Capitellum Fracture

Be aware of coronal shear fracture of the capitellum that includes the capitellum and part of the trochlea. The coronal shear fracture involves the capitellum and extends medially to include part of the trochlea. You will see a double arc on the lateral x-rays. One arc represents the capitellum, and the other arc is the lateral ridge of the trochlea. Fracture of the capitellum in general, can be missed on the lateral view x-ray if the fragment is too small. There are four types of capitellar fractures.

Type I constitutes a large fragment of bone and articular cartilage. Type II is characterized by a small shell of bone and articular cartilage. Type III is a comminuted fracture of the capitellum. Type IV is a vertical shear type with the fracture extending medially to include the capitellum and trochlea. You can see the double bubble or double arc on the lateral x-rays of Type IV fractures. Fractures of the capitellum may be associated with other injuries to the ligaments or to the bones. Fractures may also block movement of the elbow or cause instability of the elbow. Rarely a CT scan is needed unless the fracture is a part of a complex injury of the elbow.

Treatment

Capitellar fractures can be treated with ORIF using the lateral approach. The most common outcome with ORIF is elbow stiffness. The patient may need more surgery in the future to release the elbow contractures. Type I fractures can be treated with fixation. Type II fractures can be treated with excision and occasionally fixation. Type III fractures can be treated with excision. Type IV fractures can be treated with open reduction and internal fixation. Some fractures require headless screws.

Author
Nabil Ebraheim, MD

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