Fractures of the proximal radius are common and may represent 20% of all elbow trauma. While much has been written about their treatment, the definitive method remains controversial. With most intraarticular fractures, open reduction and rigid internal fixation is the key to good results. However, the proximal radius is an exception, as the exact mechanical role of the proximal radius is unclear. While the proximal radius provides some stability to valgus stress, the medial collateral ligament of the elbow is the primary stabilizer of the elbow (8-11). Acute excision of the radial head can lead to a loss of strength, valgus instability, and proximal migration of the radius with disruption of the wrist,
while late excision of the proximal radius does not appear to be fraught with these problems. In addition, reliably good implants for the fixation in this fracture are just being developed. This has led to a variety of treatment regimens for the radial head, with everything from long-term immobilization to aggressive open reduction and internal fixation being advocated.
Radial head fractures are usually the result of a fall on the outstretched hand. They may be associated with other injuries to the forearm and elbow, including the ulnar shaft, as is found in the Monteggia fracture.
An isolated fracture of the radial head usually causes pain on the lateral side of the elbow, which is aggravated by forearm rotation. Radial head fractures may be associated with a loss of full pronation and supination above that which may be expected from just pain and swelling. When a radial head fracture is suspected, the forearm and wrist must also be examined for pain and swelling. If wrist pain is present, radioulnar dissociation with injury to the interosseous ligament of the forearm should be suspected.
Routine anteroposterior (AP) and lateral radiographs of the elbow are essential for diagnosis. They may, however, not provide all information necessary. The radiocapitellar view can be helpful (12). This view is obtained by positioning the patient for a lateral x-ray but angling the beam 45 degrees toward the shoulder. If proximal radial migration is suspected, films of the wrist must be obtained to check the ulnar variance. When there is doubt, films of the contralateral side should be obtained for comparison.
The initial treatment of a radial head fracture should consist of splinting the patient for comfort. Aspirating the elbow joint through the radiocapitellar joint is useful not only to look for intraarticular hematoma but also to inject a local anesthetic for pain relief (13). A comfortable patient can be more thoroughly examined and the presence of a block to forearm rotation can be discovered. If there is a bony block to forearm or elbow motion as a result of a displaced radial head fracture, this is an indication for operative treatment.
There have been many classifications of radial head fractures. Most of these classifications have been based on radiographic findings, and the most commonly used has been that of Mason (14). None of the radiographic classifications takes into account the functional status of the proximal radioulnar joint. For that reason, I prefer to use the classification of Mason as modified by Hotchkiss. This classification is based on the patient's radiographic fracture pattern, physical signs, and associated injuries.
According to Hotchkiss (15) a type 1 fracture is nondisplaced or minimally displaced. Forearm rotation is limited only by pain and swelling, and intraarticu-lar displacement is less than 2 mm. A type II fracture is displaced greater than 2 mm. Motion may be mechanically limited. The fracture is not severely comminuted and is amenable to internal fixation. Type 3 fractures are severely comminuted. They are not reconstructable and have a bony block to movement. They require radial head excision to regain motion. These fractures may involve an injury to the interosseous membrane and thus the wrist.
Nondisplaced or type 1 fractures can be treated nonoperatively. Most authors have reported that a brief period of immobilization followed by early functional rehabilitation produces good long-term results (16). Care must be taken in allowing early motion for fractures that involve a large majority of the articular surface, as these may displace. In the average patient, a period of immobilization of 1 to 2 weeks followed by active motion exercises will yield good results. Some loss of extension can be expected, but this does not occur in all fractures. Contracture, pain, and posttraumatic arthritis can occur despite what appears to be a well-aligned and minimally displaced fracture initially.
Treatment of type II fractures is more controversial. As noted earlier, Mason's classification is purely radiographic and did not take into account the functional status of the proximal radius. Examination of the elbow and radioulnar joints after the administration of local anesthesia can be very helpful in determining a treatment plan.
Type II fractures that do not involve a mechanical block to motion can be treated as type 1 fractures. If the patient has continued pain and stiffness after fracture union and an appropriate functional rehabilitation, a delayed radial head excision can be performed after any injury of the interosseous membrane has healed.
If the patient has a mechanical block to motion, the fracture should be treated operatively. Improvements in implant design have recently made this fracture more amenable to open reduction and internal fixation. The surgical approach to the radial head is through the lateral Kocher approach, exploiting the interval between the triceps and anconeus. Through a longitudinal capsu-lotomy, the fracture hematoma is debrided and adequate exposure is achieved. Care must be taken not to take down the annular ligament. If the annular ligament must be disrupted to gain appropriate exposure, it must be repaired prior to closure. Most often, the fracture will involve the anterolateral portion of the radial head. Care must be taken to avoid putting implants where they will impinge on either the proximal ulna or distal humerus. After anatomical reduction, fractures can be stabilized with K wires, minifragment 2.7- (Fig. 2) or 2.0-mm screws, or small buttress and blade plates. Simple fractures can be compressed with Herbert screws. Impaction of articular fragments can be elevated with bone grafting. As in type 1 fractures, late pain, loss of motion, and impairment can be treated with late radial head excision.
Type 3 injuries or comminuted fractures involving the entire radial head and neck are generally not reconstructable. If there is no injury to the interosse-ous membrane, early radial head excision can be successful. If, however, there is an interosseous membrane injury, early radial head excision will result in a proximal migration of the radius and disruption of the distal radioulnar joint. For this reason, early radial head excision should be accompanied by the implantation of a "spacer" to maintain the length of the radius and protect the interosseous ligament until it heals. Originally, radial head prostheses were developed from silicone. These implants have not been proven durable in the long term. Because
of this, a wide variety of metallic implants are now available. These are modular and durable; they come in many sizes to more closely restore anatomical relationships. Some authors have reported the need to remove these prosthetic "spacers" after a period of time because of loosening. At that point, the interosseous ligament should have healed and late functional problems been avoided.
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