Radiographic, macromorphological and hematological evaluation of hydroxyapatite ceramics with diff erent physicochemical properties

Abstract

Treatments of fragmentary fractures in case of loss regenerative potential of bone tissue require usingdiff erent composite materials. Among all of them, ceramics based on synthetic hydroxyapatite and tricalcium phosphate are considered promising. The reparative osteogenesis in spongy and compact rabbit’s bone tissueusing 3 composite materials with diff erent physicochemical propertieswas studied. A reparative osteogenesiscontrolled by monitoring clinical, radiologic and macromorphologic parameters. Composite materials infl uence on the organism was studied by determining the dynamics of hematological parameters throughout the study period. To realize this scheme was formed a 3 experimental groups and one control group of rabbits. The created defects of animals of fi rst experimental group were fi lled out with GT + α-TKF-500, thedefects of second oneanimals group fi lled out with GTlKl-2, and defects ofthird oneanimals group fi lled out with GTlKg-700. The GTlKl-700materials were doped with silicon. In control animals, bone defects were allowed to heal under a blood clot. During the studies, all animals were located in the same environment conditions. A blood samples for hematological investigation was taken from the external jugular vein before anesthesia and at the 3rd, 7th, 14th, 21st and 42nd day after surgery. X-ray examination was performed on 14th, 21st, and 42nddays.The animals were removed from the experiment on 21stand 42nd days. The samples were examined by macromorphologic method. By radiologic examination was found that composite materials had osteoconductive properties except the silicondoped example which hadosteoinductive properties. The samples of compact bone tissue of 1st and 3rd experimental groups characterized by formation of punctate osteosclerosis with a compacted contour of the periosteumon the 42nd day. But the bone samples of 2nd experimental group had compacted contours of the periosteum only. However, in the cancellous bone tissue on the 42nd day in the animals of the 1st experimental group developed point osteosclerosis, which visualized as individual granules of the composite.But in the animals of 2nd group thewhite spot which was outlined shape and homogeneous structure at the defect was found. The bone samples of 3rd animals group shoved a clearly limited point osteosclerosisforming were was found ceramic granules. In case using ofGT + α-TKF-500, a strong connection of granules from the formed bone tissue and without any periosteal growthswas noted. Using GTlKl-2 places of defects were identical to not injured sites of radial bones. Using GTlKg-700 shows that bone defect is fi lled to the level of the plane of the bone surface and covered with a periosteum without visible growths. The granules of the composite are evenly distributed in the regenerate and associated with bone tissue. The analysis of hematological parameters did not reveal any fundamental diff erences, but the use of hydroxyapatite implants is not accompanied, in contrast to spontaneous reparative osteogenesis, the development of leukocytosis, which indicates a moderate course of its infl ammatory reaction. But the latter is accompanied by a platelet reaction, the most pronounced when using implants, which is probably due to the infl uence of platelet factors and is indirect evidence of early osteoblastic reaction. Key words: fractures, rabbits, erythrocytes, leukocytes, platelets, hemoglobin.