title: Upper tibia osteotomy: long term results - realignment analysis using OASIS computer software.
abstract: BACKGROUND
  The normal values for axial alignment and joint line obliquity of the knee that indicate a successful valgus upper tibial osteotomy have not been established and reported in the literature.
  
  
  METHODS
  To identify those parameters we prospectively followed 51 patients with 54 lateral closing wedge upper tibial osteotomies performed after preoperative and postoperative analysis of standardized hip-to-ankle radiographs with a software computer program (OASIS).
  
  
  RESULTS
  Of the 54 knees, 18 (33.3%) underwent additional surgery. The average follow-up of the remaining 36 knees was 10 years (range 6.9-13.8 years). The cumulative osteotomy survival rate was 89% at 5 years and 76% at 10 years. Compared with patients whose postoperative femorotibial angle was 174 degrees -180 degrees , the patients whose postoperative femorotibial angle was <174 degrees or >180 degrees did worse with respect to osteotomy failure. Ten knees were at a decreased risk of failure. These knees had a postoperative femorotibial angle of 174 degrees -180 degrees , lateral joint line obliquity of <4 degrees , and a medial plateau force distribution of 40%-60%. The knees that met these criteria had 100% survival at 5 and 10 years, whereas the rest of the knees had survival rates of 86% and 70%, respectively.
  
  
  CONCLUSIONS
  We believe that using these criteria during preoperative planning may improve the survival of upper tibial osteotomy provided a precise, reproducible surgical technique and rigid fixation can be performed.
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: George C
authors.initials: GC
authors.lastname: Babis
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
authors.forename: Edmund Y S
authors.initials: EY
authors.lastname: Chao
authors.forename: Dirk R
authors.initials: DR
authors.lastname: Larson
authors.forename: James A
authors.initials: JA
authors.lastname: Rand
authors.forename: Franklin H
authors.initials: FH
authors.lastname: Sim
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007719:Knee Joint / Q000473:pathology / Q000601:surgery*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009985:Orthopedics / Q000379:methods*; D010027:Osteotomy / Q000379:methods*; D011300:Preoperative Care; D025321:Surgery, Computer-Assisted / Q000379:methods; D013977:Tibia / Q000601:surgery*; D055815:Young Adult