title: Simultaneous and staged bilateral total hip arthroplasty: a Danish nationwide study.
abstract: BACKGROUND
  Bilateral total hip arthroplasty (BTHA) and bilateral simultaneous total hip arthroplasty (BSTHA) are done increasingly. Previous studies evaluating outcomes after bilateral procedures have found different results. The aim of this study was to investigate length of hospital stay (LOS), 30 days readmissions and 90 days mortality after BSTHA and BTHA on a nationwide basis.
  
  
  METHODS
  All bilateral primary total hip arthroplasties performed in Denmark from January 1, 2010 to June 31, 2011 were identified using data from the Danish National Patient Registry. The staged procedures were divided into early staged BTHA (0-6 months) and late staged BTHA (6-18 months).
  
  
  RESULTS
  103 patients underwent BSTHA, 370 underwent BTHA (0-6 months) and 207 underwent BTHA (6-18 months). Median total LOS was 4 days (IQR 3) after BSTHA vs. 6 days (3) after both BTHA (0-6 months) and BTHA (6-18 months) (p < 0.001). There were no deaths in the BSTHA group vs. 1 death in each BTHA group ≤90 days postoperatively (0.3 and 0.5 %, respectively) (p = 0.755). The readmission rate ≤30 days was 1.9 % after BSTHA vs. 8.9 % (cumulated) after BTHA (0-6 months) and 15.9 % (cumulated) after BTHA (6-18 months) (p < 0.001).
  
  
  CONCLUSIONS
  If patients are carefully selected for BSTHA, the procedure appears to be safe when combined with a fast-track protocol in Denmark. We found significantly lower readmission rates and shorter total LOS in the BSTHA group compared with the BTHA groups, potentially reflecting selection bias. The results should stimulate to evaluate BSTHA in a randomised controlled trial or a detailed prospective, large multicenter study with a fast-track protocol regarding morbidity, convalescence and mortality.
authors.affiliation: Section of Surgical Pathophysiology, Rigshospitalet, Copenhagen University, Copenhagen, Denmark, martinl@dadlnet.dk.
authors.forename: Martin
authors.initials: M
authors.lastname: Lindberg-Larsen
authors.forename: Christoffer Calov
authors.initials: CC
authors.lastname: Joergensen
authors.forename: Henrik
authors.initials: H
authors.lastname: Husted
authors.forename: Henrik
authors.initials: H
authors.lastname: Kehlet
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods* / Q000401:mortality; D003718:Denmark; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010359:Patient Readmission / Q000706:statistics & numerical data; D011446:Prospective Studies; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult