Surgical Outcomes for C2 Tear Drop Fractures: Clinical Relevance to Hangman's Fracture and C2-3 Discoligamentous Injury

Objective To analyze characteristics of surgically managed tear drop (TD) fractures of the C-2 axis associated with other injuries such as hangman's fracture and C2-3 discoligamentous injury as well as treatment outcomes. Methods A total of 14 patients (eight men and six women) with TD fractures of the C-2, who were surgically treated at four national trauma centers of tertiary university hospitals from January 2000 to December 2017, were included in this retrospective study. The mean age of the patients was 45.5 years (ranging from 19 to 74 years). The characteristics, surgical treatment methods (anterior fusion vs posterior fusion), and results of 14 TD fractures of the C-2 were analyzed retrospectively. And the clinical relevance between C-2 TD fracture and hangman's fracture and C2-3 discoligamentous injury was investigated through the co-occurrence between injuries. The mean follow-up time after surgery was 22.6 months (ranging from 12 to 60 months). Results Among 14 patients with TD fracture of the C-2, four patients (28.6%) had anterior TD fracture and 10 patients (71.4%) had posterior TD fracture. All 10 posterior TD fracture patients had anterior C2-3 displacement. While two of four anterior TD fracture patients had posterior C2-3 displacement, the remaining two did not. All 14 patients of TD fracture had at least two or more other associated C-2 injuries as well as C2-3 discoligamentous injuries. About 92.9% (13/14) of the patients had typical or atypical hangman's fracture; 100% (10/10) of the posterior TD fracture patients had hangman's fracture, but 75% (3/4) of the anterior TD fracture had hangman's fracture. At admission, 13 patients were neurologically intact. However, the remaining patient had spinal cord injury with American Spinal Injury Association (ASIA) impairment scale B with C2-3 bilateral facet dislocation. All four anterior TD fracture patients underwent posterior C2-3 fusion. While four of 10 posterior TD fracture patients underwent C2-3 anterior fusion, the remaining six underwent posterior fusion. At last follow-up, 100% (14/14) of the patients achieved solid fusion, and visual analog scale for neck pain was significantly improved (5.9 vs 2.2, P < 0.001). One patient with ASIA impairment scale B had significantly improved to scale D. No major complications occurred. Conclusion Our study showed that surgically managed TD fractures of the C-2 showed a high incidence of other associated spine injuries including hangman's fracture and C2-3 discoligamentous injury. Therefore, special attention and careful radiologic evaluation are needed to investigate the presence of other associated spine injuries including hangman's fracture and C2-3 discoligamentous injury, which are likely to require surgery.