title: Tibial tuberosity transposition-advancement for lateralization of the tibial tuberosity: an ex vivo canine study.
abstract: OBJECTIVE
  To evaluate the degree of lateralization achievable and strength of tibial tuberosity transposition and advancement (TTTA) relative to pin and tension band wiring (PTBW) for lateral tibial tuberosity transposition.
  
  
  METHODS
  Six pairs of cadaveric tibiae were used. Tibial tuberosity position was determined with computed tomography (CT); bones were then randomly assigned into TTTA and PTBW groups. The PTBW group had a tibial tuberosity osteotomy and fixation with pin and tension band wiring. The TTTA group had a tibial tuberosity advancement performed with lateralization of the tibial tuberosity by 50% of cage depth, using spacers on the cranial cage screw. Postoperative CT images showed lateralization and craniocaudal deviation. Single axial distractive loading was applied to the patella at 90˚ to the tibial plateau, and peak load, energy, and stiffness were calculated.
  
  
  RESULTS
  There were significant differences in lateralization (PTBW: 67.92 ± 5.1 %; TTTA: 88.51 ± 5.5 %) (p = 0.0173) and craniocaudal deviation (PTBW: -8.30 ± 1.4 %; TTTA: 6.83 ± 0.6) (p = 0.0001). There were no significant differences in peak load to failure (N) (PTBW: 1448 ± 121; TTTA: 1597 ± 43) (p = 0.4541), energy to failure (N/mm) (PTBW: 15013 ± 2719; TTTA: 17314 ± 887) (p = 0.646), or stiffness (N/mm)(PTBW: 102.8 ± 4.7; TTTA: 92.9 ± 4.8) (p = 0.2716).
  
  
  CONCLUSIONS
  The TTTA was more effective at lateralization of the tibial tuberosity, and of comparable strength to PTBW. Greater support of the osteotomized fragment with TTTA may resist cyclic loading, and requires evaluation.
authors.affiliation: Dr. Mark Newman, BVSc, MVS, MANZCVS, University of Sydney, University Veterinary Teaching Hospital, Evelyn Williams Building B10, Sydney, New South Wales, 2006, Australia, E-mail: mark.newman@sydney.edu.au.
authors.forename: M
authors.initials: M
authors.lastname: Newman
authors.forename: N
authors.initials: N
authors.lastname: Bertollo
authors.forename: W
authors.initials: W
authors.lastname: Walsh
authors.forename: K
authors.initials: K
authors.lastname: Voss
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002102:Cadaver; D004285:Dogs / Q000601:surgery*; D019637:Orthopedic Procedures / Q000379:methods / Q000662:veterinary*; D013977:Tibia / Q000601:surgery*
keywords: Tibial tuberosity advancement; medial patellar luxation; orthopaedic implants; tibial tuberosity transposition