How Does the Position of the Wedge Influence the Tibial Slope After High Tibial Osteotomy?

Open-wedge high tibial osteotomy often results in an increase in the tibial slope. Factors responsible for this increase are not clearly defined. The purpose of this study is to assess the influence of the position of the wedge on the changes of the tibial slope. This monocentric retrospective study included 87 patients with symptomatic isolated medial osteoarthritis of the knee. All patients were operated with open-wedge high tibial osteotomy with locked plate fixation. Tibial slope was measured on lateral x-ray of the tibia referring to posterior tibial cortex. The position of the wedge was estimated by measuring the distance between the posterior tibial cortex and the posterior lower part of the wedge. Measurements were performed by the same observer using Carestream® software. Data were analyzed with the SPSS 20 statistical software. Mean tibial slope was 6,03° preoperatively and 5,98° postoperatively with a non-significant decrease of 0,05°. Mean distance between the wedge and the posterior tibial cortex was 9,02mm, there was a significant correlation between this distance and the change in tibial slope (p<0,001) (R=0,73). However, there was no significant correlation between preoperative varus, degree of correction, age or BMI and changes in tibial slope. So, we recommend, during open-wedge high tibial osteotomy, to place the wedge in the posterior part of the osteotomy to avoid an increase in tibial slope and ensure better knee function.