Improved fixation of porous-coated versus grit-blasted surface texture of hydroxyapatite-coated implants in dogs.
We inserted, in 8 dogs, implants with either porous-coated or grit-blasted titanium surface and coated with hydroxyapatite (HA) into trabecular bone in the proximal humerus, using a 1 mm gap model. After 25 weeks, push-out tests showed that energy absorption for porous-coated implants was twice that of grit-blasted implants, whereas shear stiffness was reduced by one fifth, indicating a stronger fixation of porous-coated implants. Macroscopically, all grit-blasted implants had delamination of the HA coating, whereas porous implants failed mostly at the HA-tissue interface. Porous-coated implants had 47% bone ingrowth and grit-blasted implants 70% (p = 0.02), however, no difference in absolute surface area was found. Part of the HA coating was resorbed during the implantation period as regards volume and thickness. HA coverage was more reduced on porous-coated than on grit-blasted implants (p = 0.01). No foreign-body reaction or osteolysis was seen. An important finding was that one fifth of the surface with complete resorption of HA coating was replaced by newly formed bone.
Overgaard
S
S
Department of Orthopaedics, University Hospital of Aarhus, Denmark.
Lind
M
M
Rahbek
O
O
Bünger
C
C
Søballe
K
K
D000818:Animals; D001672:Biocompatible Materials / Q000592:standards*; D001696:Biomechanical Phenomena; D018786:Bone Substitutes / Q000592:standards*; D004285:Dogs; D017886:Durapatite / Q000592:standards*; D006811:Humerus / Q000601:surgery*; D008422:Materials Testing; D016348:Osseointegration; D016062:Porosity; D013499:Surface Properties; D014025:Titanium / Q000592:standards*
D001672:Biocompatible Materials; D018786:Bone Substitutes; D017886:Durapatite; D014025:Titanium