The bovine bone protein lyophilisate Colloss improves fixation of allografted implants- an experimental study in dogs

Background Impacted morselized bone allograft is a well-established way of giving joint arthroplasties additional support in situations where there is insufficient bone stock. For long-term survival of the implant, early implant fixation is important. We hypothesized that Colloss, a bone protein lyophilisate, might improve early implant fixation of allografted implants. Method We inserted 4 porous-coated Ti implants in the distal femurs of 16 dogs. All implants were surrounded by a 2.5-mm gap, which was impacted with morselized allograft with or without Colloss. In each dog, the implants were treated with no Collos or low-, middle- or high-dose (0, 10, 20 and 40 mg) Colloss per cm(3) allograft. The observation time was 4 weeks. Results Mechanical implant fixation was improved for all 3 groups with Colloss-treated implants (p < 0.05). The best anchorage was seen in the middle- dose group, where fixation was improved by 100%. We saw a dramatic reduction in fibrous tissue on the surface of the Colloss-treated implants (p < 0.001). The Colloss groups showed increased ongrowth of new bone (p < 0.01) and accelerated gap remodeling (p < 0.05). Interpretation Colloss can improve early osseointegration and fixation of allografted implants.