title: Fractures around the lateral cortical hinge after a medial opening-wedge high tibial osteotomy: a new classification of lateral hinge fracture.
abstract: OBJECTIVE
  The purpose of this study was to determine the frequency of lateral hinge fractures after opening-wedge high tibial osteotomy and investigate the patterns of fracture and their clinical outcome.
  
  
  METHODS
  We analyzed 104 knees in 93 patients with a mean age of 68 ± 7 years. Of the knees, 74 were diagnosed as having primary osteoarthritis and 30 with osteonecrosis. The mean follow-up period was 41 months. Lateral hinge fractures were classified as follows: type I, the fracture reaches just proximal to or within the tibiofibular joint; type II, the fracture reaches the distal portion of the proximal tibiofibular joint; and type III, a lateral plateau fracture. A standard postoperative rehabilitation protocol was used for type I fractures, 3 of 5 patients with type II fractures were treated with non-weight bearing, and type III fractures were treated with non-weight bearing until visible callus formation.
  
  
  RESULTS
  The Knee Society scores for the knee and for function showed improvement from 49 ± 11 to 91 ± 7.7 points and from 62 ± 13 to 95 ± 8.2 points, respectively. Lateral cortex fractures were observed in 26 knees (25%): 19 type I, 5 type II, and 2 type III. In the type II fracture group, 2 of 5 patients were judged to have a delayed bone union. There were 2 cases of infection (2%) and 1 case of traumatic neuroma (1%) but no instances of implant failure, nonunion, or deep vein thrombosis among our patient cohort.
  
  
  CONCLUSIONS
  High tibial osteotomy patients treated with a combination of TomoFix (Synthes, Bettlach, Switzerland) and bone substitute were able to walk with full weight bearing 2 weeks after surgery. No complications were seen in 19 patients with type I fractures. Of 5 patients with type II fractures, 2 had delayed unions with a correction loss of 3° and 7°, respectively.
  
  
  METHODS
  Level IV, therapeutic case series.
authors: Department of Orthopaedic Surgery, Yokohama City University, School of Medicine, Yokohama, Japan. take0822@hotmail.com
authors: Ryohei
authors: R
authors: Takeuchi
authors: Hiroyuki
authors: H
authors: Ishikawa
authors: Ken
authors: K
authors: Kumagai
authors: Yuichiro
authors: Y
authors: Yamaguchi
authors: Naoki
authors: N
authors: Chiba
authors: Yasushi
authors: Y
authors: Akamatsu
authors: Tomoyuki
authors: T
authors: Saito
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D017102:Fracture Healing / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D010020:Osteonecrosis / Q000000981:diagnostic imaging / Q000601:surgery; D010027:Osteotomy / Q000009:adverse effects* / Q000379:methods; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000601:surgery*