the radial head is also covered with cartilage, known as the cylindrical rim, and forms the proximal radioulnar joint with the radial notch of the ulna. The radial head is not perfectly circular but rather oval-shaped. Measurements conducted by Beijing Jishuitan Hospital on fresh specimens showed a long axis of 24 mm and a short axis of 21 mm, with a ratio of 8:7 between the long and short axes. The incidence of this condition is lower in children and more common in adults.

bubble_chart Pathogenesis

Fractures caused by direct external force are rare. The common scenario is falling with the elbow in an extended position and the palm hitting the ground, where the external force causes the radial head to collide with the capitulum of the humerus in a valgus position, resulting in a fracture. It is often accompanied by injury to the capitulum of the humerus and the medial collateral ligament. This type of fracture is more common in adults and is prone to misdiagnosis. If not treated early, some patients may experience limited forearm rotation function, necessitating the removal of the radial head. Based on the morphology of the fracture, it can be classified into the following types.

(1) Crack type: This is a linear fracture without displacement. The fracture line usually runs from the lower outer side obliquely upward to the posterior side, reaching the articular surface. The annular ligament is uninjured and provides stability to the fracture, making further displacement unlikely.

(2) Depressed fracture: The articular surface of the radial head is compressed and collapses.

(3) Comminuted fracture: In cases without displacement, the shape of the radial head is preserved, and the articular surface remains intact. The annular ligament is also intact. In cases with displacement, the annular ligament is often injured.

bubble_chart Clinical Manifestations

Local pain, grade I swelling on the lateral side of the elbow, with obvious tenderness around the radial head. Limited forearm rotation, pain during passive movement, especially pronounced during supination. Elbow joint flexion and extension are not restricted, but painful during movement.

X-ray imaging can confirm the diagnosis and type.

bubble_chart Treatment Measures

Fracture, after short-term internal fixation, can begin movement. Generally, if displacement is minimal, traction is applied in the extended position, and the forearm is rotated in the adducted position to restore the round or nearly round shape of the fractured radial head, preventing obstruction of forearm rotation. After reduction, a plaster splint is used for fixation. Remove the plaster splint after 2-3 weeks to practice elbow joint movement. For comminuted fractures with displacement or unsatisfactory reduction, early radial head excision should be considered, but the surgery is limited to adult patients. The excision should not go below the articular surface of the radial tuberosity. After smoothing the fractured end and removing surrounding bone fragments, cover the rough surface of the radial stump with surrounding soft tissues and suture. Postoperatively, suspend the elbow joint in the functional position with a triangular bandage, and movement can begin after 2 weeks.