title: Durable fixation achieved with medialized, high hip center cementless THAs for Crowe II and III dysplasia.
abstract: BACKGROUND
  A high hip center total hip arthroplasty (THA) for dysplasia allows more complete socket coverage by native bone at the expense of abnormal hip biomechanics. Despite poor results with cemented components, intermediate-term results with cementless cups at a high hip center have been promising, but there are few reports at long-term followup without bone graft.
  
  
  OBJECTIVE
  The purpose of this study was to examine (1) survivorship; 2) radiographic results; and 3) hip scores at a minimum of 10 years for patients treated with high hip center cementless THA for Crowe II and III dysplasia without bone graft.
  
  
  METHODS
  We reviewed charts and radiographs of 32 patients with Crowe II or III dysplasia who were treated with high hip center cementless THA; at a mean followup of 12 years (range, 10-21 years), 23 patients (27 hips) were available for review. We sought to medialize cups to the inner table to achieve bony coverage of > 75%. At final followup, the WOMAC and Harris hip scores were recorded. Radiographic analysis including computerized wear evaluation was performed. Radiographic parameters were compared with a control group of 23 patients with Crowe I dysplasia who had cementless cups placed at an anatomic hip center; among the high hip center reconstructions, we also compared wear between those in the superolateral and superomedial quadrants.
  
  
  RESULTS
  Kaplan-Meier survivorship for all-cause revisions was 97% (95% confidence interval, 79%-99%) in the high hip center group; this was no different from the anatomic hip center group. There were no revisions for acetabular loosening. Wear rates did not differ significantly between the high hip center and the control group, but lateralized high hip centers were associated with higher (p = 0.002) wear. Hip scores were excellent in both groups.
  
  
  CONCLUSIONS
  In Crowe II and III dysplasia, a high hip center cementless cup obviates the need for bone graft and provides durable fixation beyond 10 years. Medialization of these reconstructions seems important to decrease wear.
authors.affiliation: Adult Reconstruction and Joint Replacement, Department of Orthopaedic Surgery, Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA, nawabid@hss.edu.
authors.forename: Danyal H
authors.initials: DH
authors.lastname: Nawabi
authors.forename: Morteza
authors.initials: M
authors.lastname: Meftah
authors.forename: Denis
authors.initials: D
authors.lastname: Nam
authors.forename: Amar S
authors.initials: AS
authors.lastname: Ranawat
authors.forename: Chitranjan S
authors.initials: CS
authors.lastname: Ranawat
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies; D013314:Stress, Mechanical; D013997:Time Factors; D016896:Treatment Outcome