title: Dislocation of hip hemiarthroplasty following posterolateral surgical approach: a nested case-control study.
abstract: OBJECTIVE
  Hip hemiarthroplasty dislocation is a serious complication in treatment of displaced intracapsular hip fractures. We investigated factors associated with an increased risk of dislocation after cemented hip hemiarthroplasty following the posterolateral approach.
  
  
  METHODS
  Between January 2002 and December 2008, 602 hip fractures were treated with cemented unipolar hip hemiarthroplasty. A registry-based analysis was carried out to determine the total number of hemiarthroplasty dislocations in these patients. A control group of 96 patients without dislocation was randomly selected. Logistic regression analysis was performed to evaluate clinical and operative factors associated with dislocation.
  
  
  RESULTS
  Thirty-four patients (5.6%) experienced at least one dislocation. Most were the result of a fall and occurred within two months after surgery. There was a trend for increased dislocation in patients who had been operated on more than 48 hours after admission and in patients who had a longer operative time. Smaller centre-edge angle and hip offset were observed in patients with dislocation. Recurrent dislocation was a significant problem, as 18 patients (62%) experienced multiple dislocations.
  
  
  CONCLUSIONS
  The risk of hemiarthroplasty dislocation following the posterolateral surgical approach may be reduced by prompt surgical treatment and fall prevention in the early postoperative period. Patients with smaller acetabular coverage seem more predisposed to dislocation after the posterolateral approach and may be more suitable for other surgical approaches.
authors.affiliation: Department of Orthopaedics and Traumatology, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Rami
authors.initials: R
authors.lastname: Madanat
authors.forename: Tatu J
authors.initials: TJ
authors.lastname: Mäkinen
authors.forename: Mikko T
authors.initials: MT
authors.lastname: Ovaska
authors.forename: Martti
authors.initials: M
authors.lastname: Soiva
authors.forename: Tero
authors.initials: T
authors.lastname: Vahlberg
authors.forename: Jussi
authors.initials: J
authors.lastname: Haapala
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D016022:Case-Control Studies; D005260:Female; D005265:Femoral Neck Fractures / Q000601:surgery*; D006617:Hip Dislocation / Q000209:etiology* / Q000601:surgery; D006621:Hip Joint / Q000601:surgery*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011475:Prosthesis Failure; D012189:Retrospective Studies; D012307:Risk Factors