The Effect of Opening-Wedge High Tibial Osteotomy on the Posterior Tibial Slope Assessed by Three Different Evaluation Methods

[Background]Recently, opening-wedge high tibial osteotomy (HTO) has attracted much interest due to its advantages over closing-wedge HTO. However, it has been reported to influence the posterior tibial slope (PTS), potentiating the knee for subsequent complications.[Objectives]This study aimed at evaluating: 1. How open-wedge HTO changes the PTS, and 2. how the PTS evaluation method influences the extent of the PTS change.[Methods]Patients with genu varum deformity, who underwent HTO at the center of the current study were included. Tomofix plate or Podo plate with or without bone graft were used for fixation purposes. The pre- and post-operative assessment of the PTS was performed using three different evaluation methods, including tibial anatomical axis (TAA), fibular anatomical axis (FAA) and posterior tibial cortex (PTC).[Results]A total of 119 knees from 83 patients, with mean age of 31.32 ± 10.1 years and mean follow-up of 3.1 ± 1.9 years, were included in this study. Medial compartmental osteoarthritis was the most frequent type of etiology. The pre-operative PTS was 13.16, 13.81 and 11.55 using the TAA, FAA and PTC method, respectively. The post-operative PTS was 12.59, 12.95 and 10.77 using the TAA, FAA and PTC method, respectively. The change of PTS was not statistically significant using either methods.[Conclusions]A negligible reduction of less than 1º was observed in the PTS of patients following opening-wedge HTO. The PTS assessment was not affected by the choice of evaluation method.