Which of the following fractures is characterized by an external wound?

A comminuted fracture involves the bone being shattered into multiple pieces. While it can result from severe trauma, it does not necessarily involve an external wound; the skin may remain intact. Thus, comminuted fractures are defined by the bone's condition rather than the presence of a wound.

A complicated fracture refers to a fracture that is associated with additional injuries, such as damage to surrounding tissues or organs. However, it does not specifically indicate that there is an external wound present. The term "complicated" focuses on the severity of the injury rather than the relationship between the bone and the skin.

A greenstick fracture is a type of incomplete fracture often seen in children, where the bone bends and cracks but does not break completely. It is characterized by the bending of the bone without an external wound, making it distinct from compound fractures.

An impacted fracture occurs when one bone fragment is driven into another, often as a result of compression. Similar to other fracture types, it does not inherently involve an external wound and is defined by the manner in which the bones interact rather than an injury to the skin.