title: Increase in posterior tibial slope would result in correction loss in frontal plane after medial open-wedge high tibial osteotomy.
abstract: OBJECTIVE
  The purpose of this study was to clarify the causes of the increase in the posterior tibial slope during open-wedge high tibial osteotomy (HTO) and to investigate whether its changes influenced the correction angle in frontal plane.
  
  
  METHODS
  We retrospectively reviewed 20 patients (26 knees) treated with open-wedge HTO. They were divided into the following two groups. Group A consisted of the knees whose opening gaps were fixed using a spacer plate having the trapezoidal block with a 2° posterior slope. In Group B, anterior and posterior opening gaps were fixed separately. The posterior tibial slope and the hip-knee-ankle angle were measured based on CT data. The relationship between the correction rate in frontal plane and the changes of posterior tibial slope was investigated.
  
  
  RESULTS
  Increase in the posterior tibial slope was 2.1 ± 2.5° in Group A and 0.2 ± 1.2° in Group B, which showed a statistical difference (P = 0.02). The difference between the hip-knee-ankle angles before and after operation was 5.2 ± 2.3° in Group A and 5.5 ± 2.5° in Group B. The correction rate was statistically correlated with the changes of posterior tibial slope (R = -0.55, P = 0.003).
  
  
  CONCLUSIONS
  To avoid increase in the posterior tibial slope, the trapezoidal block with a only 2° posterior slope in a spacer plate was not sufficient, and it was necessary to fix anterior and posterior gaps separately. The correction angle in frontal plane had a trade-off relationship with the changes in posterior tibial slope. Thus, we thought that increase in the posterior tibial slope might result in correction loss.
  
  
  METHODS
  Therapeutic study, Retrospective comparative study, Level III.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Kinki University, 377-2 Ohno-Higashi, Osaka-Sayama City, Osaka, 589-8511, Japan. asada@med.kindai.ac.jp
authors.forename: Shigeki
authors.initials: S
authors.lastname: Asada
authors.forename: Masao
authors.initials: M
authors.lastname: Akagi
authors.forename: Shigeshi
authors.initials: S
authors.lastname: Mori
authors.forename: Tetsunao
authors.initials: T
authors.lastname: Matsushita
authors.forename: Kazuki
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Chiaki
authors.initials: C
authors.lastname: Hamanishi
mesh_terms: D000328:Adult; D000368:Aged; D001964:Bromhexine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D012189:Retrospective Studies; D013977:Tibia / Q000033:anatomy & histology / Q000601:surgery*; D055815:Young Adult
chemical_list: D001964:Bromhexine