Articular surface of the medial proximal tibia is aligned parallel to the ground in three-dimensional space under weight-bearing conditions for healthy and osteoarthritic knees

Abstract

Purpose: The inclined articular surface in the medial compartment of the proximal tibia (MCT) is an important factor for varus knee osteoarthritis (OA). It is assumed that the MCT in advanced knee OA is aligned parallel to the ground in the coronal plane under weight-bearing (WB) conditions (parallel phenomenon) by keeping the WB line vertical to the ground. To accurately assess the parallel phenomenon of MCT, the normal vector of the approximation plane in a 3D space should be applied. This study aimed to prove the parallel phenomenon of MCT in a 3D space under WB conditions, using the normal vector for the approximation plane of MCT in osteoarthritic knees, compared with that in healthy knees.