title: Improved bone anchorage of hydroxypatite coated implants compared with tricalcium-phosphate coated implants in trabecular bone in dogs.
abstract: Tricalcium phosphate (TCP) and hydroxyapatite (HA) ceramic coatings are bioactive coatings that have been shown to stimulate bone apposition onto ceramic-coated implants. TCP and HA ceramics have well-documented differences in physical properties, but both types of ceramics are used for stimulation of bone ongrowth to cementless endo-prosthetic components clinically. However, little is known about the difference in osteoconductive properties between these coatings when inserted into trabecular bone in a controlled experimental situation. Unloaded cylindrical gritblasted titanium (Ti-6A1-4V) implants (6 x 10 mm) coated with either hydroxyapatite (HA) or tricalcium phosphate (TCP) ceramic were inserted into the proximal humerus of 20 skeletally mature dogs. The implants were initially surrounded by a 2 mm gap. Each animal received one HA-coated implant and one TCP-coated implant. All dogs were sacrificed 6 weeks after surgery. Results were evaluated by histomorphometry and mechanical push-out test. Push-out tests demonstrated that HA-coated implants were 10-fold stronger fixated in comparison to TCP-coated implant. Bone ongrowth was significantly higher for HA-coated implants compared to TCP-coated implants. Bone volume in the gap showed a tendency to less bone volume around HA-coated implants compared to TCP-coated implants but this difference was insignificant. As expected almost all of the TCP coating were resorbed after 6 weeks and almost none of the HA coating. HA-coated implants with a grit-blasted surface provide a favorable early mechanical implant anchorage most likely due to superior ceramic stability compared to TCP-coated implants.
authors.affiliation: Department of Orthopaedics and Orthopaedic Research Laboratory, Arhus University Hospital, Denmark. d290084@inet.uni2.dk
authors.forename: M
authors.initials: M
authors.lastname: Lind
authors.forename: S
authors.initials: S
authors.lastname: Overgaard
authors.forename: C
authors.initials: C
authors.lastname: Bünger
authors.forename: K
authors.initials: K
authors.lastname: Søballe
mesh_terms: D000497:Alloys; D000818:Animals; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001861:Bone Regeneration; D018786:Bone Substitutes; D001842:Bone and Bones / Q000166:cytology* / Q000187:drug effects; D002130:Calcium Phosphates / Q000494:pharmacology; D002516:Ceramics; D020099:Coated Materials, Biocompatible; D004285:Dogs; D017886:Durapatite / Q000494:pharmacology; D006811:Humerus; D013314:Stress, Mechanical; D014025:Titanium
chemical_list: D000497:Alloys; D018786:Bone Substitutes; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C031462:titanium alloy (TiAl6V4); C485838:calcium phosphate, monobasic, anhydrous; D017886:Durapatite; C020243:calcium phosphate; D014025:Titanium; C485829:calcium phosphate, dibasic, anhydrous