Validation of the modified AO sternum classification system.

INTRODUCTION

The Arbeitsgemeinschaft für Osteosynthesefragen (AO) foundation along with the Orthopaedic. Trauma Association (OTA) introduced a new classification for sternal fractures in 2018 aiming to provide greater uniformity and clinical utility for the surgical community. A previous validation study identified some critical issues such as the differentiation between type A and B fractures and localization of the fracture either in the manubrium or in the body. Due to the moderate agreement in inter- and intra-observer variability, some modifications were proposed in order to improve the performance of the classification. The aim of this study was to re-assess the inter- and intra-observer variability after adding modifications to the classification. Our hypothesis was that a significative improvement of inter- and intra-observer variability could be achieved.

MATERIAL AND METHODS

Twenty computed tomography (CT) scans of patients with sternal fractures were analyzed by six. Junior and six senior surgeons independently. Two assessments were performed with an interval of 6 weeks. The kappa (K) value was calculated in order to assess inter- and intra-observer variability.

RESULTS

The overall mean kappa value for inter-observer variability improved from 0.364 to 0.468 (p < 0.001). Inter-observer variability mean for location was 0.573 (SD 0.221) and for type was 0.441 (SD: 0.181). Intra-observer variability showed a mean of 0.703 (SD: 0.153) with a statistic significant improvement when compared to the previous study (mean 0.414, SD: 0.256, p < 0.001).

CONCLUSIONS

By modifying the AO/OTA classification of sternal fractures, the inter- and intra-observer variability improved and now shows moderate to substantial agreement.