3D-radiographic analysis does not improve the Neer and AO classifications of proximal humeral fractures

The Neer and AO fracture classifications for fractures of the proximal humerus have shown poor reproducibility based on plain radiography. We wanted to investigate whether the addition of 3-dimensional (3D) reconstructions would increase the reproducibility of classification. 7 observers independently classified 24 fractures of the proximal humerus using both plain radiographs, CT and 3D and the classification was repeated 2 months later. There was a moderate interobserver agreement when using the Neer classification, but only a fair agreement with the AO classification. The Neer system had a mean kappa value of 0.44 and the AO had a value of 0.32 for the first assessment. In the second assessment, the mean kappa values were 0.49 and 0.34, respectively. Intraobserver reproducibility was fair to substantial agreement for Neer (kappa range 0.27-0.73) and for AO (kappa range 0.29-0.74). In conclusion, the addition of CT and 3D to plain radiographs did not improve the reproducibility of the classifications of Neer and AO of the proximal humerus.