CT-Based Classification Systems for Intra-Articular Calcaneal Fractures: The Inter- and Intraobserver Variations as well as Integrality.

The aim of this study was to measure the inter- and intraobserver variations as well as integrality of the Zwipp, Crosby-Fitzgibbons, Sanders, and Eastwood-Atkins classification systems based on more accurate CT scans. Five hundred and forty-nine patients with intra-articular calcaneal fractures from January 2018 to December 2019 taken from a database in our level-I trauma center (3 affiliated hospitals) were included. For each case, normative CT (1 mm slices) scans were available. Four different observers reviewed all CT scans 2 times according to these 4 most prevalent fracture classification systems (FCSs) within a 2-month interval. For these 4 FCSs, the kappa [κ] coefficient was used to evaluate interobserver reliability and intraobserver reproducibility, and the percentage that can be classified was used to indicate integrality. The κ values were measured for Zwipp (κ = 0.38 interobserver, κ = 0.61 intraobserver), Crosby-Fitzgibbons (κ = 0.48 interobserver, κ = 0.79 intraobserver), Sanders (κ = 0.40 interobserver, κ = 0.57 intraobserver), and Eastwood-Atkins (κ = 0.44 interobserver, κ = 0.72 intraobserver). Furthermore, the integralities were calculated for Zwipp (100%), Crosby-Fitzgibbons (100%), Sanders (92%) as well as Eastwood-Atkins (89.6%). Compared with previous literatures, CT scanning with higher accuracy can significantly improve intraobserver reproducibility of Zwipp and Eastwood-Atkins FCSs, but it has no positive effect on variability of Sanders FCS and interobserver reliability of Crosby-Fitzgibbons FCS. In terms of integrality, Zwipp and Crosby-Fitzgibbons FCSs appear to be superior to the other 2 FCSs.