Morphologic study of posterior articular depression in Schatzker IV fractures.

The Schatzker classification of tibial plateau fractures is widely accepted. Type IV fractures are medial tibial plateau fractures that are either split off as a wedge fragment or depressed and comminuted. Posterior articular surface depression in Schatzker type IV tibial plateau fractures can be seen as a unique variant that increases the difficulty of reduction of the articular surface. Its morphologic characteristics have not been fully studied, and the incidence is sometimes underestimated. The goal of this study was to evaluate the morphologic characteristics of posterior articular depression in Schatzker type IV fractures based on computed tomography measurements. From January 2009 to December 2011, the medical records, including digital radiologic data, of all patients treated for tibial plateau fracture at the authors' institution were retrospectively analyzed. Articular surface depression deeper than 5 mm was the criterion for study inclusion. The depression depth, precise location of the articular depression center, surface area percentage, and distance of the fracture gap to the depression center were calculated. One hundred fifteen cases of Schatzker type IV fracture were retrieved, and a total of 47.83% (55 of 115) cases had posterior articular surface depression. The average depth of the depressed articular surface was 12.41 mm, the surface area percentage was 20.15% of the entire tibial plateau, and the gap distance from the medial direction was 41.40 mm, 2.8 times longer than that from the posterior direction, which was 14.91 mm. Posterior articular surface depression occurs in nearly half of Schatzker type IV fractures, and the posterior approach provides more direct access to the depression than the medial approach.