title: Accurate leg length measurement in total hip arthroplasty: a comparison of computer navigation and a simple manual measurement device.
abstract: BACKGROUND
  Several studies have shown that better placement of the acetabular cup and femoral stem can be achieved in total hip arthroplasty (THA) by using the computer navigation system rather than the free-hand alignment methods. However, there have been no comparisons of the relevant clinical advantages in using the computer navigation as opposed to the manual intraoperative measurement devices. The purpose of this study is to determine whether the use of computer navigation can improve postoperative leg length discrepancy (LLD) compared to the use of the measurement device.
  
  
  METHODS
  We performed a retrospective study comparing 30 computer-assisted THAs with 40 THAs performed using a simple manual measurement device.
  
  
  RESULTS
  The postoperative LLD was 3.0 mm (range, 0 to 8 mm) in the computer-assisted group and 2.9 mm (range, 0 to 10 mm) in the device group. Statistically significant difference was not seen between the two groups.
  
  
  CONCLUSIONS
  The results showed good equalization of the leg lengths using both computed tomography-based navigation and the simple manual measurement device.
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Ogawa
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors.forename: Tamon
authors.initials: T
authors.lastname: Kabata
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Maeda
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Kajino
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsuchiya
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods*; D001837:Body Weights and Measures; D005260:Female; D005269:Femur / Q000601:surgery; D006801:Humans; D007866:Leg; D007870:Leg Length Inequality / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted; D055815:Young Adult
keywords: Computed tomography-based navigation; Device; Leg length discrepancy; Total hip arthroplasty