title: Double level osteotomy of the knee: a method to retain joint-line obliquity. Clinical results.
abstract: BACKGROUND
  Although general guidelines have been proposed for proximal tibial and supracondylar osteotomies, double level osteotomy provides the advantage of maintaining neutral joint-line obliquity in addition to correcting limb malalignment around the knee. The goal of this prospective study was to determine the outcome of double level osteotomy of the knee performed after analysis with computer-aided preoperative planning software in patients with varus malalignment.
  
  
  METHODS
  Twenty-nine double level osteotomies of the knee were performed in twenty-four patients. The patients were followed for an average duration of 82.7 months (range, twenty-seven to 137 months). All knees had moderate-to-severe varus deformity and arthritis. The mean preoperative mechanical tibiofemoral angle was 193.9 degrees (that is, 13.9 degrees of varus). Preoperative and postoperative evaluations included clinical (scores according to the Knee Society system), radiographic, and computer-aided analysis of the mechanical status of the knee joint. Failure was defined as conversion of an osteotomy to a total knee arthroplasty or the presence of severe pain in a patient who declined arthroplasty.
  
  
  RESULTS
  The mean clinical and functional scores according to the Knee Society system improved from 34 and 64 points, respectively, before the osteotomy to 90 (p < 0.0001) and 81 points (p = 0.079) at the time of the final follow-up examination. One patient was lost to follow-up. One of the twenty-nine knees was subsequently converted to total knee arthroplasty forty-nine months postoperatively. The cumulative rate of survival at 100 months was 96% (95% confidence interval, +4.5 to -8.7), with eight patients remaining at risk.
  
  
  CONCLUSIONS
  Double osteotomy is a valuable procedure for patients with such a large varus deformity that appropriate realignment and load transfer to the unaffected compartment, together with an acceptable joint-line obliquity, cannot be achieved by a single osteotomy.
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, 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: James A
authors.initials: JA
authors.lastname: Rand
authors.forename: Franklin H
authors.initials: FH
authors.lastname: Sim
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D001182:Arthroscopy; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D016916:Joint Deformities, Acquired / Q000503:physiopathology / Q000601:surgery*; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D011446:Prospective Studies; D012086:Reoperation; D013977:Tibia / Q000601:surgery*; D016896:Treatment Outcome