Biphasic calcium phosphate ceramics in small bone defects: Potential influence of carrier substances and bone marrow on bone regeneration

Objectives: Synthetic calcium phosphate bone substitutes such as hydroxyapatite (HA), β-tricalcium phosphate (β-TCP) or mixtures are alternatives to autogenous bone grafts. TricOs T^® and Collagraft^® are resorbable bone substitutes consisting of biphasic calcium phosphate and a bioactive matrix. Both products have a similar HA to β-TCP ratio, but differ by their matrix. It was the aim of this study to determine the influence of matrix and autologous bone marrow on bone regeneration in a rabbit femoral condyle model. Material and methods: A critical-sized bicortical channel with a diameter of 4.5 mm was drilled through the femoral condyles in male New Zealand rabbits. Collagraft^® with bone marrow harvested from the posterior iliac crest or TricOs T ^® with and without bone marrow was introduced into the defect. Rabbits were euthanized 8 weeks later. The percentage of newly formed bone was determined by micro-computed tomography. Results: There was no significant difference between bone ingrowth at 8 weeks. Thus, TricOs T^® without bone marrow showed similar bone ingrowth as Collagraft^® with bone marrow. Furthermore, no increase of bone ingrowth could be achieved by adding bone marrow to TricOs T^® in the present setting. Conclusion: Both bone substitutes showed similar bone ingrowth in this investigation. Using TricOs T^® without bone marrow could avoid donor site morbidity due to harvesting of bone marrow. Further prospective clinical trials will be needed to investigate this approach.