Prospective case series, Level IV.

Within this study, it could be demonstrated that the rate of non-union in medial open-wedge HTO is not higher than in the lateral closed-wedge technique. Concerning the detected risk factors, the importance of the preservation of the lateral cortex is emphasised. In addition, it is necessary to discuss the risk of non-union with smokers and overweight patients when planning the therapy. Finally, it should be considered to perform iliac crest bone grafting in these high-risk patients a priori.

IV.

The results confirm our hypothesis for PH and posterior tibial slope changes after valgus HTO. However, there is no strong correlation between PH changes and the degree of frontal plane HTO correction. The incidence of patella infera increases after OW HTO, whereas the incidence of patella alta increases after CW HTO. Therefore, we recommend performing CW HTO or OW HTO with the tuberosity left at the proximal tibia in cases of patellofemoral complaints or patella infera. Neither technique leads to patellar lowering. It should be borne in mind that PH and posterior tibial slope may have been altered before planning total knee replacement after HTO.