Closing or Opening Wedge High Tibial Osteotomy: Watch Out for the Slope

In recent years, there has been a renewed interest in high tibial osteotomies. The development of new instruments and better fixation devices has significantly simplified the surgical procedure. This technique frequently is used to correct alignment in the frontal plane. However, changes in the sagittal plane after high tibial osteotomy have not been appropriately investigated. Changes in posterior tibial slope may have a profound influence on biomechanics, kinetics, and kinematics of the knee joint. Laboratory and clinical studies suggest that an increase in posterior tibial slope decreases tibial sag and forces on the posterior cruciate ligament whereas decreases protect the anterior cruciate ligament. In addition, contact forces on the articular cartilage may be altered. These findings may be helpful for the treatment of knee instabilities and articular cartilage defects either as single treatment or in combination. Open wedge osteotomies increase the posterior tibial slope and are recommended for posterior cruciate ligament or posterolateral corner injuries. Closed wedge osteotomies can decrease posterior tibial slope and may be indicated in combination with anterior cruciate ligament reconstruction in a varus malalignment with existing medial compartment changes. This article provides an overview of posterior tibial slope changes introduced by high tibial osteotomy and its resultant changes on kinematics and kinetics of the knee joint.