To evaluate risk factors of posterolateral articular depression and characteristics of the posterolateral fragment in lateral condylar and bicondylar tibial plateau fractures with joint depression.

We reviewed 48 patients of Schatzker type II and type V (type II 34, type V 14) and evaluated risk factors of posterolateral articular depression according to the posterolateral fragment, fibular fracture, and Schatzker classification. We evaluated the position of articular depression and anterolateral fracture line of the posterolateral fragment and measured anterior to posterior lengths of the posterolateral fragment.

Posterolateral articular depression was found in 20 of 34 cases (59%) with coexisting posterolateral fragment and in 16 of 21 cases (76%) with coexisting fibular fracture. There was a significant difference in the occurrence of posterolateral articular depression with the existence of the posterolateral fragment and fibular fracture (p<0.001). Multivariate regression analysis revealed that fibular fracture increased the occurrence of posterolateral articular depression (odds ratio 24.5, 95% confidence interval 2.2-267.2). Fifty-seven percentage of the anterolateral fracture line of the posterolateral fragment existed posterior to the anterior margin of the fibular head.

This study showed that fibular fracture affects posterolateral articular depression in Schatzker type II and V tibial plateau fractures. Selecting a fixation device and performing fracture reduction requires a careful consideration since the anterolateral fracture line of the posterolateral fragment exists posterior to the anterior margin of the fibular head.