title: Postoperative use of bisphosphonates and risk of revision after primary total hip arthroplasty: a nationwide population-based study.
abstract: BACKGROUND
  Recently, bisphosphonates have been linked with mechanisms that may influence longevity of orthopedic implants. We therefore evaluated the association between the use of bisphosphonates and the risk of revision after primary total hip arthroplasty (THA).
  
  
  METHODS
  We conducted a nationwide population-based nested case-control study using medical databases in Denmark. From the Danish Hip Arthroplasty Register (DHR) we included primary THA patients diagnosed with either osteoporosis or a previous osteoporotic fracture (n=16,145). Among these patients we identified 632 cases that were revised after primary THA in the period 1995-2006. The cases were matched on gender, age and year of primary THA surgery with 1262 non-revised osteoporotic THA controls. Using conditional logistic regression we estimated the risk of revision due to all causes and due to specific causes according to postoperative bisphosphonate use.
  
  
  RESULTS
  The 10-year cumulated implant revision rate in the underlying cohort of 16,145 primary THA procedures among osteoporotic patients was 8.3% (95% confidence interval (CI): 7.3-9.3). The use of bisphosphonates was associated with an adjusted relative risk of revision due to deep infections of 2.59 (95% CI; 1.30-6.53). Further, the duration of bisphosphonates use up to 120days, 120 and 240days, and more than 240days was associated with adjusted relative risks of revision due to all causes of 2.77 (95% CI; 1.65-4.64), 1.33 (95% CI; 0.63-2.72), and 0.58 (95% CI; 0.32-1.05) respectively.
  
  
  CONCLUSIONS
  The use of bisphosphonates following primary THA was associated with an increased risk of revision due to deep infection. However, long-term use was associated with a reduced risk of revision of any type. Further research is warranted in order to clarify whether these associations are truly causal.
authors.affiliation: Department of Orthopedics, Aarhus University Hospital, Denmark; Department of Clinical Epidemiology, Aarhus University Hospital, Denmark. tt@dce.au.dk
authors.forename: Theis M
authors.initials: TM
authors.lastname: Thillemann
authors.forename: Alma B
authors.initials: AB
authors.lastname: Pedersen
authors.forename: Frank
authors.initials: F
authors.lastname: Mehnert
authors.forename: Søren P
authors.initials: SP
authors.lastname: Johnsen
authors.forename: Kjeld
authors.initials: K
authors.lastname: Søballe
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D050071:Bone Density Conservation Agents / Q000009:adverse effects; D016022:Case-Control Studies; D003718:Denmark; D004164:Diphosphonates / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007902:Length of Stay; D008297:Male; D011184:Postoperative Period; D012042:Registries; D012044:Regression Analysis; D012086:Reoperation; D012306:Risk; D018570:Risk Assessment; D016896:Treatment Outcome
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates