Bone autograft is the gold standard to be used for bone defects treatment. However, it has several limiting factors such as an increased intraoperative time, morbidity in the donor region or limited availability. For this reason, there is a need to design synthetic tissue equivalents capable of performing the function of the autograft without its limitations. The aim of this study was to evaluate the in vivo bone formation capacity of two types of biomaterials, one based on carbonate hydroxyapatites and the other on mesoporous bioactive glasses, and to compare the results with those obtained with iliac crest autograft.

The experimental study was conducted on 14 adult female New Zealand rabbits that underwent a critical defect in the radius bone. The study was divided into four groups: (A) defect without material, (B) with iliac crest autograft, (C) with carbonate-hydroxyapatite (CHA) scaffold and (D) with mesoporous bioactive glass (MBG) scaffolds. Serial radiographic studies were performed at 2, 4, 6 and 12 weeks and a microCT study at the time of euthanasia at 6 and 12 weeks.

In the radiographic study, the autograft group showed the highest bone formation scores. Both biomaterial groups showed similar and higher bone formation than the defect without material, but always lower than in the autograft group. The results of the microCT study showed the highest bone volume in the study area in the autografts group. Moreover, the bone substitute groups showed greater bone volume than the group without material, but always less than in the autograft group.

In conclusion, the scaffolds based on synthetic biomaterials promoted bone formation but were not capable of reproducing the characteristics of autografts. Due to their different macroscopic characteristics, each one could be suitable for a different type of bone defect.