In vivo study of hydroxyapatite-chitosan and hydroxyapatite-tricalcium phosphate bone graft in sheep's bone as animal model

This study describes the in vivo evaluation study of bones implanted with graft of hydoxyapatite-chitosan (HA-C) and hydroxyapatite-tricalcium phosphate (HA-TCP) composite in sheep's bone as the animal model for human. This study was done in two parts, non-invasive clinical imaging study, i.e. brightness mode ultrasound (B-mode US) and conventional radiography (CR) technique, and morphological study of the bone healing process. Six sheep were used in this study and separated in two groups, three sheep for each group. The implantation surgery was done aseptically by creating a 4 mm diameter and 7 mm depth hole on each left and right hind limb of proximal medial tibial bone. First group implanted of HA-TCP at the left tibial and the second group by the HA-C composite. The right tibial of both groups served as control, which was drilled but not implanted. The CR and US were performed one day before and 7, 21, 30 days after implantation. Bones were harvested after 30, 60, and 90 days post-surgery and observed for morphological study. The B-mode US showed that inflammation and early bone remodeling occurred of both implants at subcutaneus area seven days after implantation and decreased 30 days after. Furthermore, the CR technique showed that both implant were still intact on site 90 days after, therefore, indicated minimal absorption or even not absorbed at all. The morphological evaluation showed that HA-TCP had been degradable 30 days after and continued, indicated signs for biocompatibility, biodegradability, bioresorbable, bioactivity and osteo conductivity properties. On the other hand, HA-C graft showed only biocompatibility characteristics 90 days after implantation. The result showed that the healing process of HA-TCP faster than HA-C but nevertheless, both composite still slower healing process than control bone.