title: The accuracy of a hand-held navigation system in total knee arthroplasty.
abstract: BACKGROUND
  This study aims to evaluate the effectiveness of a new hand-held navigation system. The authors of this study hypothesize that this navigation system will improve overall lower limb alignment and implant placement without causing a delay in surgery.
  
  
  METHODS
  Two hundred consecutive patients diagnosed with tricompartmental osteoarthritis and underwent total knee arthroplasty by a senior surgeon were included in this study. One hundred patients underwent TKA using the hand-held navigation system, while the other 100 patients underwent TKA using the conventional technique. The primary outcomes of this study were the overall alignment of the lower limb and the position of the components. This was determined radiologically using the: (1) Hip-Knee-Ankle angle (HKA) for lower limb alignment; (2) Coronal Femoral-Component angle (CFA); and (3) Coronal Tibia-Component angle (CTA) for component position. Normal alignment was taken as 180° ± 3° for the HKA and 90° ± 3° for both the CFA and CTA.
  
  
  RESULTS
  For the CFA, the proportion of outliers was 7 and 17% in the hand-held navigation and conventional group, respectively (p = 0.030). For the HKA and CTA, there was no difference in the proportion of outliers between the two groups. The duration of surgery was 73 ± 9 min and 87 ± 15 min in the hand-held navigation and conventional group, respectively (p < 0.001).
  
  
  CONCLUSIONS
  This hand-held navigation system is an effective intraoperative tool for reducing the proportion of outliers for femoral implant placement as well as the duration of surgery. The authors conclude that it can be considered for use to check femoral implant placement intra-operatively.
  
  
  METHODS
  III.
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore. zantesuken@hotmail.com.
authors.forename: Bryan
authors.initials: B
authors.lastname: Loh
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore. yqjchen@gmail.com.
authors.forename: Jerry Yongqiang
authors.initials: JY
authors.lastname: Chen
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore.
authors.forename: Andy Khye Soon
authors.initials: AKS
authors.lastname: Yew
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore.
authors.forename: Hee Nee
authors.initials: HN
authors.lastname: Pang
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore.
authors.forename: Darren Keng Jin
authors.initials: DKJ
authors.lastname: Tay
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore.
authors.forename: Shi-Lu
authors.initials: SL
authors.lastname: Chia
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore.
authors.forename: Ngai Nung
authors.initials: NN
authors.lastname: Lo
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hosptial, The Academia, 20 College Road, Singapore, 169856, Singapore.
authors.forename: Seng Jin
authors.initials: SJ
authors.lastname: Yeo
mesh_terms: D000368:Aged; D000843:Ankle Joint; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D017760:Bone Malalignment; D005260:Female; D005269:Femur / Q000601:surgery; D006621:Hip Joint; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D035002:Lower Extremity; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D013977:Tibia / Q000601:surgery
keywords: Hand-held navigation; Implant placement; Lower limb alignment; Total knee arthroplasty