Fractures of the capitellum are rare. The complete capitellar fracture pattern was first described in the 19th century (1853) by doctors Hahn and Steinthal; the eponym for this fracture pattern includes their names. Later, doctors Kocher and Lorenz described an additional variation of this fracture pattern; a classification system includes their names.
Because of the rarity of capitellar fractures, controversies exist regarding the most appropriate treatment. The fracture fragment is intra-articular and requires treatment and reduction to reestablish normal elbow motion. Difficulty arises from the varying sizes of the fracture fragment and from the amount of suitable subchondral bone that is present to achieve stable fixation and to allow early elbow motion. Failure of adequate intervention may result in an incongruous joint, as well as in stiffness, instability, and chronic pain.
Capitellar fractures account for 0.5-1% of all elbow fractures and 6% of all distal humeral fractures. Capitellar fractures are seen with greater frequency in females than in males; this is thought to be secondary to a greater carrying angle and an increased possibility of osteoporosis in females. In 20% of patients with capitellar fractures, radial head fractures also are found.
Capitellar fractures do not occur in children younger than 10 years. Because of the cartilaginous composition of the capitellum in children, a similar injury in a child would be a supracondylar or lateral condylar fracture.
Fractures of the capitellum occur in the coronal plane. Separating the capitellum from the lateral column, capitellar factures are the result of shear forces from a fall onto the outstretched hand or of a fall directly onto the elbow. The capitellum is susceptible to shear forces because its center of rotation is 12-15 mm anterior to the humeral shaft.
Capitellar fractures may be associated with radial head fractures and posterior dislocations of the elbow. Other associated injuries include the disruption of the medial (ulnar) collateral ligament, the interosseous membrane, and the distal radioulnar joint.
The patient is usually elderly or middle-aged and presents following a fall onto an outstretched extremity or following direct trauma to the elbow. The primary complaints are pain, swelling, and a decreased elbow range of motion (ROM).
Pain, swelling, and tenderness that are localized to the lateral elbow are evident on physical examination. Any attempt at flexion or extension motion is resisted, and the pain is accentuated with forearm rotation. Examination of the shoulder and wrist are mandatory to exclude associated injuries.
The development of smaller screws and absorbable implants has led to more successful results with open reduction and internal fixation. All efforts should be made to reduce a displaced capitellar fragment, either by closed or open techniques.
Closed reduction can be attempted for type I fractures (see Staging) under general anesthesia, as described by Ochner and colleagues (see Medical Therapy).1 However, soft-tissue attachments are rare, and stability allowing early motion may not be achieved. The most appropriate treatment of type I capitellar fractures is open reduction and internal fixation. If closed reduction is unsuccessfully attempted, open reduction is indicated.
Open reduction is indicated in all displaced fractures of the capitellum and in those for which closed reduction fails. The presence of significant comminution may preclude fixation; surgical excision of the comminuted fragments is then recommended.
The capitellum’s center of rotation lies 12-15 mm anterior to the axis of the humerus shaft, making the capitellum more susceptible to shear forces.
Capitellar fracture treatment is approached similarly to that of any intra-articular fracture. Every effort should be made to repair and stabilize displaced capitellar fractures. However, should a significant amount of comminution be present, fixation may not be possible, with excision of the fragments instead being necessary. No contraindications to surgical treatment exist other than those imposed by the patient’s medical status, ability to tolerate anesthesia, and activity level.