title: Comparative Study of Opening-Wedge High Tibial Osteotomy With and Without a Combined Computed Tomography-Based and Image-Free Navigation System.
abstract: To assess whether a combined computed tomography (CT)-based and image-free navigation system results in better coronal and sagittal alignment than the conventional method for performing opening-wedge high tibial osteotomy (OWHTO) and whether CT-based navigation results in acquisition of an accurate osteotomy plane.
  
  
  
  Sixty-two consecutive knees were randomly divided into navigated and conventional groups. The intraoperative correction angle was determined by the change in hip-knee-ankle angle in the navigated group and by the predicted medial opening width in the conventional group. Outliers of femorotibial angle (FTA) and tibial posterior slope (TPS) were defined as angles of >175° or <165° and angles of >2.5° or <-2.5°, respectively. Radiographic and clinical data were compared between the 2 groups at 2 years postoperatively.
  
  
  
  Mean postoperative FTAs were 168.5° in the navigated group and 168.1° in the conventional group. Mean change in TPS of -0.2° in the navigated group was significantly lower than that of 1.6° in the conventional group (P = .005). On postoperative CT, mean angle between the tibial plateau and osteotomy planes in the sagittal plane showed a significantly higher anterior opening of 12° in the conventional than in the navigated group (P < .001). There was a significantly greater proportion of TPS outliers in the conventional (51.6%) than in the navigated group (12.9%) (P = .001), and a significantly greater proportion within the normal range in both planes in the navigated (74.2%) than in the conventional group (48.4%) (P = .037).
  
  
  
  Combined CT-based and image-free navigation in OWHTO better preserves the original TPS and more frequently restores normal coronal and sagittal plane knee joint alignment. CT-based navigation also enabled acquisition of our target osteotomy plane in the sagittal plan. The navigation system in OWHTO was helpful for simultaneous control of the alignment in 2 planes.
  
  
  
  Level II, lesser-quality prospective randomized trial.
authors.affiliation: Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan. Electronic address: akamatsu@yokohama-cu.ac.jp.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Akamatsu
authors.affiliation: Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kusayama
authors.affiliation: Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kumagai
authors.affiliation: Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Saito
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D010027:Osteotomy / Q000379:methods*; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted; D013977:Tibia / Q000000981:diagnostic imaging* / Q000601:surgery*; D014057:Tomography, X-Ray Computed