Comparison of Osteosyntheses in Various Types of Porous Calcium Phosphate Compounds: An Experimental Study by Posterolateral Fusion of Rabbits' Lumbar Vertebrae / 대한척추외과학회지

ABSTRACT

PURPOSE: The purpose of the present study was to compare the osteoconduction in porous bodies made of various compositions of calcium phosphate compounds and other porous artificial bones. MATERIALS AND METHODS: Single-level posterolateral spinal fusions were performed on ninety rabbits. The animals were divided into nine groups by graft materials: autograft (positive control), implantation of HA, TCP, CPP, HA/TCP composite, TCP/CPP composite, Lubboc(R) and Calcium sulfate pellet (CSP), no-graft after decortication (negative control). Serial radiography, serum calcium and phosphorus levels were checked. All animals were sacrificed 12 weeks after surgery and the fusion masses were compared by manual palpation, uniaxial tensile strength measurement and histological evaluation. RESULTS: Autografted and CPP implanted groups showed significantly higher fusion ratio than TCP, TCP/CPP composite, and no-graft groups. Meanwhile, HA and HA/TCP groups showed no significant difference with other groups in fusion ratio. From the radiological examination, TCP and CPP groups seemed to show more rapid absorption of implant than HA group. The mean values of tensile strength of autografted and CPP group were significantly larger than those of TCP, TCP/CPP composite, and no-graft groups. The result of direct inspection and microscopic examination showed the TCP-contained implants lost their porous structure, whereas the other implants did not. On the light microscopy, both HA and CPP groups showed more abundant new bone growth into the pores than TCP-contained groups, but the pore size of CPP became larger than that of the HA, which manifested more rapid absorption of CPP in the living body. CONCLUSION: The porous CPP implant is considered to be more desirable bone graft substitute because it has satisfactory osteoconductive ablility and better biodegradation than porous HA. And the maintenance of porous structure is considered to be indispensable for osteoconduction.