5. Are atypical Hangman's fractures becoming typical?

BACKGROUND CONTEXT

A traditional Hangman's fracture (HF) is a bilateral fracture traversing the pars interarticularis of C2, but there is wide variability in the fracture patterns that separate the anterior elements of the C2 vertebrae from the posterior elements. One type of fracture that is increasingly being observed is the atypical HF, in which the posterior aspect of the C2 vertebral body, not the bilateral pars, is involved. While a typical HF separates the anterior elements from the posterior elements of the C2 vertebrae and increases the available space for the spinal cord, the space remaining for the spinal cord does not increase secondary to fracture in the case of an atypical HF, leading to a higher risk of neurologic injury.

PURPOSE

In this study, we review HFs treated at a single tertiary care university hospital, especially focusing on the fracture pattern and clinical characteristics associated with HFs.

STUDY DESIGN/SETTING

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PATIENT SAMPLE

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OUTCOME MEASURES

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METHODS

The subjects of this study are the 35 HF cases treated at our institution between 2010 and 2021, comprised of 22 males and 13 females with an average age of 60.6 years. The etiology, fracture pattern, neurological status, and vertebral artery (VA) integrity were retrospectively examined from hospital records.

RESULTS

The injury was caused by a traffic accident in 12 cases, a fall in 12 cases, tripping in 9 cases, and struck by a falling object in 2 cases. There were 6 cases of spinal cord injury (SCI) in this series, of which 2 cases with polytrauma died soon after arriving at the hospital: one traffic accident case and another case in that was struck by a falling steel plate. According to the Levine and Edwards Classification, there were 23 cases with Type 1, 6 cases with Type 2, 2 cases with Type 2a, and 4 cases with Type 3 injuries (of which 2 are the cases that died). There were 13 typical HFs and 22 atypical HFs in which the posterior aspect of the C2 vertebral body and not the pars was involved in at least one side. The pattern of fracture of atypical HFs, according to the Li classification, was 10 cases of Type A1, 1 case of Type A2, 7 cases of Type B1, and 4 cases of Type B2. There was no significant difference in the number of cases with SCI between the typical and atypical HF cases. Twenty^-four cases had VA integrity examined either through enhanced CT or MR angiography and 7 cases (20%) were diagnosed with VA injury. All 7 cases were closely followed without any intervention and no complications were observed. VA hypoplasia was suspected in 3 cases, and no VA injury was found the remaining 14 cases.

CONCLUSIONS

In our series, more atypical cases with vertebral body involvement were observed than traditional HFs, suggesting that atypical HFs may need to be renamed. Also in contrast to the literature, atypical HF cases were not associated with higher neurological injury. One contributing factor may be the fact that our cases were comprised of more elderly cases with low energy trauma, unlike past reports where traffic accidents were the main cause of injury. The aging Japanese population is believed to play a role, and this change in the characteristics of HF pattern may be predictive of what awaits other nations as well. Fortunately, and possibly related to the prevalence of low energy trauma, VA injury did not lead to cerebrovascular complications, but the fact that 11 cases were not evaluated for VA injury is worrisome.

FDA Device/Drug Status

This abstract does not discuss or include any applicable devices or drugs.