title: Preclinical evaluation of zoledronate to maintain bone allograft and improve implant fixation in revision joint replacement.
abstract: BACKGROUND
  Revision arthroplasty surgery is often complicated by loss of bone stock that can be managed by the use of bone allograft. The allograft provides immediate stability for the revision implant but may be resorbed, impairing subsequent implant stability. Bisphosphonates can delay allograft resorption. We hypothesized that zoledronate-impregnated allograft impacted around revision implants would improve implant fixation as characterized by mechanical push-out testing and histomorphometry.
  
  
  METHODS
  Twenty-four axially pistoning micromotion devices were inserted bilaterally into the knees of twelve dogs according to our revision protocol. This produced a standardized revision cavity with a loose implant, fibrous tissue, and a sclerotic bone rim. Revision surgery was performed eight weeks later; after stable titanium revision components were implanted, saline solution-soaked allograft was impacted around the component on the control side and allograft soaked in 0.005 mg/mL zoledronate was impacted on the intervention side. The results were evaluated after four weeks.
  
  
  RESULTS
  The zoledronate treatment resulted in a 30% increase in ultimate shear strength (p = 0.023), a 54% increase in apparent shear stiffness (p = 0.002), and a 12% increase in total energy absorption (p = 0.444). The quantity of allograft in the gap was three times greater in the zoledronate group compared with the control group (p &lt; 0.001). The volume fraction of new bone in the zoledronate group (25%; 95% confidence interval [CI], 22% to 28%) was similar to that in the control group (23%; 95% CI, 19% to 26%) (p = 0.311).
  
  
  CONCLUSIONS
  The data obtained in this canine model suggest that pretreating allograft with zoledronate may be beneficial for early stability of grafted revision arthroplasty implants, without any adverse effect on bone formation. Clinical studies are warranted.
  
  
  CONCLUSIONS
  The zoledronate treatment is simple to apply in the clinical setting. The treatment could increase early stability of revision joint replacements without impairing new bone formation. In the long term, this can potentially improve the longevity of revision joint replacements and reduce the number of subsequent revisions.
authors.affiliation: Orthopaedic Research Laboratory, Aarhus University Hospital, Norrebrogade 44, Building 1A, Aarhus C, 8000, Denmark. E-mail address for M. Sørensen: mette.sorensen@ki.au.dk.
authors.forename: Mette
authors.initials: M
authors.lastname: Sørensen
authors.forename: Jeppe
authors.initials: J
authors.lastname: Barckman
authors.forename: Joan E
authors.initials: JE
authors.lastname: Bechtold
authors.forename: Kjeld
authors.initials: K
authors.lastname: Søballe
authors.forename: Jørgen
authors.initials: J
authors.lastname: Baas
mesh_terms: D000818:Animals; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D001696:Biomechanical Phenomena; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D001862:Bone Resorption / Q000209:etiology / Q000517:prevention & control*; D016025:Bone Transplantation / Q000379:methods*; D004164:Diphosphonates / Q000627:therapeutic use*; D004285:Dogs; D005260:Female; D007093:Imidazoles / Q000627:therapeutic use*; D007720:Knee Prosthesis; D011183:Postoperative Complications / Q000517:prevention & control*; D011897:Random Allocation; D012086:Reoperation / Q000379:methods; D014184:Transplantation, Homologous / Q000379:methods; D016896:Treatment Outcome; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid