Which type of injury involves dislocation of the radial head?

The type of injury that involves dislocation of the radial head is characterized by a specific combination of fractures and dislocations. A Monteggia fracture is a particular injury pattern involving an ulna fracture combined with an anterior dislocation of the radial head. This clinical picture arises when there is a direct blow to the ulna or a fall on an outstretched hand, leading to both an injury to the ulna and compromise of the radial head.

In contrast, the other options represent different types of injuries. A Colles' fracture is a distal radius fracture typically associated with a fall onto an outstretched wrist but does not involve the radial head. A Smith’s fracture is also a fracture of the distal radius but occurs with a palmar angulation and does not involve dislocation of the radial head. A Greenstick fracture is an incomplete fracture often seen in children, which does not cause dislocation of any joints. Therefore, the correct answer is the Monteggia fracture, as it uniquely involves the dislocation of the radial head in conjunction with an ulna fracture.