FRACTURE OF HEAD AND NECK OF RADIUS
Fractures of the radial head occur primarily in adults, whereas fractures of the radial neck are more common in children. The usual causes of these injuries are indirect trauma, such as a fall on the outstretched hand, and, less commonly, a direct blow to the elbow. Radial head and neck fractures are generally classified into four groups. In type I fractures, the fracture is nondisplaced or minimally displaced. Type II fractures refer to displaced fractures of the joint margin or neck with a single fracture line. Type III fractures are comminuted fractures of the head or neck. Type IV fractures are associated with dislocation of the elbow.
Diagnosis of a radial or neck head fracture may be difficult. Pain, effusion in the elbow, and tenderness to palpation directly over the radial head or neck are the typical manifestations. If the fracture is displaced, a “click” or crepitus over the radial head or neck is detected during forearm supination or pronation. Radiographic findings in nondisplaced fractures are minimal, and the radiograph often shows only swelling in the elbow with a fat pad sign. Any radiographic evidence of fat pad displacement accompanied by tenderness over the radial head or neck strongly suggests a fracture.
Treatment of a radial head or neck fracture depends on careful clinical and radiographic evaluation. Type I fractures can be managed nonoperatively if they appear nondisplaced or minimally displaced on radiographs and demonstrate no evidence of a mechanical block on elbow range of motion. To determine the presence of a mechanical block, the elbow joint can be aspirated to remove the bloody effusion, followed by injection of lidocaine into the joint to relieve pain and allow a thorough examination. The examiner can then move the elbow painlessly through a full range of motion to assess the degree of flexion and extension and of pronation and supination and to detect any crepitus or blocked motion due to a displaced fragment. If the range of motion is adequate and there is no bone block or significant crepitus, then the elbow is placed in a posterior splint for a few days. After this period, the patient can remove the splint and begin active range-of-motion exercises for the injured elbow. Frequent follow-up radiographs are necessary to detect any late displacement of the fracture fragment.
Controversy surrounds the treatment of displaced (type II) and comminuted (type III) fractures of the radial head or neck and fractures associated with limited range of motion due to a fracture fragment. Surgical fixation is indicated for fractures with one or two large, displaced fragments that can be effectively reduced and stabilized with a plate and/or screws or Kirschner wires. Comminuted fractures that cannot be adequately reduced and stabilized with surgery usually require excision of the radial head. When the radial head is removed, the annular ligament must be preserved to maintain the integrity of the ligament complex of the proximal radioulnar joint. Radial head implants can be placed after radial head excision, but care should be taken to avoid oversizing the prosthesis, which can limit elbow range of motion. A radial head replacement should always be used after resection of the radial head when an Essex-Lopresti injury is present (fracture of the radial head with dislocation of the distal radioulnar joint and disruption of the interosseous membrane). In an Essex-Lopresti fracture, the radius will migrate proximally if the radial head is not replaced after excision, which is very debilitating to the entire forearm complex (see Plate 2-24). Placement of a radial head implant prevents proximal migration of the radius and minimizes long-term complications.
Dislocations of the elbow with comminuted fractures of the radial head or neck (type IV) are serious injuries that usually involve significant soft tissue injury. Both the joint capsule and the collateral ligaments of the elbow can be damaged, and the joint injury can lead to stiffness or persistent instability, osteoarthritic changes, and myositis ossificans. If surgery is appropriate and feasible, these type IV injuries should be surgically repaired early or replaced to decrease the occurrence of complications, such as stiffness or instability and myositis ossificans. Radial head fractures can also be associated with other injuries about the elbow, such as fractures of the capitellum, coronoid process, or olecranon. The combined injury pattern of an elbow dislocation associated with both a radial head and a coronoid process fracture has been termed a terrible triad injury.