Evaluation of the safety and reliability of the newly-proposed AO spine injury classification system

Objective: To evaluate the safety and reliability of the new AO Classification, a recent classification system for Thoraco-Lumbar Spine Trauma (TLST).

Design: Retrospective study.

Methods: We applied the new AO system in patients with TLST treated according to the TLICS. Two researchers classified injuries independently. Eight weeks later, the classification was repeated for intra and inter-observer agreement evaluation. To evaluate safety, we correlated the treatment performed based on the TLICS with the newer AO classification obtained.

Results: Fifty-four patients were included in this study, with a mean follow-up of 363.8 days. Twenty-three neurologically intact patients were initially treated conservatively. Their mean TLICS was 1.78 (1–4 points). Four patients underwent late surgery. Thirty-one patients were treated surgically. Their average TLICS was 7.22 points (4–10 points). Agreements in the four independent evaluations according to AO groups and subgroups were of 64.8% (35/54) and 55.5% (30/54) respectively. Kappa index for groups A, B and C was 0.75, 0.7 and 0.85 respectively. Kappa index for subgroups ranged from 0.16 to 0.85. Regarding safety, thirty (57.6%) patients with total subgroups agreement were analyzed. All patients with fracture in groups B and C underwent surgical treatment and patients in group A received surgery according to neurological status or failure of conservative treatment.

Conclusion: The newer AO spine classification demonstrated good reliability at the level of groups. Subgroups demonstrated worse and varying reliability. Although the safety analysis was limited due to the low level of total concordance among all evaluations, patients from group A can be treated conservatively or surgically, whereas those from groups B and C are treated surgically.