title: Risk factors for dislocation after revision total hip arthroplasty.
abstract: BACKGROUND
  Despite dislocation being the most frequent complication after revision THA, risk factors for its occurrence are not completely understood.
  
  
  OBJECTIVE
  We therefore (1) determined the overall risk of dislocation after revision THA in a large series of revision THAs using contemporary revision techniques, (2) identified patient-related risk factors predicting dislocation, and (3) identified surgical variables predicting dislocation.
  
  
  METHODS
  We performed 1211 revision THAs between June 2004 and October 2010 in 576 women and 415 men who had a mean age of 64.7 years (range, 25-95 years) at time of surgery. Forty-six (4%) were lost to followup and 13 died (1%), leaving 1152 hips followed for a minimum of 90 days (mean, 2 years; range, 90 days to 7.1 years). Multivariate logistic regression was performed to identify risk factors for dislocation. The model was also tested on patients followed for a minimum 1 year to assess any difference in longer followup.
  
  
  RESULTS
  One hundred thirteen patients dislocated over the followup period (9.8%). Factors that were different between patients who dislocated and those who remained stable included a history of at least one previous dislocation (odds ratio [OR] = 2.673), abductor deficiency (OR = 2.672), and Paprosky acetabulum class (OR = 1.522). Use of a constrained liner (OR = 0.503) and increased femoral head size (OR = 0.942) were protective against dislocation, while with longer followup a constrained liner was no longer significant.
  
  
  CONCLUSIONS
  Dislocation remains a common problem after revision THA. Identifying these risk factors can assist in patient education and surgical planning. Recognition of these risk factors in both patient type and surgical strategy is important for the surgeon performing revision THA and for minimizing these risks.
  
  
  METHODS
  Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Rush University Medical Center, 1611 West Harrison Street, Suite 300, Chicago, IL 60612, USA. nwetters@gmail.com
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Wetters
authors.forename: Trevor G
authors.initials: TG
authors.lastname: Murray
authors.forename: Mario
authors.initials: M
authors.lastname: Moric
authors.forename: Scott M
authors.initials: SM
authors.lastname: Sporer
authors.forename: Wayne G
authors.initials: WG
authors.lastname: Paprosky
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Della Valle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006617:Hip Dislocation / Q000209:etiology*; D006621:Hip Joint / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure; D012086:Reoperation; D012307:Risk Factors; D016896:Treatment Outcome