Imageology classification and treatment option for atypical Hangman fractures

Abstract

Objective The purpose of the retrospective study was to introduce a treatment option for atypical Hangman fractures (AHF) based on a new classification. Methods Sixty-seven patients with Hangman fractures were treated with a comprehensive treatment strategy. Firstly, Hangman fractures were classified as typical or atypical (AHF) lesions using computed tomography scans of the cervical spine. Secondly, AHF was divided into 1 of 4 types (type A1, A2, B1, and B2) devised by us to clarify the feature of injury. Thirdly, the injury status of disco-ligamentous complex (intact/indeterminate/ruptured) was evaluated using magnetic resonance imaging.If it was a stable lesion, conservative treatment was recommended.If not surgical treatment using anterior or/and posterior stabilization and fusion at C2-C3 level was used. Results Fifty-one patients were identified with AHF. According to our classification, thirty patients were classified as type A1, 14 cases as typeA2, 5 cases as type B1, and 2 cases as type B2 lesions. Thirteen AHF without C2-C3 instability (12 as type A1 and 1 as type B1) were treated with non-operative treatment, and 38 AHF with C2-C3 instability (18 as type A1, 14 as type A2, 4 as type B1, and 2 as type B2) were treated with operative treatment. Three patients (all with type A1 lesions) with slightly displacement of C2-3 underwent isolated direct screw osteosynthesis. The remaining 35 underwent posterior stabilization and fusion at C2-C3 level: 24 patients with posterior approach with C2 lag screws and C3 non-lag screws fixation and fusion (11 as type A1, 10 as type A2, 2 as type B1, and 1 as type B2); 3 patients with posterior approach with C1 and C3 screw-rod fixation and fusion (1 as type A1 and 1 as type B1); 7 with anterior approach by C2-3 discectomy and fusion (3 as type A1 and 4 as type A2); and 2 with anterior and posterior approach (1 as type B1 and 1 as type B2). The average follow-up period was 26 months (range, 12-86 months). Neck pain improved significantly at 3-month follow-up, and neurologic status improved at least 1 grade in 12 patients with neurologic deficits at final follow-up. Radiological evaluation showed bony fusion in all patients at 12-month follow-up. Radiological evaluation showed that all 13 AHF without C2-C3 instability treated with non-operative treatment gained fractures fusion at 3-6 month follow-up. Posterior approaches with C1 or C2 and C3 screw-rod fixation and fusion were found to obtain a better alignment of C2-C3 and satisfactory fusion of C2 pedicle factures than anterior approach. Conclusion The treatment option for AHF based on a new classification is helpful in managing such fractures, resulting in good clinical and radiological outcomes. C2 lag screws with or without C3 pedicle screws fixation via posterior approach may not only reduce fractures but also obtain alignment of C2-C3 effectively. Key words: Spinal fractures; Classification; Bone screws