Introduction

In 1814 Giovanni Battista Monteggia described two patients with a fracture of the proximal third of the ulna together with an anterior dislocation of the proximal epiphysis of the radius.¹ However it was not until 1967 that Jose Luis Bado, Professor of Medicine at the University of Montevideo, Uruguay, proposed the term Monteggia fracture dislocation.² He described ‘a group of traumatic lesions having in common a dislocation of the radio-humero-ulnar joint, associated with a fracture of the ulna at various levels or with lesions at the wrist’.

Bado classified these injuries into four types (Fig. 23.1):

• Type I comprises an anterior dislocation of the radial head with an anteriorly angulated fracture of the proximal ulna. It is the most common Monteggia fracture–dislocation.

• Type II is a posterior or posterolateral dislocation of the radial head. The ulna fracture is posteriorly angulated and often quite proximal.

• Type III fracture–dislocations are seen almost exclusively in children and involve a lateral or more accurately anterolateral radial head dislocation with a fracture of the proximal ulna metaphysis with lateral/radial angulation.

• Type IV fracture dislocations are uncommon and complex. They involve an anterior dislocation of the radial head together with a fracture of the radial and ulna shafts at the same level.

Figure 23.1 Bado classification of Monteggia fracture dislocation.²

Jupiter et al further subclassified type II Monteggia fracture dislocations into four groups depending on the position of the ulna fracture:³

• IIA – the ulnar fracture is at the level of the distal olecranon and coronoid process.

• IIB – the ulnar fracture is distal to the coronoid at the metaphyseal–diaphyseal junction.

• IIC – the ulnar fracture is diaphyseal.

• IID – the ulnar fracture is complex, extending from the olecranon to the diaphysis.

More favourable clinical outcomes were noted with types IIB and IIC rather than types IIA and IID.

Background/aetiology

Adult forearm fractures are relatively uncommon, with an incidence of 0–4 per 10 000 population per annum.⁴ The observed odds ratio for 15- to 44-year-old males is 5.4.⁴ Within this group only 1–2% have a radial head dislocation allowing them to be termed a Monteggia fracture–dislocation.⁵

The most common mechanism of a type 1 fracture dislocation is thought to be a fall onto the outstretched hand with the elbow in extension and the forearm hyperpronated.² In addition, a direct blow to the posterior aspect of the ulna will also produce this injury.

Evans, in a cadaveric study,⁶ removed all of the soft tissues from his specimens with the exception of the ligamentocapsular structures and interosseous membrane. As the forearm was taken into extreme pronation the ulna fractured, after which a gradual failure of the capsule and annular ligament resulted in an anterior dislocation of the radial head. By supination, regardless of the state of the ulna, Evans was able to reduce the radial head.

An alternative mechanism of injury proposed by Tompkins ⁷ argues that the first phase of injury is an anterior dislocation of the radial head. This he states results from a fall onto the hyperextended elbow combined with a strong reflex biceps contracture. The axially loaded force applied to the shaft of the ulna combined with the pull of the brachialis and radius through the interosseous membrane then results in a proximal ulna fracture with the observed anterior angulation.

Presentation, investigations and treatment options

Presentation

The patient normally presents with pain and a history of either a fall onto the arm or a direct blow to the forearm. In type I or IV injuries the forearm is usually held in pronation. Elbow movements are limited by pain and swelling. Usually the ulna fracture can be palpated and the direction of angulation identified. Assessment of the neurovascular state of the hand and forearm is of paramount importance, particularly with type II injuries, as these are quite commonly associated with a posterior interosseous nerve neuropraxia.

Investigations

Anteroposterior and lateral radiographs of the elbow, forearm and wrist are essential in order to avoid missing a Monteggia fracture–dislocation. Inadequate radiographs may fail to show the radial head dislocation, resulting in the patient being inappropriately treated for an isolated ulna fracture. The reported incidence of misdiagnosis varies from 16%⁸ to 52%.⁹

If doubt exists as to the extent of the patient’s injury, it is appropriate to obtain a CT scan of the elbow with three-dimensional reconstruction views in order to clearly define the anatomy of the radiocapitellar joint (Fig. 23.2).

Figure 23.2 Bado type II Monteggia fracture dislocation. (A, B) The radiographs do not show the exact anatomy of the proximal ulna fracture. (C, D) CT 3-D reconstruction of the same patient clearly identifies the fracture morphology.

In the case of a highly comminuted type IV injury, plain radiographs of the contralateral forearm may be helpful in order to allow the true length of the radius and ulna to be measured.

Clinical Pearl 23.1

Good-quality radiographs are essential in the assessment of Monteggia fracture–dislocations. If the anatomy cannot be fully defined a CT scan with three-dimensional reconstruction views should be requested (Fig. 23.2).

Treatment options

Anecdotal reports of adult Monteggia fracture dislocations show a poor outcome with conservative management – specifically a painful stiff elbow with limited forearm rotation, particularly supination.

In 1940 Speed and Boyd ⁹ published their results of treating 30 acute and 32 chronic Monteggia type I fracture dislocations. They advocated open reduction and internal fixation of the ulna fracture and if needed reconstruction of the annular ligament with a ‘fascial loop’. In 1969 a further report from the same unit with 159 cases re-emphasized the importance of surgical management.¹⁰ This has also been recommended in other studies.^11,¹²

Currently the accepted treatment option for adult Monteggia fracture dislocations is open reduction and rigid anatomical fixation of the ulnar fracture. Once this has been performed the radial head will either spontaneously reduce or will be reducible by closed manipulation.¹² If, however, in addition to the radial head dislocation, there has been a radial head fracture then consideration must be given to reconstruction, excision or replacement of the radial head.

The treatment of paediatric Monteggia fracture dislocations is discussed in Chapter 12.

Clinical Pearl 23.2

Conservative management is not appropriate for adult Monteggia fracture dislocations. Treatment should involve anatomical reconstruction of the ulna, after which the radial head dislocation will normally spontaneously reduce or can be reduced by closed manipulation.