title: Navigated Acetabular Cup Fixation for Acetabular Deformity or Revision Total Hip Arthroplasty.
abstract: OBJECTIVE
  To evaluate the usefulness of navigated acetabular cup fixation for total hip arthroplasty in patients with acetabular deformity or revision total hip arthroplasty.
  
  
  METHODS
  This study enrolled 28 patients with at least 12 months' follow-up. The safe zone of the acetabular cup was defined as 40°±10°in inclination and 15°±10°in anteversion. The authors used the navigation and radiographic data to determine whether the acetabular cup was located within the safe zone or not. To evaluate the clinical outcomes, preoperative and last follow-up Harris hip scores were checked, and the occurrence of complications was evaluated.
  
  
  RESULTS
  According to the navigation data, the mean inclination and anteversion were 38.5°±4.7°(range, 32°-50°) and 16.6°±4.0°(range, 8°-23°), respectively. According to the radiographic data the mean inclination and anteversion were 40.5°±4.6°(range, 32°-50°) and 19.4°±4.2°(range, 8°-25°), respectively. In both cases, all values were within the safe zone. Harris hip score was improved in all patients from preoperative 52.3±14.4 points (range, 29-87 points) to 88.0±9.0 points (range, 65-99 points) at the last follow-up. There was no dislocation or loosening of both cases.
  
  
  CONCLUSIONS
  Navigated acetabular cup fixation is a useful technique for total hip arthroplasty in patients with acetabular deformity or revision total hip arthroplasty because it prevents the malposition and related complications.
authors.affiliation: Department of Orthopedic Surgery, Seoul Veterans Hospital, Seoul, Korea.
authors.forename: Ho Hyun
authors.initials: HH
authors.lastname: Yun
authors.affiliation: Department of Orthopedic Surgery, Seoul Veterans Hospital, Seoul, Korea.
authors.forename: Jung-Ro
authors.initials: JR
authors.lastname: Yoon
authors.affiliation: Department of Orthopedic Surgery, Seoul Veterans Hospital, Seoul, Korea.
authors.forename: Jung Jin
authors.initials: JJ
authors.lastname: Yu
authors.affiliation: Department of Orthopedic Surgery, Seoul Veterans Hospital, Seoul, Korea.
authors.forename: Hyo-Sung
authors.initials: HS
authors.lastname: Seo
keywords: Acetabular cup fixation; Acetabular deformity; Hip; Imageless navigation; Revision