Monteggia Fracture
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PBLMedicine Group
Introduction
The eponym Monteggia fracture is most precisely used to refer to a dislocation of the proximal radioulnar joint in association with a forearm fracture. These injuries are relatively uncommon, accounting for less than 5% of all forearm fractures. The ulna fracture is usually clinically and radiographically apparent. Findings associated with the concomitant radial head dislocation are often subtle and can be overlooked. The keys to successful diagnosis of a Monteggia fracture are clinical suspicion and radiographs of the entire forearm and elbow. Properly assessing the nature of this injury in a timely fashion is imperative in order to prevent permanent disability or limb dysfunction.
History of the injury :
In 1814, Giovanni Battista Monteggia of Milan first described this injury as a fracture to the proximal third of the ulna with associated anterior dislocation of the radial head.1 Interestingly, he described this injury pattern in the pre-Roentgen era based solely on the history of injury and on physical examination findings. However, this particular fracture pattern only accounts for about 60% of these types of injuries. More than 150 years later, in 1967, Bado coined the term Monteggia lesion and classified the injury into the following 4 types :
- Type I - Fracture of the proximal or middle third of the ulna with anterior dislocation of the radial head
- Type II - Fracture of the proximal or middle third of the ulna with posterior dislocation of the radial head
- Type III - Fracture of the ulnar metaphysis with lateral dislocation of the radial head
- Type IV - Fracture of the proximal or middle third of the ulna and radius with anterior dislocation of the radial head
Problem :
The first challenge is correctly assessing the extent and nature of the injury. The ulna fracture is usually noted, commonly in the proximal third of the ulna. The olecranon, midshaft, and distal shaft may be involved. In his classic 1943 text, Watson-Jones stated that "no fracture presents so many problems; no injury is beset with greater difficulty; no treatment is characterized by more general failure."3 Some injuries associated with radiocapitellar dislocation (such as the transolecranon fracture-dislocation of the elbow) are mislabeled as Monteggia lesions, when in fact the proximal radioulnar joint remains intact. The Monteggia lesion is most precisely characterized as a forearm fracture in association with dislocation of the proximal radioulnar joint.
The radial head dislocation may not be apparent and will possibly be missed if the elbow is not included in the radiograph. Whenever a fracture of a long bone is noted, the joints above and below should be evaluated using radiographs in orthogonal planes (planes at 90° angles to each other). If one of the forearm bones is injured, injury should be looked for in the other bone and in associated joints of the forearm, elbow, and wrist. This principle also applies to a Galeazzi fracture, which is a fracture of the distal radius with concomitant dislocation of the distal radioulnar joint.
Separate radiographs should be taken of the elbow. The radial head should point towards the capitellum on all radiographs of the elbow.
Unrecognized dislocations may result from reduction of the dislocated radius prior to presentation. This may occur in the field spontaneously or as a result of manipulation by emergency responders. The treating physician may reduce an unrecognized dislocation while reducing or immobilizing the ulna fracture.
Problems relating to treatment are discussed in complications
Monteggia fractures constitute less than 5% of forearm fractures, with published literature supporting 1-2%.4,5 Of the Monteggia fractures, Bado type I is the most common (59%), followed by type III (26%), type II (5%), and type IV (1%). Monteggia fractures are one third as common as the more familiar Galeazzi fractures.
Etiology :
Monteggia fractures are primarily associated with falls on an outstretched hand with forced pronation. If the elbow is flexed, the chance of a type II or III lesion is greater. In some cases, a direct blow to the forearm can produce similar injuries. Evans in 1949 and Penrose in 1951 studied the etiology of Monteggia fractures on cadavers by stabilizing the humerus in a vise and subjecting different forces to the forearm.6,7 Penrose considered type II lesions a variation of posterior elbow dislocation. Bado believed that the type III lesion, the result of a direct lateral force on the elbow, was primarily observed in children. In essence, high-energy trauma (eg, a motor vehicle collision) and low-energy trauma (eg, a fall from a standing position) can result in the described injuries. A high index of suspicion, therefore, should be maintained with any ulna fracture.
Bado type I lesion. This is the most common type of Monteggia fracture.
Bado type I lesion.
Bado type II lesion.
Bado type III lesion with lateral displacement of the radial head.
Bado type III lesion with lateral displacement of the radial head.
Bado type IV lesion.
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Treatment
Medical Therapy :
Pain should be managed as needed in the immediate period. If the fracture is open, the status of the patient's tetanus immunization should be determined and addressed as indicated. Intravenous antibiotics should be administered to patients with open fractures. Open wounds should be irrigated with sterile saline solution and dressed with sterile, moist gauze. The radial head should be reduced in the emergency department if possible. Pediatric patients should undergo closed reduction and splint application emergently. Closed reduction in children is easiest when performed under procedural sedation or general anesthesia. Ketamine 1-2 mg/kg IV or 3-4 mg/kg IM is a very useful drug for sedation. An image intensifier should be available with real-time and static images to verify anatomic reduction of the fracture and congruent relationship of the radiohumeroulnar joint. The position of the elbow when immobilized depends on the fracture pattern as described earlier.
Nonoperative treatment is successful for most Monteggia injuries in children because (1) the majority of the fractures are inherently stable, (2) they require a shorter time for both the osseous and the ligamentous injuries to heal, (3) children have little trouble regaining motion lost through stiffness, despite immobilization of the fractures for the duration of the initial healing period (3-6 wk), and (4) the potential may exist for remodeling of mild, residual angular deformities (<10°).
Surgical Therapy :
Open fractures require emergent surgical consultation. The initial treating physician may reduce the radial head dislocation and splint this fracture. Otherwise, an orthopedic surgeon should be consulted immediately to reduce the radial head. Anatomic reduction of the ulna is usually required prior to radial head reduction. Unless the fracture is open, surgical treatment is performed on an elective basis. While most adults require operative treatment, most pediatric fractures are treated closed.
Operative fixation of complete fractures of the ulna with proximal radioulnar joint dislocation is recommended in children. The complete disruption of bone continuity is likely to be associated with substantial soft-tissue trauma in these injuries. Shortening and angulation of complete fractures after cast immobilization is not uncommon. Anatomic reduction of the ulnar fracture and radial head often requires operative treatment. In the past, transverse and short oblique fractures were adequately treated with intramedullary wire fixation. Intramedullary wires, however, cannot be relied on to maintain reduction of complete fractures that are either long oblique in pattern or comminuted; the wires therefore are not used anymore. These fractures are likely to displace or even shorten and, consequently, should be fixed with a plate and screws.
As a result of the rapidity of osseous repair and the tolerance of cast immobilization in children, the use of plate-and-screw constructs that are smaller (typically a one-third tubular or semitubular plate) and shorter (2 or 3 holes [4 or 6 cortices] proximal and distal to the fracture) than those recommended for adults are usually adequate.
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