gms | German Medical Science

Bone substitutes used clinically in different medical fields comprise a wide variety of materials and have been the focus of the last decades. The operative treatment of large bone defects has remained a challenge for trauma and orthopaedic surgeons. Autogenous bone grafting is designated as the golden standard to fill large osseous defects. However, its disadvantage such donor site morbidity and limited supply of autogenous bone have favoured the use of bone substitutes. As these materials are characterized by their unlimited availability without bearing the risk of disease transmission research on improving bone tissue healing by inorganic implants such as calcium phosphate (CaP) based bone substitutes is a field of major interest.

Growth factors released from activated platelets initiate and modulate wound healing in both soft tissue and bone. A recent strategy to promote the bony-healing is to prepare an autologous platelet concentrate suspended in plasma, also known as platelet rich plasma (PRP), that contains growth factors and administer it to bony defects. The purpose of this study was investigate the effect for stimulation of osteogenesis of Calcium Phasphat Granules in combination with autologous PRP and Calcium Phospath Granules alone. Cylindrical bone defects were created in the proximal part of the tibia of sheep with a diamond bone cutting system. The size of the defect was 25 mm in depth and 12 mm in diameter. The animals were left in vivo for different time periods of 5 days, 10 days, 6 weeks, 3 months and 6 months. Undecalcified samples were embedded and sawed into 20 µm sections for histological and immunhistochemical examination.

Particularly in the early stage of bony healing (5 and 10 days) a positive effect of the stimulation of osteogenesis was detected in the group treated by the combination of CaP Granules and PRP. Bone formation occurred already 6 weeks after implantation of PRP and CaP Granules. A decrease of thickness of bone trabecula was seen in the 6 months group compared to the 3 months group. This might be due to ostoclastic activities in the physiological process of remodelling.

The current study implies, that the combination of PRP and CaP Granules leads to a higher osteogenic stimulation in bony defects than CaP Granules alone. This shows that PRP could be one important approach to bone healing and bone ingrowth next to bone substitutes. Autologous growth factors contained in PRP act as local regulators of cellular activity and seem to have osteoinductive and angiogenetic potential. This results emphasize the importance of further research in the field of bone substitutes and autologous growth hormones.