This produces a dumbbell shape in the axial plane and the thin plate of bone acts as a stress riser that fails under excessive axial load. The olecranon and coronoid fossae form the centre of this triangle, with a thin area of bone proximal to the condylar masses and between the supracondylar pillars. The distal humerus is roughly triangular in the coronal plane, with a base formed by the transverse condylar masses (lateral epicondyle, capitellum, trochlear and medial epicondyle) and the sides formed by the medial and lateral supracondylar ridges. Īn appreciation of the morphology of the distal humerus is necessary to understand the high incidence of fractures in this region. Flexion type injuries are far less common, accounting for 1–3%, and open fractures are also rare, occurring in approximately 1% and more frequently in the older child. And falls from play equipment are frequently implicated. There is a higher incidence of injury over weekends and during the summer months. This produces an extension type fracture, which accounts for 97–99% of injuries and may be influenced by the ligamentous laxity that is common in this age group, predisposing to elbow hyper-extension. The mechanism of injury is usually a fall onto an outstretched hand, with axial transmission of body weight through the maximally extended elbow. This injury is reported to be more common in males but there is a lack of consensus, some reports indicating a higher incidence in females and a recent evaluation of a cohort of > 63,000 children over a five year period did not demonstrate a statistically significant difference. The median age of presentation is six years, and the incidence gradually reduces with age until age 15, when patients tend to present with an adult pattern. Supracondylar fractures of the distal humerus account for approximately 15% of all paediatric fractures.
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