title: Soaking morselized allograft in bisphosphonate can impair implant fixation.
abstract: The use of impacted, morselized allograft is a well-established way to provide initial stability of revision joint replacements. We investigated whether rinsing morselized allograft in bisphosphonate and subsequently impacting it around experimental titanium-coated implants would further facilitate biomechanical implant fixation and graft incorporation. In 10 dogs, a pair of titanium implants surrounded by a 2.5-mm gap was inserted into the proximal part of each humerus during two separate surgeries to allow two observation periods. The gap was filled with impacted, morselized allograft soaked in either bisphosphonate (alendronate, 2 mg/mL) or saline (control). Unbound alendronate was not rinsed away. During the first surgery, one pair of implants (alendronate and control) was inserted into one humerus. Eight weeks later, a second pair of implants was inserted into the contralateral humerus. The first pair of implants was observed for 12 weeks and the second pair for 4 weeks. Implants were evaluated by histomorphometry and biomechanical pushout test. We found substantially decreased biomechanical implant fixation for all implants surrounded by impacted, morselized allograft that had been soaked in alendronate. Furthermore, the alendronate treatment blocked formation of new bone and inhibited resorption of the graft material. Although limited by the specific dose of alendronate used and the omission of rinsing away excess bisphosphonate, this study warrants caution and calls for further experimental research before impacting alendronate-soaked morselized allograft around clinical joint replacements.
authors.affiliation: Orthopaedic Research Laboratory, Department of Orthopaedics, Aarhus University Hospital, Nørrebrogade 44, DK-8000 Aarhus C, Denmark. tvj@studmed.au.dk
authors.forename: Thomas
authors.initials: T
authors.lastname: Jakobsen
authors.forename: Jørgen
authors.initials: J
authors.lastname: Baas
authors.forename: Joan E
authors.initials: JE
authors.lastname: Bechtold
authors.forename: Brian
authors.initials: B
authors.lastname: Elmengaard
authors.forename: Kjeld
authors.initials: K
authors.lastname: Søballe
mesh_terms: D019386:Alendronate / Q000009:adverse effects*; D000818:Animals; D019643:Arthroplasty, Replacement / Q000295:instrumentation / Q000379:methods*; D001696:Biomechanical Phenomena; D050071:Bone Density Conservation Agents / Q000009:adverse effects*; D016025:Bone Transplantation; D004285:Dogs; D006811:Humerus / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D023421:Models, Animal; D016348:Osseointegration / Q000187:drug effects*; D019736:Prostheses and Implants; D011474:Prosthesis Design; D011475:Prosthesis Failure; D014025:Titanium; D014184:Transplantation, Homologous
chemical_list: D050071:Bone Density Conservation Agents; D014025:Titanium; D019386:Alendronate