title: Hip dislocations after 2,734 elective unilateral fast-track total hip arthroplasties: incidence, circumstances and predisposing factors.
abstract: METHODS
  Retrospective review of prospectively collected data.
  
  
  OBJECTIVE
  To investigate the incidence of hip dislocation 90 days after total hip arthroplasty in relation to time after surgery, mechanism of dislocation and predisposing factors.
  
  
  METHODS
  Prospective data on preoperative patient characteristics from six Danish arthroplasty departments with similar fast-track approaches were cross-referenced with the Danish National Patient Registry for complete 90-day follow-up on readmissions, including emergency-room contacts. Complete patient files and postoperative radiographs were reviewed in case of dislocations. Unadjusted comparisons were made using t test/Chi-square analyses, while evaluation of risk factors potentially predisposing to dislocations was done using uni- and multivariate regression analysis.
  
  
  RESULTS
  A total of 2,734 consecutive unselected procedures were available for analysis, of which 65 (2.4 %) had dislocations. Of these, eight were during index admission and five were treated and discharged from the emergency room. Mechanisms of dislocation were most often movement while supine or sitting for the first 30 days and due to squatting/bending from day 31 to 90. The 65 patients with dislocations had suboptimal cup placement in 34 (52.3 %), and a femoral head size of <36 mm in 20 (30.8 %) cases. Predisposing factors of dislocation were age ≥75 [OR:1.96 (1.18-3.38)], pharmacologically treated psychiatric disease [OR:2.37 (1.29-4.36)] and department of surgery [OR:2.27 (1.31-3.40)] but not hospital stay of <4 days. Departments with recommendations for activity restrictions had fewer dislocations than a department without restrictions.
  
  
  CONCLUSIONS
  Patients ≥75 years and with pharmacologically treated psychiatric disease may be at increased risk of dislocations after fast-track total hip arthroplasty. Further studies including detailed information on patient and prosthesis characteristics, and activity restrictions are needed to reduce the risk of dislocation.
authors.affiliation: Section for Surgical Pathophysiology 4074, Rigshospitalet, Copenhagen University, Copenhagen, Denmark, christoffer.calov.joergensen@regionh.dk.
authors.forename: Christoffer C
authors.initials: CC
authors.lastname: Jørgensen
authors.forename: Per
authors.initials: P
authors.lastname: Kjaersgaard-Andersen
authors.forename: Søren
authors.initials: S
authors.lastname: Solgaard
authors.forename: Henrik
authors.initials: H
authors.lastname: Kehlet
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000706:statistics & numerical data; D003718:Denmark; D017558:Elective Surgical Procedures; D005260:Female; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D015994:Incidence; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors