title: Less outliers in pinless navigation compared with conventional surgery in total knee arthroplasty.
abstract: OBJECTIVE
  The aim of this study was to investigate the effectiveness of a new pinless navigation system (BrainLAB(®) VectorVision(®) Knee 2.5 Navigation System) as an intra-operative alignment check in total knee arthroplasty using conventional cutting jigs.
  
  
  METHODS
  200 patients who underwent total knee arthroplasty using conventional technique or pinless navigation by a senior surgeon were included in the study and prospectively followed up. Intra-operative readings from the pinless navigation system were recorded, and post-operative long limb radiographic films were taken. The accepted values for normal alignment were 180 ± 3° for Hip-Knee-Ankle Angle and 90 ± 3° for Coronal Femoral-Component Angle or Coronal Tibia-Component Angle.
  
  
  RESULTS
  There was no difference in the duration of surgery. The mean Coronal Femoral-Component Angle was 89.8 ± 2.0° and 91.3 ± 2.3° in the pinless navigation and conventional group, respectively (p < 0.001). For Hip-Knee-Ankle Angle, the proportion of outliers was 10 % in the pinless navigation group compared to 26 % in the conventional group (p = 0.005). For Coronal Femoral-Component Angle and Coronal Tibia-Component Angle, the proportion of outliers was 7 and 4 %, respectively, in the pinless navigation group, compared to 22 and 19 % in the conventional group (p = 0.004 and p = 0.001, respectively). The measurements of Coronal Femoral-Component Angle and Coronal Tibia-Component Angle on post-operative radiographic films were similar to intra-operative readings.
  
  
  CONCLUSIONS
  This study showed that pinless navigation is an effective tool for reducing the proportion of outliers, without significantly increasing the duration of surgery. The authors recommend its use in total knee arthroplasty using conventional cutting jigs.
authors: Department of Orthopaedic Surgery, Singapore General Hospital, Block 6 Level 7, Outram Road, Singapore, 169608, Singapore, yqjchen@gmail.com.
authors: Jerry Yongqiang
authors: JY
authors: Chen
authors: Pak Lin
authors: PL
authors: Chin
authors: Darren Keng Jin
authors: DK
authors: Tay
authors: Shi-Lu
authors: SL
authors: Chia
authors: Ngai Nung
authors: NN
authors: Lo
authors: Seng Jin
authors: SJ
authors: Yeo
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D025321:Surgery, Computer-Assisted