RADIAL HEAD FRACTURES

EPIDEMIOLOGY

Radial head fractures account for 1.7% to 5.4% of all fractures, and one-third of all elbow fractures.

One-third of patients have associated injuries such as fracture or ligamentous damage of the shoulder, humerus, forearm, wrist, or hand.

ANATOMY

The capitellum and the radial head are reciprocally curved.

Force transmission across the radiocapitellar articulation takes place at all angles of elbow flexion and is greatest in full extension.

Full rotation of the head of the radius requires accurate anatomic positioning in the lesser sigmoid notch.

The radial head plays a role in valgus stability of the elbow, but the degree of conferred stability remains disputed.

The radial head is a secondary restraint to valgus forces and seems to function by shifting the center of varus–valgus rotation laterally, so the moment arm and forces on the medial ligaments are smaller.

Clinically, the radial head is most important when there is injury to both the ligamentous and muscle–tendon units about the elbow.

The radial head acts in concert with the interosseous ligament of the forearm to provide longitudinal stability.

Proximal migration of the radius can occur after radial head excision if the interosseous ligament is disrupted.

MECHANISM OF INJURY

Most injuries result from a fall onto the outstretched hand, the higher energy injuries representing falls from a height or during sports.

The radial head fractures when it impacts the capitellum. This may occur with a pure axial load, with a posterolateral rotatory force, or as the radial head dislocates posteriorly as part of a posterior Monteggia fracture or posterior olecranon fracture-dislocation.

• Axial load at 0 to 35 degrees elbow flexion results in a coronoid fracture.

• Axial load at 0 to 80 degrees elbow flexion results in a radial head fracture.

It is frequently associated with injury to the ligamentous structures of the elbow.

It is less commonly associated with fracture of the capitellum.

CLINICAL EVALUATION

Patients typically present with limited elbow and forearm motion and pain on passive rotation of the forearm.

Well-localized tenderness overlying the radial head may be present, as well as an elbow effusion.

The ipsilateral distal forearm and wrist should be examined. Tenderness to palpation or stress at the distal radioulnar joint may indicate the presence of an Essex–Lopresti lesion (radial head fracture-dislocation with associated interosseous ligament and distal radioulnar joint disruption).

Medial collateral ligament competence should be tested, especially with type IV radial head fractures in which valgus instability may result. This may be difficult in the acute setting.

Aspiration of the hemarthrosis through a direct lateral approach with injection of lidocaine will decrease acute pain and allow evaluation of passive range of motion. This can help identify a mechanical block to motion.

RADIOGRAPHIC EVALUATION

Standard anteroposterior (AP) and lateral radiographs of the elbow should be obtained, with oblique views (Greenspan view) for further fracture definition or in cases in which fracture is suspected but not apparent on AP and lateral views.

A Greenspan view is taken with the forearm in neutral rotation and the radiographic beam angled 45 degrees cephalad; this view provides visualization of the radiocapitellar articulation (Fig. 20.1).

Nondisplaced fractures may not be readily appreciable, but they may be suggested by a positive fat pad sign (posterior more sensitive than anterior) on the lateral radiograph, especially if clinically suspected.

Complaints of forearm or wrist pain should be assessed with appropriate radiographic evaluation.

Computed tomography of the elbow may be utilized for further fracture definition for preoperative planning, especially in cases of comminution or fragment displacement.

CLASSIFICATION

Mason (Fig. 20.2)

Type I: Nondisplaced fractures

Type II: Marginal fractures with displacement (impaction, depression, angulation)

Type III: Comminuted fractures involving the entire head

Type IV: Associated with dislocation of the elbow (Johnston)

Orthopaedic Trauma Association Classification of Proximal Radius/Ulna Fractures

See Fracture and Dislocation Compendium at http://ota.org/compendium/index.htm.

TREATMENT GOALS

Correction of any block to forearm rotation

Early range of elbow and forearm motion

Stability of the forearm and elbow

Limitation of the potential for ulnohumeral and radiocapitellar arthrosis, although the latter seems uncommon

TREATMENT

Nonoperative

Nondisplaced and most isolated displaced fractures of the radial head with no block to elbow motion can be treated nonoperatively.

Symptomatic management consists of a sling and early range of motion 24 to 48 hours after injury as pain subsides.

Aspiration of the radiocapitellar joint with or without injection of local anesthesia has been advocated by some authors for pain relief.

Persistent pain, contracture, and inflammation may represent capitellar fracture (possibly osteochondral) that was not appreciated on radiographs and can be assessed by magnetic resonance imaging.

Operative

Open Reduction and Internal Fixation Isolated Partial Radial Head Fractures

The one accepted indication for operative treatment of a displaced partial radial head fracture (Mason II) is a block to motion. This can be assessed by lidocaine injection into the elbow joint.

A relative indication is displacement greater than 2 mm of a large fragment (>25% of the radial head circumference) without a block to motion.

A lateral (Kocher or Kaplan) exposure with the patient positioned supine and the arm placed on a hand table can be used to approach the radial head; this approach uses the interval between the anconeus and extensor carpi ulnaris. One should take care to protect the uninjured lateral collateral ligament complex. Hardware should be placed only within the 90-degree arc between the radial styloid and the Lister tubercle (safe zone) (Fig. 20.3).

The anterolateral aspect of the radial head is usually involved and is readily exposed through these intervals.

After the fragment has been reduced, it is stabilized using one or two small screws.

Partial Radial Head Fracture as Part of a Complex Injury

Partial head fragments that are part of a complex injury are often displaced and unstable with little or no soft tissue attachments.

Open reduction and internal fixation may be performed when stable, reliable fixation can be achieved. This is reserved for simple patterns only.

In an unstable elbow or forearm injury, it may be preferable to resect the remaining intact radial head and replace it with a metal prosthesis.

Fractures Involving the Entire Head of the Radius

When treating a fracture-dislocation of the forearm or elbow with an associated fracture involving the entire head of the radius and/or radial neck, open reduction and internal fixation should only be considered a viable option if stable, reliable fixation can be achieved. Otherwise, prosthetic replacement is indicated.

The optimal fracture for open reduction and internal fixation has three or fewer articular fragments without impaction or deformity; each should be of sufficient size and bone quality to accept screw fixation, and there should be little or no metaphyseal bone loss.

Once reconstructed with screws, the radial head is secured to the radial neck with a plate.

The plate should be placed posteriorly with the forearm supinated; otherwise, it may impinge on the ulna and restrict forearm rotation (Fig. 20.3).

Prosthetic Replacement

The rationale for use is as a spacer to prevent proximal migration of the radius.

Long-term studies of fracture-dislocations and Essex–Lopresti lesions demonstrated poor function with silicone implants. Metallic (titanium, Vitallium) radial head implants have been used with increasing frequency and are the prosthetic implants of choice in the unstable elbow.

A major problem with a metal radial head prosthesis is oversizing the radial head implant and thus potentially “overstuffing” the joint.

Radial Head Excision

It is rarely indicated anymore for isolated injuries in the acute phase and never in a potentially unstable situation (fracture-dislocation, Essex–Lopresti, or Monteggia).

A direct lateral approach is preferred; the posterior interosseous nerve is at risk with this approach. The level of the excision should be kept proximal to the annular ligament.

Patients generally have few complaints, mild occasional pain, and nearly normal range of motion; the distal radioulnar joint is rarely symptomatic, with proximal migration averaging 2 mm (except with associated Essex–Lopresti lesion). Symptomatic migration of the radius may necessitate radioulnar synostosis.

Late excision for Mason types II and III fractures produces good to excellent results in 80% of cases.

Essex–Lopresti Lesion

This is defined as longitudinal disruption of forearm interosseous ligament, usually combined with radial head fracture and/or dislocation plus distal radioulnar joint injury.

It is difficult to diagnose; wrist pain is the most sensitive sign of distal radioulnar joint injury.

One should assess the distal radioulnar joint on the lateral x-ray view.

Treatment requires restoring stability of both elbow and distal radioulnar joint components of injury.

Radial head excision in this injury will result in proximal migration of the radius.

Treatment is repair or replacement of the radial head with evaluation of the distal radioulnar joint.

Postoperative Care

With stable fixation, it is essential to begin early active or active assisted flexion–extension and pronation–supination exercises.

Immobilization should last no longer than 5 to 7 days.

COMPLICATIONS

Contracture may occur secondary to prolonged immobilization or in cases with unremitting pain, swelling, and inflammation, even after seemingly minimal trauma. These may represent unrecognized capitellar osteochondral injuries. After a brief period of immobilization, the patient should be encouraged to do flexion–extension and supination–pronation exercises. The outcome may be maximized by a formal, supervised therapy regimen.

• A firm or solid end point with range of elbow motion may represent mature contracture, impinging implants, or heterotopic ossification.

• Risk factors for heterotopic ossification include floating elbow fractures, multiple elbow

  surgeries, delay to surgery, and prolonged immobilization. The effectiveness of indomethacin or radiation therapy for prevention of heterotopic ossification is controversial.

Chronic wrist pain may represent an unrecognized interosseous ligament, distal radioulnar joint, or triangular fibrocartilage complex injury. Recognition of such injuries is important, especially in Mason type III or IV fractures in which radial head excision is considered. Proximal migration of the radius may require radioulnar synostosis to prevent progressive migration.

Posttraumatic osteoarthritis: This may occur especially in the presence of articular incongruity or with free osteochondral fragments.

Complex regional pain syndrome: This may occur following nonoperative or operative management of radial head fractures and may be related to the injury itself.

Missed fracture-dislocation: Unrecognized (occult) fracture-dislocation of the elbow may result in a late dislocation owing to a failure to address associated ligamentous injuries of the elbow.