Inter- and Intra-observer Variation of Schatzker Classification of Tibial Plateau Fractures and Morphological Characteristics of Each Fracture Subtype on Computed Tomography Scan

Abstract

Background: There is little information regarding inter- and intra-observer variation when classifying tibial plateau fractures using Schatzker classification system. There is paucity of literature regarding morphological characteristics of each Schatzker subtype on computerized tomography. Materials and Methods: Fifty-three patients (age 18–70 years) of either sex with fresh (<3 weeks old), closed tibial plateau fracture were included after obtaining their informed consent. Patients with previous surgery around tibia or knee and the ones with pathological fractures were excluded from the study. Standard plain radiographs (anterior, posterior, and lateral views) and an additional noncontrast computed tomography (CT) scan (with three-dimensional reconstruction) of knee and leg of the affected side were done. Five different surgeons classified these fractures as per Schatzker classification on two separate occasions. The intra- and inter-observer variations were calculated using the kappa test of Cohen. Additional morphological characteristics were also evaluated on CT scan. Results: The mean kappa values for five observers (A to E) for inter-observer agreement on Schatzker classification were 0.41 (moderate). The mean kappa value for intra-observer agreement was 0.71 (substantial). Six morphological characteristics were defined on CT scan-lateral condylar impaction (79.2%), tibial tuberosity fracture (3.8%), coronal plane (3.8%), tibial spine avulsion (22.6%), medial condylar impaction (17%), and posteromedial shear fracture (7.5%). Conclusion: There is inter- and intra-observer variation in Schatzker classification of tibial plateau fracture. The intra-observer variation (kappa 0.71) was found to be greater than the inter-observer variation (kappa 0.41). The additional morphological characteristics of tibial plateau fractures are better evaluated on CT scan. The articular depression, splits, and fracture geometry are better delineated on a CT scan than on plain X-rays alone.

Keywords

• ct scan; observer variation; schatzker classification; tibial plateau fractures