title: Three-dimensional transfer of the tibial tuberosity for patellar instability with patella alta.
abstract: BACKGROUND
  Although patellar instability can be treated with several surgical procedures, the appropriate surgical treatment for patellar instability with patella alta has not yet been investigated. The objective of this study is to find out whether three-dimensional transfer of the tibial tuberosity elicits good knee functionality with improved patella alta and prevents further patellar dislocation.
  
  
  METHODS
  Twelve knees (10 patients) underwent surgery for patellar instability with patella alta from 2007 to 2011. The surgery performed was a three-dimensional transfer for the anteromedial distalization of the tibial tuberosity. Predisposing anatomical factors for patellar instability were evaluated preoperatively; femorotibial angle (FTA), patella alta (IS ratio), trochlear dysplasia (sulcus angle) and tilting angle (lateral tilt). The function of the knee was assessed before and after surgery by Lysholm and Kujala score.
  
  
  RESULTS
  Before surgery, the IS ratio was 1.34 ± 0.13, lateral tilt was 22.4° ± 6.5°, and the sulcus angle was 151.7° ± 8.3°, indicating patella alta, laterality, and trochlear dysplasia. After surgery, the IS ratio and lateral tilt significantly improved to 0.95 ± 0.13, and 10.6° ± 3.4°, respectively. FTA and sulcus angle were not altered. Lysholm and Kujala score improved from 63.8 to 94.7 and 67.0 to 94.1 points, respectively. Most patients displayed good outcomes except for one patient who suffered re-dislocation by hitting their knee on the floor, 2.5 years after surgery.
  
  
  CONCLUSIONS
  Three-dimensional tibial tuberosity transfer was shown to correct the patella position and result in a good clinical outcome. This method is introduced as an alternative surgery for patellar instability with patella alta.
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Otsuki
authors.forename: Mikio
authors.initials: M
authors.lastname: Nakajima
authors.forename: Shuhei
authors.initials: S
authors.lastname: Oda
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Hoshiyama
authors.forename: Kenta
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Jotoku
authors.forename: Masashi
authors.initials: M
authors.lastname: Neo
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000601:surgery*; D007719:Knee Joint; D008297:Male; D019637:Orthopedic Procedures / Q000379:methods; D010329:Patella; D012189:Retrospective Studies; D013977:Tibia / Q000637:transplantation*; D055815:Young Adult