[Experimental study of the biocompatible and osteoinductive behavior of the hydroxyapatite/ultra-high molecular weight polyethtlene composite].

Objective: To compare the biocompatibility and osteoinductive behavior of HA (hydroxyapatite) and HA/UHMWPE (ultra-high molecular weight polyethtlene) composite in orbital implantation.

Methods: Osteoectomy of the upper orbital rim was perform on 24 adult New Zealand rabbits. The animals were randomly divided into 4 groups with 6 of each. The HA, HA/UHMWPE composite or UHMWPE (10 mm x 10 mm x 3 mm in size) was implanted to the upper orbital defect of the animal in respective group. Animals were sacrificed at 1, 4, 8, 12 weeks. Histopathologic sections of the implants were evaluated and compared with light and transmission electron microscopy study.

Results: During the experimental period of 12 weeks, there was no implant extrusion or displacement. In the groups of HA and HA/UHMWPE composite, vascular ingrowth and fibroblasts were observed shortly and osteocytes were seen at 8 weeks. Calcium deposition of the implants showed a laminar fashion at 12 weeks. In the group of UHMWPE, fibrous membranes were seen around the implant at 1 week. Transmission electron microscopy study showed that in the HA and HA/UHMWPE groups, fibroblasts and vascular ingrowth could be seen, but osteocytes were not observed.

Conclusion: HA/UHMWPE composite demonstrated biocompatibility and osteoinductive property. It would be a good substitute for bone, particularly for orbital bone.