409.Monteggia Fracture (Part II)
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DISCUSSION
The forearm functions as a ring composed of the radius and ulna as well as the proximal and distal radioulnar joints. A break in the ring is commonly associated with a fracture or dislocation in another part of the ring. When a forearm fracture is seen on radiographs, both the wrist and the elbow must be evaluated to exclude associated dislocations and additional fractures. Monteggia fracture-dislocations are unstable injuries composed of a proximal ulna fracture and dislocation of the radial head. Failure to recognize the associated radial head dislocation may lead to long-term complications, requiring more extensive surgery.
Monteggia fracture-dislocations are usually the result of a fall on an outstretched hand with forced pronation, fall with flexed elbow, or direct blow to the forearm. High-energy trauma, such as in a motor vehicle collision, can also result in this type of injury, but are often associated with additional injuries.
The most commonly used classification system for Monteggia fractures is the Bado classification.
Type 1—The classic Monteggia fracture-dislocation. Most common in children. Anterior dislocation of the radial head and fracture of the proximal ulnar diaphysis, with apex anterior angulation.
Type 2—Most common in adults. Posterior or posterolateral dislocation of the radial head and fracture of ulna diaphysis with apex posterior angulation. Often associated with radial head fractures and lateral collateral ligament disruption. Associated with osteoporosis.
Type 3—Less common than Type 1 and also mostly seen in children. Lateral or anterolateral dislocation of the radial head and fracture of the ulna just distal to the coronoid process. Very similar to Type 1.
Type 4—Rare. Type 1 with fracture of the proximal radius shaft.
Notes：
1. pronation /prəu'neiʃən/ /prəu'neiʃən/ n. 手掌向下
2. diaphysis /daɪ'æfɪsɪs/ /daɪ'æfəsɪs/ n. 骨干
3. osteoporosis /ˌɒstɪəʊpə'rəʊsɪs/ /ˌɑstɪopə'rosɪs/ n. 骨质疏松症
来源：每天朗读一段医学影像学英语文章
圈主
深圳市人民医院放射科副主任医师杨敏洁