Comparison of the AOSpine subaxial cervical spine injury classification system and the Allen classification

The AOSpine group has launched a new subaxial cervical spine injury system (AOSCIS) based on morphology. The objective of this study was to use the AOSCIS and compare it to the widely used Allen classification (AC) based on mechanics for subaxial cervical spine injury. Twenty-two consecutive patients with subaxial cervical spine injury who received posterior cervical fixation in our hospital were included in this study. Medical records were evaluated retrospectively. The evaluated factors were as follows: preoperative ASIA impaired scale (AIS), AOSCIS, AC, and diffuse idiopathic skeletal hyperostosis (DISH). There was AIS A in nine patients, AIS C in four patients, AIS D in four patients, and AIS E in five patients. Two patients with AOSCIS B2 were classified as AC DF1. Two AOSCIS F3 patients were classified as AC CE1. Eighteen AOSCIS C patients were classified into multiple categories: five as AC DF2, three as DF3, one as CF4, one as CF5, four as DE2, three as CE3+DE1, and one as CE3+VC2. All of the AOSCIS A0 (F) or B patients were classified as AC stage 1, and all of the AOSCIS C patients were classified as AC stage 2 and higher (P<0.05). All of six patients with DISH were classified as AOSCIS C and CE3, DE2, or DF3. AOSCIS and AC are correlated. Conducting an evaluation using both systems helps us to better comprehend subaxial cervical spine injuries.