Biomechanical evaluation of repairing rabbit cancellous bone defect by implanting porous carbonated hydroxyapatite cement / 中国组织工程研究

ABSTRACT

BACKGROUND: A new material of porous carbonated hydroxyapatite cement (PCHC) is discovered using foaming technique.The new material characterizes original solidification and forms porous structure.OBJECTIVE: To investigate the biomechanical effect of PCHC on repairing cancellous bone defect.METHODS: Among 30 New Land rabbits, 25 ones were considered as surgery group, whose bilateral condyles of femur was used to establish bone defect model (5.5 mm diameter and 12 mm depth). PCHC was implanted into the left side, which was considered as the experimental group, and carbonated hydroxyapatite cement (CHC) was implanted into the right side, which was considered as the control group. Another 5 rabbits were used as normal mechanical control group. Both PCHC and CHC were dip in simulated body fluid (SBF) to test mechanical intension. PCHC and CHC were then implanted into muscles of back in the surgery group. Rabbits Were-sacrificed after 2, 4, 8, 12, and 16 weeks postoperatively. Mechanical analysis was tested following intra-bone and intramuscular implantation, and compressive strength was then tested following dipping into SBF.RESULTS AND CONCLUSION: PCHC: Intra-bone mechanical strength was lower at 2 weeks, the lowest at 4 weeks, but then closed to intension of normal cancellated bone at 8 weeks, higher than normal cancellated bone at 12 weeks, and recovered to the level of normal cancellated bone at 16 weeks. CHC: Intra-bone strength was higher than that of PCHC at 2 weeks, decreased at 4 weeks, gradually increased at 8, 12, and 16 weeks, but still lower than intension of normal cancallated bone. Compressive strength of both PCHC and CHC was not changed following dipping in SBF; however, compressive strength was changed remarkably following intramuscular implantation. The results demonstrated that PCHC characterized by immobilization in situ and mechanical supporting. Thus it could be used for one kind of bone substitute material to repair the bone defect.