Fracture morphology and injury mechanisms of tibial plateau fracture: analysis of 200 cases

Objective To classify tibial plateau fractures based on the analysis of the morphology and injury mechanisms of 200 cases of tibial plateau feature. Methods We collected the X-ray and CT images of 200 consecutive cases of tibial plateau fracture in 199 patients who had been treated at our department from January 2010 to April 2011. They were 134 males and 65 females, from 15 to 77 years of age (average, 45.7 years). According to the Schatzker classification, 9 cases were type Ⅰ (4.5% ), 105 type Ⅱ (52.5% ), 19 type Ⅳ (9.5% ), 37 type Ⅴ (18.5% ), 30 type Ⅵ (15.0% ), and none type Ⅲ. The fracture morphology and injury mechanism of each case were analyzed to propose a new classification system. Results Fractures of tibial plateau can be classified into the following five types: (a) Lateral condylar fracture and valgus injury (100 cases, 50% ). The injury mechanism is the axial force on the valgus and extended knee joint. (b) Fracture-dislocation injury (24 cases, 12.0% ). This type includes typical Schatzker type Ⅳ, and some cases of Schatzker type Ⅵ associated with lateral subluxation. Its mechanism is a compound force of valgus, varus, rotational and axial stresses. The rotational force is the key factor leading to subluxation of the knee joint. (c) Double-condylar fracture (40 cases, 20.0% ). This type is caused by an axial force on the extended knee, including Schatzker type Ⅴ and some cases of Schatzker type Ⅵ not associated with knee subluxation. (d) Posterior condylar fracture and flexion injury (32 cases, 16.0% ). This type only involves the posterior condylar plateau, and is caused by an axial force on the flexed knee. Based on the morphology, posterior condylar fractures can be further divided into three subtypes: simple split of posteromedial condyle, simple collapse of posterolateral condyle, and a combination of the two. (e) Frontal plateau compression fracture and hyperextension injury (4 cases, 2.0% ). This type is caused by an axial force on the hyper-extended knee. It is characterized by significant compression of the anterior plateau and intact posterior plateau. Conclusion Based on the morphological features and injury mechanisms, tibial plateau fractures can be classified into 5 types: lateral condylar fracture, fracture-dislocation injury, double-condylar fracture, posterior condylar fracture, and frontal plateau compression fracture. Key words: Knee joint; Fractures, bone; Radiography; Injury mechanism; Fracture classification