Detailed description of anatomy of the fracture line in hangman's injury: a retrospective observational study on motor vehicle accident victims

Analysis of the clinical characteristics of adult patients with hangman's fractures: A retrospective study based on multicenter clinical data

Background

There are few reports on the clinical characteristics of adult patients with hangman's fractures.

Methods

The clinical data of adult patients were collected from the hangman's fracture database of 7 medical centers. Data on patients who met the inclusion and exclusion criteria were retrospectively analyzed. Data, including gender, age, mechanism of injury, fracture classification, and treatment, were statistically analyzed.

Results

A total of 216 eligible patients (160 males and 56 females, with a mean age of 49.7 years) were selected. There was no statistically significant difference in gender distribution of different age groups. The male-to-female ratio was similar in the young group (18–44 years) and the middle-aged group (45–64 years) (both about 3:1) but decreased in the elderly group (65 years and above) (about 2:1). Overall, high-energy injury was the main mechanism of injury. There was a statistically significant difference in the percentage of patients with high-energy injury in various age groups (the highest in the young group, and the lowest in the elderly group). Overall, unstable fracture was the main fracture type, with a higher proportion in the young and elderly groups than that in the middle-aged group, but there was no statistically significant difference. From the perspective of treatment options, the percentage of patients receiving surgery was higher in the young and elderly groups than that in the middle-aged group.

Conclusion

Hangman's fracture is predominant in males of all age groups, with high-energy injury as the main mechanism of injury. Unstable fracture is common fracture type. The percentage of patients receiving surgery in the young and elderly groups is higher than that in the middle-aged group, which may be correlated with the high incidence of unstable fracture and the life characteristics of the patients in the young and elderly age groups.

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.

Mechanically Relevant Anatomy of the Axis Vertebra and Its Relation to Hangman's Fracture: An Illustrated Essay

To describe the biomechanically relevant anatomy of the Axis vertebra and the load transfer patterns within the bone, and on that basis, to postulate its mechanism of injury, a literature review was conducted of the anatomy and biomechanics of Axis fractures. Two hypotheses have been presented: the internal gear hypothesis and the leaf spring hypothesis. Both are based on the trabecular anatomy of the vertebra and its load transmission patterns. The relationship of the Axis with Hangman’s injury is also discussed. According to the leaf spring hypothesis, the C2 pedicle corresponds to the shackle in the assembly and constitutes the weak link. The trabecular architecture of the Axis is such that the primary compression of the trabeculae is directed from the superior facet to the C2–3 endplate, with few trabeculae directed to the inferior facet. Along with the trabecular void in this area, this renders the isthmus vulnerable to trauma. The isthmus of the Axis is biomechanically susceptible to injury due to its unique anatomy in relation to the whole cervical spine and the internal load transmission patterns of the bone. The author suggests that in the flexion type of Hangman’s injury, the C1–2 posterior ligaments are disrupted and need to be addressed.

Transpedicular lag screw placement in traumatic cervical spondylolisthesis: Case report and systematic review of the literature

Traumatic spondylolisthesis of C2-C3 is an unstable fracture. Posterior fixation techniques can be employed with intraoperative navigation, however this tool is not available to all spine surgeons. Furthermore, the evidence for posterior surgical stabilization of C2, while adhering to motion preservation principles is currently unknown. The authors describe a patient who had fractures of the pedicle and vertebral body of C2 and C3, which was successfully stabilized with freehand placement of C2 pedicle lag screws and subsequent C2-C5 fixation. Subsequently, a systematic review was performed to evaluate studies that utilized C2 lag screw placement in patients with traumatic spondylolisthesis of the axis (TSA). Eight retrospective case series were identified (N = 63 patients). Five studies evaluated an open posterior cervical approach and 3 investigated a percutaneous approach. Follow-up time ranged from 2 to 48 months and fusion was successful in most cases. No intra-operative complications were reported. On final follow-up, 2 patients had unintentional C2-C3 fusion, and 3 had C2-C3 instability. Three minor complications (urinary tract infection, surgical site hematoma, respiratory infection) were also reported, that resolved with medical management. Freehand placement of C2 pedicle lag screws may be a viable option in select cases. While posterior C2 lag-screw fixation demonstrated successful fusion in most patients with TSA, the supporting evidence is limited to level IV studies.

Relevant findings on postmortem CT and postmortem MRI in hanging, ligature strangulation and manual strangulation and their additional value compared to autopsy - a systematic review

Several articles have described the use of postmortem computed tomography (CT) and postmortem magnetic resonance imaging (MRI) in forensic medicine. Although access to CT scanners and, particularly, access to MRI scanners, is still limited for several institutes, both modalities are being applied with increasing frequency in the forensic setting. Certainly, postmortem imaging can provide crucial information prior to autopsy, and this method has even been considered a replacement to autopsy in selected cases by some forensic institutes. However, the role of postmortem imaging has to be assessed individually according to various injury categories and causes of death. Therefore, this systematic review focuses on the role of postmortem CT and MRI in cases of hanging and ligature and manual strangulation. We assessed the most common and relevant findings on CT and MRI in cases of strangulation and compared the detectability of these findings among CT, MRI and autopsy. According to the available literature, mainly fractures of the hyoid bone or thyroid cartilage were investigated using postmortem CT. Compared to autopsy, CT demonstrated equivalent results concerning the detection of these fractures. A currently described "gas bubble sign" may even facilitate the detection of laryngeal fractures on CT. Regarding the detection of hemorrhages in the soft tissue of the neck, postmortem MRI is more suitable for the detection of this "vital sign" in strangulation. Compared to autopsy, postmortem MRI is almost equally accurate for the detection of hemorrhages in the neck. Another "vital sign", gas within the soft tissue in hanging, which is hardly detectable by conventional autopsy, can be clearly depicted by CT and MRI. The number of cases of manual and ligature strangulation that were investigated by means of postmortem CT and MRI is much smaller than the number of cases of hanging that were investigated by CT and MRI. Likewise, judicial hanging and the hangman's fracture on postmortem imaging were described in only a few cases. Based on the results of this systematic review, we discuss the additional value of CT and MRI in fatal strangulation compared to autopsy, and we reflect on where the literature is currently lacking.

Trabecular Anatomy of the Axis Vertebra: A Study of Shaded Volume-Rendered Computed Tomography Images

BACKGROUND

To date, trabecular morphology studies have been conducted on thin-section computed tomography (CT) scans of cadaveric bone. Here we describe the trabecular anatomy of the axis vertebra as revealed by an innovative imaging tool.

METHODS

Ten patients who underwent thin-slice CT scans for suspected cervical spine injury were prospectively subjected to shaded volume-rendered 3-dimensional reconstruction of the images. The trabecular anatomy thus depicted was recreated, and the mechanical vectors were deduced independently by a senior radiologist and spine surgeon and then matched. The clinical implications were postulated.

RESULTS

The most striking trabeculae are the vertical compression trabeculae connecting the C1 facet to the C3 body. The center of the body of C2 has a space with sparse trabeculae; similarly, the pars interarticularis also has a clear void. The dens contain predominantly tensile trabeculae that are retained even in older patients. Midline remnants of the odontoid body synchondrosis persist even into late adulthood.

CONCLUSIONS

Shaded volume-rendered imaging appears to be an excellent tool for studying the trabecular anatomy of cancellous bone. The weight-bearing trabeculae run from the C1-2 facet to the C3 body; the inferior facet contributes little to weight-bearing.

Imaging findings of flexion type of hangman's fracture; an attempt for a more objective evaluation with newly introduced scoring system

OBJECTIVE

To identify the flexion type of hangman's fracture on imaging studies.

METHODS

38 cases of hangman's fracture were retrospectively studied and categorized into flexion and non-flexion groups. Plain radiograph, CT and MRI of these patients were evaluated; 13 radiological parameters that might define flexion injuries were measured. The data were statistically analyzed to identify good criteria and to rank them according to their importance in predicting flexion.

RESULTS

Seven radiological criteria that have the highest correlation with flexion injury were identified. These are C2-3 lower end-plate angle, C2-3 posterior body angle, interspinous angle, disc disruption (MRI), widening of interspinous distance, disruption of the posterior ligamentous complex (MRI) and angle at the fracture site. Scoring 1 point for each positive criterion, a total score of 4 predicts flexion injury with 100% sensitivity and 96.9% specificity. Score of 5 has 83.3% sensitivity and 100% specificity.

CONCLUSION

Flexion hangman's injury can be diagnosed by the presence of four out of seven radiological criteria in the newly introduced scoring system. The authors believe that this method may help spinal surgeons in their selection of therapeutic strategy. Advances in knowledge: This study introduces fast, simple and more objective imaging criteria for the diagnosis of flexion hangman's injury and separates it from the non-flexion pattern.