Detailed observation of anatomical location and pattern in Hangman's fracture based on computed tomography three-dimensional reconstruction.

Objective: To observe the precise anatomical location and pattern of the fracture lines in Hangman's fracture.

Methods: Three-dimensional computed CT images of 210 patients with Hangman's fracture were collected. According to the involvement of anatomical structures, the injuries were classified into facet joint injury and pure bony injury. The C2 ring was also divided into: anterior, middle, and posterior elements. The anatomical structures involvement and fracture patterns were observed.

Result: Total 520 anatomical structures injuries were involved in 210 patients Hangman's fractures, including 298 facet joints injuries (57.3%) and 222 bony injuries (42.7%). The most common facet joints injury was superior articular facet injury of C2, and the most common pure bony injury was pediculoisthmic component fracture. The injuries of anterior element (60.6%) were more common than that of middle (20.4%) or posterior (19.0%) element. One injury in anterior element on one side and another injury located in the anterior, middle or posterior element other side was the most common fracture pattern. Injury of middle element on one side with another injury located in the middle or posterior element could be also observed.

Conclusion: In Hangman's fractures, fracture lines could occur in any part of C2 ring. Facet joints injuries were more common than pure bony injuries, and the injuries of anterior element were also more common than that of middle or posterior element. The high prevalence of facet joints injuries means that most of Hangman's fractures may be involved with intra-articular injuries.