Autologous bone versus calcium-phosphate ceramics in treatment of experimental bone defects.

Autologous bone grafting is currently considered the treatment of choice for correction of large bone defects. However, to avoid morbidity associated with autologous bone harvesting many artificial bone-substitute materials have been developed over the years. A new generation of resorbable materials is emerging, with promising results so far. In order to investigate the possibility to use one of these new materials as an alternative with better results than hydroxyapatite, an experimental study was performed. A new resorbable calcium phosphate particles and paste forms, the latter of which hardens in situ after application. In 28 sheep, a 3-cm segmental tibial defect was made and intramedullary fixed by an interlocking nail. Twelve weeks after defect filling, radiological, biomechanical, and histological examinations were performed. Mean radiographic and biomechanical tests results were compared with the Mann-Whitney test. Significance was set at p<0.05. Radiographically, the resorbable paste group performed better than all other groups. Biomechanical investigations showed a higher torsional stiffness (p=0.049) for the resorbable calcium-phosphate paste group in comparison with autologous bone. On histological examination, no adverse effects were observed in the calcium-phosphate groups. Resorption by osteoclasts was seen in the resorbable implants. In conclusion, the current study shows an advantageous radiological and mechanical outcome for resorbable calcium phosphates. This indicates that these new materials might be a potential alternative for autologous bone grafting in humans.