title: Alendronate treatment in the revision setting, with and without controlled implant motion: an experimental study in dogs.
abstract: BACKGROUND
  Bisphosphonates have been proposed to delay or prevent loosening of joint replacement implants by reducing bone resorption. It is known, however, that implant motion prevents the bone anchorage necessary to maintain secure implant fixation.
  
  
  METHODS
  We used our experimental implant model with controlled motion to evaluate the relative effects of implant motion and bisphosphonate. We implemented our established 8-week experimental revision protocol to obtain a bony and soft tissue setting of revision joint replacement in 16 dogs. At 8 weeks, we had stabilized half of the implants. The other half of the implants continued pistoning. Half of the dogs were exposed to alendronate (oral).
  
  
  RESULTS
  Stabilization of the revision implant was more effective at improving fixation (higher shear strength) than administering alendronate. As expected, the fibrous membrane remained under unstable conditions, even with alendronate. With alendronate and stabilized implants, increased bone was observed near the sclerotic shell of the revision cavity, but it was reduced with alendronate when the implant was unstable.
  
  
  CONCLUSIONS
  Our findings suggest that it may be difficult for alendronate administration alone to rescue implants that are already loose. In implants that have not progressed to loosening, alendronate may increase bone density at the border with the sclerotic shell, but the effect of this bone in delaying eventual loosening is not known.
authors.affiliation: Department of Orthopaedic Surgery, Aarhus Hospital, Aarhus, Denmark.
authors.forename: Kjeld
authors.initials: K
authors.lastname: Søballe
authors.forename: Xinqian
authors.initials: X
authors.lastname: Chen
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Jensen
authors.forename: Louis
authors.initials: L
authors.lastname: Kidder
authors.forename: Joan E
authors.initials: JE
authors.lastname: Bechtold
mesh_terms: D019386:Alendronate / Q000008:administration & dosage*; D000818:Animals; D019643:Arthroplasty, Replacement / Q000009:adverse effects / Q000379:methods; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D001862:Bone Resorption; D004285:Dogs; D005260:Female; D011475:Prosthesis Failure; D016059:Range of Motion, Articular; D012086:Reoperation; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D050071:Bone Density Conservation Agents; D019386:Alendronate