title: The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty.
abstract: OBJECTIVE
  The aim of this study was to investigate the post-operative radiological outcomes of patient-specific instrumentation (PSI) surgery versus conventional total knee arthroplasty (TKA).
  
  
  METHODS
  Sixty patients scheduled for a primary TKA were prospectively divided into PSI or conventional technique. Coronal and sagittal radiographic long limb films were taken post-operatively. The accepted values for normal alignment were 180° ± 3° for hip-knee-ankle angle; 90° ± 3° for coronal femoral component angle or coronal tibia component angle; 0° to 3° flexion for sagittal femoral component angle and 0° to 7° posterior slope for sagittal tibia component angle.
  
  
  RESULTS
  For hip-knee-ankle angle, there were 21 % more outliers in the PSI group compared to the conventional group (p = 0.045). Most of these outliers had valgus deformity in the PSI group and varus deformity in the conventional group (p = 0.045). For implant placement, there was no difference in the proportion of outliers between the two groups. There was also no difference in the duration of surgery.
  
  
  CONCLUSIONS
  This study showed that PSI surgery is associated with a larger proportion of outliers for lower limb alignment. PSI surgery as an alternative to conventional TKA is not advisable.
  
  
  METHODS
  II.
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Block 6 Level 7, Outram Road, Singapore, 169608, Singapore, yqjchen@gmail.com.
authors.forename: Jerry Yongqiang
authors.initials: JY
authors.lastname: Chen
authors.forename: Seng Jin
authors.initials: SJ
authors.lastname: Yeo
authors.forename: Andy Khye Soon
authors.initials: AK
authors.lastname: Yew
authors.forename: Darren Keng Jin
authors.initials: DK
authors.lastname: Tay
authors.forename: Shi-Lu
authors.initials: SL
authors.lastname: Chia
authors.forename: Ngai Nung
authors.initials: NN
authors.lastname: Lo
authors.forename: Pak Lin
authors.initials: PL
authors.lastname: Chin
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D011859:Radiography; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery; D054159:Torsion, Mechanical; D016896:Treatment Outcome