Effects of calcium ion implantation on osseointegration of surface-blasted titanium alloy femoral implants in a canine total hip arthroplasty model

Osteoconductivity of titanium-alloy implants may be improved when surface-modified by calcium ion (Ca²⁺) implantation. We studied the effects of Ca²⁺ implantation on osseointegration of a grit-blasted titanium-alloy stem using a canine total hip arthroplasty model. Fifteen dogs underwent bilateral hip arthroplasties and were sacrificed at 1, 6, and 12 months postoperatively. The hip components were evaluated by radiographic, qualitative, and quantitative histology methods. Radiographically and histologically, both Ca²⁺-implanted and non—Ca²⁺-implanted stems were well integrated. Ca²⁺-implanted stems had greater new bone apposition than non—Ca²⁺-implanted stems, although the difference was significant only at 1 month (15.8% ± 3.5% of the implant perimeter for non—Ca²⁺-implanted, 25.4% ± 4.7% for Ca²⁺-implanted, P<.05). This result could be related to chronological decrease of the dissolution rate of calcium ions from Ca²⁺-implanted surface. Although further improvement of the Ca²⁺ implantation technique for a sustained osteoconductive effect is necessary, Ca²⁺ implantation may be beneficial for early fixation of titanium-alloy implants.