The Journal of Bone and Joint Surgery, Vol 77, Issue 9 1380-1395, Copyright © 1995 by Journal of Bone and Joint Surgery, Inc
The influence of surface-blasting on the incorporation of titanium-alloy implants in a rabbit intramedullary model
JE Feighan, VM Goldberg, D Davy, JA Parr and S Stevenson
Department of Orthopaedics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-5000, USA.
The apposition of new bone to polished solid implants and to implants with
surfaces that had been blasted with one of three methods of grit-blasting
was studied in a rabbit intramedullary model to test the hypothesis that
blasted implant surfaces support osseous integration. Intramedullary
titanium-alloy (Ti-6Al-4V) plugs, press-fit into the distal aspect of the
femoral canal, were implanted bilaterally in fifty-six rabbits. Four
surface treatments were studied: polished (a surface roughness of 0.4 to
0.6 micrometer) and blasted with stainless-steel shot (a surface roughness
of five to seven micrometers), with thirty-six-grit aluminum oxide (a
surface roughness of five to seven micrometers), or with sixty-grit
aluminum oxide (a surface roughness of three to five micrometers).
Localized attachment of new bone to the surfaces of the blasted implants
was present radiographically at twelve weeks. The total bone area was
significantly affected by the level of the section (the diaphysis had a
greater bone area than the proximal part of the metaphysis and the proximal
part of the metaphysis had a greater bone area than the distal part of the
metaphysis; p < 0.001) and the quadrant within each section (the
posterior and anterior quadrants had greater bone area than the medial and
lateral quadrants; p < 0.00001). The length of the bone-implant
interface was significantly affected by the surface treatment (the length
of the bone-implant interface for the implants that had been blasted with
sixty-grit aluminum oxide was greater than the length for the polished
implants; p = 0.02), the time after implantation (the interface was longer
at six and twelve weeks than at three weeks; p < 0.00001), and the level
of the section (the interface was longer at the diaphysis than at the
proximal part of the metaphysis and longer at the proximal part of the
metaphysis than at the distal part of the metaphysis; p = 0.004). Blasting
of the surface of titanium-alloy implants did not have an effect on the
area of bone formation around the implants, but it did significantly affect
the area of bone formation on the implant and the shear strength at the
bone-implant interface. The two effects were not necessarily parallel, as
significantly less (p < 0.05) bone formed on implants that had been
blasted with stainless-steel shot than on those blasted with aluminum grit,
whereas their interface shear strengths were similar.