Radial Head Fractures 

Radial head and neck fractures and dislocations have been treated by closed and open methods. Early attempts at closed treatment with casting resulted in stiffness and loss of function in the elbow. Consequently, treatment has evolved so that only patients with fractures stable enough to allow early motion undergo closed treatment, while essentially all other patients are treated with a form of surgical treatment. See images below.

Surgical methods have included excision of the fracture fragments, replacement, and internal fixation. Problems with proximal radial migration, especially with excision but also with replacement, and problems with the replacement implants have led to the belief that anatomic reduction and internal fixation is currently the treatment of choice for unstable and displaced radial head and neck fractures and dislocations.^{[1, 2, 3, 4, 5]}

Radial head fractures and dislocations are traumatic injuries that require adequate treatment to prevent disability from stiffness, deformity, posttraumatic arthritis, nerve damage, or other serious complications. Radial head fractures and dislocations may be isolated just to the radial head (and neck) and the lateral elbow (and proximal forearm), or they may be part of a combined complex fracture injury pattern involving the other structures of the elbow, distal humerus, or forearm and wrist.

Frequency

The radial head is fractured in about 20% of cases of elbow trauma, and about 33% of elbow fractures and dislocations include injury to the radial head and/or neck.

Except for the occurrence of congenital radial head dislocations, which are by definition congenital, radial head fractures and dislocations are the result of trauma, usually from a fall on the outstretched arm with the force of impact transmitted up the hand through the wrist and forearm to the radial head, which is forced into the capitellum.

Recognizing the congenital radial head dislocation (see image below), where the radial head is larger and rounder than expected, is important because operative treatment to reduce a congenital radial head dislocation is not indicated.

See Relevant Anatomy, below. The radial head is intra-articular, so anatomic reduction of bone fragments is necessary to minimize the risks of lateral posttraumatic arthritis from mechanical grinding. The intra-articular position also means that soft-tissue attachments to the most proximal portion of the bone are limited, so fractured fragments frequently lose their blood supply, resulting in avascular necrosis and potential nonunion. Luckily, the radial head mostly acts as a spacer preventing proximal migration of the radius, and as long as it maintains its structural support, the patient may do well even if the bone dies.

History

The patient with radial head fracture-dislocations usually presents with a history of a fall on the outstretched hand. Blunt or penetrating trauma rarely causes radial head injury. The wrist, especially the distal radioulnar joint, may be damaged simultaneously, and the presence of wrist pain, grinding, or swelling should be determined. The presence of bleeding, even with small puncture wounds, should alert the examiner to the possibility of open injury. Neurovascular symptoms of numbness, tingling, or loss of sensation should be identified to rule out nerve or vascular injury. The presence of severe pain should alert the examiner to the possibility of compartment syndrome.

Physical examination

Patients with radial head fractures and dislocations present with localized swelling, tenderness, and decreased motion. The physician needs to carefully examine any wounds to make sure no open fractures are present. Evaluating wounds over the subcutaneous border of the ulna is especially important in fracture-dislocations to avoid missing open fractures. The examiner should also palpate the elbow, especially the radial head, feeling for deformity, and the wrist should be examined, especially feeling for stability of the distal radioulnar joint. All 3 major nerves of the forearm are in danger with elbow fractures and dislocations, so the examiner should also carefully assess neurovascular function for all of the nerves of the forearm and hand. Radial nerve function is especially important to assess with displaced fractures through the neck of the radius. The motor (posterior interosseous) branch provides extension for the fingers and wrist(see Relevant Anatomy, below).

The examiner must also assess the firmness of all compartments, check for pain with passive stretch, and measure compartment pressures if in doubt to avoid missing compartment syndromes. Elbow stability needs to be assessed even with seemingly nondisplaced radial neck fractures. The elbow is tested with valgus stress at 30° of flexion to determine the competency of the medial collateral ligament.

The goal of treatment of radial head fractures and dislocations, as with all orthopedic injuries, is a successful functional outcome. A successful outcome correlates directly with accuracy of anatomic reduction, restoration of mechanical stability that allows early motion, and attention to the soft tissues. Treatment can be closed, with immediate early motion to prevent stiffness in stable fractures, or it may be open, with surgical reconstruction depending on the fracture type. Specific indications are discussed in Treatment, below.

The elbow joint consists of 3 bones and 3 joints. The bones are the distal humerus , proximal ulna, and proximal radius. The ulnotrochlear joint is between the olecranon process of the ulna and the medial condyle of the humerus. This is a constrained joint that allows only flexion/extension. The radiocapitellar joint is between the radial head and the lateral condyle of the humerus. This joint is less constrained and allows both flexion and extension and forearm rotation. Finally, the radioulnar joint is between the radial head and the proximal ulna. This joint is minimally constrained and allows forearm rotation.

The joints are controlled by the ligamentous anatomy of the elbow. The elbow joint (ulnotrochlear joint) is constrained by the medial collateral ligament, which has well-defined anterior, posterior, and transverse bundles. The elbow is also constrained by the lateral collateral ligament, which is poorly defined, and the radial collateral, lateral ulnohumeral, and accessory collateral ligaments provide stability. The radioulnar joint is constrained by the annular ligament.

The neurovascular structures of the elbow are easily damaged in fractures and dislocations of the elbow. The physician needs to be especially aware of the ulnar nerve proximally because it passes behind the medial epicondyle and the posterior interosseous nerve, wraps around the radial neck, and is most likely to be damaged with radial head fractures or dislocations or during surgery to correct these injuries. The median nerve and brachial artery are in danger in the front of the elbow.

No contraindications to treatment exist. Contraindications for surgical treatment are listed as indications for nonoperative treatment in Treatment, Medical therapy, below.