An Atypical Type-II Monteggia Fracture Equivalent Lesion

Forearm fractures are common childhood injuries, accounting for about 45% of all fractures and 62% of upper-limb fractures1-3. Approximately 75% to 84% of fractures occur in the distal third of the forearm, 15% to 18% occur in the middle third, and 1% to 7% occur in the proximal third4. Monteggia lesions account for 5% of all forearm fractures5,6. The Monteggia lesion is a radial head fracture or dislocation in association with a concomitant fracture of the metaphysis or diaphysis of the ulna2,6-11. It was first described in 1814 by Giovanni Battista Monteggia12. In 1967, Bado5 introduced a classification system for Monteggia lesions that is well established in clinical orthopaedic practice13. Bado’s classification subdivided Monteggia fracture-dislocations into four types of true Monteggia lesions; he also introduced equivalent lesions of this fracture pattern (Table I). The equivalent lesions are rare and usually occur in children14-19. Equivalent lesions are fractures that have the same mechanism of injury, with a similar radiographic pattern and method of treatment20. In 1991, Jupiter et al. provided the subclassification of a posterior Monteggia lesion based on anatomic location of the ulnar fracture and the pattern of radial head injury9. View this table: TABLE I Bado Classification for Monteggia Lesions5 The type-II Monteggia fracture is well described and has an incidence of 15% to 70%21,22. In his original classification, Bado stated that there were no equivalents to type-II Monteggia lesions other than epiphyseal fracture of the radial head or fracture of the radial neck5,20. In the orthopaedic literature, there are reports of type-II Monteggia fractures and equivalent type-II lesions (which occur mostly in adults)9, …