title: Comparison of tibial bone coverage of 6 knee prostheses: a magnetic resonance imaging study with controlled rotation.
abstract: OBJECTIVE
  To compare the extent of tibial bone covered by the tibial tray in 6 most commonly used total knee arthroplasty designs in order to strike a balance between mediolateral cortical fit and optimal tibial component rotation.
  
  
  METHODS
  In 74 men and 27 women aged 17 to 60 (mean, 32) years with suspected soft-tissue injuries, their magnetic resonance images of the knee in full extension were superimposed with scans of the tibial trays of the 6 designs (one asymmetric and 5 symmetric). The tibial coverage by the tray and any posterolateral/posteromedial overhang/underhang were measured.
  
  
  RESULTS
  All 6 tray designs achieved tibial bone coverage of over 80%. Only 28% of all trays achieved optimal posterolateral fit, whereas 49% had posterolateral overhang enough to cause popliteal tendon impingement. Although the asymmetric tray provided highest tibial coverage (88%), its rates of relative and absolute posterolateral and posteromedial overhang were also highest (64%).
  
  
  CONCLUSIONS
  The asymmetric tray provided improved tibial coverage at the expense of posterolateral and posteromedial overhang of the tibial tray.
authors.affiliation: Sydney Knee Specialists, Edgecliff, NSW, Australia. dr4734@hotmail.com
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Wernecke
authors.forename: Ian A
authors.initials: IA
authors.lastname: Harris
authors.forename: Michael T W
authors.initials: MT
authors.lastname: Houang
authors.forename: Bradley G
authors.initials: BG
authors.lastname: Seeto
authors.forename: Darren B
authors.initials: DB
authors.lastname: Chen
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: MacDessi
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012189:Retrospective Studies; D012399:Rotation; D013977:Tibia; D055815:Young Adult