RADIAL HEAD FRACTURES: REPLACEMENT CONSIDERATIONS AND APPROACHES

Radial Head Fractures

Replacement Considerations and Approaches

Julious P. Smith III, Larry D. Field, and Felix H. Savoie III

Mason classified radial head fractures into three types based upon the extent and severity of the fracture pattern. Type I fractures were nondisplaced fractures. Type II fractures were displaced fractures without comminution. Type III fractures were comminuted. More recently, Morrey has used an additional classification level to describe these fractures: simple or complex. Complex radial head fractures are those that occur in conjunction with other fractures and/or ligament injuries. Simple fractures are isolated. Radial head prosthetic replacement is used most commonly in association with complex Mason type III fractures.

Indications

Mason type III fracture in association with:

1. Medial collateral ligament (MCL) injury

2. Elbow dislocation

3. Major coronoid fracture

4. Mechanical block to motion

5. Interosseus ligament or distal radio-ulnar joint (DRUJ) injury (Essex-Lopresti lesion)

6. Proximal ulna/olecranon fracture

7. Lateral ulnar collateral ligament injury

8. Failed open reduction and internal fixation of radial head

9. Radial shortening after radial head excision

Contraindications

1. Active infection, especially about the elbow

2. Simple radial head fractures, Mason I or II

3. Complex radial head fractures where ORIF is possible

4. Open epiphyses

5. Inadequate radial bone stock

6. Elderly, low demand, or medically unstable patient

7. Upper extremity palsy or paralysis involving the elbow

Mechanism of Injury

Radial head fractures are usually produced by longitudinal loading of the pronated forearm, such as occurs in a fall on an outstretched hand. This force causes posterior translation of the radius and ulna at the elbow and loads the anterior portion of the radial head, which is usually the site of the resulting fracture (Fig. 43–1).

Physical Examination

1. Tenderness and swelling present at the lateral elbow

2. Painful range of motion of the elbow, especially with supination/pronation

3. Bruising and soft tissue injury

4. Possible mechanical block to elbow motion

5. Possible varus or valgus elbow laxity

6. Possible tenderness and swelling at the wrist (Essex-Lopresti lesion)

Diagnostic Tests

1. Standard anteroposterior and lateral radiographs of elbow will show the radial head fracture along with associated fractures or dislocations (Figs. 43–2A through D). Assessment of X-rays can sometimes be difficult due to overlying structures.

2. Bony computed tomography scan of the elbow will help delineate the severity and displacement of the fracture.

Special Considerations

Biomechanically, prosthetic replacement of the radial head is not always necessary, and excision of the comminuted radial head is the more common treatment for isolated fractures. Investigators including Morrey have shown that valgus stability of the elbow is independent of the radial head in the presence of an intact MCL. The longitudinal stability of the radius is also basically independent of the radial head if the interosseus ligament and distal radioulnar joint are intact. If the MCL is injured, however, then the radial head becomes an important component of the valgus stability of the elbow. Similarly, Essex-Lopresti-type lesions allow proximal migration of the radius if the radial head is removed. These associated lesions increase the biomechanical importance of the radial head and create the need for its replacement.

There are two types of radial head prostheses that are commonly used today: silicone and evolve modular (Fig. 43–3). Both of these prostheses have produced mixed results. Some long-term studies on silicone implants have reported that the prosthesis can crack and elicit foreign body reactions. Evolve modular prostheses have been reported to loosen. Both, however, have been shown to increase stability and reduce proximal migration of the radius in the short term. The use ofboth prostheses continues to be recommended cautiously.

Preoperative Planning and Timing of Surgery

1. Operation within the first 24 hours after injury is recommended, if possible, to minimize the risk of ectopic bone formation.

2. Thorough evaluation of the elbow should be done preoperatively to assess all concomitant elbow injuries. Associated injuries are the most common cause of complications and failures with this procedure.

Special Instruments

1. Prosthetic radial head trials and instruments

2. High-speed burr

3. Osteotomes

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